/**
 * @file
 * Define vertical tabs functionality.
 */

/**
 * Triggers when form values inside a vertical tab changes.
 *
 * This is used to update the summary in vertical tabs in order to know what
 * are the important fields' values.
 *
 * @event summaryUpdated
 */

(function($, Drupal, drupalSettings) {
  /**
   * Show the parent vertical tab pane of a targeted page fragment.
   *
   * In order to make sure a targeted element inside a vertical tab pane is
   * visible on a hash change or fragment link click, show all parent panes.
   *
   * @param {jQuery.Event} e
   *   The event triggered.
   * @param {jQuery} $target
   *   The targeted node as a jQuery object.
   */
  const handleFragmentLinkClickOrHashChange = (e, $target) => {
    $target.parents('.vertical-tabs__pane').each((index, pane) => {
      $(pane)
        .data('verticalTab')
        .focus();
    });
  };

  /**
   * This script transforms a set of details into a stack of vertical tabs.
   *
   * Each tab may have a summary which can be updated by another
   * script. For that to work, each details element has an associated
   * 'verticalTabCallback' (with jQuery.data() attached to the details),
   * which is called every time the user performs an update to a form
   * element inside the tab pane.
   *
   * @type {Drupal~behavior}
   *
   * @prop {Drupal~behaviorAttach} attach
   *   Attaches behaviors for vertical tabs.
   */
  Drupal.behaviors.verticalTabs = {
    attach(context) {
      const width = drupalSettings.widthBreakpoint || 640;
      const mq = `(max-width: ${width}px)`;

      if (window.matchMedia(mq).matches) {
        return;
      }

      /**
       * Binds a listener to handle fragment link clicks and URL hash changes.
       */
      $('body')
        .once('vertical-tabs-fragments')
        .on(
          'formFragmentLinkClickOrHashChange.verticalTabs',
          handleFragmentLinkClickOrHashChange,
        );

      $(context)
        .find('[data-vertical-tabs-panes]')
        .once('vertical-tabs')
        .each(function() {
          const $this = $(this).addClass('vertical-tabs__panes');
          const focusID = $this.find(':hidden.vertical-tabs__active-tab').val();
          let tabFocus;

          // Check if there are some details that can be converted to
          // vertical-tabs.
          const $details = $this.find('> details');
          if ($details.length === 0) {
            return;
          }

          // Create the tab column.
          const tabList = $('<ul class="vertical-tabs__menu"></ul>');
          $this
            .wrap('<div class="vertical-tabs clearfix"></div>')
            .before(tabList);

          // Transform each details into a tab.
          $details.each(function() {
            const $that = $(this);
            const verticalTab = new Drupal.verticalTab({
              title: $that.find('> summary').text(),
              details: $that,
            });
            tabList.append(verticalTab.item);
            $that
              .removeClass('collapsed')
              // prop() can't be used on browsers not supporting details element,
              // the style won't apply to them if prop() is used.
              .attr('open', true)
              .addClass('vertical-tabs__pane')
              .data('verticalTab', verticalTab);
            if (this.id === focusID) {
              tabFocus = $that;
            }
          });

          $(tabList)
            .find('> li')
            .eq(0)
            .addClass('first');
          $(tabList)
            .find('> li')
            .eq(-1)
            .addClass('last');

          if (!tabFocus) {
            // If the current URL has a fragment and one of the tabs contains an
            // element that matches the URL fragment, activate that tab.
            const $locationHash = $this.find(window.location.hash);
            if (window.location.hash && $locationHash.length) {
              tabFocus = $locationHash.closest('.vertical-tabs__pane');
            } else {
              tabFocus = $this.find('> .vertical-tabs__pane').eq(0);
            }
          }
          if (tabFocus.length) {
            tabFocus.data('verticalTab').focus();
          }
        });
    },
  };

  /**
   * The vertical tab object represents a single tab within a tab group.
   *
   * @constructor
   *
   * @param {object} settings
   *   Settings object.
   * @param {string} settings.title
   *   The name of the tab.
   * @param {jQuery} settings.details
   *   The jQuery object of the details element that is the tab pane.
   *
   * @fires event:summaryUpdated
   *
   * @listens event:summaryUpdated
   */
  Drupal.verticalTab = function(settings) {
    const self = this;
    $.extend(this, settings, Drupal.theme('verticalTab', settings));

    this.link.attr('href', `#${settings.details.attr('id')}`);

    this.link.on('click', e => {
      e.preventDefault();
      self.focus();
    });

    // Keyboard events added:
    // Pressing the Enter key will open the tab pane.
    this.link.on('keydown', event => {
      if (event.keyCode === 13) {
        event.preventDefault();
        self.focus();
        // Set focus on the first input field of the visible details/tab pane.
        $('.vertical-tabs__pane :input:visible:enabled')
          .eq(0)
          .trigger('focus');
      }
    });

    this.details
      .on('summaryUpdated', () => {
        self.updateSummary();
      })
      .trigger('summaryUpdated');
  };

  Drupal.verticalTab.prototype = {
    /**
     * Displays the tab's content pane.
     */
    focus() {
      this.details
        .siblings('.vertical-tabs__pane')
        .each(function() {
          const tab = $(this).data('verticalTab');
          tab.details.hide();
          tab.item.removeClass('is-selected');
        })
        .end()
        .show()
        .siblings(':hidden.vertical-tabs__active-tab')
        .val(this.details.attr('id'));
      this.item.addClass('is-selected');
      // Mark the active tab for screen readers.
      $('#active-vertical-tab').remove();
      this.link.append(
        `<span id="active-vertical-tab" class="visually-hidden">${Drupal.t(
          '(active tab)',
        )}</span>`,
      );
    },

    /**
     * Updates the tab's summary.
     */
    updateSummary() {
      this.summary.html(this.details.drupalGetSummary());
    },

    /**
     * Shows a vertical tab pane.
     *
     * @return {Drupal.verticalTab}
     *   The verticalTab instance.
     */
    tabShow() {
      // Display the tab.
      this.item.show();
      // Show the vertical tabs.
      this.item.closest('.js-form-type-vertical-tabs').show();
      // Update .first marker for items. We need recurse from parent to retain
      // the actual DOM element order as jQuery implements sortOrder, but not
      // as public method.
      this.item
        .parent()
        .children('.vertical-tabs__menu-item')
        .removeClass('first')
        .filter(':visible')
        .eq(0)
        .addClass('first');
      // Display the details element.
      this.details.removeClass('vertical-tab--hidden').show();
      // Focus this tab.
      this.focus();
      return this;
    },

    /**
     * Hides a vertical tab pane.
     *
     * @return {Drupal.verticalTab}
     *   The verticalTab instance.
     */
    tabHide() {
      // Hide this tab.
      this.item.hide();
      // Update .first marker for items. We need recurse from parent to retain
      // the actual DOM element order as jQuery implements sortOrder, but not
      // as public method.
      this.item
        .parent()
        .children('.vertical-tabs__menu-item')
        .removeClass('first')
        .filter(':visible')
        .eq(0)
        .addClass('first');
      // Hide the details element.
      this.details.addClass('vertical-tab--hidden').hide();
      // Focus the first visible tab (if there is one).
      const $firstTab = this.details
        .siblings('.vertical-tabs__pane:not(.vertical-tab--hidden)')
        .eq(0);
      if ($firstTab.length) {
        $firstTab.data('verticalTab').focus();
      }
      // Hide the vertical tabs (if no tabs remain).
      else {
        this.item.closest('.js-form-type-vertical-tabs').hide();
      }
      return this;
    },
  };

  /**
   * Theme function for a vertical tab.
   *
   * @param {object} settings
   *   An object with the following keys:
   * @param {string} settings.title
   *   The name of the tab.
   *
   * @return {object}
   *   This function has to return an object with at least these keys:
   *   - item: The root tab jQuery element
   *   - link: The anchor tag that acts as the clickable area of the tab
   *       (jQuery version)
   *   - summary: The jQuery element that contains the tab summary
   */
  Drupal.theme.verticalTab = function(settings) {
    const tab = {};
    tab.item = $(
      '<li class="vertical-tabs__menu-item" tabindex="-1"></li>',
    ).append(
      (tab.link = $('<a href="#"></a>')
        .append(
          (tab.title = $(
            '<strong class="vertical-tabs__menu-item-title"></strong>',
          ).text(settings.title)),
        )
        .append(
          (tab.summary = $(
            '<span class="vertical-tabs__menu-item-summary"></span>',
          )),
        )),
    );
    return tab;
  };
})(jQuery, Drupal, drupalSettings);
