(function ($) {

Drupal.behaviors.dateAdmin = {};

Drupal.behaviors.dateAdmin.attach = function (context, settings) {
  // Remove timezone handling options for fields without hours granularity.
  var $hour = $('#edit-field-settings-granularity-hour').once('date-admin');
  if ($hour.length) {
    new Drupal.dateAdmin.TimezoneHandler($hour);
  }
};


Drupal.dateAdmin = {};

/**
 * Constructor for the TimezoneHandler object.
 *
 * This object is responsible for showing the timezone handling options dropdown
 * when the user has chosen to collect hours as part of the date field, and
 * hiding it otherwise.
 */
Drupal.dateAdmin.TimezoneHandler = function ($checkbox) {
  this.$checkbox = $checkbox;
  this.$dropdown = $('#edit-field-settings-tz-handling');
  this.$timezoneDiv = $('.form-item-field-settings-tz-handling');
  // Store the initial value of the timezone handling dropdown.
  this.storeTimezoneHandling();
  // Toggle the timezone handling section when the user clicks the "Hour"
  // checkbox.
  this.$checkbox.bind('click', $.proxy(this.clickHandler, this));
  // Trigger the click handler so that if the checkbox is unchecked on initial
  // page load, the timezone handling section will be hidden.
  this.clickHandler();
};

/**
 * Event handler triggered when the user clicks the "Hour" checkbox.
 */
Drupal.dateAdmin.TimezoneHandler.prototype.clickHandler = function () {
  if (this.$checkbox.is(':checked')) {
    this.restoreTimezoneHandlingOptions();
  }
  else {
    this.hideTimezoneHandlingOptions();
  }
};

/**
 * Hide the timezone handling options section of the form.
 */
Drupal.dateAdmin.TimezoneHandler.prototype.hideTimezoneHandlingOptions = function () {
  this.storeTimezoneHandling();
  this.$dropdown.val('none');
  this.$timezoneDiv.hide();
};

/**
 * Show the timezone handling options section of the form.
 */
Drupal.dateAdmin.TimezoneHandler.prototype.restoreTimezoneHandlingOptions = function () {
  var val = this.getTimezoneHandling();
  this.$dropdown.val(val);
  this.$timezoneDiv.show();
};

/**
 * Store the current value of the timezone handling dropdown.
 */
Drupal.dateAdmin.TimezoneHandler.prototype.storeTimezoneHandling = function () {
  this._timezoneHandling = this.$dropdown.val();
};

/**
 * Return the stored value of the timezone handling dropdown.
 */
Drupal.dateAdmin.TimezoneHandler.prototype.getTimezoneHandling = function () {
  return this._timezoneHandling;
};

})(jQuery);