1 files changed, 84 insertions, 0 deletions
diff --git a/src/main/java/gregtech/api/recipe/RecipeMetadataKey.java b/src/main/java/gregtech/api/recipe/RecipeMetadataKey.java
new file mode 100644
index 0000000000..2156421835
--- /dev/null
+++ b/src/main/java/gregtech/api/recipe/RecipeMetadataKey.java
@@ -0,0 +1,84 @@
+package gregtech.api.recipe;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.annotation.Nullable;
+import javax.annotation.ParametersAreNonnullByDefault;
+
+import org.jetbrains.annotations.Contract;
+
+import gregtech.api.recipe.metadata.IRecipeMetadataStorage;
+import gregtech.api.util.FieldsAreNonnullByDefault;
+import gregtech.api.util.MethodsReturnNonnullByDefault;
+import gregtech.nei.RecipeDisplayInfo;
+
+/**
+ * Unique key for the {@link IRecipeMetadataStorage}. It's also responsible for drawing metadata info on NEI.
+ * <p>
+ * You can use {@link gregtech.api.recipe.metadata.SimpleRecipeMetadataKey} if your metadata does not need NEI handling.
+ *
+ * @param <T> Type of the metadata to use.
+ */
+@ParametersAreNonnullByDefault
+@MethodsReturnNonnullByDefault
+@FieldsAreNonnullByDefault
+public abstract class RecipeMetadataKey<T> {
+
+    private static final Set<RecipeMetadataKey<?>> allIdentifiers = new HashSet<>();
+    private final Class<T> clazz;
+    private final String identifier;
+
+    protected RecipeMetadataKey(Class<T> clazz, String identifier) {
+        this.clazz = clazz;
+        this.identifier = identifier;
+        if (allIdentifiers.contains(this)) {
+            throw new IllegalArgumentException(
+                "Cannot register metadata key with exact same properties: " + identifier + "@" + clazz);
+        }
+        allIdentifiers.add(this);
+    }
+
+    /**
+     * Draws info about the metadata.
+     *
+     * @param recipeInfo Object to use for drawing text.
+     * @param value      Metadata stored in the recipe. Can be safely {@link #cast}ed to the desired type.
+     */
+    public abstract void drawInfo(RecipeDisplayInfo recipeInfo, @Nullable Object value);
+
+    @Nullable
+    public T cast(@Nullable Object o) {
+        return clazz.cast(o);
+    }
+
+    @Contract("_, !null -> !null")
+    @Nullable
+    public T cast(@Nullable Object o, @Nullable T defaultValue) {
+        T val = cast(o);
+        return val != null ? val : defaultValue;
+    }
+
+    @Override
+    public String toString() {
+        return "RecipeMetadataKey{" + "clazz=" + clazz.getName() + ", identifier=" + identifier + '\'' + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        RecipeMetadataKey<?> that = (RecipeMetadataKey<?>) o;
+
+        if (!clazz.equals(that.clazz)) return false;
+        return identifier.equals(that.identifier);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = clazz.hashCode();
+        result = 31 * result + identifier.hashCode();
+        return result;
+    }
+}