ComplecatedSmartHomeWithoutCommand.JS

// Receivers: Devices
class Light {
  turnOn() {
    console.log("Lights are ON");
  }
  turnOff() {
    console.log("Lights are OFF");
  }
}

class MusicPlayer {
  playSong(song) {
    console.log(`Playing song: ${song}`);
  }
  stop() {
    console.log("Music stopped");
  }
}

// Smart Home Controller (Tightly Coupled)
class SmartHomeController {
  constructor(light, musicPlayer) {
    this.light = light;
    this.musicPlayer = musicPlayer;
    this.history = [];
  }

  // Light Controls
  turnOnLight() {
    this.light.turnOn();
    this.history.push(() => this.light.turnOff());
  }

  turnOffLight() {
    this.light.turnOff();
    this.history.push(() => this.light.turnOn());
  }

  // Music Controls
  playMusic(song) {
    this.musicPlayer.playSong(song);
    this.history.push(() => this.musicPlayer.stop());
  }

  stopMusic() {
    this.musicPlayer.stop();
    // No undo for stop unless we track previous song manually!
  }

  // Undo last action
  pressUndo() {
    const undo = this.history.pop();
    if (undo) undo();
  }
}

// Usage
const light = new Light();
const musicPlayer = new MusicPlayer();
const controller = new SmartHomeController(light, musicPlayer);

controller.turnOnLight();        // Lights are ON
controller.playMusic("Imagine"); // Playing song: Imagine

controller.pressUndo(); // Music stopped
controller.pressUndo(); // Lights are OFF