Chris@0: /**
Chris@0:  * @file
Chris@0:  * Manages page tabbing modifications made by modules.
Chris@0:  */
Chris@0: 
Chris@0: /**
Chris@0:  * Allow modules to respond to the constrain event.
Chris@0:  *
Chris@0:  * @event drupalTabbingConstrained
Chris@0:  */
Chris@0: 
Chris@0: /**
Chris@0:  * Allow modules to respond to the tabbingContext release event.
Chris@0:  *
Chris@0:  * @event drupalTabbingContextReleased
Chris@0:  */
Chris@0: 
Chris@0: /**
Chris@0:  * Allow modules to respond to the constrain event.
Chris@0:  *
Chris@0:  * @event drupalTabbingContextActivated
Chris@0:  */
Chris@0: 
Chris@0: /**
Chris@0:  * Allow modules to respond to the constrain event.
Chris@0:  *
Chris@0:  * @event drupalTabbingContextDeactivated
Chris@0:  */
Chris@0: 
Chris@0: (function ($, Drupal) {
Chris@0:   /**
Chris@0:    * Provides an API for managing page tabbing order modifications.
Chris@0:    *
Chris@0:    * @constructor Drupal~TabbingManager
Chris@0:    */
Chris@0:   function TabbingManager() {
Chris@0:     /**
Chris@0:      * Tabbing sets are stored as a stack. The active set is at the top of the
Chris@0:      * stack. We use a JavaScript array as if it were a stack; we consider the
Chris@0:      * first element to be the bottom and the last element to be the top. This
Chris@0:      * allows us to use JavaScript's built-in Array.push() and Array.pop()
Chris@0:      * methods.
Chris@0:      *
Chris@0:      * @type {Array.<Drupal~TabbingContext>}
Chris@0:      */
Chris@0:     this.stack = [];
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Add public methods to the TabbingManager class.
Chris@0:    */
Chris@0:   $.extend(TabbingManager.prototype, /** @lends Drupal~TabbingManager# */{
Chris@0: 
Chris@0:     /**
Chris@0:      * Constrain tabbing to the specified set of elements only.
Chris@0:      *
Chris@0:      * Makes elements outside of the specified set of elements unreachable via
Chris@0:      * the tab key.
Chris@0:      *
Chris@0:      * @param {jQuery} elements
Chris@0:      *   The set of elements to which tabbing should be constrained. Can also
Chris@0:      *   be a jQuery-compatible selector string.
Chris@0:      *
Chris@0:      * @return {Drupal~TabbingContext}
Chris@0:      *   The TabbingContext instance.
Chris@0:      *
Chris@0:      * @fires event:drupalTabbingConstrained
Chris@0:      */
Chris@0:     constrain(elements) {
Chris@0:       // Deactivate all tabbingContexts to prepare for the new constraint. A
Chris@0:       // tabbingContext instance will only be reactivated if the stack is
Chris@0:       // unwound to it in the _unwindStack() method.
Chris@0:       const il = this.stack.length;
Chris@0:       for (let i = 0; i < il; i++) {
Chris@0:         this.stack[i].deactivate();
Chris@0:       }
Chris@0: 
Chris@0:       // The "active tabbing set" are the elements tabbing should be constrained
Chris@0:       // to.
Chris@0:       const $elements = $(elements).find(':tabbable').addBack(':tabbable');
Chris@0: 
Chris@0:       const tabbingContext = new TabbingContext({
Chris@0:         // The level is the current height of the stack before this new
Chris@0:         // tabbingContext is pushed on top of the stack.
Chris@0:         level: this.stack.length,
Chris@0:         $tabbableElements: $elements,
Chris@0:       });
Chris@0: 
Chris@0:       this.stack.push(tabbingContext);
Chris@0: 
Chris@0:       // Activates the tabbingContext; this will manipulate the DOM to constrain
Chris@0:       // tabbing.
Chris@0:       tabbingContext.activate();
Chris@0: 
Chris@0:       // Allow modules to respond to the constrain event.
Chris@0:       $(document).trigger('drupalTabbingConstrained', tabbingContext);
Chris@0: 
Chris@0:       return tabbingContext;
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Restores a former tabbingContext when an active one is released.
Chris@0:      *
Chris@0:      * The TabbingManager stack of tabbingContext instances will be unwound
Chris@0:      * from the top-most released tabbingContext down to the first non-released
Chris@0:      * tabbingContext instance. This non-released instance is then activated.
Chris@0:      */
Chris@0:     release() {
Chris@0:       // Unwind as far as possible: find the topmost non-released
Chris@0:       // tabbingContext.
Chris@0:       let toActivate = this.stack.length - 1;
Chris@0:       while (toActivate >= 0 && this.stack[toActivate].released) {
Chris@0:         toActivate--;
Chris@0:       }
Chris@0: 
Chris@0:       // Delete all tabbingContexts after the to be activated one. They have
Chris@0:       // already been deactivated, so their effect on the DOM has been reversed.
Chris@0:       this.stack.splice(toActivate + 1);
Chris@0: 
Chris@0:       // Get topmost tabbingContext, if one exists, and activate it.
Chris@0:       if (toActivate >= 0) {
Chris@0:         this.stack[toActivate].activate();
Chris@0:       }
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Makes all elements outside of the tabbingContext's set untabbable.
Chris@0:      *
Chris@0:      * Elements made untabbable have their original tabindex and autofocus
Chris@0:      * values stored so that they might be restored later when this
Chris@0:      * tabbingContext is deactivated.
Chris@0:      *
Chris@0:      * @param {Drupal~TabbingContext} tabbingContext
Chris@0:      *   The TabbingContext instance that has been activated.
Chris@0:      */
Chris@0:     activate(tabbingContext) {
Chris@0:       const $set = tabbingContext.$tabbableElements;
Chris@0:       const level = tabbingContext.level;
Chris@0:       // Determine which elements are reachable via tabbing by default.
Chris@0:       const $disabledSet = $(':tabbable')
Chris@0:         // Exclude elements of the active tabbing set.
Chris@0:         .not($set);
Chris@0:       // Set the disabled set on the tabbingContext.
Chris@0:       tabbingContext.$disabledElements = $disabledSet;
Chris@0:       // Record the tabindex for each element, so we can restore it later.
Chris@0:       const il = $disabledSet.length;
Chris@0:       for (let i = 0; i < il; i++) {
Chris@0:         this.recordTabindex($disabledSet.eq(i), level);
Chris@0:       }
Chris@0:       // Make all tabbable elements outside of the active tabbing set
Chris@0:       // unreachable.
Chris@0:       $disabledSet
Chris@0:         .prop('tabindex', -1)
Chris@0:         .prop('autofocus', false);
Chris@0: 
Chris@0:       // Set focus on an element in the tabbingContext's set of tabbable
Chris@0:       // elements. First, check if there is an element with an autofocus
Chris@0:       // attribute. Select the last one from the DOM order.
Chris@0:       let $hasFocus = $set.filter('[autofocus]').eq(-1);
Chris@0:       // If no element in the tabbable set has an autofocus attribute, select
Chris@0:       // the first element in the set.
Chris@0:       if ($hasFocus.length === 0) {
Chris@0:         $hasFocus = $set.eq(0);
Chris@0:       }
Chris@0:       $hasFocus.trigger('focus');
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Restores that tabbable state of a tabbingContext's disabled elements.
Chris@0:      *
Chris@0:      * Elements that were made untabbable have their original tabindex and
Chris@0:      * autofocus values restored.
Chris@0:      *
Chris@0:      * @param {Drupal~TabbingContext} tabbingContext
Chris@0:      *   The TabbingContext instance that has been deactivated.
Chris@0:      */
Chris@0:     deactivate(tabbingContext) {
Chris@0:       const $set = tabbingContext.$disabledElements;
Chris@0:       const level = tabbingContext.level;
Chris@0:       const il = $set.length;
Chris@0:       for (let i = 0; i < il; i++) {
Chris@0:         this.restoreTabindex($set.eq(i), level);
Chris@0:       }
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Records the tabindex and autofocus values of an untabbable element.
Chris@0:      *
Chris@0:      * @param {jQuery} $el
Chris@0:      *   The set of elements that have been disabled.
Chris@0:      * @param {number} level
Chris@0:      *   The stack level for which the tabindex attribute should be recorded.
Chris@0:      */
Chris@0:     recordTabindex($el, level) {
Chris@0:       const tabInfo = $el.data('drupalOriginalTabIndices') || {};
Chris@0:       tabInfo[level] = {
Chris@0:         tabindex: $el[0].getAttribute('tabindex'),
Chris@0:         autofocus: $el[0].hasAttribute('autofocus'),
Chris@0:       };
Chris@0:       $el.data('drupalOriginalTabIndices', tabInfo);
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Restores the tabindex and autofocus values of a reactivated element.
Chris@0:      *
Chris@0:      * @param {jQuery} $el
Chris@0:      *   The element that is being reactivated.
Chris@0:      * @param {number} level
Chris@0:      *   The stack level for which the tabindex attribute should be restored.
Chris@0:      */
Chris@0:     restoreTabindex($el, level) {
Chris@0:       const tabInfo = $el.data('drupalOriginalTabIndices');
Chris@0:       if (tabInfo && tabInfo[level]) {
Chris@0:         const data = tabInfo[level];
Chris@0:         if (data.tabindex) {
Chris@0:           $el[0].setAttribute('tabindex', data.tabindex);
Chris@0:         }
Chris@0:         // If the element did not have a tabindex at this stack level then
Chris@0:         // remove it.
Chris@0:         else {
Chris@0:           $el[0].removeAttribute('tabindex');
Chris@0:         }
Chris@0:         if (data.autofocus) {
Chris@0:           $el[0].setAttribute('autofocus', 'autofocus');
Chris@0:         }
Chris@0: 
Chris@0:         // Clean up $.data.
Chris@0:         if (level === 0) {
Chris@0:           // Remove all data.
Chris@0:           $el.removeData('drupalOriginalTabIndices');
Chris@0:         }
Chris@0:         else {
Chris@0:           // Remove the data for this stack level and higher.
Chris@0:           let levelToDelete = level;
Chris@0:           while (tabInfo.hasOwnProperty(levelToDelete)) {
Chris@0:             delete tabInfo[levelToDelete];
Chris@0:             levelToDelete++;
Chris@0:           }
Chris@0:           $el.data('drupalOriginalTabIndices', tabInfo);
Chris@0:         }
Chris@0:       }
Chris@0:     },
Chris@0:   });
Chris@0: 
Chris@0:   /**
Chris@0:    * Stores a set of tabbable elements.
Chris@0:    *
Chris@0:    * This constraint can be removed with the release() method.
Chris@0:    *
Chris@0:    * @constructor Drupal~TabbingContext
Chris@0:    *
Chris@0:    * @param {object} options
Chris@0:    *   A set of initiating values
Chris@0:    * @param {number} options.level
Chris@0:    *   The level in the TabbingManager's stack of this tabbingContext.
Chris@0:    * @param {jQuery} options.$tabbableElements
Chris@0:    *   The DOM elements that should be reachable via the tab key when this
Chris@0:    *   tabbingContext is active.
Chris@0:    * @param {jQuery} options.$disabledElements
Chris@0:    *   The DOM elements that should not be reachable via the tab key when this
Chris@0:    *   tabbingContext is active.
Chris@0:    * @param {bool} options.released
Chris@0:    *   A released tabbingContext can never be activated again. It will be
Chris@0:    *   cleaned up when the TabbingManager unwinds its stack.
Chris@0:    * @param {bool} options.active
Chris@0:    *   When true, the tabbable elements of this tabbingContext will be reachable
Chris@0:    *   via the tab key and the disabled elements will not. Only one
Chris@0:    *   tabbingContext can be active at a time.
Chris@0:    */
Chris@0:   function TabbingContext(options) {
Chris@0:     $.extend(this, /** @lends Drupal~TabbingContext# */{
Chris@0: 
Chris@0:       /**
Chris@0:        * @type {?number}
Chris@0:        */
Chris@0:       level: null,
Chris@0: 
Chris@0:       /**
Chris@0:        * @type {jQuery}
Chris@0:        */
Chris@0:       $tabbableElements: $(),
Chris@0: 
Chris@0:       /**
Chris@0:        * @type {jQuery}
Chris@0:        */
Chris@0:       $disabledElements: $(),
Chris@0: 
Chris@0:       /**
Chris@0:        * @type {bool}
Chris@0:        */
Chris@0:       released: false,
Chris@0: 
Chris@0:       /**
Chris@0:        * @type {bool}
Chris@0:        */
Chris@0:       active: false,
Chris@0:     }, options);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Add public methods to the TabbingContext class.
Chris@0:    */
Chris@0:   $.extend(TabbingContext.prototype, /** @lends Drupal~TabbingContext# */{
Chris@0: 
Chris@0:     /**
Chris@0:      * Releases this TabbingContext.
Chris@0:      *
Chris@0:      * Once a TabbingContext object is released, it can never be activated
Chris@0:      * again.
Chris@0:      *
Chris@0:      * @fires event:drupalTabbingContextReleased
Chris@0:      */
Chris@0:     release() {
Chris@0:       if (!this.released) {
Chris@0:         this.deactivate();
Chris@0:         this.released = true;
Chris@0:         Drupal.tabbingManager.release(this);
Chris@0:         // Allow modules to respond to the tabbingContext release event.
Chris@0:         $(document).trigger('drupalTabbingContextReleased', this);
Chris@0:       }
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Activates this TabbingContext.
Chris@0:      *
Chris@0:      * @fires event:drupalTabbingContextActivated
Chris@0:      */
Chris@0:     activate() {
Chris@0:       // A released TabbingContext object can never be activated again.
Chris@0:       if (!this.active && !this.released) {
Chris@0:         this.active = true;
Chris@0:         Drupal.tabbingManager.activate(this);
Chris@0:         // Allow modules to respond to the constrain event.
Chris@0:         $(document).trigger('drupalTabbingContextActivated', this);
Chris@0:       }
Chris@0:     },
Chris@0: 
Chris@0:     /**
Chris@0:      * Deactivates this TabbingContext.
Chris@0:      *
Chris@0:      * @fires event:drupalTabbingContextDeactivated
Chris@0:      */
Chris@0:     deactivate() {
Chris@0:       if (this.active) {
Chris@0:         this.active = false;
Chris@0:         Drupal.tabbingManager.deactivate(this);
Chris@0:         // Allow modules to respond to the constrain event.
Chris@0:         $(document).trigger('drupalTabbingContextDeactivated', this);
Chris@0:       }
Chris@0:     },
Chris@0:   });
Chris@0: 
Chris@0:   // Mark this behavior as processed on the first pass and return if it is
Chris@0:   // already processed.
Chris@0:   if (Drupal.tabbingManager) {
Chris@0:     return;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * @type {Drupal~TabbingManager}
Chris@0:    */
Chris@0:   Drupal.tabbingManager = new TabbingManager();
Chris@0: }(jQuery, Drupal));