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/*
 * Copyright 2013-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 org.qas.api.internal.util.json;

import org.qas.api.AuthClientException;

import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.LinkedList;
import java.util.List;

/**
 * Jsons
 *
 * @author Dzung Nguyen
 * @version $Id Jsons 2014-03-27 09:52:30z dungvnguyen $
 * @since 1.0
 */
public final class Jsons {
  //~ class members ===========================================================
  private Jsons() {
    throw new AssertionError("The Jsons utilities must not be instantiated.");
  }

  /**
   * Load a JSON string into an instantiated object. All the public fields of the object will
   * be set by the values in the JSON string associated with the field name.

   * Because of the naming convention in Java, the first letter of the field name will be capitalized
   * for another look-up in the JSON, if the original field name is not found.
   * @param clazz Class of the object which the JSON string would be loaded into.
   * @param source JSON string.
   * @return An instantiated object of the given Class
   * @throws JsonException
   */
  public static  T toObject (Class clazz, String source) throws JsonException {
    JsonObject jsonObect = new JsonObject(source);
    try {
      return toObject(clazz, jsonObect);
    } catch (Exception e) {
      throw new JsonException(e);
    }
  }

  private static  T toObject(Class clazz, JsonObject jsonObject) throws JsonException, IllegalArgumentException, IllegalAccessException {
    T newObject;
    try {
      newObject = createInstance(clazz);
    } catch (Exception e){
      throw new AuthClientException("Failed to instantiate class", e);
    }
    for (Field objectField : clazz.getFields()) {
      String fieldName = objectField.getName();
      Class fieldType = objectField.getType();
      Object fieldValue;
      try {
        fieldValue = parseField(jsonObject, fieldType, fieldName);
      } catch (Exception e) {
        fieldValue = parseField(jsonObject, fieldType, fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1));
      }
      objectField.set(newObject, fieldValue);
    }
    return newObject;
  }

  /**
   * Get the value associated with a key, and parse it according to the provided Class.
   */
  private static Object parseField(JsonObject jsonObject, Class clazz, String key) throws JsonException, IllegalArgumentException, IllegalAccessException {
    // Boolean
    if (clazz.equals(Boolean.class) || clazz.equals(boolean.class))
      return jsonObject.getBoolean(key);
      // Double
    else if (clazz.equals(Double.class) || clazz.equals(double.class))
      return jsonObject.getDouble(key);
      // Integer
    else if (clazz.equals(Integer.class) || clazz.equals(int.class))
      return jsonObject.getInt(key);
      // Long
    else if (clazz.equals(Long.class) || clazz.equals(long.class))
      return jsonObject.getLong(key);
      // String
    else if (clazz.equals(String.class))
      return jsonObject.getString(key);
      // Char
    else if (clazz.equals(Character.class) || clazz.equals(char.class))
      return jsonObject.getString(key).charAt(0);
      // Array
    else if (clazz.isArray()) {
      Class componentType = clazz.getComponentType();
      JsonArray jsonArray = jsonObject.getJsonArray(key);
      Object array = Array.newInstance(componentType, jsonArray.length());
      for (int i = 0; i < jsonArray.length(); i++) {
        Array.set(array, i, parseField(jsonArray, componentType, i));
      }
      return array;
    }
    // Handled as a nested Class object
    else {
      JsonObject nestedObject = jsonObject.getJsonObject(key);
      return toObject(clazz, nestedObject);
    }
  }

  /**
   * Get the value associated with an index, and parse it according to the provided Class.
   */
  private static Object parseField(JsonArray jsonArray, Class clazz, int index) throws JsonException, IllegalArgumentException, IllegalAccessException {
    // Boolean
    if (clazz.equals(Boolean.class) || clazz.equals(boolean.class))
      return jsonArray.getBoolean(index);
      // Double
    else if (clazz.equals(Double.class) || clazz.equals(double.class))
      return jsonArray.getDouble(index);
      // Integer
    else if (clazz.equals(Integer.class) || clazz.equals(int.class))
      return jsonArray.getInt(index);
      // Long
    else if (clazz.equals(Long.class) || clazz.equals(long.class))
      return jsonArray.getLong(index);
      // String
    else if (clazz.equals(String.class))
      return jsonArray.getString(index);
      // Char
    else if (clazz.equals(Character.class) || clazz.equals(char.class))
      return jsonArray.getString(index).charAt(0);
      // Array
    else if (clazz.isArray()) {
      Class componentType = clazz.getComponentType();
      JsonArray nestedJSONArray = jsonArray.getJsonArray(index);
      List