// attempt to fix vsync with opengl on windows
// 	https://bugs.chromium.org/p/chromium/issues/detail?id=467617
// 	https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/content/d3dkmthk/nf-d3dkmthk-d3dkmtwaitforverticalblankevent
// 	NOTE: requires installing windows driver kit addon for msvc
// 	TODO: not working with hdc provided by SDL, try enumerating display devices as described here:
// 		https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/content/d3dkmthk/nf-d3dkmthk-d3dkmtopenadapterfromhdc
// 	NOTE: the above seems to make some difference in lowering cpu usage, but cpu stays at max frequency even when relatively idle.

// TODO: if d3dkmt... doensn't work, try DWMFlush() https://docs.microsoft.com/en-us/windows/desktop/api/dwmapi/nf-dwmapi-dwmflush
// 	glfw uses this https://github.com/glfw/glfw/blob/master/src/wgl_context.c
//
// 	if that doesn't work... https://docs.microsoft.com/en-us/windows/desktop/api/timeapi/nf-timeapi-timebeginperiod
// 	to increase schedular granularity. can then use sleep(1) for 1ms resolution

#pragma once

#include <cstdint>

#include "SDL_syswm.h"

#if defined(_WIN32)
#include "windows.h"
#include "d3dkmthk.h"

typedef uint32_t D3DKMT_HANDLE;
typedef struct {
	D3DKMT_HANDLE hAdapter = NULL;
	UINT vidID = 0;
} platform_win_device_handles;
platform_win_device_handles g_platform_win_device_handles;

#endif // _WIN32


inline bool
platform_init(SDL_Window* window)
{
#if defined(_WIN32)
	D3DKMT_HANDLE hAdapter = NULL;
	UINT vidID = 0;
	D3DKMT_OPENADAPTERFROMHDC OpenAdapterData;
	DISPLAY_DEVICE dd;
	HDC hdc;

	memset(&dd, 0, sizeof(dd));
	dd.cb = sizeof dd;

	for (int i = 0; EnumDisplayDevicesA(NULL, i, &dd, 0); ++i) {
		if (dd.StateFlags & DISPLAY_DEVICE_PRIMARY_DEVICE)
			break;
	}

	hdc = CreateDC(NULL, dd.DeviceName, NULL, NULL);
	if (hdc == NULL)
		return false;

	OpenAdapterData.hDc = hdc;
	if ((D3DKMTOpenAdapterFromHdc(&OpenAdapterData)) >= 0) {
		DeleteDC(hdc);
		g_platform_win_device_handles.hAdapter = OpenAdapterData.hAdapter;
		g_platform_win_device_handles.vidID = OpenAdapterData.VidPnSourceId;
		return true;
	}

	DeleteDC(hdc);
	return false;
#endif	// _WIN32

	return true;
}

inline void
platform_wait_for_vblank(bool wait=true)
{
	if (!wait) return;

#if defined(_WIN32)
	_D3DKMT_WAITFORVERTICALBLANKEVENT waitForVBlankData;
	memset(&waitForVBlankData, 0, sizeof(waitForVBlankData));
	waitForVBlankData.hAdapter = g_platform_win_device_handles.hAdapter;
	waitForVBlankData.VidPnSourceId = g_platform_win_device_handles.vidID;
	NTSTATUS ret = D3DKMTWaitForVerticalBlankEvent(&waitForVBlankData);

	switch (ret) {
		case 0x00000000: // STATUS_SUCCESS
			//OutputDebugString("Success\r\n");
			break;
		//case STATUS_DEVICE_REMOVED:
		//	OutputDebugString("STATUS_DEVICE_REMOVED\r\n");
		//	break;
		case STATUS_INVALID_PARAMETER:
			OutputDebugString("STATUS_INVALID_PARAMETER\r\n");
			break;
		default:
			OutputDebugString("????");
	}
#endif // _WIN32

	// TODO: implement/test for linux
}