/**
 * 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.cookie
 * @requires fb.prelude
 *           fb.qs
 *           fb.event
 */

/**
 * Cookie Support.
 *
 * @class FB.Cookie
 * @static
 * @access private
 */
FB.provide('Cookie', {
  /**
   * Holds the base_domain property to match the Cookie domain.
   *
   * @access private
   * @type String
   */
  _domain: null,

  /**
   * Indicate if Cookie support should be enabled.
   *
   * @access private
   * @type Boolean
   */
  _enabled: false,

  /**
   * Enable or disable Cookie support.
   *
   * @access private
   * @param val {Boolean} true to enable, false to disable
   */
  setEnabled: function(val) {
    FB.Cookie._enabled = val;
  },

  /**
   * Return the current status of the cookie system.
   *
   * @access private
   * @returns {Boolean} true if Cookie support is enabled
   */
  getEnabled: function() {
    return FB.Cookie._enabled;
  },

  /**
   * Try loading the session from the Cookie.
   *
   * @access private
   * @return {Object} the session object from the cookie if one is found
   */
  load: function() {
    var
      // note, we have the opening quote for the value in the regex, but do
      // not have a closing quote. this is because the \b already handles it.
      cookie = document.cookie.match('\\bfbs_' + FB._apiKey + '="([^;]*)\\b'),
      session;

    if (cookie) {
      // url encoded session stored as "sub-cookies"
      session = FB.QS.decode(cookie[1]);
      // decodes as a string, convert to a number
      session.expires = parseInt(session.expires, 10);
      // capture base_domain for use when we need to clear
      FB.Cookie._domain = session.base_domain;
    }

    return session;
  },

  /**
   * Helper function to set cookie value.
   *
   * @access private
   * @param val    {String} the string value (should already be encoded)
   * @param ts     {Number} a unix timestamp denoting expiry
   * @param domain {String} optional domain for cookie
   */
  setRaw: function(val, ts, domain) {
    document.cookie =
      'fbs_' + FB._apiKey + '="' + val + '"' +
      (val && ts == 0 ? '' : '; expires=' + new Date(ts * 1000).toGMTString()) +
      '; path=/' +
      (domain ? '; domain=.' + domain : '');

    // capture domain for use when we need to clear
    FB.Cookie._domain = domain;
  },

  /**
   * Set the cookie using the given session object.
   *
   * @access private
   * @param session {Object} the session object
   */
  set: function(session) {
    session
      ? FB.Cookie.setRaw(
          FB.QS.encode(session),
          session.expires,
          session.base_domain)
      : FB.Cookie.clear();
  },

  /**
   * Clear the cookie.
   *
   * @access private
   */
  clear: function() {
    FB.Cookie.setRaw('', 0, FB.Cookie._domain);
  }
});