/*
 * Copyright (C) 2014 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.emay.sdk.util.json.gson.internal.bind;

import cn.emay.sdk.util.json.gson.Gson;
import cn.emay.sdk.util.json.gson.TypeAdapter;
import cn.emay.sdk.util.json.gson.TypeAdapterFactory;
import cn.emay.sdk.util.json.gson.annotations.JsonAdapter;
import cn.emay.sdk.util.json.gson.internal.ConstructorConstructor;
import cn.emay.sdk.util.json.gson.reflect.TypeToken;

/**
 * Given a type T, looks for the annotation {@link JsonAdapter} and uses an
 * instance of the specified class as the default type adapter.
 *
 * @since 2.3
 */
public final class JsonAdapterAnnotationTypeAdapterFactory implements TypeAdapterFactory {

	private final ConstructorConstructor constructorConstructor;

	public JsonAdapterAnnotationTypeAdapterFactory(ConstructorConstructor constructorConstructor) {
		this.constructorConstructor = constructorConstructor;
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
		JsonAdapter annotation = targetType.getRawType().getAnnotation(JsonAdapter.class);
		if (annotation == null) {
			return null;
		}
		return (TypeAdapter<T>) getTypeAdapter(constructorConstructor, gson, targetType, annotation);
	}

	@SuppressWarnings("unchecked") // Casts guarded by conditionals.
	static TypeAdapter<?> getTypeAdapter(ConstructorConstructor constructorConstructor, Gson gson, TypeToken<?> fieldType, JsonAdapter annotation) {
		Class<?> value = annotation.value();
		TypeAdapter<?> typeAdapter;
		if (TypeAdapter.class.isAssignableFrom(value)) {
			Class<TypeAdapter<?>> typeAdapterClass = (Class<TypeAdapter<?>>) value;
			typeAdapter = constructorConstructor.get(TypeToken.get(typeAdapterClass)).construct();
		} else if (TypeAdapterFactory.class.isAssignableFrom(value)) {
			Class<TypeAdapterFactory> typeAdapterFactory = (Class<TypeAdapterFactory>) value;
			typeAdapter = constructorConstructor.get(TypeToken.get(typeAdapterFactory)).construct().create(gson, fieldType);
		} else {
			throw new IllegalArgumentException("@JsonAdapter value must be TypeAdapter or TypeAdapterFactory reference.");
		}
		if (typeAdapter != null) {
			typeAdapter = typeAdapter.nullSafe();
		}
		return typeAdapter;
	}
}