Command Pattern

// Receiver - الجهاز
class TV {
  on() { return "📺 TV is ON"; }
  off() { return "📺 TV is OFF"; }
  volumeUp() { return "🔊 Volume UP"; }
}

// Command Interface
class Command {
  execute() { throw "implement!"; }
  undo() { throw "implement!"; }
}

// Concrete Commands
class TurnOnCommand extends Command {
  constructor(tv) { super(); this.tv = tv; }
  execute() { return this.tv.on(); }
  undo() { return this.tv.off(); } // الـ Undo!
}

class VolumeUpCommand extends Command {
  constructor(tv) { super(); this.tv = tv; }
  execute() { return this.tv.volumeUp(); }
}

// Invoker - الريموت
class Remote {
  constructor() { this.history = []; }
  
  setCommand(cmd) { this.command = cmd; }
  
  press() {
    this.history.push(this.command);
    return this.command.execute();
  }
  
  undo() {
    const cmd = this.history.pop();
    return cmd ? cmd.undo() : "Nothing to undo!";
  }
}