ckeditor/ckeditor5-block-quote

/**
 * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
 */

/**
 * @module block-quote/blockquoteediting
 */

import Plugin from '@ckeditor/ckeditor5-core/src/plugin';

import BlockQuoteCommand from './blockquotecommand';

/**
 * The block quote editing.
 *
 * Introduces the `'blockQuote'` command and the `'blockQuote'` model element.
 *
 * @extends module:core/plugin~Plugin
 */
export default class BlockQuoteEditing extends Plugin {
    /**
     * @inheritDoc
     */
    static get pluginName() {
        return 'BlockQuoteEditing';
    }

    /**
     * @inheritDoc
     */
    init() {
        const editor = this.editor;
        const schema = editor.model.schema;

        editor.commands.add( 'blockQuote', new BlockQuoteCommand( editor ) );

        schema.register( 'blockQuote', {
            allowWhere: '$block',
            allowContentOf: '$root'
        } );

        // Disallow blockQuote in blockQuote.
        schema.addChildCheck( ( ctx, childDef ) => {
            if ( ctx.endsWith( 'blockQuote' ) && childDef.name == 'blockQuote' ) {
                return false;
            }
        } );

        editor.conversion.elementToElement( { model: 'blockQuote', view: 'blockquote' } );

        // Postfixer which cleans incorrect model states connected with block quotes.
        editor.model.document.registerPostFixer( writer => {
            const changes = editor.model.document.differ.getChanges();

            for ( const entry of changes ) {
                if ( entry.type == 'insert' ) {
                    const element = entry.position.nodeAfter;

                    if ( !element ) {
                        // We are inside a text node.
                        continue;
                    }

                    if ( element.is( 'blockQuote' ) && element.isEmpty ) {
                        // Added an empty blockQuote - remove it.
                        writer.remove( element );

                        return true;
                    } else if ( element.is( 'blockQuote' ) && !schema.checkChild( entry.position, element ) ) {
                        // Added a blockQuote in incorrect place - most likely inside another blockQuote. Unwrap it
                        // so the content inside is not lost.
                        writer.unwrap( element );

                        return true;
                    } else if ( element.is( 'element' ) ) {
                        // Just added an element. Check its children to see if there are no nested blockQuotes somewhere inside.
                        const range = writer.createRangeIn( element );

                        for ( const child of range.getItems() ) {
                            if ( child.is( 'blockQuote' ) && !schema.checkChild( writer.createPositionBefore( child ), child ) ) {
                                writer.unwrap( child );

                                return true;
                            }
                        }
                    }
                } else if ( entry.type == 'remove' ) {
                    const parent = entry.position.parent;

                    if ( parent.is( 'blockQuote' ) && parent.isEmpty ) {
                        // Something got removed and now blockQuote is empty. Remove the blockQuote as well.
                        writer.remove( parent );

                        return true;
                    }
                }
            }

            return false;
        } );
    }

    /**
     * @inheritDoc
     */
    afterInit() {
        const editor = this.editor;
        const command = editor.commands.get( 'blockQuote' );

        // Overwrite default Enter key behavior.
        // If Enter key is pressed with selection collapsed in empty block inside a quote, break the quote.
        // This listener is added in afterInit in order to register it after list's feature listener.
        // We can't use a priority for this, because 'low' is already used by the enter feature, unless
        // we'd use numeric priority in this case.
        this.listenTo( this.editor.editing.view.document, 'enter', ( evt, data ) => {
            const doc = this.editor.model.document;
            const positionParent = doc.selection.getLastPosition().parent;

            if ( doc.selection.isCollapsed && positionParent.isEmpty && command.value ) {
                this.editor.execute( 'blockQuote' );
                this.editor.editing.view.scrollToTheSelection();

                data.preventDefault();
                evt.stop();
            }
        } );
    }
}