Add support for external items anywhere that accepts an item key (#335)

- Only oraxen and mythicmobs are currently supported

api/src/main/java/dev/aurelium/auraskills/api/registry/NamespacedId.java

@@ -7,10 +7,12 @@ public class NamespacedId {
 
     public static final String AURASKILLS = "auraskills";
     private final String namespace;
+    private final String originalKey;
     private final String key;
 
     private NamespacedId(String namespace, String key) {
         this.namespace = namespace.toLowerCase(Locale.ROOT);
+        this.originalKey = key;
         this.key = key.toLowerCase(Locale.ROOT);
     }
 
@@ -33,6 +35,15 @@ public String getKey() {
         return key;
     }
 
+    /**
+     * Gets the original key portion of the NamespacedId, which is the key in the case it was created with.
+     *
+     * @return the original key
+     */
+    public String getOriginalKey() {
+        return originalKey;
+    }
+
     /**
      * Returns the full String representation of the NamespacedId, with a / separating the
      * namespace and the key.

bukkit/src/main/java/dev/aurelium/auraskills/bukkit/hooks/mythicmobs/MythicMobsHook.java

@@ -32,11 +32,18 @@ public MythicMobsHook(AuraSkills plugin, ConfigurationNode config) {
         this.plugin = plugin;
         this.damageHandler = new DamageHandler();
 
+        registerItemProvider();
+
         // Wait for loot manager to be created, but add parser before it is loaded
         plugin.getScheduler().executeSync(() ->
                 plugin.getLootTableManager().getLootManager().registerCustomEntityParser(new MythicEntityLootParser(plugin)));
     }
 
+    private void registerItemProvider() {
+        plugin.getItemRegistry().registerExternalItemProvider("mythicmobs",
+                (id) -> MythicBukkit.inst().getItemManager().getItemStack(id));
+    }
+
     @EventHandler
     public void onMythicSkillDamage(MythicDamageEvent event) {
         // This is always some sort of skill/mechanic damage.

bukkit/src/main/java/dev/aurelium/auraskills/bukkit/item/BukkitItemRegistry.java

@@ -58,9 +58,14 @@ public ItemStack getItem(NamespacedId key) {
         ItemStack item = items.get(key);
         if (item != null) {
             return item.clone();
-        } else {
-            return null;
         }
+
+        ExternalItemProvider provider = externalItemProviders.get(key.getNamespace());
+        if (provider != null) {
+            return provider.getItem(key.getOriginalKey());
+        }
+
+        return null;
     }
 
     public Map<NamespacedId, ItemStack> getItems() {