Implement block and entity picking

api/src/main/java/com/viaversion/viaversion/api/minecraft/BlockPosition.java

@@ -37,6 +37,13 @@ public class BlockPosition {
         return new BlockPosition(x + face.modX(), y + face.modY(), z + face.modZ());
     }
 
+    public double distanceFromCenterSquared(final double x, final double y, final double z) {
+        final double dx = this.x + 0.5 - x;
+        final double dy = this.y + 0.5 - y;
+        final double dz = this.z + 0.5 - z;
+        return dx * dx + dy * dy + dz * dz;
+    }
+
     public int x() {
         return x;
     }

bukkit/src/main/java/com/viaversion/viaversion/bukkit/platform/BukkitViaLoader.java

@@ -26,24 +26,25 @@ import com.viaversion.viaversion.api.protocol.version.ProtocolVersion;
 import com.viaversion.viaversion.bukkit.listeners.UpdateListener;
 import com.viaversion.viaversion.bukkit.listeners.multiversion.PlayerSneakListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_14_4to1_15.EntityToggleGlideListener;
-import com.viaversion.viaversion.bukkit.listeners.v1_19_3to1_19_4.ArmorToggleListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_18_2to1_19.BlockBreakListener;
+import com.viaversion.viaversion.bukkit.listeners.v1_19_3to1_19_4.ArmorToggleListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_20_5to1_21.LegacyChangeItemListener;
+import com.viaversion.viaversion.bukkit.listeners.v1_20_5to1_21.PaperPlayerChangeItemListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_8to1_9.ArmorListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_8to1_9.BlockListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_8to1_9.DeathListener;
 import com.viaversion.viaversion.bukkit.listeners.v1_8to1_9.HandItemCache;
 import com.viaversion.viaversion.bukkit.listeners.v1_8to1_9.PaperPatch;
-import com.viaversion.viaversion.bukkit.listeners.v1_20_5to1_21.PaperPlayerChangeItemListener;
-import com.viaversion.viaversion.bukkit.listeners.v1_20_5to1_21.PlayerChangeItemListener;
 import com.viaversion.viaversion.bukkit.providers.BukkitAckSequenceProvider;
 import com.viaversion.viaversion.bukkit.providers.BukkitBlockConnectionProvider;
 import com.viaversion.viaversion.bukkit.providers.BukkitInventoryQuickMoveProvider;
+import com.viaversion.viaversion.bukkit.providers.BukkitPickItemProvider;
 import com.viaversion.viaversion.bukkit.providers.BukkitViaMovementTransmitter;
 import com.viaversion.viaversion.protocols.v1_11_1to1_12.provider.InventoryQuickMoveProvider;
 import com.viaversion.viaversion.protocols.v1_12_2to1_13.blockconnections.ConnectionData;
 import com.viaversion.viaversion.protocols.v1_12_2to1_13.blockconnections.providers.BlockConnectionProvider;
 import com.viaversion.viaversion.protocols.v1_18_2to1_19.provider.AckSequenceProvider;
+import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.provider.PickItemProvider;
 import com.viaversion.viaversion.protocols.v1_8to1_9.provider.HandItemProvider;
 import com.viaversion.viaversion.protocols.v1_8to1_9.provider.MovementTransmitterProvider;
 import java.util.HashSet;
@@ -188,6 +189,11 @@ public class BukkitViaLoader implements ViaPlatformLoader {
                 new LegacyChangeItemListener(plugin).register();
             }
         }
+        if (serverProtocolVersion.olderThan(ProtocolVersion.v1_21_4)) {
+            if (PaperViaInjector.hasMethod(Material.class, "isItem")) {
+                Via.getManager().getProviders().use(PickItemProvider.class, new BukkitPickItemProvider(plugin));
+            }
+        }
     }
 
     private boolean hasGetHandMethod() {

bukkit/src/main/java/com/viaversion/viaversion/bukkit/platform/PaperViaInjector.java

@@ -65,12 +65,7 @@ public final class PaperViaInjector {
     }
 
     private static boolean hasServerProtocolMethod() {
-        try {
+        return hasMethod("org.bukkit.UnsafeValues", "getProtocolVersion");
-            Class.forName("org.bukkit.UnsafeValues").getDeclaredMethod("getProtocolVersion");
-            return true;
-        } catch (final ClassNotFoundException | NoSuchMethodException e) {
-            return false;
-        }
     }
 
     private static boolean hasPaperInjectionMethod() {
@@ -78,12 +73,7 @@ public final class PaperViaInjector {
     }
 
     private static boolean hasIsStoppingMethod() {
-        try {
+        return hasMethod(Bukkit.class, "isStopping");
-            Bukkit.class.getDeclaredMethod("isStopping");
-            return true;
-        } catch (final NoSuchMethodException e) {
-            return false;
-        }
     }
 
     private static boolean hasPacketLimiter() {
@@ -98,4 +88,22 @@ public final class PaperViaInjector {
             return false;
         }
     }
+
+    public static boolean hasMethod(final String className, final String method) {
+        try {
+            Class.forName(className).getDeclaredMethod(method);
+            return true;
+        } catch (final ClassNotFoundException | NoSuchMethodException e) {
+            return false;
+        }
+    }
+
+    public static boolean hasMethod(final Class<?> clazz, final String method) {
+        try {
+            clazz.getDeclaredMethod(method);
+            return true;
+        } catch (final NoSuchMethodException e) {
+            return false;
+        }
+    }
 }

bukkit/src/main/java/com/viaversion/viaversion/bukkit/providers/BukkitPickItemProvider.java

@@ -0,0 +1,182 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2024 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viaversion.bukkit.providers;
+
+import com.viaversion.viaversion.ViaVersionPlugin;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.BlockPosition;
+import com.viaversion.viaversion.bukkit.platform.PaperViaInjector;
+import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.provider.PickItemProvider;
+import java.util.UUID;
+import org.bukkit.Bukkit;
+import org.bukkit.GameMode;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.block.Block;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemFactory;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.bukkit.inventory.meta.BlockStateMeta;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public final class BukkitPickItemProvider extends PickItemProvider {
+    private static final boolean HAS_PLACEMENT_MATERIAL_METHOD = PaperViaInjector.hasMethod("org.bukkit.block.BlockData", "getPlacementMaterial");
+    private static final boolean HAS_SPAWN_EGG_METHOD = PaperViaInjector.hasMethod(ItemFactory.class, "getSpawnEgg");
+    private static final double BLOCK_RANGE = 4.5 + 1;
+    private static final double BLOCK_RANGE_SQUARED = BLOCK_RANGE * BLOCK_RANGE;
+    private static final double ENTITY_RANGE = 3 + 3;
+    private final ViaVersionPlugin plugin;
+
+    public BukkitPickItemProvider(final ViaVersionPlugin plugin) {
+        this.plugin = plugin;
+    }
+
+    @Override
+    public void pickItemFromBlock(final UserConnection connection, final BlockPosition blockPosition, final boolean includeData) {
+        final UUID uuid = connection.getProtocolInfo().getUuid();
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
+            final Player player = plugin.getServer().getPlayer(uuid);
+            if (player == null) {
+                return;
+            }
+
+            final Location playerLocation = player.getLocation();
+            if (blockPosition.distanceFromCenterSquared(playerLocation.getX(), playerLocation.getY(), playerLocation.getZ()) > BLOCK_RANGE_SQUARED) {
+                return;
+            }
+
+            final Block block = player.getWorld().getBlockAt(blockPosition.x(), blockPosition.y(), blockPosition.z());
+            if (block.getType() == Material.AIR) {
+                return;
+            }
+
+            final ItemStack item = blockToItem(block, includeData && player.getGameMode() == GameMode.CREATIVE);
+            if (item != null) {
+                pickItem(player, item);
+            }
+        });
+    }
+
+    private @Nullable ItemStack blockToItem(final Block block, final boolean includeData) {
+        if (HAS_PLACEMENT_MATERIAL_METHOD) {
+            final ItemStack item = new ItemStack(block.getBlockData().getPlacementMaterial(), 1);
+            if (includeData && item.getItemMeta() instanceof final BlockStateMeta blockStateMeta) {
+                blockStateMeta.setBlockState(block.getState());
+            }
+            return item;
+        } else if (block.getType().isItem()) {
+            return new ItemStack(block.getType(), 1);
+        }
+        return null;
+    }
+
+    @Override
+    public void pickItemFromEntity(final UserConnection connection, final int entityId, final boolean includeData) {
+        if (!HAS_SPAWN_EGG_METHOD) {
+            return;
+        }
+
+        final UUID uuid = connection.getProtocolInfo().getUuid();
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
+            final Player player = plugin.getServer().getPlayer(uuid);
+            if (player == null) {
+                return;
+            }
+
+            final Entity entity = player.getWorld().getNearbyEntities(player.getLocation(), ENTITY_RANGE, ENTITY_RANGE, ENTITY_RANGE).stream()
+                .filter(e -> e.getEntityId() == entityId)
+                .findAny()
+                .orElse(null);
+            if (entity == null) {
+                return;
+            }
+
+            final Material spawnEggType = Bukkit.getItemFactory().getSpawnEgg(entity.getType());
+            if (spawnEggType != null) {
+                pickItem(player, new ItemStack(spawnEggType, 1));
+            }
+        });
+    }
+
+    private void pickItem(final Player player, final ItemStack item) {
+        // Find matching item
+        final PlayerInventory inventory = player.getInventory();
+        final ItemStack[] contents = inventory.getStorageContents();
+        int sourceSlot = -1;
+        for (int i = 0; i < contents.length; i++) {
+            final ItemStack content = contents[i];
+            if (content == null || !content.isSimilar(item)) {
+                continue;
+            }
+
+            sourceSlot = i;
+            break;
+        }
+
+        if (sourceSlot != -1) {
+            moveToHotbar(inventory, sourceSlot, contents);
+        } else if (player.getGameMode() == GameMode.CREATIVE) {
+            spawnItem(item, inventory, contents);
+        }
+    }
+
+    private void spawnItem(final ItemStack item, final PlayerInventory inventory, final ItemStack[] contents) {
+        final int targetSlot = findEmptyHotbarSlot(inventory, inventory.getHeldItemSlot());
+        inventory.setHeldItemSlot(targetSlot);
+        final ItemStack heldItem = inventory.getItem(targetSlot);
+        int emptySlot = targetSlot;
+        if (heldItem != null && heldItem.getType() != Material.AIR) {
+            // Swap to the first free slot in the inventory, else add it to the current hotbar slot
+            for (int i = 0; i < contents.length; i++) {
+                if (contents[i] == null || contents[i].getType() == Material.AIR) {
+                    emptySlot = i;
+                    break;
+                }
+            }
+        }
+
+        inventory.setItem(emptySlot, heldItem);
+        inventory.setItemInMainHand(item);
+    }
+
+    private void moveToHotbar(final PlayerInventory inventory, final int sourceSlot, final ItemStack[] contents) {
+        if (sourceSlot <= 9) {
+            inventory.setHeldItemSlot(sourceSlot);
+            return;
+        }
+
+        final int heldSlot = inventory.getHeldItemSlot();
+        final int targetSlot = findEmptyHotbarSlot(inventory, heldSlot);
+        inventory.setHeldItemSlot(targetSlot);
+        final ItemStack heldItem = inventory.getItem(targetSlot);
+        inventory.setItemInMainHand(contents[sourceSlot]);
+        inventory.setItem(sourceSlot, heldItem);
+    }
+
+    private int findEmptyHotbarSlot(final PlayerInventory inventory, final int heldSlot) {
+        for (int i = 0; i < 9; i++) {
+            final ItemStack item = inventory.getItem(i);
+            if (item == null || item.getType() == Material.AIR) {
+                return i;
+            }
+        }
+        return heldSlot;
+    }
+}

common/src/main/java/com/viaversion/viaversion/protocols/v1_21_2to1_21_4/Protocol1_21_2To1_21_4.java

@@ -23,6 +23,7 @@ import com.viaversion.viaversion.api.data.MappingDataBase;
 import com.viaversion.viaversion.api.minecraft.Particle;
 import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
 import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_21_4;
+import com.viaversion.viaversion.api.platform.providers.ViaProviders;
 import com.viaversion.viaversion.api.protocol.AbstractProtocol;
 import com.viaversion.viaversion.api.protocol.packet.provider.PacketTypesProvider;
 import com.viaversion.viaversion.api.protocol.packet.provider.SimplePacketTypesProvider;
@@ -35,6 +36,7 @@ import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundCon
 import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundConfigurationPackets1_21;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.packet.ServerboundPacket1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.packet.ServerboundPackets1_21_4;
+import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.provider.PickItemProvider;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter.BlockItemPacketRewriter1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter.ComponentRewriter1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter.EntityPacketRewriter1_21_4;
@@ -190,6 +192,11 @@ public final class Protocol1_21_2To1_21_4 extends AbstractProtocol<ClientboundPa
         super.onMappingDataLoaded();
     }
 
+    @Override
+    public void register(final ViaProviders providers) {
+        providers.register(PickItemProvider.class, new PickItemProvider());
+    }
+
     @Override
     public void init(final UserConnection connection) {
         addEntityTracker(connection, new EntityTrackerBase(connection, EntityTypes1_21_4.PLAYER));

common/src/main/java/com/viaversion/viaversion/protocols/v1_21_2to1_21_4/provider/PickItemProvider.java

@@ -0,0 +1,31 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2024 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viaversion.protocols.v1_21_2to1_21_4.provider;
+
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.BlockPosition;
+import com.viaversion.viaversion.api.platform.providers.Provider;
+
+public class PickItemProvider implements Provider {
+
+    public void pickItemFromBlock(final UserConnection connection, final BlockPosition blockPosition, final boolean includeData) {
+    }
+
+    public void pickItemFromEntity(final UserConnection connection, final int entityId, final boolean includeData) {
+    }
+}

common/src/main/java/com/viaversion/viaversion/protocols/v1_21_2to1_21_4/rewriter/BlockItemPacketRewriter1_21_4.java

@@ -19,7 +19,9 @@ package com.viaversion.viaversion.protocols.v1_21_2to1_21_4.rewriter;
 
 import com.viaversion.nbt.tag.CompoundTag;
 import com.viaversion.nbt.tag.IntTag;
+import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.BlockPosition;
 import com.viaversion.viaversion.api.minecraft.data.StructuredDataContainer;
 import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
 import com.viaversion.viaversion.api.minecraft.item.Item;
@@ -31,6 +33,7 @@ import com.viaversion.viaversion.api.type.types.version.Types1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.Protocol1_21_2To1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.packet.ServerboundPacket1_21_4;
 import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.packet.ServerboundPackets1_21_4;
+import com.viaversion.viaversion.protocols.v1_21_2to1_21_4.provider.PickItemProvider;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ClientboundPacket1_21_2;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.packet.ClientboundPackets1_21_2;
 import com.viaversion.viaversion.rewriter.BlockRewriter;
@@ -61,8 +64,18 @@ public final class BlockItemPacketRewriter1_21_4 extends StructuredItemRewriter<
             wrapper.write(Types.VAR_INT, (int) slot);
         });
 
-        protocol.cancelServerbound(ServerboundPackets1_21_4.PICK_ITEM_FROM_BLOCK);
+        protocol.registerServerbound(ServerboundPackets1_21_4.PICK_ITEM_FROM_BLOCK, null, wrapper -> {
-        protocol.cancelServerbound(ServerboundPackets1_21_4.PICK_ITEM_FROM_ENTITY);
+            final BlockPosition blockPosition = wrapper.read(Types.BLOCK_POSITION1_14);
+            final boolean includeData = wrapper.read(Types.BOOLEAN);
+            Via.getManager().getProviders().get(PickItemProvider.class).pickItemFromBlock(wrapper.user(), blockPosition, includeData);
+            wrapper.cancel();
+        });
+        protocol.registerServerbound(ServerboundPackets1_21_4.PICK_ITEM_FROM_ENTITY, null, wrapper -> {
+            final int entityId = wrapper.read(Types.VAR_INT);
+            final boolean includeData = wrapper.read(Types.BOOLEAN);
+            Via.getManager().getProviders().get(PickItemProvider.class).pickItemFromEntity(wrapper.user(), entityId, includeData);
+            wrapper.cancel();
+        });
 
         protocol.registerClientbound(ClientboundPackets1_21_2.SET_CURSOR_ITEM, this::passthroughClientboundItem);
         registerSetPlayerInventory(ClientboundPackets1_21_2.SET_PLAYER_INVENTORY);