#include <iostream>
using namespace std;

// Command Interface
class Command{
  public:
	virtual void execute() = 0;
};
 
// Receiver Class
class Light{
  public:
	void on() {
		cout << "The light is on\n";
	}
	void off() {
		cout << "The light is off\n";
	}
}; 

// Command for turning on the light
class LightOnCommand:public Command{
	Light *pLight;
  public:
    LightOnCommand(Light& light) : pLight(&light) {}
	void execute(){
		pLight->on();
	}
};
 
// Command for turning off the light
class LightOffCommand : public Command {
	Light *pLight;
  public:
    LightOffCommand(Light& light) : pLight(&light) {}
	void execute(){
		pLight->off();
	}
};

// Invoker - Stores the ConcreteCommand object 
class RemoteControl {
	Command *pCmd;
  public:
	void setCommand(Command& cmd){
		pCmd = &cmd;
	}
	void buttonPressed() {
		pCmd->execute();
	} 
};
 
// The client
int main() {
	// Receiver 
	Light light;

	// concrete Command objects 
	LightOnCommand lightOn(light);
	LightOffCommand lightOff(light);

	// invoker objects
	RemoteControl controller;

	// execute (Invocation)
	controller.setCommand(lightOn);
	controller.buttonPressed();
	controller.setCommand(lightOff);
	controller.buttonPressed();

	return 0;
}