Use proper meta based on material

src/main/java/net/minestom/server/item/ItemStackBuilder.java

@@ -1,13 +1,17 @@
 package net.minestom.server.item;
 
 import net.kyori.adventure.text.Component;
-import net.minestom.server.item.meta.CompassMeta;
+import net.minestom.server.item.meta.*;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
 import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Consumer;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 public class ItemStackBuilder {
@@ -24,9 +28,34 @@ public class ItemStackBuilder {
         this.storeBuilder = storeBuilder;
     }
 
+    private static final Map<Material, Supplier<ItemMetaBuilder>> MATERIAL_SUPPLIER_MAP = new ConcurrentHashMap<>();
+
+    static {
+        MATERIAL_SUPPLIER_MAP.put(Material.POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LINGERING_POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.SPLASH_POTION, PotionMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.TIPPED_ARROW, PotionMeta.Builder::new);
+
+        MATERIAL_SUPPLIER_MAP.put(Material.FILLED_MAP, MapMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.COMPASS, CompassMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.ENCHANTED_BOOK, EnchantedBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.CROSSBOW, CrossbowMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.WRITABLE_BOOK, WritableBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.WRITTEN_BOOK, WrittenBookMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.FIREWORK_STAR, FireworkEffectMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.FIREWORK_ROCKET, FireworkMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.PLAYER_HEAD, PlayerHeadMeta.Builder::new);
+
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_HELMET, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_CHESTPLATE, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_LEGGINGS, LeatherArmorMeta.Builder::new);
+        MATERIAL_SUPPLIER_MAP.put(Material.LEATHER_BOOTS, LeatherArmorMeta.Builder::new);
+    }
+
     protected ItemStackBuilder(@NotNull Material material) {
-        // TODO: meta depends on material
+        this(material,
-        this(material, new CompassMeta.Builder(), new ItemStoreBuilder());
+                MATERIAL_SUPPLIER_MAP.getOrDefault(material, DefaultMeta::new).get(),
+                new ItemStoreBuilder());
     }
 
     @Contract(value = "_ -> this")
@@ -88,4 +117,21 @@ public class ItemStackBuilder {
         return new ItemStack(material, amount, metaBuilder.build(), storeBuilder.build());
     }
 
+    private static final class DefaultMeta extends ItemMetaBuilder {
+        @Override
+        public @NotNull ItemMeta build() {
+            return new ItemMeta(this);
+        }
+
+        @Override
+        public void read(@NotNull NBTCompound nbtCompound) {
+            // Empty
+        }
+
+        @Override
+        protected @NotNull Supplier<@NotNull ItemMetaBuilder> getSupplier() {
+            return DefaultMeta::new;
+        }
+    }
+
 }

src/main/java/net/minestom/server/item/meta/EnchantedBookMeta.java

@@ -8,6 +8,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Supplier;
 
@@ -17,7 +18,7 @@ public class EnchantedBookMeta extends ItemMeta implements ItemMetaBuilder.Provi
 
     protected EnchantedBookMeta(@NotNull ItemMetaBuilder metaBuilder, Map<Enchantment, Short> storedEnchantmentMap) {
         super(metaBuilder);
-        this.storedEnchantmentMap = storedEnchantmentMap;
+        this.storedEnchantmentMap = new HashMap<>(storedEnchantmentMap);
     }
 
     /**
@@ -32,7 +33,7 @@ public class EnchantedBookMeta extends ItemMeta implements ItemMetaBuilder.Provi
 
     public static class Builder extends ItemMetaBuilder {
 
-        private Map<Enchantment, Short> enchantments;
+        private Map<Enchantment, Short> enchantments = new HashMap<>();
 
         public Builder enchantments(Map<Enchantment, Short> enchantments) {
             this.enchantments = enchantments;

src/main/java/net/minestom/server/item/meta/PotionMeta.java

@@ -13,7 +13,7 @@ import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.NBTList;
 import org.jglrxavpok.hephaistos.nbt.NBTTypes;
 
-import java.util.Collections;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Supplier;
 
@@ -28,7 +28,7 @@ public class PotionMeta extends ItemMeta implements ItemMetaBuilder.Provider<Pot
                          Color color) {
         super(metaBuilder);
         this.potionType = potionType;
-        this.customPotionEffects = Collections.unmodifiableList(customPotionEffects);
+        this.customPotionEffects = new ArrayList<>(customPotionEffects);
         this.color = color;
     }
 
@@ -40,7 +40,6 @@ public class PotionMeta extends ItemMeta implements ItemMetaBuilder.Provider<Pot
         return customPotionEffects;
     }
 
-
     public Color getColor() {
         return color;
     }
@@ -48,7 +47,7 @@ public class PotionMeta extends ItemMeta implements ItemMetaBuilder.Provider<Pot
     public static class Builder extends ItemMetaBuilder {
 
         private PotionType potionType;
-        private List<CustomPotionEffect> customPotionEffects;
+        private List<CustomPotionEffect> customPotionEffects = new ArrayList<>();
         private Color color;
 
         public Builder potionType(@NotNull PotionType potionType) {