ckeditor/ckeditor5-autoformat

/**
 * @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 autoformat/blockautoformatediting
 */

import LiveRange from '@ckeditor/ckeditor5-engine/src/model/liverange';

/**
 * The block autoformatting engine. It allows to format various block patterns. For example,
 * it can be configured to turn a paragraph starting with `*` and followed by a space into a list item.
 *
 * The autoformatting operation is integrated with the undo manager,
 * so the autoformatting step can be undone if the user's intention was not to format the text.
 *
 * See the constructors documentation to learn how to create custom inline autoformatters. You can also use
 * the {@link module:autoformat/autoformat~Autoformat} feature which enables a set of default autoformatters
 * (lists, headings, bold and italic).
 */
export default class BlockAutoformatEditing {
    /**
     * @inheritDoc
     */
    static get pluginName() {
        return 'BlockAutoformatEditing';
    }

    /**
     * Creates a listener triggered on `change` event in the document.
     * Calls the callback when inserted text matches the regular expression or the command name
     * if provided instead of the callback.
     *
     * Examples of usage:
     *
     * To convert a paragraph to heading 1 when `- ` is typed, using just the command name:
     *
     *        new BlockAutoformatEditing( editor, /^\- $/, 'heading1' );
     *
     * To convert a paragraph to heading 1 when `- ` is typed, using just the callback:
     *
     *        new BlockAutoformatEditing( editor, /^\- $/, ( context ) => {
     *            const { match } = context;
     *            const headingLevel = match[ 1 ].length;
     *
     *            editor.execute( 'heading', {
     *                formatId: `heading${ headingLevel }`
     *            } );
     *         } );
     *
     * @param {module:core/editor/editor~Editor} editor The editor instance.
     * @param {RegExp} pattern The regular expression to execute on just inserted text.
     * @param {Function|String} callbackOrCommand The callback to execute or the command to run when the text is matched.
     * In case of providing the callback, it receives the following parameter:
     * * {Object} match RegExp.exec() result of matching the pattern to inserted text.
     */
    constructor( editor, pattern, callbackOrCommand ) {
        let callback;
        let command = null;

        if ( typeof callbackOrCommand == 'function' ) {
            callback = callbackOrCommand;
        } else {
            // We assume that the actual command name was provided.
            command = editor.commands.get( callbackOrCommand );

            callback = () => {
                editor.execute( callbackOrCommand );
            };
        }

        editor.model.document.on( 'change', ( evt, batch ) => {
            if ( command && !command.isEnabled ) {
                return;
            }

            if ( batch.type == 'transparent' ) {
                return;
            }

            const changes = Array.from( editor.model.document.differ.getChanges() );
            const entry = changes[ 0 ];

            // Typing is represented by only a single change.
            if ( changes.length != 1 || entry.type !== 'insert' || entry.name != '$text' || entry.length != 1 ) {
                return;
            }

            const blockToFormat = entry.position.parent;

            // Block formatting should trigger only if the entire content of a paragraph is a single text node... (see ckeditor5#5671).
            if ( !blockToFormat.is( 'paragraph' ) || blockToFormat.childCount !== 1 ) {
                return;
            }

            const match = pattern.exec( blockToFormat.getChild( 0 ).data );

            // ...and this text node's data match the pattern.
            if ( !match ) {
                return;
            }

            // Use enqueueChange to create new batch to separate typing batch from the auto-format changes.
            editor.model.enqueueChange( writer => {
                // Matched range.
                const start = writer.createPositionAt( blockToFormat, 0 );
                const end = writer.createPositionAt( blockToFormat, match[ 0 ].length );
                const range = new LiveRange( start, end );

                const wasChanged = callback( { match } );

                // Remove matched text.
                if ( wasChanged !== false ) {
                    writer.remove( range );
                }

                range.detach();
            } );
        } );
    }
}