ckeditor/ckeditor5-heading

/**
 * @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 heading/headingui
 */

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

import { createDropdown, addListToDropdown } from '@ckeditor/ckeditor5-ui/src/dropdown/utils';
import { getLocalizedOptions } from './utils';

import Collection from '@ckeditor/ckeditor5-utils/src/collection';

import '../theme/heading.css';

/**
 * The headings UI feature. It introduces the `headings` dropdown.
 *
 * @extends module:core/plugin~Plugin
 */
export default class HeadingUI extends Plugin {
    /**
     * @inheritDoc
     */
    init() {
        const editor = this.editor;
        const t = editor.t;
        const options = getLocalizedOptions( editor );
        const defaultTitle = t( 'Choose heading' );
        const dropdownTooltip = t( 'Heading' );

        // Register UI component.
        editor.ui.componentFactory.add( 'heading', locale => {
            const titles = {};
            const itemDefinitions = new Collection();

            const headingCommand = editor.commands.get( 'heading' );
            const paragraphCommand = editor.commands.get( 'paragraph' );

            const commands = [ headingCommand ];

            for ( const option of options ) {
                const def = {
                    type: 'button',
                    model: new Model( {
                        label: option.title,
                        class: option.class,
                        withText: true
                    } )
                };

                if ( option.model === 'paragraph' ) {
                    def.model.bind( 'isOn' ).to( paragraphCommand, 'value' );
                    def.model.set( 'commandName', 'paragraph' );
                    commands.push( paragraphCommand );
                } else {
                    def.model.bind( 'isOn' ).to( headingCommand, 'value', value => value === option.model );
                    def.model.set( {
                        commandName: 'heading',
                        commandValue: option.model
                    } );
                }

                // Add the option to the collection.
                itemDefinitions.add( def );

                titles[ option.model ] = option.title;
            }

            const dropdownView = createDropdown( locale );
            addListToDropdown( dropdownView, itemDefinitions );

            dropdownView.buttonView.set( {
                isOn: false,
                withText: true,
                tooltip: dropdownTooltip
            } );

            dropdownView.extendTemplate( {
                attributes: {
                    class: [
                        'ck-heading-dropdown'
                    ]
                }
            } );

            dropdownView.bind( 'isEnabled' ).toMany( commands, 'isEnabled', ( ...areEnabled ) => {
                return areEnabled.some( isEnabled => isEnabled );
            } );

            dropdownView.buttonView.bind( 'label' ).to( headingCommand, 'value', paragraphCommand, 'value', ( value, para ) => {
                const whichModel = value || para && 'paragraph';
                // If none of the commands is active, display default title.
                return titles[ whichModel ] ? titles[ whichModel ] : defaultTitle;
            } );

            // Execute command when an item from the dropdown is selected.
            this.listenTo( dropdownView, 'execute', evt => {
                editor.execute( evt.source.commandName, evt.source.commandValue ? { value: evt.source.commandValue } : undefined );
                editor.editing.view.focus();
            } );

            return dropdownView;
        } );
    }
}