Fix item nbt being reset when dragging (#206)

arclight-common/src/main/java/io/izzel/arclight/common/bridge/bukkit/CraftItemStackBridge.java

@@ -0,0 +1,8 @@
+package io.izzel.arclight.common.bridge.bukkit;
+
+import net.minecraft.item.ItemStack;
+
+public interface CraftItemStackBridge {
+
+    ItemStack bridge$getHandle();
+}

arclight-common/src/main/java/io/izzel/arclight/common/mixin/bukkit/CraftItemStackMixin.java

@@ -1,5 +1,6 @@
 package io.izzel.arclight.common.mixin.bukkit;
 
+import io.izzel.arclight.common.bridge.bukkit.CraftItemStackBridge;
 import io.izzel.arclight.common.bridge.bukkit.ItemMetaBridge;
 import io.izzel.arclight.common.bridge.bukkit.MaterialBridge;
 import io.izzel.arclight.common.bridge.item.ItemStackBridge;
@@ -10,19 +11,27 @@ import org.bukkit.Material;
 import org.bukkit.craftbukkit.v.inventory.CraftItemFactory;
 import org.bukkit.craftbukkit.v.inventory.CraftItemStack;
 import org.bukkit.craftbukkit.v.inventory.CraftMetaItem;
+import org.bukkit.craftbukkit.v.legacy.CraftLegacy;
 import org.bukkit.inventory.meta.ItemMeta;
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
+import java.util.Objects;
+
 @Mixin(value = CraftItemStack.class, remap = false)
-public abstract class CraftItemStackMixin {
+public abstract class CraftItemStackMixin implements CraftItemStackBridge {
 
     // @formatter:off
     @Shadow static Material getType(ItemStack item) { return null; }
     @Shadow static boolean hasItemMeta(ItemStack item) { return false; }
+    @Shadow ItemStack handle;
+    @Shadow public abstract Material getType();
+    @Shadow public abstract short getDurability();
+    @Shadow public abstract boolean hasItemMeta();
     // @formatter:on
 
     @Inject(method = "getItemMeta(Lnet/minecraft/item/ItemStack;)Lorg/bukkit/inventory/meta/ItemMeta;",
@@ -31,8 +40,14 @@ public abstract class CraftItemStackMixin {
         Material type = getType(item);
         if (((MaterialBridge) (Object) type).bridge$getType() != MaterialPropertySpec.MaterialType.VANILLA) {
             if (hasItemMeta(item)) {
-                CraftMetaItem metaItem = new CraftMetaItem(item.getTag());
+                CompoundNBT tag = item.getTag();
-                ((ItemMetaBridge) metaItem).bridge$offerUnhandledTags(item.getTag());
+                CraftMetaItem metaItem;
+                if (tag != null) {
+                    metaItem = new CraftMetaItem(tag);
+                    ((ItemMetaBridge) metaItem).bridge$offerUnhandledTags(tag);
+                } else {
+                    metaItem = new CraftMetaItem(new CompoundNBT());
+                }
                 ((ItemMetaBridge) metaItem).bridge$setForgeCaps(((ItemStackBridge) (Object) item).bridge$getForgeCaps());
                 cir.setReturnValue(metaItem);
             } else {
@@ -49,4 +64,53 @@ public abstract class CraftItemStackMixin {
             ((ItemStackBridge)(Object) item).bridge$setForgeCaps(forgeCaps.copy());
         }
     }
+
+    /**
+     * @author IzzelAliz
+     * @reason
+     */
+    @Overwrite
+    public boolean isSimilar(org.bukkit.inventory.ItemStack stack) {
+        if (stack == null) {
+            return false;
+        }
+        if (stack == (Object) this) {
+            return true;
+        }
+        if (!(stack instanceof CraftItemStack)) {
+            return stack.getClass() == org.bukkit.inventory.ItemStack.class && stack.isSimilar((org.bukkit.inventory.ItemStack) (Object) this);
+        }
+
+        CraftItemStack that = (CraftItemStack) stack;
+        if (handle == ((CraftItemStackBridge) (Object) that).bridge$getHandle()) {
+            return true;
+        }
+        if (handle == null || ((CraftItemStackBridge) (Object) that).bridge$getHandle() == null) {
+            return false;
+        }
+        Material comparisonType = CraftLegacy.fromLegacy(that.getType()); // This may be called from legacy item stacks, try to get the right material
+        if (!(comparisonType == this.getType() && getDurability() == that.getDurability())) {
+            return false;
+        }
+        return hasItemMeta()
+            ? (that.hasItemMeta()
+            && Objects.equals(handle.getTag(), ((CraftItemStackBridge) (Object) that).bridge$getHandle().getTag())
+            && Objects.equals(((ItemStackBridge) (Object) handle).bridge$getForgeCaps(), ((ItemStackBridge) (Object) ((CraftItemStackBridge) (Object) that).bridge$getHandle()).bridge$getForgeCaps()))
+            : !that.hasItemMeta();
+    }
+
+    @Inject(method = "hasItemMeta(Lnet/minecraft/item/ItemStack;)Z", cancellable = true, at = @At("HEAD"))
+    private static void arclight$hasMeta(ItemStack item, CallbackInfoReturnable<Boolean> cir) {
+        if (item != null) {
+            CompoundNBT forgeCaps = ((ItemStackBridge) (Object) item).bridge$getForgeCaps();
+            if (forgeCaps != null && !forgeCaps.isEmpty()) {
+                cir.setReturnValue(true);
+            }
+        }
+    }
+
+    @Override
+    public ItemStack bridge$getHandle() {
+        return handle;
+    }
 }

arclight-common/src/main/java/io/izzel/arclight/common/mixin/bukkit/CraftMetaItemMixin.java

@@ -116,6 +116,13 @@ public class CraftMetaItemMixin implements ItemMetaBridge {
         return 61 * hash + (this.forgeCaps != null ? this.forgeCaps.hashCode() : 0);
     }
 
+    @Inject(method = "isEmpty", cancellable = true,at = @At("HEAD"))
+    private void arclight$forgeCapsEmpty(CallbackInfoReturnable<Boolean> cir) {
+        if (this.forgeCaps != null && !this.forgeCaps.isEmpty()) {
+            cir.setReturnValue(false);
+        }
+    }
+
     @Inject(method = "equalsCommon", cancellable = true, at = @At("HEAD"))
     private void arclight$forgeCapsEquals(CraftMetaItem that, CallbackInfoReturnable<Boolean> cir) {
         CompoundNBT forgeCaps = ((ItemMetaBridge) that).bridge$getForgeCaps();