// Copyright Epic Games, Inc. All Rights Reserved.
	
#include "CoreMinimal.h"

#if WINDOWS_USE_FEATURE_LAUNCH

#include "Misc/App.h"
#include "Misc/OutputDeviceError.h"
#include "LaunchEngineLoop.h"
#include "HAL/ExceptionHandling.h"
#include "HAL/PlatformMallocCrash.h"
#include "Windows/WindowsHWrapper.h"
#include <shellapi.h>

#if UE_BUILD_DEBUG
#include <crtdbg.h>
#endif

DEFINE_LOG_CATEGORY_STATIC(LogLaunchWindows, Log, All);

extern int32 GuardedMain( const TCHAR* CmdLine );
extern void LaunchStaticShutdownAfterError();

// http://developer.download.nvidia.com/devzone/devcenter/gamegraphics/files/OptimusRenderingPolicies.pdf
// The following line is to favor the high performance NVIDIA GPU if there are multiple GPUs
// Has to be .exe module to be correctly detected.
extern "C" { _declspec(dllexport) uint32 NvOptimusEnablement = 0x00000001; }

// And the AMD equivalent
// Also has to be .exe module to be correctly detected.
extern "C" { _declspec(dllexport) uint32 AmdPowerXpressRequestHighPerformance = 0x00000001; }

// Opt in to new D3D12 redist and tell the loader where to search for D3D12Core.dll.
// The D3D loader looks for these symbol exports in the .exe module.
// We only support this on x64 Windows Desktop platforms. Other platforms or non-redist-aware 
// versions of Windows will transparently load default OS-provided D3D12 library.
#define USE_D3D12_REDIST (PLATFORM_DESKTOP && PLATFORM_CPU_X86_FAMILY && PLATFORM_64BITS && 1)
#if USE_D3D12_REDIST
extern "C" { _declspec(dllexport) extern const UINT D3D12SDKVersion = 602; }
extern "C" { _declspec(dllexport) extern const char* D3D12SDKPath = u8".\\D3D12\\"; }
#endif // USE_D3D12_REDIST

/**
 * Maintain a named mutex to detect whether we are the first instance of this game
 */
HANDLE GNamedMutex = NULL;

/** Whether we should pause before exiting. used by UCC */
bool		GShouldPauseBeforeExit;

void ReleaseNamedMutex( void )
{
	if( GNamedMutex )
	{
		ReleaseMutex( GNamedMutex );
		GNamedMutex = NULL;
	}
}

bool MakeNamedMutex( const TCHAR* CmdLine )
{
	bool bIsFirstInstance = false;

	TCHAR MutexName[MAX_SPRINTF] = TEXT( "" );

	FCString::Strcpy( MutexName, MAX_SPRINTF, TEXT( "UnrealEngine4" ) );

	GNamedMutex = CreateMutex( NULL, true, MutexName );

	if( GNamedMutex	&& GetLastError() != ERROR_ALREADY_EXISTS && !FParse::Param( CmdLine, TEXT( "NEVERFIRST" ) ) )
	{
		// We're the first instance!
		bIsFirstInstance = true;
	}
	else
	{
		// Still need to release it in this case, because it gave us a valid copy
		ReleaseNamedMutex();
		// There is already another instance of the game running.
		bIsFirstInstance = false;
	}

	return( bIsFirstInstance );
}

/**
 * Handler for CRT parameter validation. Triggers error
 *
 * @param Expression - the expression that failed crt validation
 * @param Function - function which failed crt validation
 * @param File - file where failure occured
 * @param Line - line number of failure
 * @param Reserved - not used
 */
void InvalidParameterHandler(const TCHAR* Expression,
							 const TCHAR* Function, 
							 const TCHAR* File, 
							 uint32 Line, 
							 uintptr_t Reserved)
{
	UE_LOG(LogLaunchWindows, Fatal,TEXT("SECURE CRT: Invalid parameter detected.\nExpression: %s Function: %s. File: %s Line: %d\n"), 
		Expression ? Expression : TEXT("Unknown"), 
		Function ? Function : TEXT("Unknown"), 
		File ? File : TEXT("Unknown"), 
		Line );
}

/**
 * Setup the common debug settings 
 */
void SetupWindowsEnvironment( void )
{
	// all crt validation should trigger the callback
	_set_invalid_parameter_handler(InvalidParameterHandler);

#if UE_BUILD_DEBUG
	// Disable the message box for assertions and just write to debugout instead
	_CrtSetReportMode( _CRT_ASSERT, _CRTDBG_MODE_DEBUG );
	// don't fill buffers with 0xfd as we make assumptions for FNames st we only use a fraction of the entire buffer
	_CrtSetDebugFillThreshold( 0 );
#endif
}
/**
 * The inner exception handler catches crashes/asserts in native C++ code and is the only way to get the correct callstack
 * when running a 64-bit executable. However, XAudio2 doesn't always like this and it may result in no sound.
 */
#ifdef _WIN64
	bool GEnableInnerException = true;
#else
	bool GEnableInnerException = false;
#endif

/**
 * The inner exception handler catches crashes/asserts in native C++ code and is the only way to get the correct callstack
 * when running a 64-bit executable. However, XAudio2 doesn't like this and it may result in no sound.
 */
LAUNCH_API int32 GuardedMainWrapper( const TCHAR* CmdLine )
{
	int32 ErrorLevel = 0;
	if ( GEnableInnerException )
	{
#if !PLATFORM_SEH_EXCEPTIONS_DISABLED
	 	__try
#endif
		{
			// Run the guarded code.
			ErrorLevel = GuardedMain( CmdLine );
		}
#if !PLATFORM_SEH_EXCEPTIONS_DISABLED
		__except( ReportCrash( GetExceptionInformation() ), EXCEPTION_CONTINUE_SEARCH )
		{
			// Deliberately do nothing but avoid warning C6322: Empty _except block.
			(void)0;
		}
#endif
	}
	else
	{
		// Run the guarded code.
		ErrorLevel = GuardedMain( CmdLine );
	}
	return ErrorLevel;
}

/**
 * The command-line invocation string, processed using the standard Windows CommandLineToArgvW implementation.
 * This need to be a static global to avoid object unwinding errors in WinMain when SEH is enabled.
 */
static FString GSavedCommandLine;

bool ProcessCommandLine()
{
	int argc = 0;
	LPWSTR* argv = ::CommandLineToArgvW(::GetCommandLineW(), &argc);
	if (argv != nullptr)
	{
		// Reconstruct our command line string in a format suitable for consumption by the FParse class
		GSavedCommandLine = "";
		for (int32 Option = 1; Option < argc; Option++)
		{
			GSavedCommandLine += TEXT(" ");
			
			// Inject quotes in the correct position to preserve arguments containing whitespace
			FString Temp = argv[Option];
			if (Temp.Contains(TEXT(" ")))
			{
				int32 Quote = 0;
				if(Temp.StartsWith(TEXT("-")))
				{
					int32 Separator;
					if (Temp.FindChar('=', Separator))
					{
						Quote = Separator + 1;
					}
				}
				Temp = Temp.Left(Quote) + TEXT("\"") + Temp.Mid(Quote) + TEXT("\"");
			}
			GSavedCommandLine += Temp;
		}
		
		// Free memory allocated for CommandLineToArgvW() arguments
		::LocalFree(argv);
		return true;
	}
	
	return false;
}

LAUNCH_API int32 LaunchWindowsStartup( HINSTANCE hInInstance, HINSTANCE hPrevInstance, char*, int32 nCmdShow, const TCHAR* CmdLine )
{
	TRACE_BOOKMARK(TEXT("WinMain.Enter"));

	// Setup common Windows settings
	SetupWindowsEnvironment();

	int32 ErrorLevel			= 0;
	hInstance				= hInInstance;

	if (!CmdLine)
	{
		CmdLine = ::GetCommandLineW();

		// Attempt to process the command-line arguments using the standard Windows implementation
		// (This ensures behavior parity with other platforms where argc and argv are used.)
		if ( ProcessCommandLine() )
		{
			CmdLine = *GSavedCommandLine;
		}
	}

	// If we're running in unattended mode, make sure we never display error dialogs if we crash.
	if ( FParse::Param( CmdLine, TEXT("unattended") ) )
	{
		SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX | SEM_NOOPENFILEERRORBOX);
	}

#if !(UE_BUILD_SHIPPING && WITH_EDITOR)
	// Named mutex we use to figure out whether we are the first instance of the game running. This is needed to e.g.
	// make sure there is no contention when trying to save the shader cache.
	GIsFirstInstance = MakeNamedMutex( CmdLine );

	if ( FParse::Param( CmdLine,TEXT("crashreports") ) )
	{
		GAlwaysReportCrash = true;
	}
#endif

	bool bNoExceptionHandler = FParse::Param(CmdLine,TEXT("noexceptionhandler"));
	(void)bNoExceptionHandler;

	bool bIgnoreDebugger = FParse::Param(CmdLine, TEXT("IgnoreDebugger"));
	(void)bIgnoreDebugger;

	bool bIsDebuggerPresent = FPlatformMisc::IsDebuggerPresent() && !bIgnoreDebugger;
	(void)bIsDebuggerPresent;

	// Using the -noinnerexception parameter will disable the exception handler within native C++, which is call from managed code,
	// which is called from this function.
	// The default case is to have three wrapped exception handlers 
	// Native: WinMain() -> Native: GuardedMainWrapper().
	// The inner exception handler in GuardedMainWrapper() catches crashes/asserts in native C++ code and is the only way to get the
	// correct callstack when running a 64-bit executable. However, XAudio2 sometimes (?) don't like this and it may result in no sound.
#ifdef _WIN64
	if ( FParse::Param(CmdLine,TEXT("noinnerexception")) || FApp::IsBenchmarking() || bNoExceptionHandler)
	{
		GEnableInnerException = false;
	}
#endif	

	// When we're running embedded, assume that the outer application is going to be handling crash reporting
#if UE_BUILD_DEBUG
	if (GUELibraryOverrideSettings.bIsEmbedded || !GAlwaysReportCrash)
#else
	if (GUELibraryOverrideSettings.bIsEmbedded || bNoExceptionHandler || (bIsDebuggerPresent && !GAlwaysReportCrash))
#endif
	{
		// Don't use exception handling when a debugger is attached to exactly trap the crash. This does NOT check
		// whether we are the first instance or not!
		ErrorLevel = GuardedMain( CmdLine );
	}
	else
	{
		// Use structured exception handling to trap any crashes, walk the the stack and display a crash dialog box.
#if !PLATFORM_SEH_EXCEPTIONS_DISABLED
		__try
#endif
 		{
			GIsGuarded = 1;
			// Run the guarded code.
			ErrorLevel = GuardedMainWrapper( CmdLine );
			GIsGuarded = 0;
		}
#if !PLATFORM_SEH_EXCEPTIONS_DISABLED
		__except( GEnableInnerException ? EXCEPTION_EXECUTE_HANDLER : ReportCrash( GetExceptionInformation( ) ) )
		{
#if !(UE_BUILD_SHIPPING && WITH_EDITOR)
			// Release the mutex in the error case to ensure subsequent runs don't find it.
			ReleaseNamedMutex();
#endif
			// Crashed.
			ErrorLevel = 1;
			if(GError)
			{
				GError->HandleError();
			}
			LaunchStaticShutdownAfterError();
			FPlatformMallocCrash::Get().PrintPoolsUsage();
			FPlatformMisc::RequestExit( true );
		}
#endif
	}

	TRACE_BOOKMARK(TEXT("WinMain.Exit"));

	return ErrorLevel;
}

LAUNCH_API void LaunchWindowsShutdown()
{
	// Final shut down.
	FEngineLoop::AppExit();

#if !(UE_BUILD_SHIPPING && WITH_EDITOR)
	// Release the named mutex again now that we are done.
	ReleaseNamedMutex();
#endif

	// pause if we should
	if (GShouldPauseBeforeExit)
	{
		Sleep(INFINITE);
	}
}

int32 WINAPI WinMain(_In_ HINSTANCE hInInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ char* pCmdLine, _In_ int32 nCmdShow)
{
	int32 Result = LaunchWindowsStartup(hInInstance, hPrevInstance, pCmdLine, nCmdShow, nullptr);
	LaunchWindowsShutdown();
	return Result;
}

#endif //WINDOWS_USE_FEATURE_LAUNCH