Added Enchantment.conflictsWith() and EnchantmentTarget.includes(). Addresses BUKKIT-1159 and addresses BUKKIT-1160

By: Celtic Minstrel <celtic.minstrel.ca@some.place>

paper-api/src/main/java/org/bukkit/enchantments/Enchantment.java

@@ -160,7 +160,16 @@ public abstract class Enchantment {
     public abstract EnchantmentTarget getItemTarget();
 
     /**
-     * Checks if this Enchantment may be applied to the given {@link ItemStack}
+     * Check if this enchantment conflicts with another enchantment.
+     *
+     * @param other The enchantment to check against
+     * @return True if there is a conflict.
+     */
+    public abstract boolean conflictsWith(Enchantment other);
+
+    /**
+     * Checks if this Enchantment may be applied to the given {@link ItemStack}.
+     * This does not check if it conflicts with any enchantmentds already applied to the item.
      *
      * @param item Item to test
      * @return True if the enchantment may be applied, otherwise False

paper-api/src/main/java/org/bukkit/enchantments/EnchantmentTarget.java

@@ -1,5 +1,8 @@
 package org.bukkit.enchantments;
 
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+
 /**
  * Represents the applicable target for a {@link Enchantment}
  */
@@ -7,45 +10,153 @@ public enum EnchantmentTarget {
     /**
      * Allows the Enchantment to be placed on all items
      */
-    ALL,
+    ALL {
+        @Override
+        public boolean includes(Material item) {
+            return true;
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on armor
      */
-    ARMOR,
+    ARMOR {
+        @Override
+        public boolean includes(Material item) {
+            return ARMOR_FEET.includes(item)
+                || ARMOR_LEGS.includes(item)
+                || ARMOR_HEAD.includes(item)
+                || ARMOR_TORSO.includes(item);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on feet slot armor
      */
-    ARMOR_FEET,
+    ARMOR_FEET {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.LEATHER_BOOTS)
+                || item.equals(Material.CHAINMAIL_BOOTS)
+                || item.equals(Material.IRON_BOOTS)
+                || item.equals(Material.DIAMOND_BOOTS)
+                || item.equals(Material.GOLD_BOOTS);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on leg slot armor
      */
-    ARMOR_LEGS,
+    ARMOR_LEGS {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.LEATHER_LEGGINGS)
+                || item.equals(Material.CHAINMAIL_LEGGINGS)
+                || item.equals(Material.IRON_LEGGINGS)
+                || item.equals(Material.DIAMOND_LEGGINGS)
+                || item.equals(Material.GOLD_LEGGINGS);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on torso slot armor
      */
-    ARMOR_TORSO,
+    ARMOR_TORSO {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.LEATHER_CHESTPLATE)
+                || item.equals(Material.CHAINMAIL_CHESTPLATE)
+                || item.equals(Material.IRON_CHESTPLATE)
+                || item.equals(Material.DIAMOND_CHESTPLATE)
+                || item.equals(Material.GOLD_CHESTPLATE);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on head slot armor
      */
-    ARMOR_HEAD,
+    ARMOR_HEAD {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.LEATHER_HELMET)
+                || item.equals(Material.CHAINMAIL_HELMET)
+                || item.equals(Material.DIAMOND_HELMET)
+                || item.equals(Material.IRON_HELMET)
+                || item.equals(Material.GOLD_HELMET);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on weapons (swords)
      */
-    WEAPON,
+    WEAPON {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.WOOD_SWORD)
+                || item.equals(Material.STONE_SWORD)
+                || item.equals(Material.IRON_SWORD)
+                || item.equals(Material.DIAMOND_SWORD)
+                || item.equals(Material.GOLD_SWORD);
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on tools (spades, pickaxe, hoes, axes)
      */
-    TOOL,
+    TOOL {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.WOOD_SPADE)
+                || item.equals(Material.STONE_SPADE)
+                || item.equals(Material.IRON_SPADE)
+                || item.equals(Material.DIAMOND_SPADE)
+                || item.equals(Material.GOLD_SPADE)
+                || item.equals(Material.WOOD_PICKAXE)
+                || item.equals(Material.STONE_PICKAXE)
+                || item.equals(Material.IRON_PICKAXE)
+                || item.equals(Material.DIAMOND_PICKAXE)
+                || item.equals(Material.GOLD_PICKAXE)
+                || item.equals(Material.WOOD_HOE)         // NOTE: No vanilla enchantments for this
+                || item.equals(Material.STONE_HOE)        // NOTE: No vanilla enchantments for this
+                || item.equals(Material.IRON_HOE)         // NOTE: No vanilla enchantments for this
+                || item.equals(Material.DIAMOND_HOE)      // NOTE: No vanilla enchantments for this
+                || item.equals(Material.GOLD_HOE)         // NOTE: No vanilla enchantments for this
+                || item.equals(Material.WOOD_AXE)
+                || item.equals(Material.STONE_AXE)
+                || item.equals(Material.IRON_AXE)
+                || item.equals(Material.DIAMOND_AXE)
+                || item.equals(Material.GOLD_AXE)
+                || item.equals(Material.SHEARS)           // NOTE: No vanilla enchantments for this
+                || item.equals(Material.FISHING_ROD)      // NOTE: No vanilla enchantments for this
+                || item.equals(Material.FLINT_AND_STEEL); // NOTE: No vanilla enchantments for this
+        }
+    },
 
     /**
      * Allows the Enchantment to be placed on bows.
      */
-    BOW;
+    BOW {
+        @Override
+        public boolean includes(Material item) {
+            return item.equals(Material.BOW);
+        }
+    };
+
+    /**
+     * Check whether this target includes the specified item.
+     *
+     * @param item The item to check
+     * @return True if the target includes the item
+     */
+    public abstract boolean includes(Material item);
+
+    /**
+     * Check whether this target includes the specified item.
+     *
+     * @param item The item to check
+     * @return True if the target includes the item
+     */
+    public boolean includes(ItemStack item) {
+        return includes(item.getType());
+    }
 }

paper-api/src/main/java/org/bukkit/enchantments/EnchantmentWrapper.java

@@ -43,4 +43,9 @@ public class EnchantmentWrapper extends Enchantment {
     public String getName() {
         return getEnchantment().getName();
     }
+
+    @Override
+    public boolean conflictsWith(Enchantment other) {
+        return getEnchantment().conflictsWith(other);
+    }
 }

paper-api/src/test/java/org/bukkit/configuration/file/TestEnchantment.java

@@ -47,4 +47,9 @@ public class TestEnchantment extends Enchantment {
         return true;
     }
 
+    @Override
+    public boolean conflictsWith(Enchantment other) {
+        return false;
+    }
+
 }