codemirror-collab-ext-master/src/ts/RemoteCursorManager.ts

/*
 * Copyright (c) 2019 Convergence Labs, Inc.
 *
 * This file is part of the CodeMirror Collaborative Extensions, which is
 * released under the terms of the MIT license. A copy of the MIT license
 * is usually provided as part of this source code package in the LICENCE
 * file. If it was not, please see <https://opensource.org/licenses/MIT>
 */

import {Position} from "codemirror";
import {IRemoteCursorManagerOptions} from "./IRemoteCursorManagerOptions";
import {RemoteCursor} from "./RemoteCursor";
import {RemoteCursorWidget} from "./RemoteCursorWidget";
import {Validation} from "./Validation";

/**
 * The RemoteCursorManager class is responsible for creating and managing a
 * set of indicators that show where remote users's cursors are located when
 * using CodeMirror in a collaborative editing context.  The RemoteCursorManager
 * leverages CodeMirror's Widget concept to add cursor nodes to the editor.
 */
export class RemoteCursorManager {

  /**
   * The default values for optional parameters.
   * @internal
   */
  private static readonly DEFAULT_OPTIONS = {tooltips: true, tooltipDuration: 1};

  /**
   * A counter that generates unique ids for the cursor widgets.
   * @internal
   */
  private _nextWidgetId: number;

  /**
   * Tracks the current cursor widgets by the userland id.
   * @internal
   */
  private readonly _cursorWidgets: Map<string, any>;

  /**
   * The options (and defaults) used to configure this instance.
   * @internal
   */
  private readonly _options: IRemoteCursorManagerOptions;

  /**
   * Creates a new RemoteCursorManager with the supplied options.
   *
   * @param options
   *   The options that will configure the RemoteCursorManager behavior.
   */
  constructor(options: IRemoteCursorManagerOptions) {
    if (typeof  options !== "object") {
      throw new Error("'options' is a required parameter and must be an object.");
    }

    // Override the defaults.
    options = {...RemoteCursorManager.DEFAULT_OPTIONS, ...options};

    if (options.editor === undefined || options.editor === null) {
      throw new Error(`options.editor must be defined but was: ${options.editor}`);
    }

    this._options = options;
    this._cursorWidgets = new Map<string, RemoteCursorWidget>();
    this._nextWidgetId = 0;
  }

  /**
   * Adds a new remote cursor to the editor.
   *
   * @param id
   *   A unique id that will be used to reference this cursor.
   * @param color
   *   The css color that the cursor and tooltip should be rendered in.
   * @param label
   *   An optional label for the tooltip. If tooltips are enabled.
   *
   * @returns
   *   The remote cursor widget that will be added to the editor.
   */
  public addCursor(id: string, color: string, label?: string): RemoteCursor {
    Validation.assertString(id, "id");
    Validation.assertString(color, "color");

    if (this._options.tooltips && typeof "label" !== "string") {
      throw new Error("'label' is required when tooltips are enabled.");
    }

    const widgetId = "" + this._nextWidgetId++;
    const tooltipDurationMs = this._options.tooltipDuration * 1000;
    const cursorWidget = new RemoteCursorWidget(
      this._options.editor,
      widgetId,
      color,
      label,
      this._options.tooltips,
      tooltipDurationMs,
      () => this.removeCursor(id));
    this._cursorWidgets.set(id, cursorWidget);

    return new RemoteCursor(cursorWidget);
  }

  /**
   * Removes the remote cursor from the editor.
   *
   * @param id
   *   The unique id of the cursor to remove.
   */
  public removeCursor(id: string): void {
    Validation.assertString(id, "id");

    const remoteCursorWidget = this._getCursor(id);
    if (!remoteCursorWidget.isDisposed()) {
      remoteCursorWidget.dispose();
    }
    this._cursorWidgets.delete(id);
  }

  /**
   * Updates the location of the specified remote cursor using a CodeMirror
   * Position object.
   *
   * @param id
   *   The unique id of the cursor to remove.
   * @param position
   *   The location of the cursor to set.
   */
  public setCursorPosition(id: string, position: Position) {
    Validation.assertString(id, "id");

    const remoteCursorWidget = this._getCursor(id);
    remoteCursorWidget.setPosition(position);
  }

  /**
   * Updates the location of the specified remote cursor based on a zero-based
   * text index.
   *
   * @param id
   *   The unique id of the cursor to remove.
   * @param index
   *   The location of the cursor to set.
   */
  public setCursorIndex(id: string, index: number) {
    Validation.assertString(id, "id");

    const remoteCursorWidget = this._getCursor(id);
    remoteCursorWidget.setIndex(index);
  }

  /**
   * Shows the specified cursor. Note the cursor may be scrolled out of view.
   *
   * @param id
   *   The unique id of the cursor to show.
   */
  public showCursor(id: string): void {
    Validation.assertString(id, "id");

    const remoteCursorWidget = this._getCursor(id);
    remoteCursorWidget.show();
  }

  /**
   * Hides the specified cursor.
   *
   * @param id
   *   The unique id of the cursor to show.
   */
  public hideCursor(id: string): void {
    Validation.assertString(id, "id");

    const remoteCursorWidget = this._getCursor(id);
    remoteCursorWidget.hide();
  }

  /**
   * A helper method that gets a cursor by id, or throws an exception.
   * @internal
   */
  private _getCursor(id: string): RemoteCursorWidget {
    if (!this._cursorWidgets.has(id)) {
      throw new Error("No such cursor: " + id);
    }

    return this._cursorWidgets.get(id);
  }
}