#include <Windows.h>

#include <chrono>
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
using namespace std::chrono;

namespace
{

// ------------------------------------------------------------------------------------------------
static void map_test_file (fs::path const& filePath, bool withPause)
{
  withPause = false;

  // Open file
  HANDLE hFile = ::CreateFileW(filePath.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
  if (!hFile)
  {
    std::cerr << "Failed opening file handle\n";
    std::exit(-1);
  }

  // Get file size
  size_t fileSize {};
  {
    LARGE_INTEGER sz {};
    if (FALSE == ::GetFileSizeEx(hFile, &sz))
    {
      std::cerr << "Failed getting file size\n";
      std::exit(-1);
    }

    if (sz.QuadPart <= 0) // cannot map a 0 byte file
    {
      std::cerr << "Can't map an empty file\n";
      std::exit(-1);
    }

    fileSize = (size_t)sz.QuadPart;
  }

  // Create a file mapping
  HANDLE hMap = ::CreateFileMappingW(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
  if (!hMap)
  {
    std::cerr << "Failed creating mapping object\n";
    std::exit(-1);
  }

  auto t0 = steady_clock::now();

  // Map the entire file
  void* pData = ::MapViewOfFile(
    hMap,
    FILE_MAP_READ,
    0, 0,
    fileSize
  );

  auto t1 = steady_clock::now();

  if (!pData)
  {
    std::cerr << "Failed mapping view of file\n";
    std::exit(-1);
  }

  const auto dur = duration_cast<microseconds>(t1 - t0);
  std::cout << "Opened mapped file in " << dur.count() << "us\n";

  ::UnmapViewOfFile(pData);
  ::CloseHandle(hMap);
  ::CloseHandle(hFile);
}

} // anon namespace


// ================================================================================================
int main (int argc, char *argv[])
{
  // Check arguments
  if (argc < 2)
  {
    std::cerr << "Usage: map_file_test <file to map>\n";
    std::exit(-1);
  }

  // Get file to map
  const fs::path filePath = argv[1];
  if (std::error_code ec {}; !fs::exists(filePath, ec))
  {
    std::cerr << "Specified file \"" << filePath.string() << "\" doesn't exist\n";
    std::exit(-1);
  }

  // Test mapping before loading DLL
  std::cout << "Testing without nvoglv64.dll loaded\n";
  map_test_file(filePath, false);

  // Load troublesome DLL
  std::cout << "Loading nvoglv64.dll\n";

  // Note: nvoglv64.dll lives in a different sub-folder on each system
  const fs::path dllPath = [] ()
  {
    for (auto const& ent : fs::recursive_directory_iterator{R"(C:\Windows\System32\DriverStore\FileRepository)"})
    {
      const fs::path curPath = ent.path();
      if (curPath.filename() == "nvoglv64.dll")
        return curPath;
    }
  }();

  HMODULE hMod = ::LoadLibraryW(dllPath.c_str());
  if (!hMod)
  {
    std::cerr << "Failed loading nvoglv64.dll from " << dllPath.string() << "\n";
    std::exit(-1);
  }

  // Test mapping after loading DLL
  std::cout << "Testing with nvoglv64.dll loaded\n";
  map_test_file(filePath, true);

  // Cleanup
  ::FreeLibrary(hMod);
  return 0;
}