// Copyright 2012 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <string>

#include "Core/Host.h"

#include "VideoBackends/OGL/GLInterface/WGL.h"

#include "VideoCommon/RenderBase.h"
#include "VideoCommon/VertexShaderManager.h"
#include "VideoCommon/VideoConfig.h"

static HDC hDC = nullptr;       // Private GDI Device Context
static HGLRC hRC = nullptr;     // Permanent Rendering Context
static HINSTANCE dllHandle = nullptr; // Handle to OpenGL32.dll

// typedef from wglext.h
typedef BOOL(WINAPI * PFNWGLSWAPINTERVALEXTPROC) (int interval);
static PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT = nullptr;

void cInterfaceWGL::SwapInterval(int Interval)
{
	if (wglSwapIntervalEXT)
		wglSwapIntervalEXT(Interval);
	else
		ERROR_LOG(VIDEO, "No support for SwapInterval (framerate clamped to monitor refresh rate).");
}
void cInterfaceWGL::Swap()
{
	SwapBuffers(hDC);
}

void* cInterfaceWGL::GetFuncAddress(const std::string& name)
{
	void* func = (void*)wglGetProcAddress((LPCSTR)name.c_str());
	if (func == nullptr)
		func = (void*)GetProcAddress(dllHandle, (LPCSTR)name.c_str());
	return func;
}

// Draw messages on top of the screen
bool cInterfaceWGL::PeekMessages()
{
	// TODO: peekmessage
	MSG msg;
	while (PeekMessage(&msg, 0, 0, 0, PM_REMOVE))
	{
		if (msg.message == WM_QUIT)
			return FALSE;
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return TRUE;
}

// Create rendering window.
// Call browser: Core.cpp:EmuThread() > main.cpp:Video_Initialize()
bool cInterfaceWGL::Create(void *window_handle, bool core)
{
	if (window_handle == nullptr)
		return false;

	HWND window_handle_reified = reinterpret_cast<HWND>(window_handle);
	RECT window_rect = {0};

	if (!GetClientRect(window_handle_reified, &window_rect))
		return false;

	// Control window size and picture scaling
	int twidth  = (window_rect.right - window_rect.left);
	int theight = (window_rect.bottom - window_rect.top);
	s_backbuffer_width = twidth;
	s_backbuffer_height = theight;

	m_window_handle = window_handle_reified;

#ifdef _WIN32
	dllHandle = LoadLibrary(TEXT("OpenGL32.dll"));
#endif

	PIXELFORMATDESCRIPTOR pfd =         // pfd Tells Windows How We Want Things To Be
	{
		sizeof(PIXELFORMATDESCRIPTOR),  // Size Of This Pixel Format Descriptor
		1,                              // Version Number
		PFD_DRAW_TO_WINDOW |            // Format Must Support Window
			PFD_SUPPORT_OPENGL |        // Format Must Support OpenGL
			PFD_DOUBLEBUFFER,           // Must Support Double Buffering
		PFD_TYPE_RGBA,                  // Request An RGBA Format
		32,                             // Select Our Color Depth
		0, 0, 0, 0, 0, 0,               // Color Bits Ignored
		0,                              // 8bit Alpha Buffer
		0,                              // Shift Bit Ignored
		0,                              // No Accumulation Buffer
		0, 0, 0, 0,                     // Accumulation Bits Ignored
		0,                              // 0Bit Z-Buffer (Depth Buffer)
		0,                              // 0bit Stencil Buffer
		0,                              // No Auxiliary Buffer
		PFD_MAIN_PLANE,                 // Main Drawing Layer
		0,                              // Reserved
		0, 0, 0                         // Layer Masks Ignored
	};

	int      PixelFormat;               // Holds The Results After Searching For A Match

	if (!(hDC = GetDC(window_handle_reified)))
	{
		PanicAlert("(1) Can't create an OpenGL Device context. Fail.");
		return false;
	}

	if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd)))
	{
		PanicAlert("(2) Can't find a suitable PixelFormat.");
		return false;
	}

	if (!SetPixelFormat(hDC, PixelFormat, &pfd))
	{
		PanicAlert("(3) Can't set the PixelFormat.");
		return false;
	}

	if (!(hRC = wglCreateContext(hDC)))
	{
		PanicAlert("(4) Can't create an OpenGL rendering context.");
		return false;
	}

	return true;
}

bool cInterfaceWGL::MakeCurrent()
{
	bool success = wglMakeCurrent(hDC, hRC) ? true : false;
	if (success)
	{
		// Grab the swap interval function pointer
		wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)GLInterface->GetFuncAddress("wglSwapIntervalEXT");
	}
	return success;
}

bool cInterfaceWGL::ClearCurrent()
{
	return wglMakeCurrent(hDC, nullptr) ? true : false;
}

// Update window width, size and etc. Called from Render.cpp
void cInterfaceWGL::Update()
{
	RECT rcWindow;
	GetClientRect(m_window_handle, &rcWindow);

	// Get the new window width and height
	s_backbuffer_width  = (rcWindow.right - rcWindow.left);
	s_backbuffer_height = (rcWindow.bottom - rcWindow.top);
}

// Close backend
void cInterfaceWGL::Shutdown()
{
	if (hRC)
	{
		if (!wglMakeCurrent(nullptr, nullptr))
			NOTICE_LOG(VIDEO, "Could not release drawing context.");

		if (!wglDeleteContext(hRC))
			ERROR_LOG(VIDEO, "Attempt to release rendering context failed.");

		hRC = nullptr;
	}

	if (hDC && !ReleaseDC(m_window_handle, hDC))
	{
		ERROR_LOG(VIDEO, "Attempt to release device context failed.");
		hDC = nullptr;
	}
}