// Copyright (C) 2015 The Android Open Source Project
//
// 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 com.googlesource.gerrit.plugins.manager.gson;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.gson.JsonElement;

public class SmartJson {

  private final JsonElement jsonElem;

  private SmartJson(JsonElement elem) {
    this.jsonElem = elem;
  }

  public static SmartJson of(JsonElement fromJson) {
    return new SmartJson(fromJson);
  }

  public Optional<String> getOptionalString(String fieldName) {
    return getOptional(fieldName).transform(new Function<SmartJson, String>() {
      @Override
      public String apply(SmartJson elem) {
        if (!elem.jsonElem.isJsonPrimitive()) {
          throw new IllegalArgumentException("cannot convert " + elem.jsonElem
              + " into a String");
        }
        return elem.jsonElem.getAsString();
      }
    });
  }

  public String getString(String fieldName) {
    return getOptionalString(fieldName).or("");
  }

  public Optional<SmartJson> getOptional(String fieldName) {
    if (jsonElem != null && jsonElem.getAsJsonObject().get(fieldName) != null) {
      return Optional.of(SmartJson
          .of(jsonElem.getAsJsonObject().get(fieldName)));
    } else {
      return Optional.absent();
    }
  }

  public SmartJson get(String fieldName) {
    return getOptional(fieldName).get();
  }

  public JsonElement get() {
    return jsonElem;
  }
}