/**
 * Copyright 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.
 *
 *
 *
 * @provides fb.qs
 * @requires fb.prelude
 */

/**
 * Query String encoding & decoding.
 *
 * @class FB.QS
 * @static
 * @access private
 */
FB.copy('QS', {
  /**
   * Encode parameters to a query string.
   *
   * @access private
   * @param   params {Object}  the parameters to encode
   * @param   sep    {String}  the separator string (defaults to '&')
   * @param   encode {Boolean} indicate if the key/value should be URI encoded
   * @return        {String}  the query string
   */
  encode: function(params, sep, encode) {
    sep    = sep === undefined ? '&' : sep;
    encode = encode === false ? function(s) { return s; } : encodeURIComponent;

    var
      pairs = [],
      k;

    for (k in params) {
      if (params.hasOwnProperty(k) &&
          params[k] !== null &&
          typeof params[k] != 'undefined') {
        pairs.push(encode(k) + '=' + encode(params[k]));
      }
    }
    pairs.sort();
    return pairs.join(sep);
  },

  /**
   * Decode a query string into a parameters object.
   *
   * @access private
   * @param   str {String} the query string
   * @return     {Object} the parameters to encode
   */
  decode: function(str) {
    var
      decode = decodeURIComponent,
      params = {},
      parts  = str.split('&'),
      i,
      pair;

    for (i=0; i<parts.length; i++) {
      pair = parts[i].split('=', 2);
      if (pair && pair[0]) {
        params[decode(pair[0])] = decode(pair[1]);
      }
    }

    return params;
  }
});