ckeditor/ckeditor5-engine

/**
 * @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 engine/dataprocessor/htmldataprocessor
 */

/* globals document, DOMParser */

import BasicHtmlWriter from './basichtmlwriter';
import DomConverter from '../view/domconverter';

/**
 * The HTML data processor class.
 * This data processor implementation uses HTML as input and output data.
 *
 * @implements module:engine/dataprocessor/dataprocessor~DataProcessor
 */
export default class HtmlDataProcessor {
    /**
     * Creates a new instance of the HTML data processor class.
     *
     * @param {module:engine/view/document~Document} document The view document instance.
     */
    constructor( document ) {
        /**
         * A DOM parser instance used to parse an HTML string to an HTML document.
         *
         * @private
         * @member {DOMParser}
         */
        this._domParser = new DOMParser();

        /**
         * A DOM converter used to convert DOM elements to view elements.
         *
         * @private
         * @member {module:engine/view/domconverter~DomConverter}
         */
        this._domConverter = new DomConverter( document, { blockFillerMode: 'nbsp' } );

        /**
         * A basic HTML writer instance used to convert DOM elements to an HTML string.
         *
         * @private
         * @member {module:engine/dataprocessor/basichtmlwriter~BasicHtmlWriter}
         */
        this._htmlWriter = new BasicHtmlWriter();
    }

    /**
     * Converts a provided {@link module:engine/view/documentfragment~DocumentFragment document fragment}
     * to data format — in this case to an HTML string.
     *
     * @param {module:engine/view/documentfragment~DocumentFragment} viewFragment
     * @returns {String} HTML string.
     */
    toData( viewFragment ) {
        // Convert view DocumentFragment to DOM DocumentFragment.
        const domFragment = this._domConverter.viewToDom( viewFragment, document );

        // Convert DOM DocumentFragment to HTML output.
        return this._htmlWriter.getHtml( domFragment );
    }

    /**
     * Converts the provided HTML string to a view tree.
     *
     * @param {String} data An HTML string.
     * @returns {module:engine/view/node~Node|module:engine/view/documentfragment~DocumentFragment|null} A converted view element.
     */
    toView( data ) {
        // Convert input HTML data to DOM DocumentFragment.
        const domFragment = this._toDom( data );

        // Convert DOM DocumentFragment to view DocumentFragment.
        return this._domConverter.domToView( domFragment );
    }

    /**
     * Converts an HTML string to its DOM representation. Returns a document fragment containing nodes parsed from
     * the provided data.
     *
     * @private
     * @param {String} data
     * @returns {DocumentFragment}
     */
    _toDom( data ) {
        const document = this._domParser.parseFromString( data, 'text/html' );
        const fragment = document.createDocumentFragment();
        const nodes = document.body.childNodes;

        while ( nodes.length > 0 ) {
            fragment.appendChild( nodes[ 0 ] );
        }

        return fragment;
    }
}