#ifndef STATE_H
#define STATE_H
///////////////////////////////////////////////////////////////
//  state.h    - defines states in terms of the events       //
//               that trigger transitions to another state   //
//                                                           //
//  Language:    Visual C++, ver 5.0                         //
//  Platform:    Micron Dual Pentium 200, NT 4.0             //
//  Application: Design Patterns - property pattern, Su98    //
//  Author:      Jim Fawcett, CST 2-187, (314) 443-3948      //
//               fawcett@neptune.syr.edu                     //
///////////////////////////////////////////////////////////////

//  Design notes:
//    uses monostate, state, and property patterns

#include <vector>
#include <cstdlib>

using namespace std;


// an extensible enumeration of states
  const int numStates = 4;
  const int onFF = 0;
  const int goUp = 1;
  const int onSF = 2;
  const int goDn = 3;

//----< define events, store state references >----------------

class ElevBase {

public:
  virtual ElevBase* upButton() { return this; }

  virtual ElevBase* dnButton() { return this; }

  virtual ElevBase*  arrived() { return this; }

protected:
  static vector<ElevBase*> registry;  
  // shared by all elevator states

};

//----< factor makeStates function out of derived classes >----

template <class DerivedState> class ElevState : public ElevBase {

public:
  ElevBase* makeState(int s) {
    
    if(s<0 || numStates<=s) {
      cout << "  not a valid state\n"; exit(1);
    }
    ElevBase* pElevBase;
    return (pElevBase = registry[s] = new DerivedState);
  }
};

//

///////////////////////////////////////////////////////////////
//  these are the property classes                           //
///////////////////////////////////////////////////////////////

//----< on the first floor >-----------------------------------

class onFirstFloor  : public ElevState<onFirstFloor> {

public:
  ~onFirstFloor() { delete registry[onFF]; }

  ElevBase* upButton() { 
    cout << "  going up\n"; return registry[goUp]; 
  }
};

//----< going up to the second floor >-------------------------

class goingUp       : public ElevState<goingUp> {

public:
  ~goingUp() { delete registry[goUp]; }

  ElevBase* arrived() { 
    cout << "  arrived on second floor\n"; return registry[onSF]; 
  }
};

//----< on the second floor >----------------------------------

class onSecondFloor : public ElevState<onSecondFloor> {

public:
  ~onSecondFloor() { delete registry[onSF]; }

  ElevBase* dnButton() { 
    cout << "  going down\n"; return registry[goDn]; 
  }
};

//----< going down to the first floor >------------------------

class goingDown     : public ElevState<goingDown> {

public:
  ~goingDown() { delete registry[goDn]; }

  ElevBase* arrived() { 
    cout << "  arrived on first floor\n"; return registry[onFF]; 
  }
};

#endif