SPIGOT-7034: Add methods for set/get instrument in Goat Horn

src/main/java/org/bukkit/craftbukkit/inventory/CraftItemFactory.java

@@ -322,6 +322,8 @@ public final class CraftItemFactory implements ItemFactory {
             return meta instanceof CraftMetaCompass ? meta : new CraftMetaCompass(meta);
         case BUNDLE:
             return meta instanceof CraftMetaBundle ? meta : new CraftMetaBundle(meta);
+        case GOAT_HORN:
+            return meta instanceof CraftMetaMusicInstrument ? meta : new CraftMetaMusicInstrument(meta);
         default:
             return new CraftMetaItem(meta);
         }

src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java

@@ -585,6 +585,8 @@ public final class CraftItemStack extends ItemStack {
                 return new CraftMetaCompass(item.getTag());
             case BUNDLE:
                 return new CraftMetaBundle(item.getTag());
+            case GOAT_HORN:
+                return new CraftMetaMusicInstrument(item.getTag());
             default:
                 return new CraftMetaItem(item.getTag());
         }

src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java

@@ -158,6 +158,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                     .put(CraftMetaEntityTag.class, "ENTITY_TAG")
                     .put(CraftMetaCompass.class, "COMPASS")
                     .put(CraftMetaBundle.class, "BUNDLE")
+                    .put(CraftMetaMusicInstrument.class, "MUSIC_INSTRUMENT")
                     .put(CraftMetaItem.class, "UNSPECIFIC")
                     .build();
 
@@ -1418,7 +1419,8 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                         CraftMetaCompass.LODESTONE_DIMENSION.NBT,
                         CraftMetaCompass.LODESTONE_POS.NBT,
                         CraftMetaCompass.LODESTONE_TRACKED.NBT,
-                        CraftMetaBundle.ITEMS.NBT
+                        CraftMetaBundle.ITEMS.NBT,
+                        CraftMetaMusicInstrument.GOAT_HORN_INSTRUMENT.NBT
                 ));
             }
             return HANDLED_TAGS;

src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMusicInstrument.java

@@ -0,0 +1,133 @@
+package org.bukkit.craftbukkit.inventory;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.Map;
+import net.minecraft.nbt.NBTTagCompound;
+import org.bukkit.Material;
+import org.bukkit.MusicInstrument;
+import org.bukkit.NamespacedKey;
+import org.bukkit.configuration.serialization.DelegateDeserialization;
+import org.bukkit.inventory.meta.MusicInstrumentMeta;
+
+@DelegateDeserialization(CraftMetaItem.SerializableMeta.class)
+public class CraftMetaMusicInstrument extends CraftMetaItem implements MusicInstrumentMeta {
+
+    static final ItemMetaKey GOAT_HORN_INSTRUMENT = new ItemMetaKey("instrument");
+    private MusicInstrument instrument;
+
+    CraftMetaMusicInstrument(CraftMetaItem meta) {
+        super(meta);
+
+        if (meta instanceof CraftMetaMusicInstrument) {
+            CraftMetaMusicInstrument craftMetaMusicInstrument = (CraftMetaMusicInstrument) meta;
+            this.instrument = craftMetaMusicInstrument.instrument;
+        }
+    }
+
+    CraftMetaMusicInstrument(NBTTagCompound tag) {
+        super(tag);
+
+        if (tag.contains(GOAT_HORN_INSTRUMENT.NBT)) {
+            String string = tag.getString(GOAT_HORN_INSTRUMENT.NBT);
+            this.instrument = MusicInstrument.getByKey(NamespacedKey.fromString(string));
+        }
+    }
+
+    CraftMetaMusicInstrument(Map<String, Object> map) {
+        super(map);
+
+        String instrumentString = SerializableMeta.getString(map, GOAT_HORN_INSTRUMENT.BUKKIT, true);
+        if (instrumentString != null) {
+            this.instrument = MusicInstrument.getByKey(NamespacedKey.fromString(instrumentString));
+        }
+    }
+
+    @Override
+    void applyToItem(NBTTagCompound tag) {
+        super.applyToItem(tag);
+
+        if (instrument != null) {
+            tag.putString(GOAT_HORN_INSTRUMENT.NBT, instrument.getKey().toString());
+        }
+    }
+
+    @Override
+    boolean applicableTo(Material type) {
+        switch (type) {
+            case GOAT_HORN:
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    @Override
+    boolean equalsCommon(CraftMetaItem meta) {
+        if (!super.equalsCommon(meta)) {
+            return false;
+        }
+        if (meta instanceof CraftMetaMusicInstrument) {
+            CraftMetaMusicInstrument that = (CraftMetaMusicInstrument) meta;
+            return this.instrument == that.instrument;
+        }
+        return true;
+    }
+
+    @Override
+    boolean notUncommon(CraftMetaItem meta) {
+        return super.notUncommon(meta) && (meta instanceof CraftMetaMusicInstrument || isInstrumentEmpty());
+    }
+
+    @Override
+    boolean isEmpty() {
+        return super.isEmpty() && isInstrumentEmpty();
+    }
+
+    boolean isInstrumentEmpty() {
+        return instrument == null;
+    }
+
+    @Override
+    int applyHash() {
+        final int orginal;
+        int hash = orginal = super.applyHash();
+
+        if (hasInstrument()) {
+            hash = 61 * hash + instrument.hashCode();
+        }
+
+        return orginal != hash ? CraftMetaMusicInstrument.class.hashCode() ^ hash : hash;
+    }
+
+    @Override
+    public CraftMetaMusicInstrument clone() {
+        CraftMetaMusicInstrument meta = (CraftMetaMusicInstrument) super.clone();
+        meta.instrument = this.instrument;
+        return meta;
+    }
+
+    @Override
+    ImmutableMap.Builder<String, Object> serialize(ImmutableMap.Builder<String, Object> builder) {
+        super.serialize(builder);
+
+        if (hasInstrument()) {
+            builder.put(GOAT_HORN_INSTRUMENT.BUKKIT, instrument.getKey().toString());
+        }
+
+        return builder;
+    }
+
+    @Override
+    public MusicInstrument getInstrument() {
+        return instrument;
+    }
+
+    public boolean hasInstrument() {
+        return instrument != null;
+    }
+
+    @Override
+    public void setInstrument(MusicInstrument instrument) {
+        this.instrument = instrument;
+    }
+}

src/test/java/org/bukkit/craftbukkit/inventory/ItemMetaTest.java

@@ -19,6 +19,7 @@ import org.bukkit.DyeColor;
 import org.bukkit.FireworkEffect;
 import org.bukkit.FireworkEffect.Type;
 import org.bukkit.Material;
+import org.bukkit.MusicInstrument;
 import org.bukkit.NamespacedKey;
 import org.bukkit.attribute.Attribute;
 import org.bukkit.attribute.AttributeModifier;
@@ -377,6 +378,14 @@ public class ItemMetaTest extends AbstractTestingBase {
                     cleanStack.setItemMeta(meta);
                     return cleanStack;
                 }
+            },
+            new StackProvider(Material.GOAT_HORN) {
+                @Override ItemStack operate(ItemStack cleanStack) {
+                    final CraftMetaMusicInstrument meta = (CraftMetaMusicInstrument) cleanStack.getItemMeta();
+                    meta.setInstrument(MusicInstrument.ADMIRE);
+                    cleanStack.setItemMeta(meta);
+                    return cleanStack;
+                }
             }
         );