WorkspaceManager.js

/*
 * GNU AGPL-3.0 License
 *
 * Copyright (c) 2021 - present core.ai . All rights reserved.
 * Original work Copyright (c) 2014 - 2021 Adobe Systems Incorporated. All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see https://opensource.org/licenses/AGPL-3.0.
 *
 */

// @INCLUDE_IN_API_DOCS

/**
* Manages layout of panels surrounding the editor area, and size of the editor area (but not its contents).
 *
 * Updates panel sizes when the window is resized. Maintains the max resizing limits for panels, based on
 * currently available window size.
 *
 * Events:
 * `workspaceUpdateLayout` When workspace size changes for any reason (including panel show/hide panel resize, or the window resize).
 *              The 2nd arg is the available workspace height.
 *              The 3rd arg is a refreshHint flag for internal use (passed in to recomputeLayout)
 * @module view/WorkspaceManager
 */
define(function (require, exports, module) {


    const AppInit                 = require("utils/AppInit"),
        EventDispatcher         = require("utils/EventDispatcher"),
        KeyBindingManager = require("command/KeyBindingManager"),
        Resizer                 = require("utils/Resizer"),
        AnimationUtils          = require("utils/AnimationUtils"),
        Strings                 = require("strings"),
        PluginPanelView         = require("view/PluginPanelView"),
        PanelView               = require("view/PanelView"),
        EditorManager           = require("editor/EditorManager"),
        MainViewManager         = require("view/MainViewManager"),
        KeyEvent                = require("utils/KeyEvent");

    /**
     * Panel ID for the default launcher panel shown when no other panels are open.
     * @const
     * @private
     */
    const DEFAULT_PANEL_ID = "workspace.defaultPanel";


    /**
     * Event triggered when the workspace layout updates.
     * @const
     */
    const EVENT_WORKSPACE_UPDATE_LAYOUT = "workspaceUpdateLayout";

    /**
     * Event triggered when a panel is shown.
     * @const
     */
    const EVENT_WORKSPACE_PANEL_SHOWN = PanelView.EVENT_PANEL_SHOWN;

    /**
     * Event triggered when a panel is hidden.
     * @const
     */
    const EVENT_WORKSPACE_PANEL_HIDDEN = PanelView.EVENT_PANEL_HIDDEN;

    /**
     * Width of the main toolbar in pixels.
     * @const
     * @private
     */
    const MAIN_TOOLBAR_WIDTH = 30;

    /**
     * The ".content" vertical stack (editor + all header/footer panels)
     * @type {jQueryObject}
     * @private
     */
    var $windowContent;

    /**
     * The "#editor-holder": has only one visible child, the current CodeMirror instance (or the no-editor placeholder)
     * @type {jQueryObject}
     * @private
     */
    var $editorHolder;


    /**
     * The "#main-toolbay": to the right side holding plugin panels and icons
     * @type {jQueryObject}
     * @private
     */
    var $mainToolbar;

    /**
     * The "#main-plugin-panel": The plugin panel main container
     * @type {jQueryObject}
     * @private
     */
    let $mainPluginPanel;

    /**
     * The "#plugin-icons-bar": holding all the plugin icons
     * @type {jQueryObject}
     * @private
     */
    let $pluginIconsBar;

    /**
     * A map from panel ID's to all related panels
     * @private
     */
    var panelIDMap = {};

    /**
     * Have we already started listening for the end of the ongoing window resize?
     * @private
     * @type {boolean}
     */
    var windowResizing = false;

    let lastShownBottomPanelStack = [];

    /** @type {jQueryObject} The single container wrapping all bottom panels */
    let $bottomPanelContainer;

    /** @type {jQueryObject} Chevron toggle in the status bar */
    let $statusBarPanelToggle;

    /** @type {boolean} True while the status bar toggle button is handling a click */
    let _statusBarToggleInProgress = false;

    /**
     * Calculates the available height for the full-size Editor (or the no-editor placeholder),
     * accounting for the current size of all visible panels, toolbar, & status bar.
     * @return {number}
     * @private
     */
    function calcAvailableHeight() {
        var availableHt = $windowContent.height();

        $editorHolder.siblings().each(function (i, elem) {
            var $elem = $(elem);
            if ($elem.css("display") !== "none" && $elem.css("position") !== "absolute") {
                availableHt -= $elem.outerHeight();
            }
        });

        // Clip value to 0 (it could be negative if a panel wants more space than we have)
        return Math.max(availableHt, 0);
    }

    /**
     * Updates panel resize limits to disallow making panels big enough to shrink editor area below 0
     * @private
     */
    function updateResizeLimits() {
        var editorAreaHeight = $editorHolder.height();

        $editorHolder.siblings().each(function (i, elem) {
            var $elem = $(elem);
            if ($elem.css("display") === "none") {
                $elem.data("maxsize", editorAreaHeight);
            } else {
                $elem.data("maxsize", editorAreaHeight + $elem.outerHeight());
            }
        });

        var sidebarWidth = $("#sidebar").outerWidth() || 0;
        $mainToolbar.data("maxsize", Math.min(window.innerWidth * 0.75, window.innerWidth - sidebarWidth - 100));
    }


    /**
     * Calculates a new size for editor-holder and resizes it accordingly, then and dispatches the "workspaceUpdateLayout"
     * event. (The editors within are resized by EditorManager, in response to that event).
     * @private
     * @param {boolean=} refreshHint  true to force a complete refresh
     */
    function triggerUpdateLayout(refreshHint) {
        // Find how much space is left for the editor
        let editorAreaHeight = calcAvailableHeight();

        $editorHolder.height(editorAreaHeight);  // affects size of "not-editor" placeholder as well

        let pluginPanelWidth = $mainToolbar.width() - $pluginIconsBar.width();
        $mainPluginPanel.width(pluginPanelWidth);

        // Resize editor to fill the space
        exports.trigger(EVENT_WORKSPACE_UPDATE_LAYOUT, editorAreaHeight, refreshHint);
    }


    /**
     * Trigger editor area resize whenever the window is resized
     * @private
     */
    function handleWindowResize() {
        // These are not initialized in Jasmine Spec Runner window until a test
        // is run that creates a mock document.
        if (!$windowContent || !$editorHolder) {
            return;
        }

        // Clamp plugin panel toolbar width so it doesn't encroach into the sidebar/content area
        if (currentlyShownPanel && $mainToolbar.is(":visible")) {
            _clampPluginPanelWidth(currentlyShownPanel);
        }

        // FIXME (issue #4564) Workaround https://github.com/codemirror/CodeMirror/issues/1787
        triggerUpdateLayout();

        // Re-apply maximize height when the window resizes so the panel stays maximized
        if (PanelView.isMaximized() && $bottomPanelContainer && $bottomPanelContainer.is(":visible")) {
            let maxHeight = $editorHolder.height() + $bottomPanelContainer.height();
            $bottomPanelContainer.height(maxHeight);
            triggerUpdateLayout();
        }

        if (!windowResizing) {
            windowResizing = true;

            // We don't need any fancy debouncing here - we just need to react before the user can start
            // resizing any panels at the new window size. So just listen for first mousemove once the
            // window resize releases mouse capture.
            $(window.document).one("mousemove", function () {
                windowResizing = false;
                updateResizeLimits();
            });
        }
    }

    /** Trigger editor area resize whenever the given panel is shown/hidden/resized
     * @private
     * @param {!jQueryObject} $panel the jquery object in which to attach event handlers
     */
    function listenToResize($panel) {
        // Update editor height when shown/hidden, & continuously as panel is resized
        $panel.on("panelCollapsed panelExpanded panelResizeUpdate", function () {
            triggerUpdateLayout();
        });
        // Update max size of sibling panels when shown/hidden, & at *end* of resize gesture
        $panel.on("panelCollapsed panelExpanded panelResizeEnd", function () {
            updateResizeLimits();
        });
    }

    /**
     * Creates a new resizable panel beneath the editor area and above the status bar footer. Panel is initially invisible.
     * The panel's size & visibility are automatically saved & restored as a view-state preference.
     *
     * @param {!string} id  Unique id for this panel. Use package-style naming, e.g. "myextension.feature.panelname"
     * @param {!jQueryObject} $panel  DOM content to use as the panel. Need not be in the document yet. Must have an id
     *      attribute, for use as a preferences key.
     * @param {number=} minSize  @deprecated No longer used. Pass `undefined`.
     * @param {string=} title  Display title shown in the bottom panel tab bar.
     * @return {!Panel}
     */
    function createBottomPanel(id, $panel, minSize, title) {
        $bottomPanelContainer.append($panel);
        $panel.hide();
        updateResizeLimits();
        let bottomPanel = new PanelView.Panel($panel, id, title);
        panelIDMap[id] = bottomPanel;
        return bottomPanel;
    }

    /**
     * Destroys a bottom panel, removing it from internal registries, the tab bar, and the DOM.
     * After calling this, the panel ID is no longer valid and the Panel instance should not be reused.
     *
     * @param {!string} id  The panel ID that was passed to createBottomPanel.
     */
    function destroyBottomPanel(id) {
        let panel = panelIDMap[id];
        if (!panel) {
            return;
        }
        if (typeof panel.destroy === 'function') {
            panel.destroy();
        }
        delete panelIDMap[id];
    }

    /**
     * Creates a new resizable plugin panel associated with the given toolbar icon. Panel is initially invisible.
     * The panel's size & visibility are automatically saved & restored. Only one panel can be associated with a
     * toolbar icon.
     *
     * @param {!string} id  Unique id for this panel. Use package-style naming, e.g. "myextension.panelname". will
     *      overwrite an existing panel id if present.
     * @param {!jQueryObject} $panel  DOM content to use as the panel. Need not be in the document yet. Must have an id
     *      attribute, for use as a preferences key.
     * @param {number=} minSize  Minimum height of panel in px.
     * @param {!jQueryObject} $toolbarIcon An icon that should be present in main-toolbar to associate this panel to.
     *      The panel will be shown only if the icon is visible on the toolbar and the user clicks on the icon.
     * @param {?number=} initialSize  Optional Initial size of panel in px. If not given, panel will use minsize
     *      or current size.
     * @return {!Panel}
     */
    function createPluginPanel(id, $panel, minSize, $toolbarIcon, initialSize) {
        if(!$toolbarIcon){
            throw new Error("invalid $toolbarIcon provided to create createPluginPanel");
        }

        $mainPluginPanel[0].appendChild($panel[0]);

        let pluginPanel = new PluginPanelView.Panel($panel, id, $toolbarIcon, minSize, initialSize);
        panelIDMap[id] = pluginPanel;
        pluginPanel.hide();

        return pluginPanel;
    }

    /**
     * Returns an array of all panel ID's
     * @returns {Array} List of ID's of all bottom panels
     */
    function getAllPanelIDs() {
        var property, panelIDs = [];
        for (property in panelIDMap) {
            if (panelIDMap.hasOwnProperty(property)) {
                panelIDs.push(property);
            }
        }
        return panelIDs;
    }

    /**
     * Gets the Panel interface for the given ID. Can return undefined if no panel with the ID is found.
     * @param   {string} panelID
     * @returns {Object} Panel object for the ID or undefined
     */
    function getPanelForID(panelID) {
        return panelIDMap[panelID];
    }

    /**
     * Called when an external widget has appeared and needs some of the space occupied
     *  by the mainview manager
     * @param {boolean} refreshHint true to refresh the editor, false if not
     */
    function recomputeLayout(refreshHint) {
        triggerUpdateLayout(refreshHint);
        updateResizeLimits();
    }


    /* Attach to key parts of the overall UI, once created */
    AppInit.htmlReady(function () {
        $windowContent = $(".content");
        $editorHolder = $("#editor-holder");
        $mainToolbar = $("#main-toolbar");
        $mainPluginPanel = $("#main-plugin-panel");
        $pluginIconsBar = $("#plugin-icons-bar");

        // --- Create the bottom panel tabbed container ---
        $bottomPanelContainer = $('<div id="bottom-panel-container" class="vert-resizable top-resizer"></div>');
        let $bottomPanelTabBar = $('<div id="bottom-panel-tab-bar"></div>');
        let $bottomPanelTabsOverflow = $('<div class="bottom-panel-tabs-overflow"></div>');
        let $tabBarActions = $('<div class="bottom-panel-tab-bar-actions"></div>');
        $tabBarActions.append(
            $('<span class="bottom-panel-hide-btn"><i class="fa-solid fa-minus"></i></span>')
                .attr('title', Strings.BOTTOM_PANEL_MINIMIZE)
        );
        $tabBarActions.append(
            $('<span class="bottom-panel-maximize-btn"><i class="fa-regular fa-square"></i></span>')
                .attr('title', Strings.BOTTOM_PANEL_MAXIMIZE)
        );
        $bottomPanelTabBar.append($bottomPanelTabsOverflow);
        $bottomPanelTabBar.append($tabBarActions);
        $bottomPanelContainer.append($bottomPanelTabBar);
        $bottomPanelContainer.insertBefore("#status-bar");
        $bottomPanelContainer.hide();

        // Initialize PanelView with container DOM references and tab bar click handlers
        PanelView.init($bottomPanelContainer, $bottomPanelTabBar, $bottomPanelTabsOverflow,
            $editorHolder, recomputeLayout, DEFAULT_PANEL_ID);

        // Create status bar chevron toggle for bottom panel
        $statusBarPanelToggle = $('<div id="status-panel-toggle" class="indicator global-indicator"><i class="fa-solid fa-angles-up"></i></div>')
            .attr('title', Strings.BOTTOM_PANEL_SHOW);
        $("#status-indicators").prepend($statusBarPanelToggle);

        $statusBarPanelToggle.on("click", function () {
            _statusBarToggleInProgress = true;
            _togglePanels();
            _statusBarToggleInProgress = false;
        });

        // Make the container resizable (not individual panels)
        Resizer.makeResizable($bottomPanelContainer[0], Resizer.DIRECTION_VERTICAL, Resizer.POSITION_TOP,
            200, false, undefined, true);
        listenToResize($bottomPanelContainer);

        // Track maximize state live during drag-resize so the icon updates
        // immediately rather than waiting for mouseup. panelResizeUpdate fires
        // after listenToResize's handler has already called triggerUpdateLayout(),
        // so $editorHolder height is up-to-date at this point.
        $bottomPanelContainer.on("panelResizeUpdate panelResizeEnd", function () {
            let editorHeight = $editorHolder.height();
            if (PanelView.isMaximized() && editorHeight > PanelView.MAXIMIZE_THRESHOLD) {
                PanelView.exitMaximizeOnResize();
            } else if (!PanelView.isMaximized() && editorHeight <= PanelView.MAXIMIZE_THRESHOLD) {
                PanelView.enterMaximizeOnResize();
            }
        });

        $bottomPanelContainer.on("panelCollapsed", function () {
            $statusBarPanelToggle.find("i")
                .removeClass("fa-angles-down")
                .addClass("fa-angles-up");
            $statusBarPanelToggle.attr("title", Strings.BOTTOM_PANEL_SHOW);
            if (!_statusBarToggleInProgress) {
                AnimationUtils.animateUsingClass($statusBarPanelToggle[0], "flash", 800);
            }
            // When the container collapses while tabs are still open, clear the
            // shown stack so the Escape-key handler doesn't silently close tabs
            // that the user can't even see.
            let openIds = PanelView.getOpenBottomPanelIDs();
            for (let i = 0; i < openIds.length; i++) {
                lastShownBottomPanelStack = lastShownBottomPanelStack.filter(item => item !== openIds[i]);
            }
        });

        $bottomPanelContainer.on("panelExpanded", function () {
            $statusBarPanelToggle.find("i")
                .removeClass("fa-angles-up")
                .addClass("fa-angles-down");
            $statusBarPanelToggle.attr("title", Strings.BOTTOM_PANEL_HIDE_TOGGLE);
            if (!_statusBarToggleInProgress) {
                AnimationUtils.animateUsingClass($statusBarPanelToggle[0], "flash", 800);
            }
            // When the container re-expands, add the open panels to the shown stack.
            let openIds = PanelView.getOpenBottomPanelIDs();
            for (let i = 0; i < openIds.length; i++) {
                lastShownBottomPanelStack = lastShownBottomPanelStack.filter(item => item !== openIds[i]);
                lastShownBottomPanelStack.push(openIds[i]);
            }
        });

        // Sidebar is a special case: it isn't a Panel, and is not created dynamically. Need to explicitly
        // listen for resize here.
        listenToResize($("#sidebar"));
        listenToResize($("#main-toolbar"));
    });

    /**
     * Unit test only: allow passing in mock DOM notes, e.g. for use with SpecRunnerUtils.createMockEditor()
     * @private
     */
    function _setMockDOM($mockWindowContent, $mockEditorHolder, $mockMainToolbar, $mockMainPluginPanel, $mockPluginIconsBar) {
        $windowContent = $mockWindowContent;
        $editorHolder = $mockEditorHolder;
        $mainToolbar = $mockMainToolbar;
        $mainPluginPanel = $mockMainPluginPanel;
        $pluginIconsBar = $mockPluginIconsBar;
    }

    /* Add this as a capture handler so we're guaranteed to run it before the editor does its own
     * refresh on resize.
     */
    window.addEventListener("resize", handleWindowResize, true);


    EventDispatcher.makeEventDispatcher(exports);

    PanelView.on(PanelView.EVENT_PANEL_SHOWN, (event, panelID)=>{
        lastShownBottomPanelStack = lastShownBottomPanelStack.filter(item => item !== panelID);
        lastShownBottomPanelStack.push(panelID);
        exports.trigger(EVENT_WORKSPACE_PANEL_SHOWN, panelID);
        triggerUpdateLayout();
    });
    PanelView.on(PanelView.EVENT_PANEL_HIDDEN, (event, panelID)=>{
        lastShownBottomPanelStack = lastShownBottomPanelStack.filter(item => item !== panelID);
        exports.trigger(EVENT_WORKSPACE_PANEL_HIDDEN, panelID);
        triggerUpdateLayout();
    });

    let currentlyShownPanel = null,
        panelShowInProgress = false,
        initialSizeSetOnce = {};

    function _getInitialSize(panel) {
        let setOnce = initialSizeSetOnce[panel.panelID];
        if(setOnce){
            return undefined; // we haev lalready set the initial size once, let resizer figure out size to apply now.
        }
        initialSizeSetOnce[panel.panelID] = true;
        return panel.initialSize;
    }

    function _clampPluginPanelWidth(panelBeingShown) {
        let sidebarWidth = $("#sidebar").outerWidth() || 0;
        let pluginIconsBarWidth = $pluginIconsBar.outerWidth();
        let minToolbarWidth = (panelBeingShown.minWidth || 0) + pluginIconsBarWidth;
        let maxToolbarWidth = Math.max(
            minToolbarWidth,
            Math.min(window.innerWidth * 0.75, window.innerWidth - sidebarWidth - 100)
        );
        let currentWidth = $mainToolbar.width();
        if (currentWidth > maxToolbarWidth || currentWidth < minToolbarWidth) {
            let clampedWidth = Math.max(minToolbarWidth, Math.min(currentWidth, maxToolbarWidth));
            $mainToolbar.width(clampedWidth);
            $windowContent.css("right", clampedWidth);
            Resizer.resyncSizer($mainToolbar[0]);
        }
    }

    function _showPluginSidePanel(panelID) {
        let panelBeingShown = getPanelForID(panelID);
        let pluginIconsBarWidth = $pluginIconsBar.outerWidth();
        let minToolbarWidth = (panelBeingShown.minWidth || 0) + pluginIconsBarWidth;
        Resizer.makeResizable($mainToolbar, Resizer.DIRECTION_HORIZONTAL, Resizer.POSITION_LEFT,
            minToolbarWidth, false, undefined, true,
            undefined, $windowContent, undefined, _getInitialSize(panelBeingShown));
        Resizer.show($mainToolbar[0]);
        _clampPluginPanelWidth(panelBeingShown);
        recomputeLayout(true);
    }

    function _hidePluginSidePanel() {
        $mainToolbar.css('width', MAIN_TOOLBAR_WIDTH);
        $windowContent.css('right', MAIN_TOOLBAR_WIDTH);
        Resizer.removeSizable($mainToolbar[0]);
        recomputeLayout(true);
    }

    PluginPanelView.on(PluginPanelView.EVENT_PANEL_SHOWN, (event, panelID)=>{
        panelShowInProgress = true;
        _showPluginSidePanel(panelID);
        if(currentlyShownPanel){
            currentlyShownPanel.hide();
        }
        currentlyShownPanel = getPanelForID(panelID);
        exports.trigger(EVENT_WORKSPACE_PANEL_SHOWN, panelID);
        panelShowInProgress = false;
    });

    PluginPanelView.on(PluginPanelView.EVENT_PANEL_HIDDEN, (event, panelID)=>{
        if(!panelShowInProgress){
            _hidePluginSidePanel();
            currentlyShownPanel = null;
        }
        exports.trigger(EVENT_WORKSPACE_PANEL_HIDDEN, panelID);
    });

    /**
     * Responsible to check if the panel is visible or not.
     * Returns true if visible else false.
     * @param panelID
     * @returns {boolean}
     */
    function isPanelVisible(panelID) {
        let panel = getPanelForID(panelID);
        if(panel && panel.isVisible()){
            return true;
        }
        return false;
    }

    /**
     * Programmatically sets the plugin panel content width to the given value in pixels.
     * The total toolbar width is adjusted to account for the plugin icons bar.
     * Width is clamped to respect panel minWidth and max size (75% of window).
     * No-op if no panel is currently visible.
     * @param {number} width  Desired content width in pixels
     */
    function setPluginPanelWidth(width) {
        if (!currentlyShownPanel) {
            return;
        }
        var pluginIconsBarWidth = $pluginIconsBar.outerWidth();
        var newToolbarWidth = width + pluginIconsBarWidth;

        // Respect min/max constraints
        var minSize = currentlyShownPanel.minWidth || 0;
        var minToolbarWidth = minSize + pluginIconsBarWidth;
        var sidebarWidth = $("#sidebar").outerWidth() || 0;
        var maxToolbarWidth = Math.min(window.innerWidth * 0.75, window.innerWidth - sidebarWidth - 100);
        newToolbarWidth = Math.max(newToolbarWidth, minToolbarWidth);
        newToolbarWidth = Math.min(newToolbarWidth, maxToolbarWidth);

        $mainToolbar.width(newToolbarWidth);
        $windowContent.css("right", newToolbarWidth);
        Resizer.resyncSizer($mainToolbar[0]);
        recomputeLayout(true);
    }

    // Escape key and toggle panel special handling
    let _escapeKeyConsumers = {};

    /**
     * If any widgets related to the editor needs to handle the escape key event, add it here. returning true from the
     * registered handler will prevent primary escape key toggle panel behavior of phoenix. Note that returning true
     * will no stop the event bubbling, that has to be controlled with the event parameter forwarded to the handler.
     * @param {string} consumerName a unique name for your consumer
     * @param {function(event)} eventHandler If the eventHandler returns true for this callback, the escape key event
     *        will not lead to panel toggle default behavior.
     * @return {boolean} true if added
     */
    function addEscapeKeyEventHandler(consumerName, eventHandler) {
        if(_escapeKeyConsumers[consumerName]){
            console.error("EscapeKeyEvent consumer of same name already registered: ", consumerName);
            return false;
        }
        if(typeof eventHandler !== 'function'){
            console.error(`EscapeKeyEvent invalid eventHandler: ${consumerName}, ${eventHandler}`);
            return false;
        }
        _escapeKeyConsumers[consumerName] = eventHandler;
        return true;
    }

    /**
     * Removing the escape key event consumer.
     * @param {string} consumerName used to register the consumer.
     * @return {boolean} true if removed
     */
    function removeEscapeKeyEventHandler(consumerName) {
        if(_escapeKeyConsumers[consumerName]){
            delete _escapeKeyConsumers[consumerName];
            return true;
        } else {
            console.error("EscapeKeyEvent no such consumer to remove: ", consumerName);
        }
        return false;
    }

    /**
     * Shows the default launcher panel when no other panels are open.
     * @private
     */
    function _showDefaultPanel() {
        let defaultPanel = panelIDMap[DEFAULT_PANEL_ID];
        if (defaultPanel) {
            defaultPanel.show();
        }
    }

    /**
     * Toggle the bottom panel container: hide if visible, show if there are
     * open panels, or show the default panel when nothing is open.
     * @private
     * @return {boolean} true if the toggle was handled
     */
    function _togglePanels() {
        if (!$bottomPanelContainer) {
            return false;
        }
        if ($bottomPanelContainer.is(":visible")) {
            Resizer.hide($bottomPanelContainer[0]);
        } else if (PanelView.getOpenBottomPanelIDs().length > 0) {
            Resizer.show($bottomPanelContainer[0]);
        } else {
            _showDefaultPanel();
        }
        triggerUpdateLayout();
        return true;
    }

    function _handleEscapeKey() {
        return _togglePanels();
    }

    /**
     * Shift+Escape: toggle focus between editor and active bottom panel
     * @param event
     * @returns {boolean}
     * @private
     */
    function _handleShiftEscape(event) {
        if (!event.shiftKey) {
            return false;
        }
        if (EditorManager.getFocusedEditor()) {
            // Editor has focus — focus the panel
            let activePanel = PanelView.getActiveBottomPanel();
            if(!activePanel || !activePanel.isVisible()){
                _togglePanels();
                activePanel = PanelView.getActiveBottomPanel();
            }
            activePanel.focus();
        } else {
            // Focus is elsewhere (panel, sidebar, etc.) — focus the editor
            MainViewManager.focusActivePane();
        }
        event.stopPropagation();
        event.preventDefault();
        return true;
    }

    // pressing escape when focused on editor will toggle the bottom panel container
    // pressing shift+escape toggles focus between editor and active bottom panel
    function _handleKeydown(event) {
        if(event.keyCode !== KeyEvent.DOM_VK_ESCAPE || KeyBindingManager.isInOverlayMode()){
            return;
        }

        // Shift+Escape: toggle focus between editor and active bottom panel
        if (_handleShiftEscape(event)) {
            return;
        }

        for(let consumerName of Object.keys(_escapeKeyConsumers)){
            if(_escapeKeyConsumers[consumerName](event)){
                return;
            }
        }

        let focussedEditor = EditorManager.getFocusedEditor();
        if(!focussedEditor || EditorManager.getFocusedInlineEditor()){
            // if there is no editor in focus, we do no panel toggling
            // if there is an editor with an inline widget in focus, the escape key will be
            // handled by the inline widget itself first.
            return;
        }
        const dropdownOpen = $(".dropdown.open").is(":visible");
        if(dropdownOpen || focussedEditor.canConsumeEscapeKeyEvent()){
            return;
        }

        _handleEscapeKey();

        event.stopPropagation();
        event.preventDefault();
    }
    window.document.body.addEventListener("keydown", _handleKeydown, true);

    // Define public API
    exports.createBottomPanel               = createBottomPanel;
    exports.destroyBottomPanel              = destroyBottomPanel;
    exports.createPluginPanel               = createPluginPanel;
    exports.isPanelVisible                  = isPanelVisible;
    exports.setPluginPanelWidth             = setPluginPanelWidth;
    exports.recomputeLayout                 = recomputeLayout;
    exports.getAllPanelIDs                  = getAllPanelIDs;
    exports.getPanelForID                   = getPanelForID;
    exports.getOpenBottomPanelIDs           = PanelView.getOpenBottomPanelIDs;
    exports.hideAllOpenBottomPanels         = PanelView.hideAllOpenPanels;
    exports.addEscapeKeyEventHandler        = addEscapeKeyEventHandler;
    exports.removeEscapeKeyEventHandler     = removeEscapeKeyEventHandler;
    exports._setMockDOM                     = _setMockDOM;
    exports.EVENT_WORKSPACE_UPDATE_LAYOUT   = EVENT_WORKSPACE_UPDATE_LAYOUT;
    exports.EVENT_WORKSPACE_PANEL_SHOWN     = EVENT_WORKSPACE_PANEL_SHOWN;
    exports.EVENT_WORKSPACE_PANEL_HIDDEN    = EVENT_WORKSPACE_PANEL_HIDDEN;
    exports.DEFAULT_PANEL_ID                = DEFAULT_PANEL_ID;

    /**
     * Constant representing the type of bottom panel
     * @type {string}
     */
    exports.PANEL_TYPE_BOTTOM_PANEL         = PanelView.PANEL_TYPE_BOTTOM_PANEL;

    /**
     * Constant representing the type of plugin panel
     * @type {string}
     */
    exports.PANEL_TYPE_PLUGIN_PANEL         = PluginPanelView.PANEL_TYPE_PLUGIN_PANEL;
});