Add other major NMS implementations

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/DataWatcherKey.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import com.google.common.base.Optional;
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_10_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_10_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_10_R1.ItemStack;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.h;
+    private static final DataWatcherSerializer<Optional<ItemStack>> ITEM_STACK_SERIALIZER = DataWatcherRegistry.f;
+    private static final DataWatcherSerializer<String> STRING_SERIALIZER = DataWatcherRegistry.d;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<String> CUSTOM_NAME = new DataWatcherKey<>(2, STRING_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<Optional<ItemStack>> ITEM_STACK = new DataWatcherKey<>(6, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(11, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(12, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import com.google.common.base.Optional;
+import me.filoghost.fcommons.Strings;
+import org.bukkit.craftbukkit.v1_10_R1.inventory.CraftItemStack;
+import org.bukkit.inventory.ItemStack;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, Strings.truncate(customName, 300));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, Optional.fromNullable(CraftItemStack.asNMSCopy(itemStack)));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.DataWatcher;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketDataSerializer;
+import net.minecraft.server.v1_10_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private static final ReflectField<DataWatcher> DATA_WATCHER_FIELD =
+            ReflectField.lookup(DataWatcher.class, PacketPlayOutSpawnEntityLiving.class, "m");
+
+    private final Packet<?> rawPacket;
+
+    private EntityLivingSpawnNMSPacket(Packet<?> rawPacket, DataWatcher dataWatcher) {
+        this.rawPacket = rawPacket;
+        try {
+            DATA_WATCHER_FIELD.set(rawPacket, dataWatcher);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> builder(
+            EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeByte(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        // Entries are deserialized and saved into a field which is not used during the re-serialization, set as empty
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+
+        Packet<?> rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+        return new Builder(rawPacket, PacketByteBuffer.get());
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> {
+
+        private final Packet<?> rawPacket;
+
+        private Builder(Packet<?> rawPacket, PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+            this.rawPacket = rawPacket;
+        }
+
+        @Override
+        EntityLivingSpawnNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityLivingSpawnNMSPacket(rawPacket, new SerializedDataWatcher(packetByteBuffer));
+        }
+
+    }
+
+
+    private static class SerializedDataWatcher extends DataWatcher {
+
+        private final byte[] serializedValue;
+
+        SerializedDataWatcher(PacketByteBuffer dataByteBuffer) {
+            super(null);
+            serializedValue = new byte[dataByteBuffer.readableBytes()];
+            dataByteBuffer.readBytes(serializedValue);
+        }
+
+        @Override
+        public void a(PacketDataSerializer packetDataSerializer) {
+            packetDataSerializer.writeBytes(serializedValue);
+        }
+
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeByte(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_10_R1.Packet;
+import net.minecraft.server.v1_10_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 78;
+    static final int ITEM = 2;
+    static final int SLIME = 55;
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_10_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_10_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/VersionNMSManager.java

@@ -5,32 +5,113 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_10_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_10_R1.Entity;
+import net.minecraft.server.v1_10_R1.NetworkManager;
+import net.minecraft.server.v1_10_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_10_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<Integer> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(int.class, Entity.class, "entityCount");
+    private final Supplier<Integer> fallbackEntityIDGenerator;
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.fallbackEntityIDGenerator = new FallbackEntityIDGenerator();
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            testStaticFieldReadWrite(ENTITY_ID_COUNTER_FIELD);
+
+            return () -> {
+                try {
+                    int nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+                    ENTITY_ID_COUNTER_FIELD.setStatic(nmsEntityIDCounter + 1);
+                    return nmsEntityIDCounter;
+                } catch (ReflectiveOperationException e) {
+                    // Should not happen, access is tested beforehand
+                    return fallbackEntityIDGenerator.get();
+                }
+            };
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return fallbackEntityIDGenerator;
+        }
+    }
+
+    private <T> void testStaticFieldReadWrite(ReflectField<T> field) throws ReflectiveOperationException {
+        T value = field.getStatic();
+        field.setStatic(value);
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_10_R1.Packet;
+import org.bukkit.craftbukkit.v1_10_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_10_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_10_R1/VersionNMSPacketList.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_10_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/DataWatcherKey.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_11_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_11_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_11_R1.ItemStack;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.h;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.f;
+    private static final DataWatcherSerializer<String> STRING_SERIALIZER = DataWatcherRegistry.d;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<String> CUSTOM_NAME = new DataWatcherKey<>(2, STRING_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(6, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(11, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(12, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.fcommons.Strings;
+import org.bukkit.craftbukkit.v1_11_R1.inventory.CraftItemStack;
+import org.bukkit.inventory.ItemStack;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, Strings.truncate(customName, 300));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.DataWatcher;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketDataSerializer;
+import net.minecraft.server.v1_11_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private static final ReflectField<DataWatcher> DATA_WATCHER_FIELD =
+            ReflectField.lookup(DataWatcher.class, PacketPlayOutSpawnEntityLiving.class, "m");
+
+    private final Packet<?> rawPacket;
+
+    private EntityLivingSpawnNMSPacket(Packet<?> rawPacket, DataWatcher dataWatcher) {
+        this.rawPacket = rawPacket;
+        try {
+            DATA_WATCHER_FIELD.set(rawPacket, dataWatcher);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> builder(
+            EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        // Entries are deserialized and saved into a field which is not used during the re-serialization, set as empty
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+
+        Packet<?> rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+        return new Builder(rawPacket, PacketByteBuffer.get());
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> {
+
+        private final Packet<?> rawPacket;
+
+        private Builder(Packet<?> rawPacket, PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+            this.rawPacket = rawPacket;
+        }
+
+        @Override
+        EntityLivingSpawnNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityLivingSpawnNMSPacket(rawPacket, new SerializedDataWatcher(packetByteBuffer));
+        }
+
+    }
+
+
+    private static class SerializedDataWatcher extends DataWatcher {
+
+        private final byte[] serializedValue;
+
+        SerializedDataWatcher(PacketByteBuffer dataByteBuffer) {
+            super(null);
+            serializedValue = new byte[dataByteBuffer.readableBytes()];
+            dataByteBuffer.readBytes(serializedValue);
+        }
+
+        @Override
+        public void a(PacketDataSerializer packetDataSerializer) {
+            packetDataSerializer.writeBytes(serializedValue);
+        }
+
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeByte(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_11_R1.Packet;
+import net.minecraft.server.v1_11_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 78;
+    static final int ITEM = 2;
+    static final int SLIME = 55;
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_11_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_11_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/VersionNMSManager.java

@@ -5,32 +5,113 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_11_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_11_R1.Entity;
+import net.minecraft.server.v1_11_R1.NetworkManager;
+import net.minecraft.server.v1_11_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_11_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<Integer> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(int.class, Entity.class, "entityCount");
+    private final Supplier<Integer> fallbackEntityIDGenerator;
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.fallbackEntityIDGenerator = new FallbackEntityIDGenerator();
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            testStaticFieldReadWrite(ENTITY_ID_COUNTER_FIELD);
+
+            return () -> {
+                try {
+                    int nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+                    ENTITY_ID_COUNTER_FIELD.setStatic(nmsEntityIDCounter + 1);
+                    return nmsEntityIDCounter;
+                } catch (ReflectiveOperationException e) {
+                    // Should not happen, access is tested beforehand
+                    return fallbackEntityIDGenerator.get();
+                }
+            };
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return fallbackEntityIDGenerator;
+        }
+    }
+
+    private <T> void testStaticFieldReadWrite(ReflectField<T> field) throws ReflectiveOperationException {
+        T value = field.getStatic();
+        field.setStatic(value);
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_11_R1.Packet;
+import org.bukkit.craftbukkit.v1_11_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_11_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_11_R1/VersionNMSPacketList.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_11_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/DataWatcherKey.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_12_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_12_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_12_R1.ItemStack;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.h;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.f;
+    private static final DataWatcherSerializer<String> STRING_SERIALIZER = DataWatcherRegistry.d;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<String> CUSTOM_NAME = new DataWatcherKey<>(2, STRING_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(6, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(11, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(12, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.fcommons.Strings;
+import org.bukkit.craftbukkit.v1_12_R1.inventory.CraftItemStack;
+import org.bukkit.inventory.ItemStack;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, Strings.truncate(customName, 300));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.DataWatcher;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketDataSerializer;
+import net.minecraft.server.v1_12_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private static final ReflectField<DataWatcher> DATA_WATCHER_FIELD =
+            ReflectField.lookup(DataWatcher.class, PacketPlayOutSpawnEntityLiving.class, "m");
+
+    private final Packet<?> rawPacket;
+
+    private EntityLivingSpawnNMSPacket(Packet<?> rawPacket, DataWatcher dataWatcher) {
+        this.rawPacket = rawPacket;
+        try {
+            DATA_WATCHER_FIELD.set(rawPacket, dataWatcher);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> builder(
+            EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        // Entries are deserialized and saved into a field which is not used during the re-serialization, set as empty
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+
+        Packet<?> rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+        return new Builder(rawPacket, PacketByteBuffer.get());
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> {
+
+        private final Packet<?> rawPacket;
+
+        private Builder(Packet<?> rawPacket, PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+            this.rawPacket = rawPacket;
+        }
+
+        @Override
+        EntityLivingSpawnNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityLivingSpawnNMSPacket(rawPacket, new SerializedDataWatcher(packetByteBuffer));
+        }
+
+    }
+
+
+    private static class SerializedDataWatcher extends DataWatcher {
+
+        private final byte[] serializedValue;
+
+        SerializedDataWatcher(PacketByteBuffer dataByteBuffer) {
+            super(null);
+            serializedValue = new byte[dataByteBuffer.readableBytes()];
+            dataByteBuffer.readBytes(serializedValue);
+        }
+
+        @Override
+        public void a(PacketDataSerializer packetDataSerializer) {
+            packetDataSerializer.writeBytes(serializedValue);
+        }
+
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeByte(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_12_R1.Packet;
+import net.minecraft.server.v1_12_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 78;
+    static final int ITEM = 2;
+    static final int SLIME = 55;
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_12_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_12_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/VersionNMSManager.java

@@ -5,32 +5,113 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_12_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_12_R1.Entity;
+import net.minecraft.server.v1_12_R1.NetworkManager;
+import net.minecraft.server.v1_12_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<Integer> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(int.class, Entity.class, "entityCount");
+    private final Supplier<Integer> fallbackEntityIDGenerator;
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.fallbackEntityIDGenerator = new FallbackEntityIDGenerator();
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            testStaticFieldReadWrite(ENTITY_ID_COUNTER_FIELD);
+
+            return () -> {
+                try {
+                    int nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+                    ENTITY_ID_COUNTER_FIELD.setStatic(nmsEntityIDCounter + 1);
+                    return nmsEntityIDCounter;
+                } catch (ReflectiveOperationException e) {
+                    // Should not happen, access is tested beforehand
+                    return fallbackEntityIDGenerator.get();
+                }
+            };
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return fallbackEntityIDGenerator;
+        }
+    }
+
+    private <T> void testStaticFieldReadWrite(ReflectField<T> field) throws ReflectiveOperationException {
+        T value = field.getStatic();
+        field.setStatic(value);
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_12_R1.Packet;
+import org.bukkit.craftbukkit.v1_12_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_12_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_12_R1/VersionNMSPacketList.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_12_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/DataWatcherKey.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_13_R2.DataWatcherRegistry;
+import net.minecraft.server.v1_13_R2.DataWatcherSerializer;
+import net.minecraft.server.v1_13_R2.IChatBaseComponent;
+import net.minecraft.server.v1_13_R2.ItemStack;
+
+import java.util.Optional;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.i;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.g;
+    private static final DataWatcherSerializer<Optional<IChatBaseComponent>> OPTIONAL_CHAT_COMPONENT_SERIALIZER = DataWatcherRegistry.f;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<Optional<IChatBaseComponent>> CUSTOM_NAME = new DataWatcherKey<>(2, OPTIONAL_CHAT_COMPONENT_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(6, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(11, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(12, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/DataWatcherPacketBuilder.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.fcommons.Strings;
+import net.minecraft.server.v1_13_R2.IChatBaseComponent;
+import org.bukkit.craftbukkit.v1_13_R2.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.v1_13_R2.util.CraftChatMessage;
+import org.bukkit.inventory.ItemStack;
+
+import java.util.Optional;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, getCustomNameDataWatcherValue(customName));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    private Optional<IChatBaseComponent> getCustomNameDataWatcherValue(String customName) {
+        customName = Strings.truncate(customName, 300);
+        if (!Strings.isEmpty(customName)) {
+            return Optional.of(CraftChatMessage.fromString(customName, false)[0]);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.DataWatcher;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketDataSerializer;
+import net.minecraft.server.v1_13_R2.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private static final ReflectField<DataWatcher> DATA_WATCHER_FIELD =
+            ReflectField.lookup(DataWatcher.class, PacketPlayOutSpawnEntityLiving.class, "m");
+
+    private final Packet<?> rawPacket;
+
+    private EntityLivingSpawnNMSPacket(Packet<?> rawPacket, DataWatcher dataWatcher) {
+        this.rawPacket = rawPacket;
+        try {
+            DATA_WATCHER_FIELD.set(rawPacket, dataWatcher);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> builder(
+            EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        // Entries are deserialized and saved into a field which is not used during the re-serialization, set as empty
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+
+        Packet<?> rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+        return new Builder(rawPacket, PacketByteBuffer.get());
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> {
+
+        private final Packet<?> rawPacket;
+
+        private Builder(Packet<?> rawPacket, PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+            this.rawPacket = rawPacket;
+        }
+
+        @Override
+        EntityLivingSpawnNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityLivingSpawnNMSPacket(rawPacket, new SerializedDataWatcher(packetByteBuffer));
+        }
+
+    }
+
+
+    private static class SerializedDataWatcher extends DataWatcher {
+
+        private final byte[] serializedValue;
+
+        SerializedDataWatcher(PacketByteBuffer dataByteBuffer) {
+            super(null);
+            serializedValue = new byte[dataByteBuffer.readableBytes()];
+            dataByteBuffer.readBytes(serializedValue);
+        }
+
+        @Override
+        public void a(PacketDataSerializer packetDataSerializer) {
+            packetDataSerializer.writeBytes(serializedValue);
+        }
+
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeByte(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_13_R2.Packet;
+import net.minecraft.server.v1_13_R2.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 78;
+    static final int ITEM = 2;
+    static final int SLIME = 64;
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_13_R2.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_13_R2.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/VersionNMSManager.java

@@ -5,32 +5,113 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_13_R2;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_13_R2.Entity;
+import net.minecraft.server.v1_13_R2.NetworkManager;
+import net.minecraft.server.v1_13_R2.PlayerConnection;
+import org.bukkit.craftbukkit.v1_13_R2.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<Integer> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(int.class, Entity.class, "entityCount");
+    private final Supplier<Integer> fallbackEntityIDGenerator;
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.fallbackEntityIDGenerator = new FallbackEntityIDGenerator();
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            testStaticFieldReadWrite(ENTITY_ID_COUNTER_FIELD);
+
+            return () -> {
+                try {
+                    int nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+                    ENTITY_ID_COUNTER_FIELD.setStatic(nmsEntityIDCounter + 1);
+                    return nmsEntityIDCounter;
+                } catch (ReflectiveOperationException e) {
+                    // Should not happen, access is tested beforehand
+                    return fallbackEntityIDGenerator.get();
+                }
+            };
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return fallbackEntityIDGenerator;
+        }
+    }
+
+    private <T> void testStaticFieldReadWrite(ReflectField<T> field) throws ReflectiveOperationException {
+        T value = field.getStatic();
+        field.setStatic(value);
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_13_R2.Packet;
+import org.bukkit.craftbukkit.v1_13_R2.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_13_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_13_R2/VersionNMSPacketList.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_13_R2;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/DataWatcherKey.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_14_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_14_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_14_R1.IChatBaseComponent;
+import net.minecraft.server.v1_14_R1.ItemStack;
+
+import java.util.Optional;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.i;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.g;
+    private static final DataWatcherSerializer<Optional<IChatBaseComponent>> OPTIONAL_CHAT_COMPONENT_SERIALIZER = DataWatcherRegistry.f;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<Optional<IChatBaseComponent>> CUSTOM_NAME = new DataWatcherKey<>(2, OPTIONAL_CHAT_COMPONENT_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(7, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(13, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(14, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.fcommons.Strings;
+import net.minecraft.server.v1_14_R1.IChatBaseComponent;
+import org.bukkit.craftbukkit.v1_14_R1.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.v1_14_R1.util.CraftChatMessage;
+import org.bukkit.inventory.ItemStack;
+
+import java.util.Optional;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, getCustomNameDataWatcherValue(customName));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    private Optional<IChatBaseComponent> getCustomNameDataWatcherValue(String customName) {
+        customName = Strings.truncate(customName, 300);
+        if (!Strings.isEmpty(customName)) {
+            return Optional.of(CraftChatMessage.fromString(customName, false)[0]);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.DataWatcher;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketDataSerializer;
+import net.minecraft.server.v1_14_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private static final ReflectField<DataWatcher> DATA_WATCHER_FIELD =
+            ReflectField.lookup(DataWatcher.class, PacketPlayOutSpawnEntityLiving.class, "m");
+
+    private final Packet<?> rawPacket;
+
+    private EntityLivingSpawnNMSPacket(Packet<?> rawPacket, DataWatcher dataWatcher) {
+        this.rawPacket = rawPacket;
+        try {
+            DATA_WATCHER_FIELD.set(rawPacket, dataWatcher);
+        } catch (ReflectiveOperationException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> builder(
+            EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        // Entries are deserialized and saved into a field which is not used during the re-serialization, set as empty
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+
+        Packet<?> rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+        return new Builder(rawPacket, PacketByteBuffer.get());
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityLivingSpawnNMSPacket> {
+
+        private final Packet<?> rawPacket;
+
+        private Builder(Packet<?> rawPacket, PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+            this.rawPacket = rawPacket;
+        }
+
+        @Override
+        EntityLivingSpawnNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityLivingSpawnNMSPacket(rawPacket, new SerializedDataWatcher(packetByteBuffer));
+        }
+
+    }
+
+
+    private static class SerializedDataWatcher extends DataWatcher {
+
+        private final byte[] serializedValue;
+
+        SerializedDataWatcher(PacketByteBuffer dataByteBuffer) {
+            super(null);
+            serializedValue = new byte[dataByteBuffer.readableBytes()];
+            dataByteBuffer.readBytes(serializedValue);
+        }
+
+        @Override
+        public void a(PacketDataSerializer packetDataSerializer) {
+            packetDataSerializer.writeBytes(serializedValue);
+        }
+
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_14_R1.Packet;
+import net.minecraft.server.v1_14_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 1;
+    static final int ITEM = 34;
+    static final int SLIME = 67;
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_14_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_14_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/VersionNMSManager.java

@@ -5,32 +5,97 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_14_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_14_R1.Entity;
+import net.minecraft.server.v1_14_R1.NetworkManager;
+import net.minecraft.server.v1_14_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_14_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<AtomicInteger> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(AtomicInteger.class, Entity.class, "entityCount");
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            AtomicInteger nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+            return nmsEntityIDCounter::incrementAndGet;
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return new FallbackEntityIDGenerator();
+        }
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_14_R1.Packet;
+import org.bukkit.craftbukkit.v1_14_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_14_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_14_R1/VersionNMSPacketList.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_14_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityLivingSpawnNMSPacket.builder(
+                        entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(EntityLivingSpawnNMSPacket.builder(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/DataWatcherKey.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_15_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_15_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_15_R1.IChatBaseComponent;
+import net.minecraft.server.v1_15_R1.ItemStack;
+
+import java.util.Optional;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.i;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.g;
+    private static final DataWatcherSerializer<Optional<IChatBaseComponent>> OPTIONAL_CHAT_COMPONENT_SERIALIZER = DataWatcherRegistry.f;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<Optional<IChatBaseComponent>> CUSTOM_NAME = new DataWatcherKey<>(2, OPTIONAL_CHAT_COMPONENT_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(7, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(14, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(15, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.fcommons.Strings;
+import net.minecraft.server.v1_15_R1.IChatBaseComponent;
+import org.bukkit.craftbukkit.v1_15_R1.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.v1_15_R1.util.CraftChatMessage;
+import org.bukkit.inventory.ItemStack;
+
+import java.util.Optional;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, getCustomNameDataWatcherValue(customName));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    private Optional<IChatBaseComponent> getCustomNameDataWatcherValue(String customName) {
+        customName = Strings.truncate(customName, 300);
+        if (!Strings.isEmpty(customName)) {
+            return Optional.of(CraftChatMessage.fromString(customName, false)[0]);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityLivingSpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_15_R1.Packet;
+import net.minecraft.server.v1_15_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 1;
+    static final int ITEM = 35;
+    static final int SLIME = 68;
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_15_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_15_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/VersionNMSManager.java

@@ -5,32 +5,97 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_15_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_15_R1.Entity;
+import net.minecraft.server.v1_15_R1.NetworkManager;
+import net.minecraft.server.v1_15_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_15_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<AtomicInteger> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(AtomicInteger.class, Entity.class, "entityCount");
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            AtomicInteger nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+            return nmsEntityIDCounter::incrementAndGet;
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return new FallbackEntityIDGenerator();
+        }
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_15_R1.Packet;
+import org.bukkit.craftbukkit.v1_15_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_15_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_15_R1/VersionNMSPacketList.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_15_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/DataWatcherKey.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_16_R1.DataWatcherRegistry;
+import net.minecraft.server.v1_16_R1.DataWatcherSerializer;
+import net.minecraft.server.v1_16_R1.IChatBaseComponent;
+import net.minecraft.server.v1_16_R1.ItemStack;
+
+import java.util.Optional;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.i;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.g;
+    private static final DataWatcherSerializer<Optional<IChatBaseComponent>> OPTIONAL_CHAT_COMPONENT_SERIALIZER = DataWatcherRegistry.f;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<Optional<IChatBaseComponent>> CUSTOM_NAME = new DataWatcherKey<>(2, OPTIONAL_CHAT_COMPONENT_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(7, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(14, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(15, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/DataWatcherPacketBuilder.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.fcommons.Strings;
+import net.minecraft.server.v1_16_R1.IChatBaseComponent;
+import org.bukkit.craftbukkit.v1_16_R1.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.v1_16_R1.util.CraftChatMessage;
+import org.bukkit.inventory.ItemStack;
+
+import java.util.Optional;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, getCustomNameDataWatcherValue(customName));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    private Optional<IChatBaseComponent> getCustomNameDataWatcherValue(String customName) {
+        customName = Strings.truncate(customName, 300);
+        if (!Strings.isEmpty(customName)) {
+            return Optional.of(CraftChatMessage.fromString(customName, false)[0]);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityDestroyNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutEntityDestroy;
+
+class EntityDestroyNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityDestroyNMSPacket(EntityID... entityIDs) {
+        int[] entityIDsArray = new int[entityIDs.length];
+        for (int i = 0; i < entityIDs.length; i++) {
+            entityIDsArray[i] = entityIDs[i].getNumericID();
+        }
+
+        this.rawPacket = new PacketPlayOutEntityDestroy(entityIDsArray);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityLivingSpawnNMSPacket.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutSpawnEntityLiving;
+
+class EntityLivingSpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityLivingSpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Head rotation
+        packetByteBuffer.writeByte(0);
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntityLiving(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityMetadataNMSPacket.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutEntityMetadata;
+
+class EntityMetadataNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    private EntityMetadataNMSPacket(PacketByteBuffer packetByteBuffer) {
+        this.rawPacket = writeData(new PacketPlayOutEntityMetadata(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+    public static DataWatcherPacketBuilder<EntityMetadataNMSPacket> builder(EntityID entityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        return new Builder(packetByteBuffer);
+    }
+
+
+    private static class Builder extends DataWatcherPacketBuilder<EntityMetadataNMSPacket> {
+
+        private Builder(PacketByteBuffer packetByteBuffer) {
+            super(packetByteBuffer);
+        }
+
+        @Override
+        EntityMetadataNMSPacket createPacket(PacketByteBuffer packetByteBuffer) {
+            return new EntityMetadataNMSPacket(packetByteBuffer);
+        }
+
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityMountNMSPacket.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutMount;
+
+class EntityMountNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityMountNMSPacket(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(vehicleEntityID.getNumericID());
+        packetByteBuffer.writeIntArray(passengerEntityID.getNumericID());
+
+        this.rawPacket = writeData(new PacketPlayOutMount(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntitySpawnNMSPacket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutSpawnEntity;
+
+class EntitySpawnNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntitySpawnNMSPacket(EntityID entityID, int entityTypeID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+        packetByteBuffer.writeUUID(entityID.getUUID());
+        packetByteBuffer.writeVarInt(entityTypeID);
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // Object data
+        if (entityTypeID == EntityTypeID.ITEM) {
+            packetByteBuffer.writeInt(1); // Velocity is present and zero (otherwise by default a random velocity is applied)
+        } else {
+            packetByteBuffer.writeInt(0);
+        }
+
+        // Velocity
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+        packetByteBuffer.writeShort(0);
+
+        this.rawPacket = writeData(new PacketPlayOutSpawnEntity(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityTeleportNMSPacket.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import net.minecraft.server.v1_16_R1.Packet;
+import net.minecraft.server.v1_16_R1.PacketPlayOutEntityTeleport;
+
+class EntityTeleportNMSPacket extends VersionNMSPacket {
+
+    private final Packet<?> rawPacket;
+
+    EntityTeleportNMSPacket(EntityID entityID, double positionX, double positionY, double positionZ) {
+        PacketByteBuffer packetByteBuffer = PacketByteBuffer.get();
+
+        packetByteBuffer.writeVarInt(entityID.getNumericID());
+
+        // Position
+        packetByteBuffer.writeDouble(positionX);
+        packetByteBuffer.writeDouble(positionY);
+        packetByteBuffer.writeDouble(positionZ);
+
+        // Rotation
+        packetByteBuffer.writeByte(0);
+        packetByteBuffer.writeByte(0);
+
+        // On ground
+        packetByteBuffer.writeBoolean(false);
+
+        this.rawPacket = writeData(new PacketPlayOutEntityTeleport(), packetByteBuffer);
+    }
+
+    @Override
+    Packet<?> getRawPacket() {
+        return rawPacket;
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/EntityTypeID.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+class EntityTypeID {
+
+    static final int ARMOR_STAND = 1;
+    static final int ITEM = 37;
+    static final int SLIME = 75;
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/InboundPacketHandler.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
+import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_16_R1.PacketPlayInUseEntity;
+import org.bukkit.entity.Player;
+
+public class InboundPacketHandler extends ChannelInboundHandlerAdapter {
+
+    public static final String HANDLER_NAME = "holographic_displays_listener";
+    private static final ReflectField<Integer> ENTITY_ID_FIELD = ReflectField.lookup(int.class, PacketPlayInUseEntity.class, "a");
+
+    private final Player player;
+    private final PacketListener packetListener;
+
+    public InboundPacketHandler(Player player, PacketListener packetListener) {
+        this.player = player;
+        this.packetListener = packetListener;
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext context, Object packet) throws Exception {
+        try {
+            if (packet instanceof PacketPlayInUseEntity) {
+                int entityID = ENTITY_ID_FIELD.get(packet);
+                boolean cancel = packetListener.onAsyncEntityInteract(player, entityID);
+                if (cancel) {
+                    return;
+                }
+            }
+        } catch (Throwable t) {
+            Log.warning(NMSErrors.EXCEPTION_ON_PACKET_READ, t);
+        }
+        super.channelRead(context, packet);
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/PacketByteBuffer.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import io.netty.buffer.Unpooled;
+import net.minecraft.server.v1_16_R1.PacketDataSerializer;
+
+import java.util.UUID;
+
+class PacketByteBuffer extends PacketDataSerializer {
+
+    private static final PacketByteBuffer INSTANCE = new PacketByteBuffer();
+
+    static PacketByteBuffer get() {
+        INSTANCE.clear();
+        return INSTANCE;
+    }
+
+    private PacketByteBuffer() {
+        super(Unpooled.buffer());
+    }
+
+    void writeVarInt(int i) {
+        super.d(i);
+    }
+
+    void writeUUID(UUID uuid) {
+        super.a(uuid);
+    }
+
+    void writeIntArray(int... array) {
+        super.a(array);
+    }
+
+    <T> void writeDataWatcherEntry(DataWatcherKey<T> key, T value) {
+        writeByte(key.getIndex());
+        writeVarInt(key.getSerializerTypeID());
+        key.getSerializer().a(this, value);
+    }
+
+    void writeDataWatcherEntriesEnd() {
+        writeByte(255);
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/VersionNMSManager.java

@@ -5,32 +5,97 @@
  */
 package me.filoghost.holographicdisplays.nms.v1_16_R1;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelPipeline;
+import me.filoghost.fcommons.logging.ErrorCollector;
+import me.filoghost.fcommons.logging.Log;
+import me.filoghost.fcommons.reflection.ReflectField;
 import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.FallbackEntityIDGenerator;
+import me.filoghost.holographicdisplays.common.nms.NMSErrors;
 import me.filoghost.holographicdisplays.common.nms.NMSManager;
 import me.filoghost.holographicdisplays.common.nms.NMSPacketList;
 import me.filoghost.holographicdisplays.common.nms.PacketListener;
+import net.minecraft.server.v1_16_R1.Entity;
+import net.minecraft.server.v1_16_R1.NetworkManager;
+import net.minecraft.server.v1_16_R1.PlayerConnection;
+import org.bukkit.craftbukkit.v1_16_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
 public class VersionNMSManager implements NMSManager {
 
+    private static final ReflectField<AtomicInteger> ENTITY_ID_COUNTER_FIELD = ReflectField.lookup(AtomicInteger.class, Entity.class, "entityCount");
+    private final Supplier<Integer> entityIDGenerator;
+
+    public VersionNMSManager(ErrorCollector errorCollector) {
+        this.entityIDGenerator = getEntityIDGenerator(errorCollector);
+
+        // Force initialization of class to eventually throw exceptions early
+        DataWatcherKey.ENTITY_STATUS.getIndex();
+    }
+
+    private Supplier<Integer> getEntityIDGenerator(ErrorCollector errorCollector) {
+        try {
+            AtomicInteger nmsEntityIDCounter = ENTITY_ID_COUNTER_FIELD.getStatic();
+            return nmsEntityIDCounter::incrementAndGet;
+        } catch (ReflectiveOperationException e) {
+            errorCollector.add(e, NMSErrors.EXCEPTION_GETTING_ENTITY_ID_GENERATOR);
+            return new FallbackEntityIDGenerator();
+        }
+    }
+
     @Override
     public EntityID newEntityID() {
-        return null;
+        return new EntityID(entityIDGenerator);
     }
 
     @Override
     public NMSPacketList createPacketList() {
-        return null;
+        return new VersionNMSPacketList();
     }
 
     @Override
     public void injectPacketListener(Player player, PacketListener packetListener) {
-
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+            pipeline.addBefore("packet_handler", InboundPacketHandler.HANDLER_NAME, new InboundPacketHandler(player, packetListener));
+        });
     }
 
     @Override
     public void uninjectPacketListener(Player player) {
+        modifyPipeline(player, (ChannelPipeline pipeline) -> {
+            ChannelHandler currentListener = pipeline.get(InboundPacketHandler.HANDLER_NAME);
+            if (currentListener != null) {
+                pipeline.remove(InboundPacketHandler.HANDLER_NAME);
+            }
+        });
+    }
 
+    /*
+     * Modifying the pipeline in the main thread can cause deadlocks, delays and other concurrency issues,
+     * which can be avoided by using the event loop. Thanks to ProtocolLib for this insight.
+     */
+    private void modifyPipeline(Player player, Consumer<ChannelPipeline> pipelineModifierTask) {
+        PlayerConnection playerConnection = ((CraftPlayer) player).getHandle().playerConnection;
+        NetworkManager networkManager = playerConnection.a();
+        Channel channel = networkManager.channel;
+
+        channel.eventLoop().execute(() -> {
+            try {
+                pipelineModifierTask.accept(channel.pipeline());
+            } catch (Exception e) {
+                Log.warning(NMSErrors.EXCEPTION_MODIFYING_CHANNEL_PIPELINE, e);
+            }
+        });
     }
 
 }

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/VersionNMSPacket.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.NMSPacket;
+import net.minecraft.server.v1_16_R1.Packet;
+import org.bukkit.craftbukkit.v1_16_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+
+import java.io.IOException;
+
+abstract class VersionNMSPacket implements NMSPacket {
+
+    @Override
+    public void sendTo(Player player) {
+        ((CraftPlayer) player).getHandle().playerConnection.sendPacket(getRawPacket());
+    }
+
+    abstract Packet<?> getRawPacket();
+
+    protected static <T extends Packet<?>> T writeData(T packet, PacketByteBuffer packetByteBuffer) {
+        try {
+            packet.a(packetByteBuffer);
+            return packet;
+        } catch (IOException e) {
+            // Never thrown by the implementations
+            throw new RuntimeException(e);
+        }
+    }
+
+}

nms/v1_16_r1/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R1/VersionNMSPacketList.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R1;
+
+import me.filoghost.holographicdisplays.common.nms.AbstractNMSPacketList;
+import me.filoghost.holographicdisplays.common.nms.EntityID;
+import me.filoghost.holographicdisplays.common.nms.IndividualCustomName;
+import me.filoghost.holographicdisplays.common.nms.IndividualNMSPacket;
+import org.bukkit.inventory.ItemStack;
+
+class VersionNMSPacketList extends AbstractNMSPacketList {
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, String customName) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, IndividualCustomName individualCustomName) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.ARMOR_STAND, positionX, positionY, positionZ));
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setArmorStandMarker()
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, String customName) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(customName)
+                .build()
+        );
+    }
+
+    @Override
+    public void addArmorStandNameChangePackets(EntityID entityID, IndividualCustomName individualCustomName) {
+        add(new IndividualNMSPacket(player -> EntityMetadataNMSPacket.builder(entityID)
+                .setCustomName(individualCustomName.get(player))
+                .build()
+        ));
+    }
+
+    @Override
+    public void addItemSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ, ItemStack itemStack) {
+        add(new EntitySpawnNMSPacket(entityID, EntityTypeID.ITEM, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addItemStackChangePackets(EntityID entityID, ItemStack itemStack) {
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setItemStack(itemStack)
+                .build()
+        );
+    }
+
+    @Override
+    public void addSlimeSpawnPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityLivingSpawnNMSPacket(entityID, EntityTypeID.SLIME, positionX, positionY, positionZ));
+        add(EntityMetadataNMSPacket.builder(entityID)
+                .setInvisible()
+                .setSlimeSmall() // Required for a correct client-side collision box
+                .build()
+        );
+    }
+
+    @Override
+    public void addEntityDestroyPackets(EntityID... entityIDs) {
+        add(new EntityDestroyNMSPacket(entityIDs));
+    }
+
+    @Override
+    public void addTeleportPackets(EntityID entityID, double positionX, double positionY, double positionZ) {
+        add(new EntityTeleportNMSPacket(entityID, positionX, positionY, positionZ));
+    }
+
+    @Override
+    public void addMountPackets(EntityID vehicleEntityID, EntityID passengerEntityID) {
+        add(new EntityMountNMSPacket(vehicleEntityID, passengerEntityID));
+    }
+
+}

nms/v1_16_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R2/DataWatcherKey.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R2;
+
+import io.netty.handler.codec.EncoderException;
+import net.minecraft.server.v1_16_R2.DataWatcherRegistry;
+import net.minecraft.server.v1_16_R2.DataWatcherSerializer;
+import net.minecraft.server.v1_16_R2.IChatBaseComponent;
+import net.minecraft.server.v1_16_R2.ItemStack;
+
+import java.util.Optional;
+
+class DataWatcherKey<T> {
+
+    private static final DataWatcherSerializer<Byte> BYTE_SERIALIZER = DataWatcherRegistry.a;
+    private static final DataWatcherSerializer<Integer> INT_SERIALIZER = DataWatcherRegistry.b;
+    private static final DataWatcherSerializer<Boolean> BOOLEAN_SERIALIZER = DataWatcherRegistry.i;
+    private static final DataWatcherSerializer<ItemStack> ITEM_STACK_SERIALIZER = DataWatcherRegistry.g;
+    private static final DataWatcherSerializer<Optional<IChatBaseComponent>> OPTIONAL_CHAT_COMPONENT_SERIALIZER = DataWatcherRegistry.f;
+
+    static final DataWatcherKey<Byte> ENTITY_STATUS = new DataWatcherKey<>(0, BYTE_SERIALIZER);
+    static final DataWatcherKey<Optional<IChatBaseComponent>> CUSTOM_NAME = new DataWatcherKey<>(2, OPTIONAL_CHAT_COMPONENT_SERIALIZER);
+    static final DataWatcherKey<Boolean> CUSTOM_NAME_VISIBILITY = new DataWatcherKey<>(3, BOOLEAN_SERIALIZER);
+    static final DataWatcherKey<ItemStack> ITEM_STACK = new DataWatcherKey<>(7, ITEM_STACK_SERIALIZER);
+    static final DataWatcherKey<Byte> ARMOR_STAND_STATUS = new DataWatcherKey<>(14, BYTE_SERIALIZER);
+    static final DataWatcherKey<Integer> SLIME_SIZE = new DataWatcherKey<>(15, INT_SERIALIZER);
+
+    private final int index;
+    private final DataWatcherSerializer<T> serializer;
+    private final int serializerTypeID;
+
+    private DataWatcherKey(int index, DataWatcherSerializer<T> serializer) {
+        this.index = index;
+        this.serializer = serializer;
+        this.serializerTypeID = DataWatcherRegistry.b(serializer);
+        if (serializerTypeID < 0) {
+            throw new EncoderException("Could not find serializer ID of " + serializer);
+        }
+    }
+
+    int getIndex() {
+        return index;
+    }
+
+    DataWatcherSerializer<T> getSerializer() {
+        return serializer;
+    }
+
+    int getSerializerTypeID() {
+        return serializerTypeID;
+    }
+
+}

nms/v1_16_r2/src/main/java/me/filoghost/holographicdisplays/nms/v1_16_R2/DataWatcherPacketBuilder.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.nms.v1_16_R2;
+
+import me.filoghost.fcommons.Strings;
+import net.minecraft.server.v1_16_R2.IChatBaseComponent;
+import org.bukkit.craftbukkit.v1_16_R2.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.v1_16_R2.util.CraftChatMessage;
+import org.bukkit.inventory.ItemStack;
+
+import java.util.Optional;
+
+abstract class DataWatcherPacketBuilder<T> {
+
+    private final PacketByteBuffer packetByteBuffer;
+
+    DataWatcherPacketBuilder(PacketByteBuffer packetByteBuffer) {
+        this.packetByteBuffer = packetByteBuffer;
+    }
+
+    DataWatcherPacketBuilder<T> setInvisible() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ENTITY_STATUS, (byte) 0x20); // Invisible
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setArmorStandMarker() {
+        setInvisible();
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ARMOR_STAND_STATUS, (byte) (0x01 | 0x08 | 0x10)); // Small, no base plate, marker
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setCustomName(String customName) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME, getCustomNameDataWatcherValue(customName));
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.CUSTOM_NAME_VISIBILITY, !Strings.isEmpty(customName));
+        return this;
+    }
+
+    private Optional<IChatBaseComponent> getCustomNameDataWatcherValue(String customName) {
+        customName = Strings.truncate(customName, 300);
+        if (!Strings.isEmpty(customName)) {
+            return Optional.of(CraftChatMessage.fromString(customName, false)[0]);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    DataWatcherPacketBuilder<T> setItemStack(ItemStack itemStack) {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.ITEM_STACK, CraftItemStack.asNMSCopy(itemStack));
+        return this;
+    }
+
+    DataWatcherPacketBuilder<T> setSlimeSmall() {
+        packetByteBuffer.writeDataWatcherEntry(DataWatcherKey.SLIME_SIZE, 1);
+        return this;
+    }
+
+    T build() {
+        packetByteBuffer.writeDataWatcherEntriesEnd();
+        return createPacket(packetByteBuffer);
+    }
+
+    abstract T createPacket(PacketByteBuffer packetByteBuffer);
+
+}