UnrealEngineUWP/Engine/Source/Programs/UnrealVersionSelector/Private/UnrealVersionSelector.cpp

#include "UnrealVersionSelector.h"
#include "RequiredProgramMainCPPInclude.h"
#include "DesktopPlatformModule.h"
#include "PlatformInstallation.h"

IMPLEMENT_APPLICATION(UnrealVersionSelector, "UnrealVersionSelector")

bool RegisterCurrentEngineDirectory()
{
	// Prompt for registering this directory
	if(FPlatformMisc::MessageBoxExt(EAppMsgType::YesNo, TEXT("Configure this directory as an Unreal Engine installation?"), TEXT("Question")) != EAppReturnType::Yes)
	{
		return false;
	}

	// Get the current engine directory.
	FString EngineRootDir = FPlatformProcess::BaseDir();
	FPlatformInstallation::NormalizeEngineRootDir(EngineRootDir);

	// Get any existing tag name or register a new one
	FString Identifier;
	if (!FDesktopPlatformModule::Get()->GetEngineIdentifierFromRootDir(EngineRootDir, Identifier))
	{
		if(!FPlatformInstallation::RegisterEngineInstallation(EngineRootDir, Identifier))
		{
			FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Couldn't add engine installation."), TEXT("Error"));
			return false;
		}
	}

	// If the launcher isn't installed, set up the file associations
	if(!FDesktopPlatformModule::Get()->VerifyFileAssociations())
	{
		// Relaunch as administrator
		FString ExecutableFileName = FString(FPlatformProcess::BaseDir()) / FString(FPlatformProcess::ExecutableName(false));

		int32 ExitCode;
		if (!FPlatformProcess::ExecElevatedProcess(*ExecutableFileName, TEXT("/fileassociations"), &ExitCode) || ExitCode != 0)
		{
			return false;
		}
	}

	// Notify the user that everything is awesome.
	FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Registration successful."), TEXT("Success"));
	return true;
}

bool UpdateFileAssociations()
{
	// Update everything
	if (!FDesktopPlatformModule::Get()->UpdateFileAssociations())
	{
		FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Couldn't update file associations."), TEXT("Error"));
		return false;
	}
	return true;
}

bool SwitchVersion(const FString &ProjectFileName)
{
	// Get the current identifier
	FString Identifier;
	FDesktopPlatformModule::Get()->GetEngineIdentifierForProject(ProjectFileName, Identifier);

	// Select the new association
	if(!FPlatformInstallation::SelectEngineInstallation(Identifier))
	{
		return false;
	}

	// Update the project file
	if (!FDesktopPlatformModule::Get()->SetEngineIdentifierForProject(ProjectFileName, Identifier))
	{
		FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Couldn't set association for project. Check the file is writeable."), TEXT("Error"));
		return false;
	}

	// Notify the user that it's been changed
	return true;
}

bool GetEngineRootDirForProject(const FString &ProjectFileName, FString &OutRootDir)
{
	FString Identifier;
	return FDesktopPlatformModule::Get()->GetEngineIdentifierForProject(ProjectFileName, Identifier) && FDesktopPlatformModule::Get()->GetEngineRootDirFromIdentifier(Identifier, OutRootDir);
}

bool GetValidatedEngineRootDir(const FString &ProjectFileName, FString &OutRootDir)
{
	// Get the engine directory for this project
	if (!GetEngineRootDirForProject(ProjectFileName, OutRootDir))
	{
		// Try to set an association
		if(!SwitchVersion(ProjectFileName))
		{
			return false;
		}

		// See if it's valid now
		if (!GetEngineRootDirForProject(ProjectFileName, OutRootDir))
		{
			FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Error retrieving project root directory"), TEXT("Error"));
			return false;
		}
	}
	return true;
}

bool LaunchEditor(const FString &ProjectFileName, const FString &Arguments)
{
	// Get the engine root directory
	FString RootDir;
	if (!GetValidatedEngineRootDir(ProjectFileName, RootDir))
	{
		return false;
	}

	// Launch the editor
	if (!FPlatformInstallation::LaunchEditor(RootDir, FString::Printf(TEXT("\"%s\" %s"), *ProjectFileName, *Arguments)))
	{
		FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Failed to launch editor"), TEXT("Error"));
		return false;
	}

	return true;
}

bool GenerateProjectFiles(const FString &ProjectFileName)
{
	// Get the engine root directory
	FString RootDir;
	if (!GetValidatedEngineRootDir(ProjectFileName, RootDir))
	{
		return false;
	}

	// Build the argument list
	FString Arguments = TEXT("-game");
	if (FDesktopPlatformModule::Get()->IsSourceDistribution(RootDir))
	{
		Arguments += TEXT(" -engine");
	}

	// Launch the editor
	if (!FPlatformInstallation::GenerateProjectFiles(RootDir, FString::Printf(TEXT("\"%s\" %s"), *ProjectFileName, *Arguments)))
	{
		FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Failed to launch editor"), TEXT("Error"));
		return false;
	}

	return true;
}

int Main(const TArray<FString> &Arguments)
{
	bool bRes = false;
	if (Arguments.Num() == 0)
	{
		// Add the current directory to the list of installations
		bRes = RegisterCurrentEngineDirectory();
	}
	else if (Arguments.Num() == 1 && Arguments[0] == TEXT("/fileassociations"))
	{
		// Update all the settings.
		bRes = UpdateFileAssociations();
	}
	else if (Arguments.Num() == 2 && Arguments[0] == TEXT("/switchversion"))
	{
		// Associate with an engine label
		bRes = SwitchVersion(Arguments[1]);
	}
	else if (Arguments.Num() == 2 && Arguments[0] == TEXT("/editor"))
	{
		// Open a project with the editor
		bRes = LaunchEditor(Arguments[1], L"");
	}
	else if (Arguments.Num() == 2 && Arguments[0] == TEXT("/game"))
	{
		// Play a game using the editor executable
		bRes = LaunchEditor(Arguments[1], L"/game");
	}
	else if (Arguments.Num() == 2 && Arguments[0] == TEXT("/projectfiles"))
	{
		// Generate Visual Studio project files
		bRes = GenerateProjectFiles(Arguments[1]);
	}
	else
	{
		// Invalid command line
		FPlatformMisc::MessageBoxExt(EAppMsgType::Ok, TEXT("Invalid command line"), NULL);
	}
	return bRes ? 0 : 1;
}

#if PLATFORM_WINDOWS

	#include "AllowWindowsPlatformTypes.h"
	#include <Shellapi.h>

	int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int ShowCmd)
	{
		int ArgC;
		LPWSTR *ArgV = ::CommandLineToArgvW(GetCommandLine(), &ArgC);

		FCommandLine::Set(TEXT(""));

		TArray<FString> Arguments;
		for (int Idx = 1; Idx < ArgC; Idx++)
		{
			Arguments.Add(ArgV[Idx]);
		}

		return Main(Arguments);
	}

	#include "HideWindowsPlatformTypes.h"

#else

	int main(int ArgC, const char *ArgV[])
	{
		FCommandLine::Set(TEXT(""));
		
		TArray<FString> Arguments;
		for (int Idx = 1; Idx < ArgC; Idx++)
		{
			Arguments.Add(ArgV[Idx]);
		}
		
		return Main(Arguments);
	}

#endif