blockly/core/events/events_comment_change.ts

/**
 * @license
 * Copyright 2018 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * Class for comment change event.
 *
 * @class
 */
// Former goog.module ID: Blockly.Events.CommentChange

import type {WorkspaceComment} from '../comments/workspace_comment.js';
import * as registry from '../registry.js';
import type {Workspace} from '../workspace.js';
import {CommentBase, CommentBaseJson} from './events_comment_base.js';
import {EventType} from './type.js';

/**
 * Notifies listeners that the contents of a workspace comment has changed.
 */
export class CommentChange extends CommentBase {
  override type = EventType.COMMENT_CHANGE;

  // TODO(#6774): We should remove underscores.
  /** The previous contents of the comment. */
  oldContents_?: string;

  /** The new contents of the comment. */
  newContents_?: string;

  /**
   * @param opt_comment The comment that is being changed.  Undefined for a
   *     blank event.
   * @param opt_oldContents Previous contents of the comment.
   * @param opt_newContents New contents of the comment.
   */
  constructor(
    opt_comment?: WorkspaceComment,
    opt_oldContents?: string,
    opt_newContents?: string,
  ) {
    super(opt_comment);

    if (!opt_comment) {
      return; // Blank event to be populated by fromJson.
    }

    this.oldContents_ =
      typeof opt_oldContents === 'undefined' ? '' : opt_oldContents;
    this.newContents_ =
      typeof opt_newContents === 'undefined' ? '' : opt_newContents;
  }

  /**
   * Encode the event as JSON.
   *
   * @returns JSON representation.
   */
  override toJson(): CommentChangeJson {
    const json = super.toJson() as CommentChangeJson;
    if (!this.oldContents_) {
      throw new Error(
        'The old contents is undefined. Either pass a value to ' +
          'the constructor, or call fromJson',
      );
    }
    if (!this.newContents_) {
      throw new Error(
        'The new contents is undefined. Either pass a value to ' +
          'the constructor, or call fromJson',
      );
    }
    json['oldContents'] = this.oldContents_;
    json['newContents'] = this.newContents_;
    return json;
  }

  /**
   * Deserializes the JSON event.
   *
   * @param event The event to append new properties to. Should be a subclass
   *     of CommentChange, but we can't specify that due to the fact that
   *     parameters to static methods in subclasses must be supertypes of
   *     parameters to static methods in superclasses.
   * @internal
   */
  static fromJson(
    json: CommentChangeJson,
    workspace: Workspace,
    event?: any,
  ): CommentChange {
    const newEvent = super.fromJson(
      json,
      workspace,
      event ?? new CommentChange(),
    ) as CommentChange;
    newEvent.oldContents_ = json['oldContents'];
    newEvent.newContents_ = json['newContents'];
    return newEvent;
  }

  /**
   * Does this event record any change of state?
   *
   * @returns False if something changed.
   */
  override isNull(): boolean {
    return this.oldContents_ === this.newContents_;
  }

  /**
   * Run a change event.
   *
   * @param forward True if run forward, false if run backward (undo).
   */
  override run(forward: boolean) {
    const workspace = this.getEventWorkspace_();
    if (!this.commentId) {
      throw new Error(
        'The comment ID is undefined. Either pass a comment to ' +
          'the constructor, or call fromJson',
      );
    }
    // TODO: Remove the cast when we fix the type of getCommentById.
    const comment = workspace.getCommentById(
      this.commentId,
    ) as unknown as WorkspaceComment;
    if (!comment) {
      console.warn("Can't change non-existent comment: " + this.commentId);
      return;
    }
    const contents = forward ? this.newContents_ : this.oldContents_;
    if (contents === undefined) {
      if (forward) {
        throw new Error(
          'The new contents is undefined. Either pass a value to ' +
            'the constructor, or call fromJson',
        );
      }
      throw new Error(
        'The old contents is undefined. Either pass a value to ' +
          'the constructor, or call fromJson',
      );
    }
    comment.setText(contents);
  }
}

export interface CommentChangeJson extends CommentBaseJson {
  oldContents: string;
  newContents: string;
}

registry.register(registry.Type.EVENT, EventType.COMMENT_CHANGE, CommentChange);