#include "ggl.h"
#include "scene.h"
#include "utils.h"
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "glu32.lib")
#pragma comment(lib, "winmm.lib")

POINT originalPos;//鼠标右键被按下时的位置
bool rotateView = false;


unsigned char* LoadFileContent(const char* path, int &filesize) {
	unsigned char* fileContent = nullptr;
	filesize = 0;

	FILE *pFile = fopen(path, "rb");

	if (pFile) {
		fseek(pFile, 0, SEEK_END);//把文件指针移动至文件末尾
		int nLen = ftell(pFile);//文件位置指针当前位置相对于文件首的偏移字节数，这里其实就是得到了文件的字节长度
		if (nLen > 0) {
			rewind(pFile);//把文件指针移到头部
			fileContent = new unsigned char[nLen + 1];
			fread(fileContent, sizeof(unsigned char), nLen, pFile);
			fileContent[nLen] = '\0';
			filesize = nLen;
		}
		fclose(pFile);
	}
	return fileContent;
}

/**
* 获取每帧的消耗时间
*/
float GetFrameTime() {
	static unsigned long lastTime = 0, timeSinceComputerStart = 0;
	timeSinceComputerStart = timeGetTime();
	unsigned long frameTime = lastTime == 0 ? 0 : timeSinceComputerStart - lastTime;
	lastTime = timeSinceComputerStart;
	return float(frameTime) / 1000.0f;
}

/**
* @hwnd 发起消息的窗口
* @msg 消息类型
*/
LRESULT CALLBACK GLWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
	switch (msg) {
	case WM_RBUTTONDOWN:
		GetCursorPos(&originalPos);//获取坐标位置
		ShowCursor(false);//隐藏鼠标
		rotateView = true;
		return 0;
	case WM_RBUTTONUP:
		SetCursorPos(originalPos.x, originalPos.y);
		ShowCursor(true);
		rotateView = false;
		return 0;
	case WM_MOUSEMOVE:
		if (rotateView) {
			POINT currentPos;
			GetCursorPos(&currentPos);//再一次获取鼠标当前位置
			int deltaX = currentPos.x - originalPos.x;
			int deltaY = currentPos.y - originalPos.y;
			OnMouseMove(deltaX, deltaY);
			SetCursorPos(originalPos.x, originalPos.y);
		}
		return 0;
	case WM_KEYDOWN:
		OnKeyDown(wParam);
		return 0;
	case WM_KEYUP:
		OnKeyUp(wParam);
		return 0;
	case WM_CLOSE:
		PostQuitMessage(0);
		return 0;
	}

	return DefWindowProc(hwnd, msg, wParam, lParam);//其他消息调用window默认处理函数
}

/**
* @hinstance 本应用程序启动实例
* @hPrevInstance 上一次应用程式的实例
* @IpCmdLine 命令行的参数
* @ShowCmd 怎么显示窗口
*/
INT WINAPI WinMain(HINSTANCE hinstance, HINSTANCE hPrevInstance, LPSTR IpCmdLine, int ShowCmd) {

	/*注册窗口*/
	WNDCLASSEX wndclass;
	wndclass.cbClsExtra = 0; //窗口类型的额外空间，这里不需要
	wndclass.cbSize = sizeof(WNDCLASSEX); //窗口实际占用的内存
	wndclass.cbWndExtra = 0; //窗口的额外空间，这里不需要
	wndclass.hbrBackground = NULL; //窗口背景
	wndclass.hCursor = LoadCursor(NULL, IDC_ARROW); //定义鼠标类型
	wndclass.hIcon = NULL; //应用程序exe文件显示图标
	wndclass.hIconSm = NULL; //应用程序运行时左上角图标
	wndclass.hInstance = hinstance; //本应用程序实例
	wndclass.lpfnWndProc = GLWindowProc; //如果用户操作了窗口，本函数会被调用
	wndclass.lpszClassName = L"GLWindow";//窗口名称
	wndclass.lpszMenuName = NULL;//菜单名称
	wndclass.style = CS_VREDRAW | CS_HREDRAW;//窗口更新时的重绘方式，这里使用垂直重绘和水平重绘
	ATOM atom = RegisterClassEx(&wndclass);
	if (!atom) {
		MessageBox(NULL, L"Register failed", L"Error", MB_OK);
		return  0;
	}


	/*创建窗口*/
	//调整窗口大小
	RECT rect;
	rect.left = 0;
	rect.right = 800;
	rect.top = 0;
	rect.bottom = 600;
	AdjustWindowRect(&rect, WS_EX_OVERLAPPEDWINDOW, NULL);
	int windowWidth = rect.right - rect.left;
	int windowHeight = rect.bottom - rect.top;

	//窗口名称一定要和刚才注册窗口的保持一致
	HWND hwnd = CreateWindowEx(NULL, L"GLWindow", L"OpenGL Window", WS_OVERLAPPEDWINDOW, 100, 100, windowWidth, windowHeight, NULL, NULL, hinstance, NULL);
	
	//设置渲染环境
	HDC dc = GetDC(hwnd);//获取设备上下文
	PIXELFORMATDESCRIPTOR pfd;
	memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));
	pfd.nVersion = 1;
	pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR);
	pfd.cColorBits = 32; //颜色缓冲区每个像素为32比特4通道RGBA
	pfd.cDepthBits = 24; //深度缓冲区每个像素大小，24比特表示一个浮点数
	pfd.cStencilBits = 8; //蒙板缓冲区每像素为8比特
	pfd.iPixelType = PFD_TYPE_RGBA; //设置像素类型为RGBA
	pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER ; //表示像素最后输出到窗口
	//设置像素格式
	int pixelFormat = ChoosePixelFormat(dc, &pfd);
	SetPixelFormat(dc, pixelFormat, &pfd);
	//创建OpenGL渲染环境
	HGLRC rc = wglCreateContext(dc);
	wglMakeCurrent(dc, rc);//设置OpenGL渲染环境生效

	Init();

	/*显示窗口*/
	ShowWindow(hwnd, SW_SHOW);
	UpdateWindow(hwnd);

	/*监听并处理用户请求*/
	MSG msg;
	while (true) {
		if (PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE)) {
			if (msg.message == WM_QUIT) {
				break;
			}
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}

		Draw();
		SwapBuffers(dc);
	}

	return 0;
}