// Copyright Epic Games, Inc. All Rights Reserved.

#include "NVENC_Common.h"
#include "HAL/Platform.h"

#include "CoreMinimal.h"
#include "VideoEncoderCommon.h"
#include "HAL/PlatformProcess.h"
#include "RHI.h"

// define a function pointer for creating an instance of nvEncodeAPI
typedef NVENCSTATUS(NVENCAPI* NVENCAPIPROC)(NV_ENCODE_API_FUNCTION_LIST*);

namespace AVEncoder
{
FCriticalSection	FNVENCCommon::ProtectSingleton;
FNVENCCommon		FNVENCCommon::Singleton;

// attempt to load NVENC 
FNVENCCommon& FNVENCCommon::Setup()
{
	FScopeLock		Guard(&ProtectSingleton);
	if (!Singleton.bWasSetUp)
	{
		Singleton.bWasSetUp = true;
		Singleton.SetupNVENCFunctions();
	}
	return Singleton;
}

// shutdown - release loaded dll
void FNVENCCommon::Shutdown()
{
	FScopeLock		Guard(&ProtectSingleton);
	if (Singleton.bWasSetUp)
	{
		Singleton.bWasSetUp = false;
		Singleton.bIsAvailable = false;
		if (Singleton.DllHandle)
		{
			FPlatformProcess::FreeDllHandle(Singleton.DllHandle);
			Singleton.DllHandle = nullptr;
		}
	}
}

void FNVENCCommon::SetupNVENCFunctions()
{
	check(!bIsAvailable);

	// Can't use NVENC without a NVIDIA GPU (also no point if its not the one RHI is using)
	if (!IsRHIDeviceNVIDIA())
	{
		return;
	}

	// clear function call table
	FMemory::Memzero(static_cast<NV_ENCODE_API_FUNCTION_LIST*>(this), sizeof(NV_ENCODE_API_FUNCTION_LIST));

	// name of DLL/SO library
#if PLATFORM_WINDOWS
#if defined _WIN64
	const TCHAR* DllName = TEXT("nvEncodeAPI64.dll");
#else
	const TCHAR* DllName = TEXT("nvEncodeAPI.dll");
#endif
#elif PLATFORM_LINUX && WITH_CUDA
	const TCHAR* DllName = TEXT("libnvidia-encode.so.1");
#else
	const TCHAR* DllName = nullptr;
#endif
	if (DllName)
	{
		DllHandle = FPlatformProcess::GetDllHandle(DllName);
		if (DllHandle)
		{
			NVENCAPIPROC NvEncodeAPICreateInstanceFunc = (NVENCAPIPROC)(FPlatformProcess::GetDllExport(DllHandle, TEXT("NvEncodeAPICreateInstance")));

			checkf(NvEncodeAPICreateInstanceFunc != nullptr, TEXT("NvEncodeAPICreateInstance failed"));

			if (NvEncodeAPICreateInstanceFunc)
			{
				version = NV_ENCODE_API_FUNCTION_LIST_VER;
				NVENCSTATUS Result = NvEncodeAPICreateInstanceFunc(this);
				checkf(Result == NV_ENC_SUCCESS, TEXT("Unable to create NvEnc API function list: error %d"), Result);
				if (Result == NV_ENC_SUCCESS)
				{
					bIsAvailable = true;
				}
			}
		}
	}
}

} /* namespace AVEncoder */