#include <iostream>
#include <string>
using namespace std;

class Subject{
  public:
	virtual string Request()=0;
};

class RealSubject:public Subject{
  public:
	string Request(){
      return "Answer from Real Subject";
    }
};

class CacheProxy: public Subject{
	RealSubject realSubject;
	string answer;
  public:
 	string Request(){
 		if (answer.empty()){
		  answer = realSubject.Request();
 		  cout<<"CacheProxy::Request from Real Subject"<<endl;
 		}
 		return answer;
 	}
};

class VirtualProxy: public Subject{
	RealSubject *subject=0;
  public:
 	string Request(){
      //Creates the object only on first time call
      if (!subject){
        cout<<"Subject inactive"<<endl;
        subject = new RealSubject();
      }
      cout<<"Subject active"<<endl;
      return "Proxy: Call to " + subject->Request();
    }
    ~VirtualProxy(){
    	if(subject) delete subject;
	}
};

class ProtectionProxy: public Subject{
    //An Authentication Proxy first asks for a password
    RealSubject *subject;
    string password="abc";
  public:
 	string Authenticate(string supplied){
      if (subject) return "Protection Proxy: You already allowed to access";
      if (supplied!=password) return "Protection Proxy: No access";
      subject = new RealSubject();
      return "Protection Proxy: Authenticated";
    }
    string Request(){
      if (!subject) return "Protection Proxy: Authenticate first";
      return "Protection Proxy: Call to " + subject->Request();
    }
    ~ProtectionProxy(){
    	if(subject) delete subject;
	}
};

int main(){
    Subject *subject = new VirtualProxy();
    cout<<subject->Request()<<endl;
    cout<<subject->Request()<<endl;
	delete subject;    
    cout<<"--------------------------"<<endl;
    subject = new ProtectionProxy();
    cout<<subject->Request()<<endl;
    cout<<((ProtectionProxy*)subject)->Authenticate("WrongPassword")<<endl;
    cout<<((ProtectionProxy*)subject)->Authenticate("abc")<<endl;
    cout<<((ProtectionProxy*)subject)->Authenticate("abc")<<endl;
    cout<<subject->Request()<<endl;
    delete subject;
    cout<<"--------------------------"<<endl;
    subject = new CacheProxy();
    cout<<subject->Request()<<endl;
    cout<<subject->Request()<<endl;
    cout<<subject->Request()<<endl;
    delete subject;
    return 0;
}