(function ($) {

/**

 * A progressbar object. Initialized with the given id. Must be inserted into

 * the DOM afterwards through progressBar.element.

 *

 * method is the function which will perform the HTTP request to get the

 * progress bar state. Either "GET" or "POST".

 *

 * e.g. pb = new progressBar('myProgressBar');

 *      some_element.appendChild(pb.element);

 */

Drupal.progressBar = function (id, updateCallback, method, errorCallback) {

  var pb = this;

  this.id = id;

  this.method = method || 'GET';

  this.updateCallback = updateCallback;

  this.errorCallback = errorCallback;

  // The WAI-ARIA setting aria-live="polite" will announce changes after users

  // have completed their current activity and not interrupt the screen reader.

  this.element = $('<div class="progress" aria-live="polite"></div>').attr('id', id);

  this.element.html('<div class="bar"><div class="filled"></div></div>' +

                    '<div class="percentage"></div>' +

                    '<div class="message">&nbsp;</div>');

};

/**

 * Set the percentage and status message for the progressbar.

 */

Drupal.progressBar.prototype.setProgress = function (percentage, message) {

  if (percentage >= 0 && percentage <= 100) {

    $('div.filled', this.element).css('width', percentage + '%');

    $('div.percentage', this.element).html(percentage + '%');

  }

  $('div.message', this.element).html(message);

  if (this.updateCallback) {

    this.updateCallback(percentage, message, this);

  }

};

/**

 * Start monitoring progress via Ajax.

 */

Drupal.progressBar.prototype.startMonitoring = function (uri, delay) {

  this.delay = delay;

  this.uri = uri;

  this.sendPing();

};

/**

 * Stop monitoring progress via Ajax.

 */

Drupal.progressBar.prototype.stopMonitoring = function () {

  clearTimeout(this.timer);

  // This allows monitoring to be stopped from within the callback.

  this.uri = null;

};

/**

 * Request progress data from server.

 */

Drupal.progressBar.prototype.sendPing = function () {

  if (this.timer) {

    clearTimeout(this.timer);

  }

  if (this.uri) {

    var pb = this;

    // When doing a post request, you need non-null data. Otherwise a

    // HTTP 411 or HTTP 406 (with Apache mod_security) error may result.

    $.ajax({

      type: this.method,

      url: this.uri,

      data: '',

      dataType: 'json',

      success: function (progress) {

        // Display errors.

        if (progress.status == 0) {

          pb.displayError(progress.data);

          return;

        }

        // Update display.

        pb.setProgress(progress.percentage, progress.message);

        // Schedule next timer.

        pb.timer = setTimeout(function () { pb.sendPing(); }, pb.delay);

      },

      error: function (xmlhttp) {

        pb.displayError(Drupal.ajaxError(xmlhttp, pb.uri));

      }

    });

  }

};

/**

 * Display errors on the page.

 */

Drupal.progressBar.prototype.displayError = function (string) {

  var error = $('<div class="messages error"></div>').html(string);

  $(this.element).before(error).hide();

  if (this.errorCallback) {

    this.errorCallback(this);

  }

};

})(jQuery);