/**
 * @file auto_submit.js
 *
 * Provides a "form auto-submit" feature for the Better Exposed Filters module.
 */

(function ($, Drupal) {

  /**
   * To make a form auto submit, all you have to do is 3 things:
   *
   * Use the "better_exposed_filters/auto_submit" js library.
   *
   * On gadgets you want to auto-submit when changed, add the
   * data-bef-auto-submit attribute. With FAPI, add:
   * @code
   *  '#attributes' => array('data-bef-auto-submit' => ''),
   * @endcode
   *
   * If you want to have auto-submit for every form element, add the
   * data-bef-auto-submit-full-form to the form. With FAPI, add:
   * @code
   *   '#attributes' => array('data-bef-auto-submit-full-form' => ''),
   * @endcode
   *
   * If you want to exclude a field from the bef-auto-submit-full-form auto
   * submission, add an attribute of data-bef-auto-submit-exclude to the form
   * element. With FAPI, add:
   * @code
   *   '#attributes' => array('data-bef-auto-submit-exclude' => ''),
   * @endcode
   *
   * Finally, you have to identify which button you want clicked for autosubmit.
   * The behavior of this button will be honored if it's ajaxy or not:
   * @code
   *  '#attributes' => array('data-bef-auto-submit-click' => ''),
   * @endcode
   *
   * Currently only 'select', 'radio', 'checkbox' and 'textfield' types are
   * supported. We probably could use additional support for HTML5 input types.
   */
  Drupal.behaviors.betterExposedFiltersAutoSubmit = {
    attach: function(context) {
      // e.keyCode: key
      var ignoredKeyCodes = [
        16, // shift
        17, // ctrl
        18, // alt
        20, // caps lock
        33, // page up
        34, // page down
        35, // end
        36, // home
        37, // left arrow
        38, // up arrow
        39, // right arrow
        40, // down arrow
        9, // tab
        13, // enter
        27  // esc
      ];

      // When exposed as a block, the form #attributes are moved from the form
      // to the block element, thus the second selector.
      // @see \Drupal\block\BlockViewBuilder::preRender
      var selectors = 'form[data-bef-auto-submit-full-form], [data-bef-auto-submit-full-form] form, [data-bef-auto-submit]';

      function triggerSubmit ($target) {
        $target.closest('form').find('[data-bef-auto-submit-click]').click();
      }

      // The change event bubbles so we only need to bind it to the outer form
      // in case of a full form, or a single element when specified explicitly.
      $(selectors, context).addBack(selectors).once('bef-auto-submit').on('change keyup keypress', function (e) {
        var $target = $(e.target);

        // Don't submit on changes to excluded elements or a submit element.
        if ($target.is('[data-bef-auto-submit-exclude], :submit')) {
          return true;
        }
        // Use debounce to prevent excessive submits on text field changes.
        // Navigation key presses are ignored.
        else if ($target.is(':text:not(.hasDatepicker), textarea') && $.inArray(e.keyCode, ignoredKeyCodes) === -1) {
          Drupal.debounce(triggerSubmit, 500)($target);
        }
        // Only trigger submit if a change was the trigger (no keyup).
        else if (e.type === 'change') {
          triggerSubmit($target);
        }
      });
    }
  }

}(jQuery, Drupal));