@atlassian/aui/src/js/aui/focus-manager.js

import $ from './jquery';
import globalize from './internal/globalize';
import keyCodes from './key-code';
import {getTrigger} from './trigger';

(function initSelectors () {
    /*
    :tabbable and :focusable functions from jQuery UI v 1.10.4
    renamed to :aui-tabbable and :aui-focusable to not clash with jquery-ui if it's included.
    */

    function visible (element) {
        return ($.css(element, 'visibility') === 'visible') && $(element).is(':visible');
    }

    function focusable (element, isTabIndexNotNaN) {
        var nodeName = element.nodeName.toLowerCase();

        if (nodeName === 'aui-select') {
            return true;
        }

        if (nodeName === 'area') {
            var map = element.parentNode;
            var mapName = map.name;
            var imageMap = $('img[usemap=#' + mapName + ']').get();

            if (!element.href || !mapName || map.nodeName.toLowerCase() !== 'map') {
                return false;
            }
            return imageMap && visible(imageMap);
        }
        var isFormElement = /input|select|textarea|button|object|iframe/.test(nodeName);
        var isAnchor = nodeName === 'a';
        var isAnchorTabbable = (element.href || isTabIndexNotNaN);

        return (
            isFormElement ? !element.disabled :
                (isAnchor ? isAnchorTabbable : isTabIndexNotNaN)
        ) && visible(element);
    }

    function tabbable (element) {
        var tabIndex = $.attr(element, 'tabindex');
        var isTabIndexNaN = isNaN(tabIndex);
        var hasTabIndex = (isTabIndexNaN || tabIndex >= 0);

        return hasTabIndex && focusable(element, !isTabIndexNaN);
    }

    $.extend($.expr.pseudos, {
        'aui-focusable': element => focusable(element, !isNaN($.attr(element, 'tabindex'))),
        'aui-tabbable': tabbable
    });
}());

var RESTORE_FOCUS_DATA_KEY = '_aui-focus-restore';

/**
 * Stores information about last focused element in el.data
 *
 * @param {HTMLElement} $el - element to store the data about focus
 * @param {Element} [lastFocussedEl=document.activeElement] - last focused element
 */
function setLastFocus ($el, lastFocussedEl = document.activeElement) {
    $el.data(RESTORE_FOCUS_DATA_KEY, lastFocussedEl);
}

function getLastFocus ($el) {
    return $($el.data(RESTORE_FOCUS_DATA_KEY));
}

function elementTrapsFocus ($el) {
    return $el.is('.aui-dialog2');
}

function FocusManager() {
    this._focusTrapStack = [];
    this._handler;
}
FocusManager.defaultFocusSelector = ':aui-tabbable';
/**
 *
 * @param {HTMLElement} $el - element to move the focus onto
 * @param {Element} [$lastFocused] - last focused element
 */
FocusManager.prototype.enter = function ($el, $lastFocused) {
    setLastFocus($el, $lastFocused);

    // focus on new selector
    if ($el.attr('data-aui-focus') !== 'false') {
        var focusSelector = $el.attr('data-aui-focus-selector') || FocusManager.defaultFocusSelector;
        var $focusEl = $el.is(focusSelector) ? $el : $el.find(focusSelector);
        $focusEl.first().trigger('focus');
    }

    if (elementTrapsFocus($el)) {
        this._focusTrapStack.push($el);
        if (!this._handler) {
            this._handler = focusTrapHandler.bind(undefined, this._focusTrapStack);
            $(document).on('keydown.aui-focus-manager', this._handler);
        }
    }
};

FocusManager.prototype.exit = function ($el) {
    if (elementTrapsFocus($el)) {
        this._focusTrapStack.pop();
        if (!this._focusTrapStack.length) {
            $(document).off('.aui-focus-manager', this._handler);
            delete this._handler;
        }
    }

    // AUI-1059: remove focus from the active element when dialog is hidden
    // AUI-5014 - if focus is already outside focus trap there is no need to restore it
    var activeElement = document.activeElement;
    if ($el[0] === activeElement || $el.has(activeElement).length) {
        $(activeElement).trigger('blur');
        var $restoreFocus = getLastFocus($el);
        if ($restoreFocus.length) {
            $el.removeData(RESTORE_FOCUS_DATA_KEY);
            $restoreFocus.trigger('focus');
        }
    }
};

function focusTrapHandler(focusTrapStack, event) {
    if (focusTrapStack.length === 0) {
        return;
    }

    if (event.keyCode !== keyCodes.TAB) {
        return;
    }

    const backwards = event.shiftKey;
    const offset = backwards ? -1 : 1;

    /**
     * always the element where focus is about to be blurred
     * @type {HTMLElement}
     */
    const focusOrigin = event.target;

    const $focusTrapElement = focusTrapStack[focusTrapStack.length - 1];
    const $tabbableElements = $focusTrapElement.find(':aui-tabbable');

    // it's not possible to trap focus inside something with no focussable elements!
    if (!$tabbableElements.length) {
        return;
    }

    const originIdx = $tabbableElements.index(focusOrigin);
    let newFocusIdx = -1;

    if (originIdx > -1) {
        // the currently focussed element is inside our trap container.
        // excellent! we'll work with this.
        newFocusIdx = originIdx;
    } else {
        // the currently focussed element was outside our trap container.
        // it might be okay to leave it there, though, since AUI has a few layer elements
        // and the focussed element might be in one of those.
        // let's see if the focus was in an element that AUI roughly "controls".
        let $controlledElementWithFocus;

        // look for a layer in the "cheapest" way possible first -- check if a parent is a layer.
        $controlledElementWithFocus = $(focusOrigin).closest('.aui-layer');

        if (!$controlledElementWithFocus.length) {
            // look up the controlled layers in a different way -- by finding all controllers first,
            // then their layers.
            const $controllingElements = $focusTrapElement.find('[aria-controls]');
            const $controlledElements = $controllingElements.map(function () {
                return document.getElementById(this.getAttribute('aria-controls'));
            });

            // Find out whether the new focus target is inside a controlled element or not.
            $controlledElementWithFocus = $controlledElements.has(focusOrigin);
        }

        if ($controlledElementWithFocus.length) {
            // Find out whether we need to jump the focus out of the controlled element.
            const $subTabbable = $controlledElementWithFocus.find(':aui-tabbable');
            const subOriginIdx = $subTabbable.index(focusOrigin);
            const subMove = subOriginIdx + offset;
            if (subMove < 0 || subMove >= $subTabbable.length) {
                // This element was on the edge of the list, so we'll pop focus out.
                // We'll assume we can pop the focus to a controlled element.
                const triggerEl = getTrigger($controlledElementWithFocus.get(0));
                newFocusIdx = $tabbableElements.index(triggerEl);
            } else {
                // Focus will happen normally. Let it happen.
                return;
            }
        }
    }

    if (newFocusIdx > -1) {
        // wrap around the focus trap.
        newFocusIdx = (newFocusIdx + offset) % $tabbableElements.length;
    } else {
        // we will focus the first element in the trap.
        newFocusIdx = 0;
    }

    if ($tabbableElements.get(newFocusIdx).nodeName !== 'IFRAME') {
        $tabbableElements.eq(newFocusIdx).trigger('focus');
        event.preventDefault();
    }
}

// AUI-4403 - Previous maintainers pretended multiple FocusManager instances made sense.
// However, the class is implemented in a way that would never play well with others,
// so here I'm locking it down as a singleton.
let instance;
function getFocusManager() {
    if (!instance) {
        instance = new FocusManager();
    }
    return instance;
}
getFocusManager.global = getFocusManager();

globalize('FocusManager', getFocusManager);

export default getFocusManager;