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/*
 * SonarQube, open source software quality management tool.
 * Copyright (C) 2008-2014 SonarSource
 * mailto:contact AT sonarsource DOT com
 *
 * SonarQube is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * SonarQube is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.api.utils.text;

import org.sonar.api.utils.DateUtils;

import javax.annotation.Nullable;
import java.io.Writer;
import java.util.Date;
import java.util.Map;

/**
 * Writes JSON as a stream. This class allows plugins to not directly depend
 * on the underlying JSON library.
 * 
 * 
How to use
 *  *   StringWriter json = new StringWriter();
 *   JsonWriter writer = JsonWriter.of(json);
 *   writer
 *     .beginObject()
 *     .prop("aBoolean", true)
 *     .prop("aInt", 123)
 *     .prop("aString", "foo")
 *     .beginObject().name("aList")
 *       .beginArray()
 *         .beginObject().prop("key", "ABC").endObject()
 *         .beginObject().prop("key", "DEF").endObject()
 *       .endArray()
 *     .endObject()
 *     .close();
 * 
 *
 * @since 4.2
 */
public class JsonWriter {

  private final com.google.gson.stream.JsonWriter stream;

  private JsonWriter(Writer writer) {
    this.stream = new com.google.gson.stream.JsonWriter(writer);
    this.stream.setSerializeNulls(false);
    this.stream.setLenient(false);
  }

  // for unit testing
  JsonWriter(com.google.gson.stream.JsonWriter stream) {
    this.stream = stream;
  }

  public static JsonWriter of(Writer writer) {
    return new JsonWriter(writer);
  }

  /**
   * Begins encoding a new array. Each call to this method must be paired with
   * a call to {@link #endArray}. Output is [.
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter beginArray() {
    try {
      stream.beginArray();
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Ends encoding the current array. Output is ].
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter endArray() {
    try {
      stream.endArray();
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Begins encoding a new object. Each call to this method must be paired
   * with a call to {@link #endObject}. Output is {.
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter beginObject() {
    try {
      stream.beginObject();
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Ends encoding the current object. Output is }.
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter endObject() {
    try {
      stream.endObject();
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Encodes the property name. Output is "theName":.
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter name(String name) {
    try {
      stream.name(name);
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Encodes {@code value}. Output is true or false.
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter value(boolean value) {
    try {
      stream.value(value);
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter value(double value) {
    try {
      stream.value(value);
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter value(@Nullable String value) {
    try {
      stream.value(value);
      return this;
    } catch (Exception e) {
      throw rethrow(e);
    }
  }

  /**
   * Encodes an object that can be a :
   * 
   * primitive types: String, Number, Boolean
   * java.util.Date: encoded as datetime (see {@link #valueDateTime(java.util.Date)}
   * Map. Method toString is called for the key.
   * Iterable
   * 
   *
   * @throws org.sonar.api.utils.text.WriterException on any failure
   */
  public JsonWriter valueObject(@Nullable Object value) {
    try {
      if (value == null) {
        stream.nullValue();
      } else {
        if (value instanceof String) {
          stream.value((String) value);
        } else if (value instanceof Number) {
          stream.value((Number) value);
        } else if (value instanceof Boolean) {
          stream.value((Boolean) value);
        } else if (value instanceof Date) {
          valueDateTime((Date) value);
        } else if (value instanceof Map) {
          stream.beginObject();
          for (Map.Entry entry : ((Map) value).entrySet()) {
            stream.name(entry.getKey().toString());
            valueObject(entry.getValue());
          }
          stream.endObject();
        } else if (value instanceof Iterable) {
          stream.beginArray();
          for (Object o : (Iterable