////////////////////////////////////////////////////////////////////////////
// DllLoader.cpp : implementation and testing for DllLoader.h             //
// ver 1.1                                                                //
//                                                                        //
// Application : OOD F18 Project 2 Help                                   //
// Platform    : VS17 Community - Windows 10 Professional x64             //
// Author      : Ammar Salman, EECS Department, Syracuse University       //
//               313/788-4694, hoplite.90@hotmail.com                     //
////////////////////////////////////////////////////////////////////////////

#include "DllLoader.h"

using namespace std;

// a function to convert std::string to std::wstring (Windows.h uses a
// different string format)
std::wstring s2ws(const std::string& s)
{
	int len;
	int slength = (int)s.length() + 1;
	len = MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, 0, 0);
	wchar_t* buf = new wchar_t[len];
	MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, buf, len);
	std::wstring r(buf);
	delete[] buf;
	return r;
}
//----< alternate string converter using std C++ >-------------------

std::wstring toWstring(const std::string& s)
{
  std::wstring wstr;
  for (auto ch : s)
  {
    wstr += (wchar_t)ch;
  }
  return wstr;  // will move
}

DllLoader::DllLoader(){}


DllLoader::~DllLoader()
{
	clear(); // to make sure the DLL is unloaded
}

// accepts a DLL path and attempts to load it and extract its tests

bool DllLoader::loadAndExtract(const std::string & dll)
{
  ///////////////////////////////////////////////////////
  // all of these work - Fawcett
  //----------------------------------------------------
  // hmod = LoadLibrary(s2ws(dll).c_str()); // load DLL
  // hmod = LoadLibraryA(dll.c_str()); // load DLL
  
  hmod = LoadLibraryW(toWstring(dll).c_str()); // load DLL
  if (!hmod) return false;  // check if DLL was properly loaded

	// check if the DLL contains get_ITests() function ...
	// in other words, check if the DLL complies with the protocol

	//typedef ITests* (*gITs)();
  using gITs = ITests * (*)();  // using instead of typedef

	gITs get_ITests = (gITs)GetProcAddress(hmod, "get_ITests");
	if (!get_ITests) return false;

	// execute get_ITests() to get the collection of tests
	ITests* tests = get_ITests();
	if (tests) { // check if tests is nullptr before attempting to get its tests collection
		std::vector<ITest*> extTsts = tests->tests(); 
		extractedTests.insert(extractedTests.begin(), extTsts.begin(), extTsts.end());
		return true;
	}

	// this will only be reached if get_ITests() returned nullptr in which case the 
	// TestDriver DLL contains no tests to execute.
	return false;
}

const std::vector<ITest*>& DllLoader::tests() const
{
	return extractedTests;
}

void DllLoader::clear()
{
	if (hmod) FreeLibrary(hmod);
	extractedTests.clear();
}


#ifdef TEST_DLL_LOADER

#include <iostream>
#include <iomanip>

int main() {
	cout << "\n  Testing DLL Loader";
	cout << "\n ====================";

	DllLoader loader;

	cout << "\n\n    Loading '../Debug/TestDriver1.dll' which is a single-test TestDriver...";

	bool loaded = loader.loadAndExtract("../Debug/TestDriver1.dll");
	if (!loaded) {
		cout << " failed to load dll or failed to load tests.\n    Terminating...\n";
		return -1; 
	}

	cout << " successfully loaded";
	cout << "\n    Extracted tests:";
	for (auto test : loader.tests()) {
		cout << "\n      Test name: " << setw(30) << left << test->name() << " - Author: " << setw(20) << test->author();
		cout << "\n      Executing test...";
		bool res = test->test();
		cout << "\n\n      Test passed: " << to_string(res);
	}



	cout << "\n\n    Loading '../Debug/TestDriver2.dll' which is a multiple-tests TestDriver ...";
	loader.clear();

	loaded = loader.loadAndExtract("../Debug/TestDriver2.dll");
	if (!loaded) {
		cout << " failed to load dll or failed to load tests.\n    Terminating...\n";
		return -1;
	}

	cout << " successfully loaded";
	cout << "\n    Extracted tests:";
	for (auto test : loader.tests()) {
		cout << "\n      Test name: " << setw(30) << left << test->name() << " - Author: " << setw(20) << test->author();
		cout << "\n      Executing test...";
		bool res = test->test();
		cout << "\n\n      Test passed: " << to_string(res);
	}

	cout << "\n\n";
	return 0;
}

#endif