text: /**
   * @license Copyright (c) 2003-2022, CKSource Holding sp. z o.o. All rights reserved.
   * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
   */
  
  /**
   * @module widget/widget
   */
  
  import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
  import MouseObserver from '@ckeditor/ckeditor5-engine/src/view/observer/mouseobserver';
  import WidgetTypeAround from './widgettypearound/widgettypearound';
  import Delete from '@ckeditor/ckeditor5-typing/src/delete';
  import env from '@ckeditor/ckeditor5-utils/src/env';
  import { getLocalizedArrowKeyCodeDirection } from '@ckeditor/ckeditor5-utils/src/keyboard';
  
  import verticalNavigationHandler from './verticalnavigation';
  import { getLabel, isWidget, WIDGET_SELECTED_CLASS_NAME } from './utils';
  
  import '../theme/widget.css';
  
  /**
   * The widget plugin. It enables base support for widgets.
   *
   * See {@glink api/widget package page} for more details and documentation.
   *
   * This plugin enables multiple behaviors required by widgets:
   *
   * * The model to view selection converter for the editing pipeline (it handles widget custom selection rendering).
   * If a converted selection wraps around a widget element, that selection is marked as
   * {@link module:engine/view/selection~Selection#isFake fake}. Additionally, the `ck-widget_selected` CSS class
   * is added to indicate that widget has been selected.
   * * The mouse and keyboard events handling on and around widget elements.
   *
   * @extends module:core/plugin~Plugin
   */
  export default class Widget extends Plugin {
  	/**
  	 * @inheritDoc
  	 */
  	static get pluginName() {
  		return 'Widget';
  	}
  
  	/**
  	 * @inheritDoc
  	 */
  	static get requires() {
  		return [ WidgetTypeAround, Delete ];
  	}
  
  	/**
  	 * @inheritDoc
  	 */
  	init() {
  		const editor = this.editor;
  		const view = editor.editing.view;
  		const viewDocument = view.document;
  
  		/**
  		 * Holds previously selected widgets.
  		 *
  		 * @private
  		 * @type {Set.<module:engine/view/element~Element>}
  		 */
  		this._previouslySelected = new Set();
  
  		// Model to view selection converter.
  		// Converts selection placed over widget element to fake selection.
  		//
  		// By default, the selection is downcasted by the engine to surround the attribute element, even though its only
  		// child is an inline widget. A similar thing also happens when a collapsed marker is rendered as a UI element
  		// next to an inline widget: the view selection contains both the widget and the marker.
  		//
  		// This prevents creating a correct fake selection when this inline widget is selected. Normalize the selection
  		// in these cases based on the model:
  		//
  		//		[<attributeElement><inlineWidget /></attributeElement>] -> <attributeElement>[<inlineWidget />]</attributeElement>
  		//		[<uiElement></uiElement><inlineWidget />] -> <uiElement></uiElement>[<inlineWidget />]
  		//
  		// Thanks to this:
  		//
  		// * fake selection can be set correctly,
  		// * any logic depending on (View)Selection#getSelectedElement() also works OK.
  		//
  		// See https://github.com/ckeditor/ckeditor5/issues/9524.
  		this.editor.editing.downcastDispatcher.on( 'selection', ( evt, data, conversionApi ) => {
  			const viewWriter = conversionApi.writer;
  			const modelSelection = data.selection;
  
  			// The collapsed selection can't contain any widget.
  			if ( modelSelection.isCollapsed ) {
  				return;
  			}
  
  			const selectedModelElement = modelSelection.getSelectedElement();
  
  			if ( !selectedModelElement ) {
  				return;
  			}
  
  			const selectedViewElement = editor.editing.mapper.toViewElement( selectedModelElement );
  
  			if ( !isWidget( selectedViewElement ) ) {
  				return;
  			}
  
  			if ( !conversionApi.consumable.consume( modelSelection, 'selection' ) ) {
  				return;
  			}
  
  			viewWriter.setSelection( viewWriter.createRangeOn( selectedViewElement ), {
  				fake: true,
  				label: getLabel( selectedViewElement )
  			} );
  		} );
  
  		// Mark all widgets inside the selection with the css class.
  		// This handler is registered at the 'low' priority so it's triggered after the real selection conversion.
  		this.editor.editing.downcastDispatcher.on( 'selection', ( evt, data, conversionApi ) => {
  			// Remove selected class from previously selected widgets.
  			this._clearPreviouslySelectedWidgets( conversionApi.writer );
  
  			const viewWriter = conversionApi.writer;
  			const viewSelection = viewWriter.document.selection;
  
  			let lastMarked = null;
  
  			for ( const range of viewSelection.getRanges() ) {
  				// Note: There could be multiple selected widgets in a range but no fake selection.
  				// All of them must be marked as selected, for instance [<widget></widget><widget></widget>]
  				for ( const value of range ) {
  					const node = value.item;
  					// Do not mark nested widgets in selected one. See: #4594
  					if ( isWidget( node ) && !isChild( node, lastMarked ) ) {
  						viewWriter.addClass( WIDGET_SELECTED_CLASS_NAME, node );
  						this._previouslySelected.add( node );
  						lastMarked = node;
  					}
  				}
  			}
  		}, { priority: 'low' } );
  
  		// If mouse down is pressed on widget - create selection over whole widget.
  		view.addObserver( MouseObserver );
  		this.listenTo( viewDocument, 'mousedown', ( ...args ) => this._onMousedown( ...args ) );
  
  		// There are two keydown listeners working on different priorities. This allows other
  		// features such as WidgetTypeAround or TableKeyboard to attach their listeners in between
  		// and customize the behavior even further in different content/selection scenarios.
  		//
  		// * The first listener handles changing the selection on arrow key press
  		// if the widget is selected or if the selection is next to a widget and the widget
  		// should become selected upon the arrow key press.
  		//
  		// * The second (late) listener makes sure the default browser action on arrow key press is
  		// prevented when a widget is selected. This prevents the selection from being moved
  		// from a fake selection container.
  		this.listenTo( viewDocument, 'arrowKey', ( ...args ) => {
  			this._handleSelectionChangeOnArrowKeyPress( ...args );
  		}, { context: [ isWidget, '$text' ] } );
  
  		this.listenTo( viewDocument, 'arrowKey', ( ...args ) => {
  			this._preventDefaultOnArrowKeyPress( ...args );
  		}, { context: '$root' } );
  
  		this.listenTo( viewDocument, 'arrowKey', verticalNavigationHandler( this.editor.editing ), { context: '$text' } );
  
  		// Handle custom delete behaviour.
  		this.listenTo( viewDocument, 'delete', ( evt, data ) => {
  			if ( this._handleDelete( data.direction == 'forward' ) ) {
  				data.preventDefault();
  				evt.stop();
  			}
  		}, { context: '$root' } );
  	}
  
  	/**
  	 * Handles {@link module:engine/view/document~Document#event:mousedown mousedown} events on widget elements.
  	 *
  	 * @private
  	 * @param {module:utils/eventinfo~EventInfo} eventInfo
  	 * @param {module:engine/view/observer/domeventdata~DomEventData} domEventData
  	 */
  	_onMousedown( eventInfo, domEventData ) {
  		const editor = this.editor;
  		const view = editor.editing.view;
  		const viewDocument = view.document;
  		let element = domEventData.target;
  
  		// Do nothing for single or double click inside nested editable.
  		if ( isInsideNestedEditable( element ) ) {
  			// But at least triple click inside nested editable causes broken selection in Safari.
  			// For such event, we select the entire nested editable element.
  			// See: https://github.com/ckeditor/ckeditor5/issues/1463.
  			if ( ( env.isSafari || env.isGecko ) && domEventData.domEvent.detail >= 3 ) {
  				const mapper = editor.editing.mapper;
  				const viewElement = element.is( 'attributeElement' ) ?
  					element.findAncestor( element => !element.is( 'attributeElement' ) ) : element;
  				const modelElement = mapper.toModelElement( viewElement );
  
  				domEventData.preventDefault();
  
  				this.editor.model.change( writer => {
  					writer.setSelection( modelElement, 'in' );
  				} );
  			}
  
  			return;
  		}
  
  		// If target is not a widget element - check if one of the ancestors is.
  		if ( !isWidget( element ) ) {
  			element = element.findAncestor( isWidget );
  
  			if ( !element ) {
  				return;
  			}
  		}
  
  		// On Android selection would jump to the first table cell, on other devices
  		// we can't block it (and don't need to) because of drag and drop support.
  		if ( env.isAndroid ) {
  			domEventData.preventDefault();
  		}
  
  		// Focus editor if is not focused already.
  		if ( !viewDocument.isFocused ) {
  			view.focus();
  		}
  
  		// Create model selection over widget.
  		const modelElement = editor.editing.mapper.toModelElement( element );
  
  		this._setSelectionOverElement( modelElement );
  	}
  
  	/**
  	 * Handles {@link module:engine/view/document~Document#event:keydown keydown} events and changes
  	 * the model selection when:
  	 *
  	 * * arrow key is pressed when the widget is selected,
  	 * * the selection is next to a widget and the widget should become selected upon the arrow key press.
  	 *
  	 * See {@link #_preventDefaultOnArrowKeyPress}.
  	 *
  	 * @private
  	 * @param {module:utils/eventinfo~EventInfo} eventInfo
  	 * @param {module:engine/view/observer/domeventdata~DomEventData} domEventData
  	 */
  	_handleSelectionChangeOnArrowKeyPress( eventInfo, domEventData ) {
  		const keyCode = domEventData.keyCode;
  
  		const model = this.editor.model;
  		const schema = model.schema;
  		const modelSelection = model.document.selection;
  		const objectElement = modelSelection.getSelectedElement();
  		const direction = getLocalizedArrowKeyCodeDirection( keyCode, this.editor.locale.contentLanguageDirection );
  		const isForward = direction == 'down' || direction == 'right';
  		const isVerticalNavigation = direction == 'up' || direction == 'down';
  
  		// If object element is selected.
  		if ( objectElement && schema.isObject( objectElement ) ) {
  			const position = isForward ? modelSelection.getLastPosition() : modelSelection.getFirstPosition();
  			const newRange = schema.getNearestSelectionRange( position, isForward ? 'forward' : 'backward' );
  
  			if ( newRange ) {
  				model.change( writer => {
  					writer.setSelection( newRange );
  				} );
  
  				domEventData.preventDefault();
  				eventInfo.stop();
  			}
  
  			return;
  		}
  
  		// Handle collapsing of the selection when there is any widget on the edge of selection.
  		// This is needed because browsers have problems with collapsing such selection.
  		if ( !modelSelection.isCollapsed && !domEventData.shiftKey ) {
  			const firstPosition = modelSelection.getFirstPosition();
  			const lastPosition = modelSelection.getLastPosition();
  
  			const firstSelectedNode = firstPosition.nodeAfter;
  			const lastSelectedNode = lastPosition.nodeBefore;
  
  			if ( firstSelectedNode && schema.isObject( firstSelectedNode ) || lastSelectedNode && schema.isObject( lastSelectedNode ) ) {
  				model.change( writer => {
  					writer.setSelection( isForward ? lastPosition : firstPosition );
  				} );
  
  				domEventData.preventDefault();
  				eventInfo.stop();
  			}
  
  			return;
  		}
  
  		// Return if not collapsed.
  		if ( !modelSelection.isCollapsed ) {
  			return;
  		}
  
  		// If selection is next to object element.
  
  		const objectElementNextToSelection = this._getObjectElementNextToSelection( isForward );
  
  		if ( objectElementNextToSelection && schema.isObject( objectElementNextToSelection ) ) {
  			// Do not select an inline widget while handling up/down arrow.
  			if ( schema.isInline( objectElementNextToSelection ) && isVerticalNavigation ) {
  				return;
  			}
  
  			this._setSelectionOverElement( objectElementNextToSelection );
  
  			domEventData.preventDefault();
  			eventInfo.stop();
  		}
  	}
  
  	/**
  	 * Handles {@link module:engine/view/document~Document#event:keydown keydown} events and prevents
  	 * the default browser behavior to make sure the fake selection is not being moved from a fake selection
  	 * container.
  	 *
  	 * See {@link #_handleSelectionChangeOnArrowKeyPress}.
  	 *
  	 * @private
  	 * @param {module:utils/eventinfo~EventInfo} eventInfo
  	 * @param {module:engine/view/observer/domeventdata~DomEventData} domEventData
  	 */
  	_preventDefaultOnArrowKeyPress( eventInfo, domEventData ) {
  		const model = this.editor.model;
  		const schema = model.schema;
  		const objectElement = model.document.selection.getSelectedElement();
  
  		// If object element is selected.
  		if ( objectElement && schema.isObject( objectElement ) ) {
  			domEventData.preventDefault();
  			eventInfo.stop();
  		}
  	}
  
  	/**
  	 * Handles delete keys: backspace and delete.
  	 *
  	 * @private
  	 * @param {Boolean} isForward Set to true if delete was performed in forward direction.
  	 * @returns {Boolean|undefined} Returns `true` if keys were handled correctly.
  	 */
  	_handleDelete( isForward ) {
  		// Do nothing when the read only mode is enabled.
  		if ( this.editor.isReadOnly ) {
  			return;
  		}
  
  		const modelDocument = this.editor.model.document;
  		const modelSelection = modelDocument.selection;
  
  		// Do nothing on non-collapsed selection.
  		if ( !modelSelection.isCollapsed ) {
  			return;
  		}
  
  		const objectElement = this._getObjectElementNextToSelection( isForward );
  
  		if ( objectElement ) {
  			this.editor.model.change( writer => {
  				let previousNode = modelSelection.anchor.parent;
  
  				// Remove previous element if empty.
  				while ( previousNode.isEmpty ) {
  					const nodeToRemove = previousNode;
  					previousNode = nodeToRemove.parent;
  
  					writer.remove( nodeToRemove );
  				}
  
  				this._setSelectionOverElement( objectElement );
  			} );
  
  			return true;
  		}
  	}
  
  	/**
  	 * Sets {@link module:engine/model/selection~Selection document's selection} over given element.
  	 *
  	 * @protected
  	 * @param {module:engine/model/element~Element} element
  	 */
  	_setSelectionOverElement( element ) {
  		this.editor.model.change( writer => {
  			writer.setSelection( writer.createRangeOn( element ) );
  		} );
  	}
  
  	/**
  	 * Checks if {@link module:engine/model/element~Element element} placed next to the current
  	 * {@link module:engine/model/selection~Selection model selection} exists and is marked in
  	 * {@link module:engine/model/schema~Schema schema} as `object`.
  	 *
  	 * @protected
  	 * @param {Boolean} forward Direction of checking.
  	 * @returns {module:engine/model/element~Element|null}
  	 */
  	_getObjectElementNextToSelection( forward ) {
  		const model = this.editor.model;
  		const schema = model.schema;
  		const modelSelection = model.document.selection;
  
  		// Clone current selection to use it as a probe. We must leave default selection as it is so it can return
  		// to its current state after undo.
  		const probe = model.createSelection( modelSelection );
  		model.modifySelection( probe, { direction: forward ? 'forward' : 'backward' } );
  
  		// The selection didn't change so there is nothing there.
  		if ( probe.isEqual( modelSelection ) ) {
  			return null;
  		}
  
  		const objectElement = forward ? probe.focus.nodeBefore : probe.focus.nodeAfter;
  
  		if ( !!objectElement && schema.isObject( objectElement ) ) {
  			return objectElement;
  		}
  
  		return null;
  	}
  
  	/**
  	 * Removes CSS class from previously selected widgets.
  	 *
  	 * @private
  	 * @param {module:engine/view/downcastwriter~DowncastWriter} writer
  	 */
  	_clearPreviouslySelectedWidgets( writer ) {
  		for ( const widget of this._previouslySelected ) {
  			writer.removeClass( WIDGET_SELECTED_CLASS_NAME, widget );
  		}
  
  		this._previouslySelected.clear();
  	}
  }
  
  // Returns `true` when element is a nested editable or is placed inside one.
  //
  // @param {module:engine/view/element~Element}
  // @returns {Boolean}
  function isInsideNestedEditable( element ) {
  	while ( element ) {
  		if ( element.is( 'editableElement' ) && !element.is( 'rootElement' ) ) {
  			return true;
  		}
  
  		// Click on nested widget should select it.
  		if ( isWidget( element ) ) {
  			return false;
  		}
  
  		element = element.parent;
  	}
  
  	return false;
  }
  
  // Checks whether the specified `element` is a child of the `parent` element.
  //
  // @param {module:engine/view/element~Element} element An element to check.
  // @param {module:engine/view/element~Element|null} parent A parent for the element.
  // @returns {Boolean}
  function isChild( element, parent ) {
  	if ( !parent ) {
  		return false;
  	}
  
  	return Array.from( element.getAncestors() ).includes( parent );
  }
  