/* ************************************************************************

   qooxdoo - the new era of web development

   http://qooxdoo.org

   Copyright:
     2004-2008 1&1 Internet AG, Germany, http://www.1und1.de

   License:
     LGPL: http://www.gnu.org/licenses/lgpl.html
     EPL: http://www.eclipse.org/org/documents/epl-v10.php
     See the LICENSE file in the project's top-level directory for details.

   Authors:
     * Sebastian Werner (wpbasti)
     * Fabian Jakobs (fjakobs)

************************************************************************ */

/* ************************************************************************

#require(qx.event.handler.UserAction)

************************************************************************ */

/**
 * This class performs the auto flush of all layout relevant queues.
 */
qx.Class.define("qx.ui.core.queue.Manager",
{
  statics :
  {
    /** {Boolean} Whether a flush was scheduled */
    __scheduled : false,


    /** {Map} Internal data structure for the current job list */
    __jobs : {},


    /** {Integer} Counts how often a flush failed due to exceptions */
    __retries : 0,

    /** {Integer} Maximum number of flush retries */
    MAX_RETRIES : 10,


    /**
     * Schedule a deferred flush of all queues.
     *
     * @param job {String} The job, which should be performed. Valid values are
     *     <code>layout</code>, <code>decoration</code> and <code>element</code>.
     * @return {void}
     */
    scheduleFlush : function(job)
    {
      // Sometimes not executed in context, fix this
      var self = qx.ui.core.queue.Manager;

      self.__jobs[job] = true;

      if (!self.__scheduled)
      {
        self.__deferredCall.schedule();
        self.__scheduled = true;
      }
    },


    /**
     * Flush all layout queues in the correct order. This function is called
     * deferred if {@link #scheduleFlush} is called.
     *
     * @return {void}
     */
    flush : function()
    {
      if (qx.ui.core.queue.Manager.PAUSE) {
        return;
      }

      // Sometimes not executed in context, fix this
      var self = qx.ui.core.queue.Manager;

      // Stop when already executed
      if (self.__inFlush) {
        return;
      }

      self.__inFlush = true;

      // Cancel timeout if called manually
      self.__deferredCall.cancel();

      var jobs = self.__jobs;

      self.__executeAndRescheduleOnError(function()
      {
        // Process jobs
        while (jobs.visibility || jobs.widget || jobs.appearance || jobs.layout || jobs.element)
        {
          // No else blocks here because each flush can influence the following flushes!
          if (jobs.widget)
          {
            delete jobs.widget;
            qx.ui.core.queue.Widget.flush();
          }

          if (jobs.visibility)
          {
            delete jobs.visibility;
            qx.ui.core.queue.Visibility.flush();
          }

          if (jobs.appearance)
          {
            delete jobs.appearance;
            qx.ui.core.queue.Appearance.flush();
          }

          // Defer layout as long as possible
          if (jobs.widget || jobs.visibility || jobs.appearance) {
            continue;
          }

          if (jobs.layout)
          {
            delete jobs.layout;
            qx.ui.core.queue.Layout.flush();
          }

          // Defer element as long as possible
          if (jobs.widget || jobs.visibility || jobs.appearance || jobs.layout) {
            continue;
          }

          if (jobs.element)
          {
            delete jobs.element;
            qx.html.Element.flush();
          }
        }
      }, function() {
        self.__scheduled = false;
      });

      self.__executeAndRescheduleOnError(function()
      {
        if (jobs.dispose)
        {
          delete jobs.dispose;
          qx.ui.core.queue.Dispose.flush();
        }
      }, function() {
        // Clear flag
        self.__inFlush = false;
      });

      // flush succeeded successfully. Reset retries
      self.__retries = 0;
    },


    /**
     * Executes the callback code. If the callback throws an error the current
     * flush is cleaned up and rescheduled. The finally code is called after the
     * callback even if it has thrown an exception.
     *
     * @signature function(callback, finallyCode)
     * @param callback {Function} the callback function
     * @param finallyCode {Function} function to be called in the finally block
     */
    __executeAndRescheduleOnError : qx.core.Environment.select("qx.debug",
    {
      "true" : function(callback, finallyCode)
      {
        callback();
        finallyCode();
      },


      "false" : function(callback, finallyCode)
      {
        var self = qx.ui.core.queue.Manager;

        try
        {
          callback();
        }
        catch (e)
        {
          if (qx.core.Environment.get("qx.debug")) {
            qx.log.Logger.error(
              "Error while layout flush: " + e + "\n" +
              "Stack trace: \n" +
              qx.dev.StackTrace.getStackTraceFromError(e)
            );
          }
          self.__scheduled = false;
          self.__inFlush = false;
          self.__retries += 1;

          // this hack is used to fix [BUG #3688]
          if(
            qx.core.Environment.get("browser.name") == 'ie' &&
            qx.core.Environment.get("browser.version") <= 7
          ) {
            finallyCode();
          }

          if (self.__retries <= self.MAX_RETRIES) {
            self.scheduleFlush();
          } else {
            throw new Error(
              "Fatal Error: Flush terminated " + (self.__retries-1) + " times in a row" +
              " due to exceptions in user code. The application has to be reloaded!"
            );
          }

          throw e;
        }
        finally
        {
          finallyCode();
        }
      }
    }),


    /**
     * Handler used on touch devices to prevent the queue from manipulating
     * the dom during the touch - mouse - ... event sequence. Usually, iOS
     * devices fire a click event 300ms after the touchend event. So using
     * 500ms should be a good value to be on the save side. This is necessary
     * due to the fact that the event chain is stopped if a manipulation in
     * the DOM is done.
     *
     * @param e {qx.event.type.Data} The user action data event.
     */
    __onUserAction : function(e)
    {
      var statics = qx.ui.core.queue.Manager;
      // pospone the flush for 500ms due to the fact that iOS stops firing
      // events if the dom gets changed during the vent chain [BUG #4033]
      if (e.getData() == "touchend")
      {
        statics.PAUSE = true;
        if (statics.__pauseTimeout) {
          window.clearTimeout(statics.__pauseTimeout);
        }
        statics.__pauseTimeout = window.setTimeout(function()
        {
          statics.PAUSE = false;
          statics.__pauseTimeout = null;
          statics.flush();
        }, 500);
      } else {
        statics.flush();
      }
    }
  },




  /*
  *****************************************************************************
     DESTRUCT
  *****************************************************************************
  */

  defer : function(statics)
  {
    // Initialize deferred call
    statics.__deferredCall = new qx.util.DeferredCall(statics.flush);

    // Replace default scheduler for HTML element with local one.
    // This is quite a hack, but allows us to force other flushes
    // before the HTML element flush.
    qx.html.Element._scheduleFlush = statics.scheduleFlush;

    // Register to user action
    qx.event.Registration.addListener(window, "useraction",
      qx.core.Environment.get("event.touch") ?
        statics.__onUserAction : statics.flush
    );
  }
});
