Implement #70

src/main/java/com/github/creeper123123321/viafabric/platform/VRLoader.java

@@ -25,11 +25,15 @@
 
 package com.github.creeper123123321.viafabric.platform;
 
+import com.github.creeper123123321.viafabric.providers.VRHandItemProvider;
 import com.github.creeper123123321.viafabric.providers.VRVersionProvider;
+import net.fabricmc.api.EnvType;
+import net.fabricmc.loader.api.FabricLoader;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.ViaPlatformLoader;
 import us.myles.ViaVersion.bungee.providers.BungeeMovementTransmitter;
 import us.myles.ViaVersion.protocols.base.VersionProvider;
+import us.myles.ViaVersion.protocols.protocol1_9to1_8.providers.HandItemProvider;
 import us.myles.ViaVersion.protocols.protocol1_9to1_8.providers.MovementTransmitterProvider;
 
 public class VRLoader implements ViaPlatformLoader {
@@ -37,6 +41,15 @@ public class VRLoader implements ViaPlatformLoader {
     public void load() {
         Via.getManager().getProviders().use(MovementTransmitterProvider.class, new BungeeMovementTransmitter());
         Via.getManager().getProviders().use(VersionProvider.class, new VRVersionProvider());
+
+        if (Via.getPlatform().getConf().isItemCache()) {
+            VRHandItemProvider handProvider = new VRHandItemProvider();
+            if (FabricLoader.getInstance().getEnvironmentType() == EnvType.CLIENT) {
+                handProvider.registerClientTick();
+            }
+            handProvider.registerServerTick();
+            Via.getManager().getProviders().use(HandItemProvider.class, handProvider);
+        }
     }
 
     @Override

src/main/java/com/github/creeper123123321/viafabric/platform/VRViaConfig.java

@@ -37,7 +37,7 @@ public class VRViaConfig extends AbstractViaConfig {
     // Based on Sponge ViaVersion
     private static List<String> UNSUPPORTED = Arrays.asList("anti-xray-patch", "bungee-ping-interval",
             "bungee-ping-save", "bungee-servers", "quick-move-action-fix", "nms-player-ticking",
-            "item-cache", "velocity-ping-interval", "velocity-ping-save", "velocity-servers",
+            "velocity-ping-interval", "velocity-ping-save", "velocity-servers",
             "blockconnection-method", "change-1_9-hitbox", "change-1_14-hitbox");
 
     public VRViaConfig(File configFile) {
@@ -66,11 +66,6 @@ public class VRViaConfig extends AbstractViaConfig {
         return false;
     }
 
-    @Override
-    public boolean isItemCache() {
-        return false;
-    }
-
     @Override
     public boolean isNMSPlayerTicking() {
         return false;

src/main/java/com/github/creeper123123321/viafabric/providers/VRHandItemProvider.java

@@ -0,0 +1,133 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018- creeper123123321 <https://creeper123123321.keybase.pub/>
+ * Copyright (c) 2019- contributors <https://github.com/ViaVersion/ViaFabric/graphs/contributors>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.github.creeper123123321.viafabric.providers;
+
+import com.github.creeper123123321.viafabric.ViaFabric;
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
+import net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents;
+import net.fabricmc.fabric.api.event.world.WorldTickCallback;
+import net.minecraft.client.MinecraftClient;
+import net.minecraft.client.network.ClientPlayerEntity;
+import net.minecraft.client.world.ClientWorld;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.registry.Registry;
+import net.minecraft.world.World;
+import us.myles.ViaVersion.api.data.UserConnection;
+import us.myles.ViaVersion.api.minecraft.item.Item;
+import us.myles.ViaVersion.protocols.protocol1_9to1_8.providers.HandItemProvider;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class VRHandItemProvider extends HandItemProvider {
+    public Item clientItem = null;
+    public Map<UUID, Item> serverPlayers = new ConcurrentHashMap<>();
+
+    @Override
+    public Item getHandItem(UserConnection info) {
+        Item serverItem;
+        if (info.isClientSide()) {
+            return getClientItem();
+        } else if ((serverItem = serverPlayers.get(info.getProtocolInfo().getUuid())) != null) {
+            return new Item(serverItem);
+        }
+        return super.getHandItem(info);
+    }
+
+    private Item getClientItem() {
+        if (clientItem == null) {
+            return new Item(0, (byte) 0, (short) 0, null);
+        }
+        return new Item(clientItem);
+    }
+
+    @Environment(EnvType.CLIENT)
+    public void registerClientTick() {
+        try {
+            ClientTickEvents.END_WORLD_TICK.register(clientWorld -> tickClient());
+        } catch (NoClassDefFoundError ignored) {
+            try {
+                WorldTickCallback.EVENT.register(world -> {
+                    if (world.isClient) {
+                        tickClient();
+                    }
+                });
+            } catch (NoClassDefFoundError ignored2) {
+                ViaFabric.JLOGGER.info("Fabric Lifecycle V0/V1 isn't installed");
+            }
+        }
+    }
+
+    public void registerServerTick() {
+        try {
+            ServerTickEvents.END_WORLD_TICK.register(this::tickServer);
+        } catch (NoClassDefFoundError ignored) {
+            WorldTickCallback.EVENT.register(world -> {
+                if (!world.isClient) {
+                    tickServer(world);
+                }
+            });
+        }
+    }
+
+    private void tickClient() {
+        ClientPlayerEntity p = MinecraftClient.getInstance().player;
+        if (p != null) {
+            clientItem = fromNative(p.inventory.getMainHandStack());
+        }
+    }
+
+    private void tickServer(World world) {
+        serverPlayers.clear();
+        world.getPlayers().forEach(it -> serverPlayers
+                .put(it.getUuid(), fromNative(it.inventory.getMainHandStack())));
+    }
+
+    private Item fromNative(ItemStack original) {
+        int id = swordId(Registry.ITEM.getId(original.getItem()).toString());
+        return new Item(id, (byte) original.getCount(), (short) original.getDamage(), null);
+    }
+
+    private int swordId(String id) {
+        // https://github.com/ViaVersion/ViaVersion/blob/8de26a0ad33f5b739f5394ed80f69d14197fddc7/common/src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/Protocol1_9To1_8.java#L86
+        switch (id) {
+            case "minecraft:iron_sword":
+                return 267;
+            case "minecraft:wooden_sword":
+                return 268;
+            case "minecraft:golden_sword":
+                return 272;
+            case "minecraft:diamond_sword":
+                return 276;
+            case "minecraft:stone_sword":
+                return 283;
+        }
+        return 0;
+    }
+}