hedgedoc/src/components/render-page/iframe-communicator.ts

/*
 * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
 *
 * SPDX-License-Identifier: AGPL-3.0-only
 */

export abstract class IframeCommunicator<SEND, RECEIVE> {
  protected otherSide?: Window
  protected otherOrigin?: string

  constructor () {
    window.addEventListener("message", this.handleEvent.bind(this))
  }

  public unregisterEventListener (): void {
    window.removeEventListener("message", this.handleEvent.bind(this))
  }

  public setOtherSide (otherSide: Window, otherOrigin: string): void {
    this.otherSide = otherSide
    this.otherOrigin = otherOrigin
  }

  public unsetOtherSide (): void {
    this.otherSide = undefined
    this.otherOrigin = undefined
  }

  public getOtherSide (): Window | undefined {
    return this.otherSide
  }

  protected sendMessageToOtherSide (message: SEND): void {
    if (this.otherSide === undefined || this.otherOrigin === undefined) {
      console.error("Can't send message because otherSide is null", message)
      return
    }
    this.otherSide.postMessage(message, this.otherOrigin)
  }

  protected abstract handleEvent (event: MessageEvent<RECEIVE>): void;
}