#include <windows.h>
#include "glew.h"
#include "Glm/glm.hpp"
#include "Glm/ext.hpp"
#include <stdio.h>
#include "misc.h"
#include "model.h"
#include "timer.h"
#include "frustum.h"
#pragma comment(lib,"opengl32.lib")
#pragma comment(lib, "glew32.lib")

/**
* @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_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 lpCmdLine, int nShowCmd)
{
	/*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*/
	int windowWidth = 800;
	int windowHeight = 600;

	RECT rect;
	rect.left = 0;
	rect.right = windowWidth;
	rect.bottom = windowHeight;
	rect.top = 0;

	AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, false);

	//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

	/*glew初始化*/
	glewInit();

	/*创建program*/
	GLuint program = CreateGPUProgram("res/shader/test.vs", "res/shader/test.fs");

	GLuint posLocation, texcoordLocation, normalLocation, MLocation, VLocation, PLocation, NMLocation, textureLocation;
	posLocation = glGetAttribLocation(program, "pos");
	texcoordLocation = glGetAttribLocation(program, "texcoord");
	normalLocation = glGetAttribLocation(program, "normal");
	MLocation = glGetUniformLocation(program, "M");
	VLocation = glGetUniformLocation(program, "V");
	PLocation = glGetUniformLocation(program, "P");
	NMLocation = glGetUniformLocation(program, "NM");
	textureLocation = glGetUniformLocation(program, "U_MainTexture");


	/*load model*/
	unsigned int *indexes = nullptr;
	int vertexCount = 0, indexCount = 0;
	Timer t;
	t.Start();
	VertexData* vertexes = LoadObjModel("res/model/Sphere.obj", &indexes, vertexCount, indexCount);
	printf("load model cost %fs %d\n", t.GetPassedTime(), t.GetPassedTickers());

	if (vertexes == nullptr) {
		printf("load obj model fail\n");
	}

	/*创建vbo*/
	GLuint vbo = CreateBufferObject(GL_ARRAY_BUFFER, sizeof(VertexData) * vertexCount, GL_STATIC_DRAW, vertexes);

	/*创建IBO*/
	GLuint ibo = CreateBufferObject(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * indexCount, GL_STATIC_DRAW, indexes);

	/*创建纹理*/
	GLuint mainTexture = CreateTextureFromFile("res/image/stone.jpg");

	glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
	glEnable(GL_DEPTH_TEST);

	glViewport(0,0, windowWidth, windowHeight);

	//创建一个单位矩阵和一个投影矩阵，后面用来传递到shader
	float identify[] = {
		1,0,0,0,
		0,1,0,0,
		0,0,1,0,
		0,0,0,1
	};

	glm::mat4 model = glm::translate(0.0f, 0.0f, -3.0f);
	glm::mat4 projection = glm::perspective(45.0f, (float)windowWidth / (float)windowHeight, 0.1f, 1000.0f);
	glm::mat4 normalMatrix = glm::inverseTranspose(model);


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

	/*监听并处理用户请求*/
	MSG msg;

	auto what = [&]()->void {
		glm::mat4 normalMatrix = glm::inverseTranspose(model);

		glUseProgram(program);
		glUniformMatrix4fv(MLocation, 1, GL_FALSE, glm::value_ptr(model));
		glUniformMatrix4fv(VLocation, 1, GL_FALSE, identify);
		glUniformMatrix4fv(PLocation, 1, GL_FALSE, glm::value_ptr(projection));
		glUniformMatrix4fv(NMLocation, 1, GL_FALSE, glm::value_ptr(normalMatrix));

		glBindTexture(GL_TEXTURE_2D, mainTexture);
		glUniform1i(textureLocation, 0);

		glBindBuffer(GL_ARRAY_BUFFER, vbo);
		glEnableVertexAttribArray(posLocation);
		glVertexAttribPointer(posLocation, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), (void*)0);
		glEnableVertexAttribArray(texcoordLocation);
		glVertexAttribPointer(texcoordLocation, 2, GL_FLOAT, GL_FALSE, sizeof(VertexData), (void*)(sizeof(float) * 3));
		glEnableVertexAttribArray(normalLocation);
		glVertexAttribPointer(normalLocation, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), (void*)(sizeof(float) * 5));
		glBindBuffer(GL_ARRAY_BUFFER, 0);

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
		glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_INT, 0);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
		glUseProgram(0);
	};

	while (true) {
		if (PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE)) {
			if (msg.message == WM_QUIT) {
				break;
			}
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}

		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		what();

		SwapBuffers(dc);
	}

	return 0;
}