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

class Component{
public:
	virtual string Operation()=0;
};

class ConcreteComponent:public Component{
public:
 	string Operation(){
      return "I am walking ";
    }
};

class Decorator : public Component{
protected:
	Component *component;
public:
	virtual string Operation()=0;
    Decorator(Component *c) {
      component = c;
    }
};

class DecoratorA : public Decorator {
public:
	DecoratorA(Component *c):Decorator(c){}
    string Operation(){
      return component->Operation() + "and listening to Classic FM ";
    }
};

class DecoratorB : public Decorator {
public:
	string addedState = "past the Coffee Shop ";
 	DecoratorB(Component *c):Decorator(c){}
    string Operation() {
      return component->Operation() + "to school ";
    }
    string AddedBehavior(){
      return "and I bought a cappucino ";
    }
};

void Display(string s, Component *c){
    cout<<(s + c->Operation())<<endl;
}

int main(){
    cout<<"Decorator Pattern"<<endl<<endl;
   	ConcreteComponent component;
    Display("1. Basic component: ", &component);
    Decorator *d = new DecoratorA(&component);
    Display("2. A-decorated : ", d);
    delete d;
    d = new DecoratorB(&component);
    Display("3. B-decorated : ", d);
    delete d;
    d = new DecoratorA(&component);
    Decorator *dd = new DecoratorA(d);
    Display("4. B-A-decorated : ", dd);
    delete d;
    delete dd;
    // Explicit DecoratorB
    DecoratorB b(&component);
    d = new DecoratorA(&b);
    Display("5. A-B-decorated : ", &b);
    //Invoking its added state and added behaviour
    cout<<"\t\t\t"<<b.addedState<<b.AddedBehavior()<<endl;
    delete d;
    return 0;
}