Added ExternalDataStoreObjectAdapter

eco-api/src/main/java/com/willfp/eco/core/data/ExternalDataStore.java

@@ -3,17 +3,26 @@ package com.willfp.eco.core.data;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.function.Supplier;
 
 /**
  * A simple store key-value store for data to be stored outside of plugins.
  */
+@SuppressWarnings("unchecked")
 public final class ExternalDataStore {
     /**
      * The store.
      */
-    private static final HashMap<String, Object> data = new HashMap<>();
+    private static final Map<String, Object> DATA = new HashMap<>();
+
+    /**
+     * The store adapters.
+     */
+    private static final List<ExternalDataStoreObjectAdapter<?, ?>> STORE_ADAPTERS = new ArrayList<>();
 
     /**
      * Put data into the store.
@@ -23,7 +32,29 @@ public final class ExternalDataStore {
      */
     public static void put(@NotNull final String key,
                            @NotNull final Object value) {
-        data.put(key, value);
+        doPut(key, value);
+    }
+
+    /**
+     * Put data into the store.
+     *
+     * @param key   The key.
+     * @param value The value.
+     * @param <A>   The stored type.
+     */
+    private static <A> void doPut(@NotNull final String key,
+                                  @NotNull final A value) {
+        Object storedValue = value;
+
+        for (ExternalDataStoreObjectAdapter<?, ?> unknownAdapter : STORE_ADAPTERS) {
+            if (unknownAdapter.getAccessedClass().isInstance(value)) {
+                ExternalDataStoreObjectAdapter<A, ?> adapter = (ExternalDataStoreObjectAdapter<A, ?>) unknownAdapter;
+                storedValue = adapter.toStoredObject(value);
+                break;
+            }
+        }
+
+        DATA.put(key, storedValue);
     }
 
     /**
@@ -37,7 +68,30 @@ public final class ExternalDataStore {
     @Nullable
     public static <T> T get(@NotNull final String key,
                             @NotNull final Class<T> clazz) {
-        Object value = data.get(key);
+        return doGet(key, clazz);
+    }
+
+    /**
+     * Get data from the store.
+     *
+     * @param key   The key.
+     * @param clazz The class.
+     * @param <A>   The accessed type.
+     * @param <S>   The stored type.
+     * @return The value.
+     */
+    @Nullable
+    private static <A, S> A doGet(@NotNull final String key,
+                                  @NotNull final Class<A> clazz) {
+        Object value = DATA.get(key);
+
+        for (ExternalDataStoreObjectAdapter<?, ?> unknownAdapter : STORE_ADAPTERS) {
+            if (unknownAdapter.getStoredClass().isInstance(value) && unknownAdapter.getAccessedClass().equals(clazz)) {
+                ExternalDataStoreObjectAdapter<A, S> adapter = (ExternalDataStoreObjectAdapter<A, S>) unknownAdapter;
+                value = adapter.toAccessedObject((S) value);
+                break;
+            }
+        }
 
         if (clazz.isInstance(value)) {
             return clazz.cast(value);
@@ -79,6 +133,15 @@ public final class ExternalDataStore {
         return get(key, clazz, defaultValue.get());
     }
 
+    /**
+     * Register a new adapter.
+     *
+     * @param adapter The adapter.
+     */
+    public static void registerAdapter(@NotNull final ExternalDataStoreObjectAdapter<?, ?> adapter) {
+        STORE_ADAPTERS.add(adapter);
+    }
+
     private ExternalDataStore() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

eco-api/src/main/java/com/willfp/eco/core/data/ExternalDataStoreObjectAdapter.java

@@ -0,0 +1,69 @@
+package com.willfp.eco.core.data;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * An adapter for objects stored in {@link ExternalDataStore}.
+ *
+ * @param <A> The accessed class.
+ * @param <S> The stored class.
+ */
+public abstract class ExternalDataStoreObjectAdapter<A, S> {
+    /**
+     * The class that is accessed (read / written).
+     */
+    private final Class<? extends A> accessedClass;
+
+    /**
+     * The class that is stored internally.
+     */
+    private final Class<? extends S> storedClass;
+
+    /**
+     * Create a new adapter.
+     *
+     * @param accessedClass The class that is accessed (read / written).
+     * @param storedClass   The class that is stored internally.
+     */
+    protected ExternalDataStoreObjectAdapter(@NotNull final Class<? extends A> accessedClass,
+                                             @NotNull final Class<? extends S> storedClass) {
+        this.accessedClass = accessedClass;
+        this.storedClass = storedClass;
+    }
+
+    /**
+     * Convert an object to the stored object.
+     *
+     * @param obj The object.
+     * @return The stored object.
+     */
+    @NotNull
+    public abstract S toStoredObject(@NotNull final A obj);
+
+    /**
+     * Convert an object to the accessed object.
+     *
+     * @param obj The object.
+     * @return The accessed object.
+     */
+    @NotNull
+    public abstract A toAccessedObject(@NotNull final S obj);
+
+    /**
+     * Get the class that is accessed (read / written).
+     *
+     * @return The class.
+     */
+    public Class<? extends A> getAccessedClass() {
+        return accessedClass;
+    }
+
+    /**
+     * Get the class that is stored internally.
+     *
+     * @return The class.
+     */
+    public Class<? extends S> getStoredClass() {
+        return storedClass;
+    }
+}