/**
 * Copyright 2013 Facebook, 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.
 *
 * @providesModule ReactMarkupChecksum
 */

"use strict";

var adler32 = require('adler32');

var ReactMarkupChecksum = {
  CHECKSUM_ATTR_NAME: 'data-react-checksum',

  /**
   * @param {string} markup Markup string
   * @return {string} Markup string with checksum attribute attached
   */
  addChecksumToMarkup: function(markup) {
    var checksum = adler32(markup);
    return markup.replace(
      '>',
      ' ' + ReactMarkupChecksum.CHECKSUM_ATTR_NAME + '="' + checksum + '">'
    );
  },

  /**
   * @param {string} markup to use
   * @param {DOMElement} element root React element
   * @returns {boolean} whether or not the markup is the same
   */
  canReuseMarkup: function(markup, element) {
    var existingChecksum = element.getAttribute(
      ReactMarkupChecksum.CHECKSUM_ATTR_NAME
    );
    existingChecksum = existingChecksum && parseInt(existingChecksum, 10);
    var markupChecksum = adler32(markup);
    return markupChecksum === existingChecksum;
  }
};

module.exports = ReactMarkupChecksum;
