// StopwatchClient.cpp : 
//   Defines the entry point for the console application.
//

// std::out etc
#include <iostream>

#include "Timers_i.c"
#include "Stopwatch.h"


// NOTE:  The following line will vary depending on 
// where the Timers.dll is located.
#define TIMERSDLL "C:\\CIS630\\Chapter2\\Part2\\Timers\\Debug\\Timers.dll"

typedef HRESULT (__stdcall *DLLGETCLASSOBJECT)(REFCLSID rclsid, 
  REFIID riid, LPVOID* ppv);

// Instantiates a stopwatch object and returns it by reference
HRESULT CreateInstance(REFCLSID rclsid, REFIID riid, void** ppv)
{
  HRESULT hr = E_FAIL;
  HINSTANCE hinstDll;
  DLLGETCLASSOBJECT DllGetClassObject;

  hinstDll = LoadLibrary(TIMERSDLL);
  if (hinstDll == NULL) 
    std::cout << "Unable to load \"" TIMERSDLL "\"" << std::endl;
  else
  {
    DllGetClassObject = 
      (DLLGETCLASSOBJECT) GetProcAddress(hinstDll, 
        "DllGetClassObject");
    if (DllGetClassObject != NULL) 
      hr = DllGetClassObject(rclsid, riid, ppv);
  } 
  return hr;
}

void UseStopwatch(IStopwatch* const pStopwatch)
{
  float nElapsedTime;

  pStopwatch->Start();
  pStopwatch->ElapsedTime( &nElapsedTime );

  std::cout << "The overhead time is "  
    << nElapsedTime << std::endl;
}

int main(int argc, char* argv[])
{
  HRESULT hr;
  IUnknown* pIUnknown     = NULL;
  IUnknown* pIUnknown2    = NULL;
  IStopwatch* pStopwatch  = NULL;

  // 3rd parameter of call to CreateInstance() must be passed by
  //    reference and also cast
  hr = CreateInstance(
    CLSID_Stopwatch, IID_IUnknown, (void**) &pIUnknown);

  if ( !SUCCEEDED(hr) )
    std::cout << "ERROR: Unable to create Stopwatch!!";

  else
  {
    pIUnknown2 = pIUnknown;
    // AddRef() not called because lifetime of pIUnknown wraps
    // pIUnknown2...

    // 2nd parameter of QueryInterface() must be passed by reference
	//      and cast
    hr = pIUnknown2->QueryInterface(
      IID_IStopwatch, (void**) &pStopwatch);

    if ( !SUCCEEDED(hr) )
      std::cout << "ERROR: Unable to retrieve Stopwatch interface!!";
    else
    {

      UseStopwatch(pStopwatch);

      pStopwatch->Release();
    
      pStopwatch = NULL;
    }

    pIUnknown->Release();
  }

  return 0;
}