#pragma once

template<typename ReturnType, typename ...Params>
class FunctionBase {
  public:
    int referencecount;
    FunctionBase():referencecount(1){}
    virtual ReturnType operator()(Params... params)=0;
};


template<typename ReturnType, typename ...Params>
class CFunction : public FunctionBase<ReturnType, Params...> {
  private:
    ReturnType (*function)(Params...);
  public:
  CFunction(ReturnType (*func)(Params...)):function(func){}

  virtual ReturnType operator()(Params... params){
    return function(params...);
  }
};

template<typename ClassType, typename ReturnType, typename ...Params>
class MemberFunction : public FunctionBase<ReturnType, Params...> {
  private:
    ClassType* _thisptr;
    ReturnType (ClassType::*function)(Params...);
  public:
  MemberFunction(ClassType* thisptr, ReturnType (ClassType::*func)(Params...)):_thisptr(thisptr), function(func){}

  virtual ReturnType operator()(Params... params){
    return (_thisptr->*function)(params...);
  }
};


template <typename ReturnType, typename ...Params>
class Function {
private:
  FunctionBase<ReturnType, Params...>* function;

  void destroy(){
    function->referencecount--;
    if(function->referencecount<=0){
      delete function;
    }
  }
public:

  //c function constructor
  Function(ReturnType (*func)(Params...)){
    function = new CFunction<ReturnType, Params...>(func);
  }

  //member function constructor
  template<typename ClassType>
  Function(ClassType* thisptr, ReturnType (ClassType::*func)(Params...)){
    function = new MemberFunction<ClassType, ReturnType, Params...>(thisptr, func);
  }

  //copy constructor
  Function(const Function& rhs) {
    function = rhs.function;
    function->referencecount++;
  }

  //assignment operator
  Function& operator=(const Function& rhs) {
    if(&rhs != this){
      if(rhs->function != function){
        destroy();
        function = rhs.function;
        function->referencecount++;
      }
    }
    return *this;
  }

  ReturnType operator()(Params... params){
    return (*function)(params...);
  }


  //destructor
  ~Function(){
    destroy();
  }
};