#ifndef GUARD_observer_h
#define GUARD_observer_h

#include <list>
#include <algorithm>
#include <string>

class Subject;

class Observer
{
public:
  Observer();
  virtual void update(Subject* subject)=0;
};


class Subject
{
public:
  virtual ~Subject() {};
  void Attach(Observer* obs); 
  void Detach(Observer* obs);
  void notify();
  
 private:
  list<Observer*> observers_;
};

class ConcreteSubject : public Subject
{
 public:
  ConcreteSubject(string newname);
  void SetState(int newstate);
  int GetState();
  string GetName();
 private:
  int state_;
  string name_;
};

class ConcreteObserver : public Observer
{

 public:
  ConcreteObserver(string newname);
  void AttachSubject(ConcreteSubject* subject);
  void DetachSubject(ConcreteSubject* subject);
  virtual void update(Subject* subject);

 private:
  list<ConcreteSubject*> subjects_;
  string name_;

};

#endif