ckeditor/ckeditor5-basic-styles

/**
 * @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 basic-styles/attributecommand
 */

import Command from '@ckeditor/ckeditor5-core/src/command';

/**
 * An extension of the base {@link module:core/command~Command} class, which provides utilities for a command
 * that toggles a single attribute on a text or an element.
 *
 * `AttributeCommand` uses {@link module:engine/model/document~Document#selection}
 * to decide which nodes (if any) should be changed, and applies or removes the attribute from them.
 *
 * The command checks the {@link module:engine/model/model~Model#schema} to decide if it can be enabled
 * for the current selection and to which nodes the attribute can be applied.
 *
 * @extends module:core/command~Command
 */
export default class AttributeCommand extends Command {
    /**
     * @param {module:core/editor/editor~Editor} editor
     * @param {String} attributeKey Attribute that will be set by the command.
     */
    constructor( editor, attributeKey ) {
        super( editor );

        /**
         * The attribute that will be set by the command.
         *
         * @readonly
         * @member {String}
         */
        this.attributeKey = attributeKey;

        /**
         * Flag indicating whether the command is active. The command is active when the
         * {@link module:engine/model/selection~Selection#hasAttribute selection has the attribute} which means that:
         *
         * * If the selection is not empty – That the attribute is set on the first node in the selection that allows this attribute.
         * * If the selection is empty – That the selection has the attribute itself (which means that newly typed
         * text will have this attribute, too).
         *
         * @observable
         * @readonly
         * @member {Boolean} #value
         */
    }

    /**
     * Updates the command's {@link #value} and {@link #isEnabled} based on the current selection.
     */
    refresh() {
        const model = this.editor.model;
        const doc = model.document;

        this.value = this._getValueFromFirstAllowedNode();
        this.isEnabled = model.schema.checkAttributeInSelection( doc.selection, this.attributeKey );
    }

    /**
     * Executes the command — applies the attribute to the selection or removes it from the selection.
     *
     * If the command is active (`value == true`), it will remove attributes. Otherwise, it will set attributes.
     *
     * The execution result differs, depending on the {@link module:engine/model/document~Document#selection}:
     *
     * * If the selection is on a range, the command applies the attribute to all nodes in that range
     * (if they are allowed to have this attribute by the {@link module:engine/model/schema~Schema schema}).
     * * If the selection is collapsed in a non-empty node, the command applies the attribute to the
     * {@link module:engine/model/document~Document#selection} itself (note that typed characters copy attributes from the selection).
     * * If the selection is collapsed in an empty node, the command applies the attribute to the parent node of the selection (note
     * that the selection inherits all attributes from a node if it is in an empty node).
     *
     * @fires execute
     * @param {Object} [options] Command options.
     * @param {Boolean} [options.forceValue] If set, it will force the command behavior. If `true`, the command will apply the attribute,
     * otherwise the command will remove the attribute.
     * If not set, the command will look for its current value to decide what it should do.
     */
    execute( options = {} ) {
        const model = this.editor.model;
        const doc = model.document;
        const selection = doc.selection;
        const value = ( options.forceValue === undefined ) ? !this.value : options.forceValue;

        model.change( writer => {
            if ( selection.isCollapsed ) {
                if ( value ) {
                    writer.setSelectionAttribute( this.attributeKey, true );
                } else {
                    writer.removeSelectionAttribute( this.attributeKey );
                }
            } else {
                const ranges = model.schema.getValidRanges( selection.getRanges(), this.attributeKey );

                for ( const range of ranges ) {
                    if ( value ) {
                        writer.setAttribute( this.attributeKey, value, range );
                    } else {
                        writer.removeAttribute( this.attributeKey, range );
                    }
                }
            }
        } );
    }

    /**
     * Checks the attribute value of the first node in the selection that allows the attribute.
     * For the collapsed selection returns the selection attribute.
     *
     * @private
     * @returns {Boolean} The attribute value.
     */
    _getValueFromFirstAllowedNode() {
        const model = this.editor.model;
        const schema = model.schema;
        const selection = model.document.selection;

        if ( selection.isCollapsed ) {
            return selection.hasAttribute( this.attributeKey );
        }

        for ( const range of selection.getRanges() ) {
            for ( const item of range.getItems() ) {
                if ( schema.checkAttribute( item, this.attributeKey ) ) {
                    return item.hasAttribute( this.attributeKey );
                }
            }
        }

        return false;
    }
}