/*************************************************************************/
/*  gl_manager_windows.cpp                                               */
/*************************************************************************/
/*                       This file is part of:                           */
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#include "gl_manager_windows.h"

#ifdef WINDOWS_ENABLED
#ifdef GLES3_ENABLED

#include <stdio.h>
#include <stdlib.h>

#include <dwmapi.h>

#define WGL_CONTEXT_MAJOR_VERSION_ARB 0x2091
#define WGL_CONTEXT_MINOR_VERSION_ARB 0x2092
#define WGL_CONTEXT_FLAGS_ARB 0x2094
#define WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB 0x00000002
#define WGL_CONTEXT_PROFILE_MASK_ARB 0x9126
#define WGL_CONTEXT_CORE_PROFILE_BIT_ARB 0x00000001

#define _WGL_CONTEXT_DEBUG_BIT_ARB 0x0001

#if defined(__GNUC__)
// Workaround GCC warning from -Wcast-function-type.
#define wglGetProcAddress (void *)wglGetProcAddress
#endif

typedef HGLRC(APIENTRY *PFNWGLCREATECONTEXTATTRIBSARBPROC)(HDC, HGLRC, const int *);

static String format_error_message(DWORD id) {
	LPWSTR messageBuffer = nullptr;
	size_t size = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
			nullptr, id, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPWSTR)&messageBuffer, 0, nullptr);

	String msg = "Error " + itos(id) + ": " + String::utf16((const char16_t *)messageBuffer, size);

	LocalFree(messageBuffer);

	return msg;
}

int GLManager_Windows::_find_or_create_display(GLWindow &win) {
	// find display NYI, only 1 supported so far
	if (_displays.size()) {
		return 0;
	}

	// create
	GLDisplay d_temp = {};
	_displays.push_back(d_temp);
	int new_display_id = _displays.size() - 1;

	// create context
	GLDisplay &d = _displays[new_display_id];
	Error err = _create_context(win, d);

	if (err != OK) {
		// not good
		// delete the _display?
		_displays.remove_at(new_display_id);
		return -1;
	}

	return new_display_id;
}

static Error _configure_pixel_format(HDC hDC) {
	static PIXELFORMATDESCRIPTOR pfd = {
		sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
		1,
		PFD_DRAW_TO_WINDOW | // Format Must Support Window
				PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
				PFD_DOUBLEBUFFER,
		(BYTE)PFD_TYPE_RGBA,
		(BYTE)(OS::get_singleton()->is_layered_allowed() ? 32 : 24),
		(BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, // Color Bits Ignored
		(BYTE)(OS::get_singleton()->is_layered_allowed() ? 8 : 0), // Alpha Buffer
		(BYTE)0, // Shift Bit Ignored
		(BYTE)0, // No Accumulation Buffer
		(BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, // Accumulation Bits Ignored
		(BYTE)24, // 24Bit Z-Buffer (Depth Buffer)
		(BYTE)0, // No Stencil Buffer
		(BYTE)0, // No Auxiliary Buffer
		(BYTE)PFD_MAIN_PLANE, // Main Drawing Layer
		(BYTE)0, // Reserved
		0, 0, 0 // Layer Masks Ignored
	};

	int pixel_format = ChoosePixelFormat(hDC, &pfd);
	if (!pixel_format) // Did Windows Find A Matching Pixel Format?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	BOOL ret = SetPixelFormat(hDC, pixel_format, &pfd);
	if (!ret) // Are We Able To Set The Pixel Format?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	return OK;
}

Error GLManager_Windows::_create_context(GLWindow &win, GLDisplay &gl_display) {
	Error err = _configure_pixel_format(win.hDC);
	if (err != OK) {
		return err;
	}

	gl_display.hRC = wglCreateContext(win.hDC);
	if (!gl_display.hRC) // Are We Able To Get A Rendering Context?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	if (!wglMakeCurrent(win.hDC, gl_display.hRC)) {
		ERR_PRINT("Could not attach OpenGL context to newly created window: " + format_error_message(GetLastError()));
	}

	int attribs[] = {
		WGL_CONTEXT_MAJOR_VERSION_ARB, 3, //we want a 3.3 context
		WGL_CONTEXT_MINOR_VERSION_ARB, 3,
		//and it shall be forward compatible so that we can only use up to date functionality
		WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
		WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB /*| _WGL_CONTEXT_DEBUG_BIT_ARB*/,
		0
	}; //zero indicates the end of the array

	PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribsARB = nullptr; //pointer to the method
	wglCreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress("wglCreateContextAttribsARB");

	if (wglCreateContextAttribsARB == nullptr) //OpenGL 3.0 is not supported
	{
		wglDeleteContext(gl_display.hRC);
		gl_display.hRC = 0;
		return ERR_CANT_CREATE;
	}

	HGLRC new_hRC = wglCreateContextAttribsARB(win.hDC, 0, attribs);
	if (!new_hRC) {
		wglDeleteContext(gl_display.hRC);
		gl_display.hRC = 0;
		return ERR_CANT_CREATE;
	}

	if (!wglMakeCurrent(win.hDC, nullptr)) {
		ERR_PRINT("Could not detach OpenGL context from newly created window: " + format_error_message(GetLastError()));
	}

	wglDeleteContext(gl_display.hRC);
	gl_display.hRC = new_hRC;

	if (!wglMakeCurrent(win.hDC, gl_display.hRC)) // Try To Activate The Rendering Context
	{
		ERR_PRINT("Could not attach OpenGL context to newly created window with replaced OpenGL context: " + format_error_message(GetLastError()));
		wglDeleteContext(gl_display.hRC);
		gl_display.hRC = 0;
		return ERR_CANT_CREATE;
	}

	if (!wglSwapIntervalEXT) {
		wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress("wglSwapIntervalEXT");
	}

	return OK;
}

Error GLManager_Windows::window_create(DisplayServer::WindowID p_window_id, HWND p_hwnd, HINSTANCE p_hinstance, int p_width, int p_height) {
	HDC hDC = GetDC(p_hwnd);
	if (!hDC) {
		return ERR_CANT_CREATE;
	}

	// configure the HDC to use a compatible pixel format
	Error result = _configure_pixel_format(hDC);
	if (result != OK) {
		return result;
	}

	GLWindow win;
	win.width = p_width;
	win.height = p_height;
	win.hwnd = p_hwnd;
	win.hDC = hDC;

	win.gldisplay_id = _find_or_create_display(win);

	if (win.gldisplay_id == -1) {
		return FAILED;
	}

	// WARNING: p_window_id is an eternally growing integer since popup windows keep coming and going
	// and each of them has a higher id than the previous, so it must be used in a map not a vector
	_windows[p_window_id] = win;

	// make current
	window_make_current(p_window_id);

	return OK;
}

void GLManager_Windows::_internal_set_current_window(GLWindow *p_win) {
	_current_window = p_win;
}

void GLManager_Windows::window_resize(DisplayServer::WindowID p_window_id, int p_width, int p_height) {
	get_window(p_window_id).width = p_width;
	get_window(p_window_id).height = p_height;
}

int GLManager_Windows::window_get_width(DisplayServer::WindowID p_window_id) {
	return get_window(p_window_id).width;
}

int GLManager_Windows::window_get_height(DisplayServer::WindowID p_window_id) {
	return get_window(p_window_id).height;
}

void GLManager_Windows::window_destroy(DisplayServer::WindowID p_window_id) {
	GLWindow &win = get_window(p_window_id);
	if (_current_window == &win) {
		_current_window = nullptr;
	}
	_windows.erase(p_window_id);
}

void GLManager_Windows::release_current() {
	if (!_current_window) {
		return;
	}

	if (!wglMakeCurrent(_current_window->hDC, nullptr)) {
		ERR_PRINT("Could not detach OpenGL context from window marked current: " + format_error_message(GetLastError()));
	}
}

void GLManager_Windows::window_make_current(DisplayServer::WindowID p_window_id) {
	if (p_window_id == -1) {
		return;
	}

	// crash if our data structures are out of sync, i.e. not found
	GLWindow &win = _windows[p_window_id];

	// noop
	if (&win == _current_window) {
		return;
	}

	const GLDisplay &disp = get_display(win.gldisplay_id);
	if (!wglMakeCurrent(win.hDC, disp.hRC)) {
		ERR_PRINT("Could not switch OpenGL context to other window: " + format_error_message(GetLastError()));
	}

	_internal_set_current_window(&win);
}

void GLManager_Windows::make_current() {
	if (!_current_window) {
		return;
	}
	const GLDisplay &disp = get_current_display();
	if (!wglMakeCurrent(_current_window->hDC, disp.hRC)) {
		ERR_PRINT("Could not switch OpenGL context to window marked current: " + format_error_message(GetLastError()));
	}
}

void GLManager_Windows::swap_buffers() {
	SwapBuffers(_current_window->hDC);
}

Error GLManager_Windows::initialize() {
	return OK;
}

void GLManager_Windows::set_use_vsync(DisplayServer::WindowID p_window_id, bool p_use) {
	GLWindow &win = get_window(p_window_id);
	GLWindow *current = _current_window;

	if (&win != _current_window) {
		window_make_current(p_window_id);
	}

	if (wglSwapIntervalEXT) {
		win.use_vsync = p_use;
		wglSwapIntervalEXT(p_use ? 1 : 0);
	}

	if (current != _current_window) {
		_current_window = current;
		make_current();
	}
}

bool GLManager_Windows::is_using_vsync(DisplayServer::WindowID p_window_id) const {
	return get_window(p_window_id).use_vsync;
}

HDC GLManager_Windows::get_hdc(DisplayServer::WindowID p_window_id) {
	return get_window(p_window_id).hDC;
}

HGLRC GLManager_Windows::get_hglrc(DisplayServer::WindowID p_window_id) {
	const GLWindow &win = get_window(p_window_id);
	const GLDisplay &disp = get_display(win.gldisplay_id);
	return disp.hRC;
}

GLManager_Windows::GLManager_Windows(ContextType p_context_type) {
	context_type = p_context_type;

	direct_render = false;
	glx_minor = glx_major = 0;
	_current_window = nullptr;
}

GLManager_Windows::~GLManager_Windows() {
	release_current();
}

#endif // GLES3_ENABLED
#endif // WINDOWS