#include <base/detect.h>

#if defined(CONF_FAMILY_WINDOWS)
// For FlashWindowEx, FLASHWINFO, FLASHW_TRAY
#define _WIN32_WINNT 0x0501
#define WINVER 0x0501
#endif

#ifndef CONF_BACKEND_OPENGL_ES
#include <GL/glew.h>
#endif

#include <engine/storage.h>

#include "SDL.h"

#include "SDL_syswm.h"
#include <base/detect.h>
#include <base/math.h>
#include <cmath>
#include <stdlib.h>

#include "SDL_hints.h"

#if defined(SDL_VIDEO_DRIVER_X11)
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#endif

#include <engine/shared/config.h>

#include <base/tl/threading.h>

#if defined(CONF_VIDEORECORDER)
#include "video.h"
#endif

#include "backend_sdl.h"

#if !defined(CONF_BACKEND_OPENGL_ES)
#include "backend/opengl/backend_opengl3.h"
#endif

#if defined(CONF_BACKEND_OPENGL_ES3) || defined(CONF_BACKEND_OPENGL_ES)
#include "backend/opengles/backend_opengles3.h"
#endif

#include "graphics_threaded.h"

#include <engine/shared/image_manipulation.h>

#ifdef __MINGW32__
extern "C" {
int putenv(const char *);
}
#endif

/*
	sync_barrier - creates a full hardware fence
*/
#if defined(__GNUC__)
inline void sync_barrier()
{
	__sync_synchronize();
}
#elif defined(_MSC_VER)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
inline void sync_barrier()
{
	MemoryBarrier();
}
#else
#error missing atomic implementation for this compiler
#endif

// ------------ CGraphicsBackend_Threaded

void CGraphicsBackend_Threaded::ThreadFunc(void *pUser)
{
	CGraphicsBackend_Threaded *pThis = (CGraphicsBackend_Threaded *)pUser;

	while(!pThis->m_Shutdown)
	{
		pThis->m_Activity.Wait();
		if(pThis->m_pBuffer)
		{
#ifdef CONF_PLATFORM_MACOS
			CAutoreleasePool AutoreleasePool;
#endif
			pThis->m_pProcessor->RunBuffer(pThis->m_pBuffer);

			sync_barrier();
			pThis->m_pBuffer = 0x0;
			pThis->m_BufferDone.Signal();
		}
#if defined(CONF_VIDEORECORDER)
		if(IVideo::Current())
			IVideo::Current()->NextVideoFrameThread();
#endif
	}
}

CGraphicsBackend_Threaded::CGraphicsBackend_Threaded()
{
	m_pBuffer = 0x0;
	m_pProcessor = 0x0;
	m_pThread = 0x0;
}

void CGraphicsBackend_Threaded::StartProcessor(ICommandProcessor *pProcessor)
{
	m_Shutdown = false;
	m_pProcessor = pProcessor;
	m_pThread = thread_init(ThreadFunc, this, "CGraphicsBackend_Threaded");
	m_BufferDone.Signal();
}

void CGraphicsBackend_Threaded::StopProcessor()
{
	m_Shutdown = true;
	m_Activity.Signal();
	if(m_pThread)
		thread_wait(m_pThread);
}

void CGraphicsBackend_Threaded::RunBuffer(CCommandBuffer *pBuffer)
{
	WaitForIdle();
	m_pBuffer = pBuffer;
	m_Activity.Signal();
}

bool CGraphicsBackend_Threaded::IsIdle() const
{
	return m_pBuffer == 0x0;
}

void CGraphicsBackend_Threaded::WaitForIdle()
{
	while(m_pBuffer != 0x0)
		m_BufferDone.Wait();
}

// ------------ CCommandProcessorFragment_General

void CCommandProcessorFragment_General::Cmd_Signal(const CCommandBuffer::SCommand_Signal *pCommand)
{
	pCommand->m_pSemaphore->Signal();
}

bool CCommandProcessorFragment_General::RunCommand(const CCommandBuffer::SCommand *pBaseCommand)
{
	switch(pBaseCommand->m_Cmd)
	{
	case CCommandBuffer::CMD_NOP: break;
	case CCommandBuffer::CMD_SIGNAL: Cmd_Signal(static_cast<const CCommandBuffer::SCommand_Signal *>(pBaseCommand)); break;
	default: return false;
	}

	return true;
}

// ------------ CCommandProcessorFragment_SDL
void CCommandProcessorFragment_SDL::Cmd_Init(const SCommand_Init *pCommand)
{
	m_GLContext = pCommand->m_GLContext;
	m_pWindow = pCommand->m_pWindow;
	SDL_GL_MakeCurrent(m_pWindow, m_GLContext);
}

void CCommandProcessorFragment_SDL::Cmd_Shutdown(const SCommand_Shutdown *pCommand)
{
	SDL_GL_MakeCurrent(NULL, NULL);
}

void CCommandProcessorFragment_SDL::Cmd_Swap(const CCommandBuffer::SCommand_Swap *pCommand)
{
	SDL_GL_SwapWindow(m_pWindow);
}

void CCommandProcessorFragment_SDL::Cmd_VSync(const CCommandBuffer::SCommand_VSync *pCommand)
{
	*pCommand->m_pRetOk = SDL_GL_SetSwapInterval(pCommand->m_VSync) == 0;
}

void CCommandProcessorFragment_SDL::Cmd_VideoModes(const CCommandBuffer::SCommand_VideoModes *pCommand)
{
	SDL_DisplayMode mode;
	int maxModes = SDL_GetNumDisplayModes(pCommand->m_Screen),
	    numModes = 0;

	for(int i = -1; i < maxModes; i++)
	{
		if(i == -1)
		{
			if(SDL_GetDesktopDisplayMode(pCommand->m_Screen, &mode) < 0)
			{
				dbg_msg("gfx", "unable to get display mode: %s", SDL_GetError());
				continue;
			}
		}
		else
		{
			if(SDL_GetDisplayMode(pCommand->m_Screen, i, &mode) < 0)
			{
				dbg_msg("gfx", "unable to get display mode: %s", SDL_GetError());
				continue;
			}
		}

		bool AlreadyFound = false;
		for(int j = 0; j < numModes; j++)
		{
			if(pCommand->m_pModes[j].m_CanvasWidth == mode.w && pCommand->m_pModes[j].m_CanvasHeight == mode.h)
			{
				AlreadyFound = true;
				break;
			}
		}
		if(AlreadyFound)
			continue;

		if(mode.w > pCommand->m_MaxWindowWidth || mode.h > pCommand->m_MaxWindowHeight)
			continue;

		pCommand->m_pModes[numModes].m_CanvasWidth = mode.w * pCommand->m_HiDPIScale;
		pCommand->m_pModes[numModes].m_CanvasHeight = mode.h * pCommand->m_HiDPIScale;
		pCommand->m_pModes[numModes].m_WindowWidth = mode.w;
		pCommand->m_pModes[numModes].m_WindowHeight = mode.h;
		pCommand->m_pModes[numModes].m_Red = 8;
		pCommand->m_pModes[numModes].m_Green = 8;
		pCommand->m_pModes[numModes].m_Blue = 8;
		numModes++;
	}
	*pCommand->m_pNumModes = numModes;
}

CCommandProcessorFragment_SDL::CCommandProcessorFragment_SDL()
{
}

bool CCommandProcessorFragment_SDL::RunCommand(const CCommandBuffer::SCommand *pBaseCommand)
{
	switch(pBaseCommand->m_Cmd)
	{
	case CCommandBuffer::CMD_SWAP: Cmd_Swap(static_cast<const CCommandBuffer::SCommand_Swap *>(pBaseCommand)); break;
	case CCommandBuffer::CMD_VSYNC: Cmd_VSync(static_cast<const CCommandBuffer::SCommand_VSync *>(pBaseCommand)); break;
	case CCommandBuffer::CMD_VIDEOMODES: Cmd_VideoModes(static_cast<const CCommandBuffer::SCommand_VideoModes *>(pBaseCommand)); break;
	case CMD_INIT: Cmd_Init(static_cast<const SCommand_Init *>(pBaseCommand)); break;
	case CMD_SHUTDOWN: Cmd_Shutdown(static_cast<const SCommand_Shutdown *>(pBaseCommand)); break;
	default: return false;
	}

	return true;
}

// ------------ CCommandProcessor_SDL_OpenGL

void CCommandProcessor_SDL_OpenGL::RunBuffer(CCommandBuffer *pBuffer)
{
	for(CCommandBuffer::SCommand *pCommand = pBuffer->Head(); pCommand; pCommand = pCommand->m_pNext)
	{
		if(m_pOpenGL->RunCommand(pCommand))
			continue;

		if(m_SDL.RunCommand(pCommand))
			continue;

		if(m_General.RunCommand(pCommand))
			continue;

		dbg_msg("gfx", "unknown command %d", pCommand->m_Cmd);
	}
}

CCommandProcessor_SDL_OpenGL::CCommandProcessor_SDL_OpenGL(EBackendType BackendType, int OpenGLMajor, int OpenGLMinor, int OpenGLPatch)
{
	m_BackendType = BackendType;

	if(BackendType == BACKEND_TYPE_OPENGL_ES)
	{
#if defined(CONF_BACKEND_OPENGL_ES) || defined(CONF_BACKEND_OPENGL_ES3)
		if(OpenGLMajor < 3)
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGLES();
		}
		else
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGLES3();
		}
#endif
	}
	else if(BackendType == BACKEND_TYPE_OPENGL)
	{
#if !defined(CONF_BACKEND_OPENGL_ES)
		if(OpenGLMajor < 2)
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGL();
		}
		if(OpenGLMajor == 2)
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGL2();
		}
		if(OpenGLMajor == 3 && OpenGLMinor == 0)
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGL3();
		}
		else if((OpenGLMajor == 3 && OpenGLMinor == 3) || OpenGLMajor >= 4)
		{
			m_pOpenGL = new CCommandProcessorFragment_OpenGL3_3();
		}
#endif
	}
}

CCommandProcessor_SDL_OpenGL::~CCommandProcessor_SDL_OpenGL()
{
	delete m_pOpenGL;
}

// ------------ CGraphicsBackend_SDL_OpenGL

static bool BackendInitGlew(EBackendType BackendType, int &GlewMajor, int &GlewMinor, int &GlewPatch)
{
	if(BackendType == BACKEND_TYPE_OPENGL)
	{
#ifndef CONF_BACKEND_OPENGL_ES
		//support graphic cards that are pretty old(and linux)
		glewExperimental = GL_TRUE;
		if(GLEW_OK != glewInit())
			return false;

#ifdef GLEW_VERSION_4_6
		if(GLEW_VERSION_4_6)
		{
			GlewMajor = 4;
			GlewMinor = 6;
			GlewPatch = 0;
			return true;
		}
#endif
		if(GLEW_VERSION_4_5)
		{
			GlewMajor = 4;
			GlewMinor = 5;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_4_4)
		{
			GlewMajor = 4;
			GlewMinor = 4;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_4_3)
		{
			GlewMajor = 4;
			GlewMinor = 3;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_4_2)
		{
			GlewMajor = 4;
			GlewMinor = 2;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_4_1)
		{
			GlewMajor = 4;
			GlewMinor = 1;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_4_0)
		{
			GlewMajor = 4;
			GlewMinor = 0;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_3_3)
		{
			GlewMajor = 3;
			GlewMinor = 3;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_3_0)
		{
			GlewMajor = 3;
			GlewMinor = 0;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_2_1)
		{
			GlewMajor = 2;
			GlewMinor = 1;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_2_0)
		{
			GlewMajor = 2;
			GlewMinor = 0;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_1_5)
		{
			GlewMajor = 1;
			GlewMinor = 5;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_1_4)
		{
			GlewMajor = 1;
			GlewMinor = 4;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_1_3)
		{
			GlewMajor = 1;
			GlewMinor = 3;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_1_2_1)
		{
			GlewMajor = 1;
			GlewMinor = 2;
			GlewPatch = 1;
			return true;
		}
		if(GLEW_VERSION_1_2)
		{
			GlewMajor = 1;
			GlewMinor = 2;
			GlewPatch = 0;
			return true;
		}
		if(GLEW_VERSION_1_1)
		{
			GlewMajor = 1;
			GlewMinor = 1;
			GlewPatch = 0;
			return true;
		}
#endif
	}
	else if(BackendType == BACKEND_TYPE_OPENGL_ES)
	{
		// just assume the version we need
		GlewMajor = 3;
		GlewMinor = 0;
		GlewPatch = 0;

		return true;
	}

	return true;
}

static int IsVersionSupportedGlew(EBackendType BackendType, int VersionMajor, int VersionMinor, int VersionPatch, int GlewMajor, int GlewMinor, int GlewPatch)
{
	int InitError = 0;

	if(BackendType == BACKEND_TYPE_OPENGL)
	{
		if(VersionMajor >= 4 && GlewMajor < 4)
		{
			InitError = -1;
		}
		else if(VersionMajor >= 3 && GlewMajor < 3)
		{
			InitError = -1;
		}
		else if(VersionMajor == 3 && GlewMajor == 3)
		{
			if(VersionMinor >= 3 && GlewMinor < 3)
			{
				InitError = -1;
			}
			if(VersionMinor >= 2 && GlewMinor < 2)
			{
				InitError = -1;
			}
			if(VersionMinor >= 1 && GlewMinor < 1)
			{
				InitError = -1;
			}
			if(VersionMinor >= 0 && GlewMinor < 0)
			{
				InitError = -1;
			}
		}
		else if(VersionMajor >= 2 && GlewMajor < 2)
		{
			InitError = -1;
		}
		else if(VersionMajor == 2 && GlewMajor == 2)
		{
			if(VersionMinor >= 1 && GlewMinor < 1)
			{
				InitError = -1;
			}
			if(VersionMinor >= 0 && GlewMinor < 0)
			{
				InitError = -1;
			}
		}
		else if(VersionMajor >= 1 && GlewMajor < 1)
		{
			InitError = -1;
		}
		else if(VersionMajor == 1 && GlewMajor == 1)
		{
			if(VersionMinor >= 5 && GlewMinor < 5)
			{
				InitError = -1;
			}
			if(VersionMinor >= 4 && GlewMinor < 4)
			{
				InitError = -1;
			}
			if(VersionMinor >= 3 && GlewMinor < 3)
			{
				InitError = -1;
			}
			if(VersionMinor >= 2 && GlewMinor < 2)
			{
				InitError = -1;
			}
			else if(VersionMinor == 2 && GlewMinor == 2)
			{
				if(VersionPatch >= 1 && GlewPatch < 1)
				{
					InitError = -1;
				}
				if(VersionPatch >= 0 && GlewPatch < 0)
				{
					InitError = -1;
				}
			}
			if(VersionMinor >= 1 && GlewMinor < 1)
			{
				InitError = -1;
			}
			if(VersionMinor >= 0 && GlewMinor < 0)
			{
				InitError = -1;
			}
		}
	}

	return InitError;
}

EBackendType CGraphicsBackend_SDL_OpenGL::DetectBackend()
{
#ifndef CONF_BACKEND_OPENGL_ES
#ifdef CONF_BACKEND_OPENGL_ES3
	const char *pEnvDriver = getenv("DDNET_DRIVER");
	if(pEnvDriver && str_comp(pEnvDriver, "GLES") == 0)
		return BACKEND_TYPE_OPENGL_ES;
	else
		return BACKEND_TYPE_OPENGL;
#else
	return BACKEND_TYPE_OPENGL;
#endif
#else
	return BACKEND_TYPE_OPENGL_ES;
#endif
}

void CGraphicsBackend_SDL_OpenGL::ClampDriverVersion(EBackendType BackendType)
{
	if(BackendType == BACKEND_TYPE_OPENGL)
	{
		//clamp the versions to existing versions(only for OpenGL major <= 3)
		if(g_Config.m_GfxOpenGLMajor == 1)
		{
			g_Config.m_GfxOpenGLMinor = clamp(g_Config.m_GfxOpenGLMinor, 1, 5);
			if(g_Config.m_GfxOpenGLMinor == 2)
				g_Config.m_GfxOpenGLPatch = clamp(g_Config.m_GfxOpenGLPatch, 0, 1);
			else
				g_Config.m_GfxOpenGLPatch = 0;
		}
		else if(g_Config.m_GfxOpenGLMajor == 2)
		{
			g_Config.m_GfxOpenGLMinor = clamp(g_Config.m_GfxOpenGLMinor, 0, 1);
			g_Config.m_GfxOpenGLPatch = 0;
		}
		else if(g_Config.m_GfxOpenGLMajor == 3)
		{
			g_Config.m_GfxOpenGLMinor = clamp(g_Config.m_GfxOpenGLMinor, 0, 3);
			if(g_Config.m_GfxOpenGLMinor < 3)
				g_Config.m_GfxOpenGLMinor = 0;
			g_Config.m_GfxOpenGLPatch = 0;
		}
	}
	else if(BackendType == BACKEND_TYPE_OPENGL_ES)
	{
#if !defined(CONF_BACKEND_OPENGL_ES3)
		// Make sure GLES is set to 1.0 (which is equivalent to OpenGL 1.3), if its not set to >= 3.0(which is equivalent to OpenGL 3.3)
		if(g_Config.m_GfxOpenGLMajor < 3)
		{
			g_Config.m_GfxOpenGLMajor = 1;
			g_Config.m_GfxOpenGLMinor = 0;
			g_Config.m_GfxOpenGLPatch = 0;

			// GLES also doesnt know GL_QUAD
			g_Config.m_GfxQuadAsTriangle = 1;
		}
#else
		g_Config.m_GfxOpenGLMajor = 3;
		g_Config.m_GfxOpenGLMinor = 0;
		g_Config.m_GfxOpenGLPatch = 0;
#endif
	}
}

bool CGraphicsBackend_SDL_OpenGL::IsModernAPI(EBackendType BackendType)
{
	if(BackendType == BACKEND_TYPE_OPENGL)
		return (g_Config.m_GfxOpenGLMajor == 3 && g_Config.m_GfxOpenGLMinor == 3) || g_Config.m_GfxOpenGLMajor >= 4;
	else if(BackendType == BACKEND_TYPE_OPENGL_ES)
		return g_Config.m_GfxOpenGLMajor >= 3;

	return false;
}

void CGraphicsBackend_SDL_OpenGL::GetDriverVersion(EGraphicsDriverAgeType DriverAgeType, int &Major, int &Minor, int &Patch)
{
	if(m_BackendType == BACKEND_TYPE_OPENGL)
	{
		if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_LEGACY)
		{
			Major = 1;
			Minor = 4;
			Patch = 0;
		}
		else if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_DEFAULT)
		{
			Major = 3;
			Minor = 0;
			Patch = 0;
		}
		else if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_MODERN)
		{
			Major = 3;
			Minor = 3;
			Patch = 0;
		}
	}
	else if(m_BackendType == BACKEND_TYPE_OPENGL_ES)
	{
		if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_LEGACY)
		{
			Major = 1;
			Minor = 0;
			Patch = 0;
		}
		else if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_DEFAULT)
		{
			Major = 3;
			Minor = 0;
			Patch = 0;
		}
		else if(DriverAgeType == GRAPHICS_DRIVER_AGE_TYPE_MODERN)
		{
			Major = 3;
			Minor = 0;
			Patch = 0;
		}
	}
}

int CGraphicsBackend_SDL_OpenGL::Init(const char *pName, int *Screen, int *pWidth, int *pHeight, int FsaaSamples, int Flags, int *pDesktopWidth, int *pDesktopHeight, int *pCurrentWidth, int *pCurrentHeight, IStorage *pStorage)
{
	// print sdl version
	{
		SDL_version Compiled;
		SDL_version Linked;

		SDL_VERSION(&Compiled);
		SDL_GetVersion(&Linked);
		dbg_msg("sdl", "SDL version %d.%d.%d (compiled = %d.%d.%d)", Linked.major, Linked.minor, Linked.patch,
			Compiled.major, Compiled.minor, Compiled.patch);
	}

	if(!SDL_WasInit(SDL_INIT_VIDEO))
	{
		if(SDL_InitSubSystem(SDL_INIT_VIDEO) < 0)
		{
			dbg_msg("gfx", "unable to init SDL video: %s", SDL_GetError());
			return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_SDL_INIT_FAILED;
		}
	}

	m_BackendType = DetectBackend();

	ClampDriverVersion(m_BackendType);

	m_UseNewOpenGL = IsModernAPI(m_BackendType);

	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, g_Config.m_GfxOpenGLMajor);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, g_Config.m_GfxOpenGLMinor);
	dbg_msg("gfx", "Created OpenGL %zu.%zu context.", (size_t)g_Config.m_GfxOpenGLMajor, (size_t)g_Config.m_GfxOpenGLMinor);

	if(m_BackendType == BACKEND_TYPE_OPENGL)
	{
		if(g_Config.m_GfxOpenGLMajor == 3 && g_Config.m_GfxOpenGLMinor == 0)
		{
			SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
		}
		else if(m_UseNewOpenGL)
		{
			SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
		}
	}
	else if(m_BackendType == BACKEND_TYPE_OPENGL_ES)
	{
		SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
	}

	// set screen
	SDL_Rect ScreenPos;
	m_NumScreens = SDL_GetNumVideoDisplays();
	if(m_NumScreens > 0)
	{
		if(*Screen < 0 || *Screen >= m_NumScreens)
			*Screen = 0;
		if(SDL_GetDisplayBounds(*Screen, &ScreenPos) != 0)
		{
			dbg_msg("gfx", "unable to retrieve screen information: %s", SDL_GetError());
			return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_SDL_SCREEN_INFO_REQUEST_FAILED;
		}
	}
	else
	{
		dbg_msg("gfx", "unable to retrieve number of screens: %s", SDL_GetError());
		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_SDL_SCREEN_REQUEST_FAILED;
	}

	// store desktop resolution for settings reset button
	SDL_DisplayMode DisplayMode;
	if(SDL_GetDesktopDisplayMode(*Screen, &DisplayMode))
	{
		dbg_msg("gfx", "unable to get desktop resolution: %s", SDL_GetError());
		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_SDL_SCREEN_RESOLUTION_REQUEST_FAILED;
	}

	bool IsDesktopChanged = *pDesktopWidth == 0 || *pDesktopHeight == 0 || *pDesktopWidth != DisplayMode.w || *pDesktopHeight != DisplayMode.h;

	*pDesktopWidth = DisplayMode.w;
	*pDesktopHeight = DisplayMode.h;

	// use desktop resolution as default resolution, clamp resolution if users's display is smaller than we remembered
	if(*pWidth == 0 || *pHeight == 0 || (IsDesktopChanged && (*pWidth > *pDesktopWidth || *pHeight > *pDesktopHeight)))
	{
		*pWidth = *pDesktopWidth;
		*pHeight = *pDesktopHeight;
	}

	// set flags
	int SdlFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_INPUT_GRABBED | SDL_WINDOW_INPUT_FOCUS | SDL_WINDOW_MOUSE_FOCUS;
	if(Flags & IGraphicsBackend::INITFLAG_HIGHDPI)
		SdlFlags |= SDL_WINDOW_ALLOW_HIGHDPI;
	if(Flags & IGraphicsBackend::INITFLAG_RESIZABLE)
		SdlFlags |= SDL_WINDOW_RESIZABLE;
	if(Flags & IGraphicsBackend::INITFLAG_BORDERLESS)
		SdlFlags |= SDL_WINDOW_BORDERLESS;
	if(Flags & IGraphicsBackend::INITFLAG_FULLSCREEN)
	{
		// when we are at fullscreen, we really shouldn't allow window sizes, that aren't supported by the driver
		bool SupportedResolution = false;
		SDL_DisplayMode mode;
		int maxModes = SDL_GetNumDisplayModes(g_Config.m_GfxScreen);

		for(int i = 0; i < maxModes; i++)
		{
			if(SDL_GetDisplayMode(g_Config.m_GfxScreen, i, &mode) < 0)
			{
				dbg_msg("gfx", "unable to get display mode: %s", SDL_GetError());
				continue;
			}

			if(*pWidth == mode.w && *pHeight == mode.h)
			{
				SupportedResolution = true;
				break;
			}
		}
		if(SupportedResolution)
			SdlFlags |= SDL_WINDOW_FULLSCREEN;
		else
			SdlFlags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
	}
	else if(Flags & (IGraphicsBackend::INITFLAG_DESKTOP_FULLSCREEN))
	{
		SdlFlags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
	}

	// set gl attributes
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	if(FsaaSamples)
	{
		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, FsaaSamples);
	}
	else
	{
		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 0);
		SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 0);
	}

	if(g_Config.m_InpMouseOld)
		SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_MODE_WARP, "1");

	m_pWindow = SDL_CreateWindow(
		pName,
		SDL_WINDOWPOS_CENTERED,
		SDL_WINDOWPOS_CENTERED,
		*pWidth,
		*pHeight,
		SdlFlags);

	// set caption
	if(m_pWindow == NULL)
	{
		dbg_msg("gfx", "unable to create window: %s", SDL_GetError());
		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_SDL_WINDOW_CREATE_FAILED;
	}

	m_GLContext = SDL_GL_CreateContext(m_pWindow);

	if(m_GLContext == NULL)
	{
		SDL_DestroyWindow(m_pWindow);
		dbg_msg("gfx", "unable to create OpenGL context: %s", SDL_GetError());
		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_OPENGL_CONTEXT_FAILED;
	}

	int GlewMajor = 0;
	int GlewMinor = 0;
	int GlewPatch = 0;

	if(!BackendInitGlew(m_BackendType, GlewMajor, GlewMinor, GlewPatch))
	{
		SDL_GL_DeleteContext(m_GLContext);
		SDL_DestroyWindow(m_pWindow);
		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_UNKNOWN;
	}

	int InitError = 0;
	const char *pErrorStr = NULL;

	InitError = IsVersionSupportedGlew(m_BackendType, g_Config.m_GfxOpenGLMajor, g_Config.m_GfxOpenGLMinor, g_Config.m_GfxOpenGLPatch, GlewMajor, GlewMinor, GlewPatch);

	// SDL_GL_GetDrawableSize reports HiDPI resolution even with SDL_WINDOW_ALLOW_HIGHDPI not set, which is wrong
	if(SdlFlags & SDL_WINDOW_ALLOW_HIGHDPI)
		SDL_GL_GetDrawableSize(m_pWindow, pCurrentWidth, pCurrentHeight);
	else
		SDL_GetWindowSize(m_pWindow, pCurrentWidth, pCurrentHeight);

	SDL_GL_SetSwapInterval(Flags & IGraphicsBackend::INITFLAG_VSYNC ? 1 : 0);
	SDL_GL_MakeCurrent(NULL, NULL);

	if(InitError != 0)
	{
		SDL_GL_DeleteContext(m_GLContext);
		SDL_DestroyWindow(m_pWindow);

		// try setting to glew supported version
		g_Config.m_GfxOpenGLMajor = GlewMajor;
		g_Config.m_GfxOpenGLMinor = GlewMinor;
		g_Config.m_GfxOpenGLPatch = GlewPatch;

		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_OPENGL_VERSION_FAILED;
	}

	// start the command processor
	m_pProcessor = new CCommandProcessor_SDL_OpenGL(m_BackendType, g_Config.m_GfxOpenGLMajor, g_Config.m_GfxOpenGLMinor, g_Config.m_GfxOpenGLPatch);
	StartProcessor(m_pProcessor);

	mem_zero(m_aErrorString, sizeof(m_aErrorString) / sizeof(m_aErrorString[0]));

	// issue init commands for OpenGL and SDL
	CCommandBuffer CmdBuffer(1024, 512);
	//run sdl first to have the context in the thread
	CCommandProcessorFragment_SDL::SCommand_Init CmdSDL;
	CmdSDL.m_pWindow = m_pWindow;
	CmdSDL.m_GLContext = m_GLContext;
	CmdBuffer.AddCommandUnsafe(CmdSDL);
	RunBuffer(&CmdBuffer);
	WaitForIdle();
	CmdBuffer.Reset();

	if(InitError == 0)
	{
		CCommandProcessorFragment_OpenGLBase::SCommand_Init CmdOpenGL;
		CmdOpenGL.m_pTextureMemoryUsage = &m_TextureMemoryUsage;
		CmdOpenGL.m_pStorage = pStorage;
		CmdOpenGL.m_pCapabilities = &m_Capabilites;
		CmdOpenGL.m_pInitError = &InitError;
		CmdOpenGL.m_pCapabilities = &m_Capabilites;
		CmdOpenGL.m_RequestedMajor = g_Config.m_GfxOpenGLMajor;
		CmdOpenGL.m_RequestedMinor = g_Config.m_GfxOpenGLMinor;
		CmdOpenGL.m_RequestedPatch = g_Config.m_GfxOpenGLPatch;
		CmdOpenGL.m_GlewMajor = GlewMajor;
		CmdOpenGL.m_GlewMinor = GlewMinor;
		CmdOpenGL.m_GlewPatch = GlewPatch;
		CmdOpenGL.m_pInitError = &InitError;
		CmdOpenGL.m_pErrStringPtr = &pErrorStr;
		CmdOpenGL.m_pVendorString = m_aVendorString;
		CmdOpenGL.m_pVersionString = m_aVersionString;
		CmdOpenGL.m_pRendererString = m_aRendererString;
		CmdOpenGL.m_RequestedBackend = m_BackendType;
		CmdBuffer.AddCommandUnsafe(CmdOpenGL);

		RunBuffer(&CmdBuffer);
		WaitForIdle();
		CmdBuffer.Reset();

		if(InitError == -2)
		{
			CCommandProcessorFragment_OpenGLBase::SCommand_Shutdown CmdGL;
			CmdBuffer.AddCommandUnsafe(CmdGL);
			RunBuffer(&CmdBuffer);
			WaitForIdle();
			CmdBuffer.Reset();

			g_Config.m_GfxOpenGLMajor = m_Capabilites.m_ContextMajor;
			g_Config.m_GfxOpenGLMinor = m_Capabilites.m_ContextMinor;
			g_Config.m_GfxOpenGLPatch = m_Capabilites.m_ContextPatch;
		}
	}

	if(InitError != 0)
	{
		CCommandProcessorFragment_SDL::SCommand_Shutdown Cmd;
		CmdBuffer.AddCommandUnsafe(Cmd);
		RunBuffer(&CmdBuffer);
		WaitForIdle();
		CmdBuffer.Reset();

		// stop and delete the processor
		StopProcessor();
		delete m_pProcessor;
		m_pProcessor = 0;

		SDL_GL_DeleteContext(m_GLContext);
		SDL_DestroyWindow(m_pWindow);

		// try setting to version string's supported version
		if(InitError == -2)
		{
			g_Config.m_GfxOpenGLMajor = m_Capabilites.m_ContextMajor;
			g_Config.m_GfxOpenGLMinor = m_Capabilites.m_ContextMinor;
			g_Config.m_GfxOpenGLPatch = m_Capabilites.m_ContextPatch;
		}

		if(pErrorStr != NULL)
		{
			str_copy(m_aErrorString, pErrorStr, sizeof(m_aErrorString) / sizeof(m_aErrorString[0]));
		}

		return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_OPENGL_VERSION_FAILED;
	}

	if(SetWindowScreen(g_Config.m_GfxScreen))
	{
		// query the current displaymode, when running in fullscreen
		// this is required if DPI scaling is active
		if(SdlFlags & SDL_WINDOW_FULLSCREEN)
		{
			SDL_DisplayMode CurrentDisplayMode;
			SDL_GetCurrentDisplayMode(g_Config.m_GfxScreen, &CurrentDisplayMode);

			*pCurrentWidth = CurrentDisplayMode.w;
			*pCurrentHeight = CurrentDisplayMode.h;

			// since the window is centered, calculate how much the viewport has to be fixed
			//int XOverflow = (*pWidth > *pCurrentWidth ? (*pWidth - *pCurrentWidth) : 0);
			//int YOverflow = (*pHeight > *pCurrentHeight ? (*pHeight - *pCurrentHeight) : 0);
			//TODO: current problem is, that the opengl driver knows about the scaled display,
			//so the viewport cannot be adjusted for resolutions, that are higher than allowed by the display driver

			CCommandBuffer::SCommand_Update_Viewport CmdSDL;
			CmdSDL.m_X = 0;
			CmdSDL.m_Y = 0;

			CmdSDL.m_Width = CurrentDisplayMode.w;
			CmdSDL.m_Height = CurrentDisplayMode.h;
			CmdBuffer.AddCommandUnsafe(CmdSDL);
			RunBuffer(&CmdBuffer);
			WaitForIdle();
			CmdBuffer.Reset();
		}
	}

	// return
	return EGraphicsBackendErrorCodes::GRAPHICS_BACKEND_ERROR_CODE_NONE;
}

int CGraphicsBackend_SDL_OpenGL::Shutdown()
{
	// issue a shutdown command
	CCommandBuffer CmdBuffer(1024, 512);
	CCommandProcessorFragment_OpenGLBase::SCommand_Shutdown CmdGL;
	CmdBuffer.AddCommandUnsafe(CmdGL);
	RunBuffer(&CmdBuffer);
	WaitForIdle();
	CmdBuffer.Reset();

	CCommandProcessorFragment_SDL::SCommand_Shutdown Cmd;
	CmdBuffer.AddCommandUnsafe(Cmd);
	RunBuffer(&CmdBuffer);
	WaitForIdle();
	CmdBuffer.Reset();

	// stop and delete the processor
	StopProcessor();
	delete m_pProcessor;
	m_pProcessor = 0;

	SDL_GL_DeleteContext(m_GLContext);
	SDL_DestroyWindow(m_pWindow);

	SDL_QuitSubSystem(SDL_INIT_VIDEO);
	return 0;
}

int CGraphicsBackend_SDL_OpenGL::MemoryUsage() const
{
	return m_TextureMemoryUsage;
}

void CGraphicsBackend_SDL_OpenGL::Minimize()
{
	SDL_MinimizeWindow(m_pWindow);
}

void CGraphicsBackend_SDL_OpenGL::Maximize()
{
	// TODO: SDL
}

void CGraphicsBackend_SDL_OpenGL::SetWindowParams(int FullscreenMode, bool IsBorderless)
{
	if(FullscreenMode > 0)
	{
		if(FullscreenMode == 1)
		{
#if defined(CONF_PLATFORM_MACOS) || defined(CONF_PLATFORM_HAIKU) // Todo SDL: remove this when fixed (game freezes when losing focus in fullscreen)
			SDL_SetWindowFullscreen(m_pWindow, SDL_WINDOW_FULLSCREEN_DESKTOP);
#else
			SDL_SetWindowFullscreen(m_pWindow, SDL_WINDOW_FULLSCREEN);
#endif
		}
		else if(FullscreenMode == 2)
		{
			SDL_SetWindowFullscreen(m_pWindow, SDL_WINDOW_FULLSCREEN_DESKTOP);
		}
	}
	else
	{
		SDL_SetWindowFullscreen(m_pWindow, 0);
		SDL_SetWindowBordered(m_pWindow, SDL_bool(!IsBorderless));
	}
}

bool CGraphicsBackend_SDL_OpenGL::SetWindowScreen(int Index)
{
	if(Index >= 0 && Index < m_NumScreens)
	{
		SDL_Rect ScreenPos;
		if(SDL_GetDisplayBounds(Index, &ScreenPos) == 0)
		{
			SDL_SetWindowPosition(m_pWindow,
				SDL_WINDOWPOS_CENTERED_DISPLAY(Index),
				SDL_WINDOWPOS_CENTERED_DISPLAY(Index));
			return true;
		}
	}

	return false;
}

int CGraphicsBackend_SDL_OpenGL::GetWindowScreen()
{
	return SDL_GetWindowDisplayIndex(m_pWindow);
}

int CGraphicsBackend_SDL_OpenGL::WindowActive()
{
	return SDL_GetWindowFlags(m_pWindow) & SDL_WINDOW_INPUT_FOCUS;
}

int CGraphicsBackend_SDL_OpenGL::WindowOpen()
{
	return SDL_GetWindowFlags(m_pWindow) & SDL_WINDOW_SHOWN;
}

void CGraphicsBackend_SDL_OpenGL::SetWindowGrab(bool Grab)
{
	SDL_SetWindowGrab(m_pWindow, Grab ? SDL_TRUE : SDL_FALSE);
}

void CGraphicsBackend_SDL_OpenGL::ResizeWindow(int w, int h)
{
	SDL_SetWindowSize(m_pWindow, w, h);
}

void CGraphicsBackend_SDL_OpenGL::GetViewportSize(int &w, int &h)
{
	SDL_GL_GetDrawableSize(m_pWindow, &w, &h);
}

void CGraphicsBackend_SDL_OpenGL::NotifyWindow()
{
	// get window handle
	SDL_SysWMinfo info;
	SDL_VERSION(&info.version);
	if(!SDL_GetWindowWMInfo(m_pWindow, &info))
	{
		dbg_msg("gfx", "unable to obtain window handle");
		return;
	}

#if defined(CONF_FAMILY_WINDOWS)
	FLASHWINFO desc;
	desc.cbSize = sizeof(desc);
	desc.hwnd = info.info.win.window;
	desc.dwFlags = FLASHW_TRAY;
	desc.uCount = 3; // flash 3 times
	desc.dwTimeout = 0;

	FlashWindowEx(&desc);
#elif defined(SDL_VIDEO_DRIVER_X11) && !defined(CONF_PLATFORM_MACOS)
	Display *dpy = info.info.x11.display;
	Window win = info.info.x11.window;

	// Old hints
	XWMHints *wmhints;
	wmhints = XAllocWMHints();
	wmhints->flags = XUrgencyHint;
	XSetWMHints(dpy, win, wmhints);
	XFree(wmhints);

	// More modern way of notifying
	static Atom demandsAttention = XInternAtom(dpy, "_NET_WM_STATE_DEMANDS_ATTENTION", true);
	static Atom wmState = XInternAtom(dpy, "_NET_WM_STATE", true);
	XChangeProperty(dpy, win, wmState, XA_ATOM, 32, PropModeReplace,
		(unsigned char *)&demandsAttention, 1);
#endif
}

IGraphicsBackend *CreateGraphicsBackend() { return new CGraphicsBackend_SDL_OpenGL; }