/**
 * Copyright 2012-2019 The Feign Authors
 *
 * 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 feign.gson;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.TypeAdapter;
import com.google.gson.reflect.TypeToken;
import java.lang.reflect.Type;
import java.util.Map;
import static feign.Util.resolveLastTypeParameter;

final class GsonFactory {

  private GsonFactory() {}

  /**
   * Registers type adapters by implicit type. Adds one to read numbers in a {@code Map<String,
   * Object>} as Integers.
   */
  static Gson create(Iterable<TypeAdapter<?>> adapters) {
    GsonBuilder builder = new GsonBuilder().setPrettyPrinting();
    builder.registerTypeAdapter(new TypeToken<Map<String, Object>>() {}.getType(),
        new DoubleToIntMapTypeAdapter());
    for (TypeAdapter<?> adapter : adapters) {
      Type type = resolveLastTypeParameter(adapter.getClass(), TypeAdapter.class);
      builder.registerTypeAdapter(type, adapter);
    }
    return builder.create();
  }
}