#include "glad/glad.h"
#include "shader.h"
#include <GLFW/glfw3.h>
#include <cmath>

// 三角形顶点
float vertices[] = {
    // 第一个三角形
    0.4f, 0.4f, 0.0f,   // 右上角
    0.4f, -0.4f, 0.0f,  // 右下角
    -0.4f, -0.4f, 0.0f, // 左下角
    -0.4f, 0.4f, 0.0f   // 左上角
};

// 索引
unsigned int indices[] = {
    0, 1, 3, // 第一个三角形
    1, 2, 3  // 第二个三角形
};

void framebuffer_size_callback(GLFWwindow *window, int width, int height);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

int main() {

  // 设置 glfw
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
  // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

  // 创建窗口
  GLFWwindow *window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
  if (window == NULL) {
    std::cout << "Failed to create GLFW window" << std::endl;
    glfwTerminate();
    return -1;
  }
  glfwMakeContextCurrent(window);

  // 加载glad
  if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
    std::cout << "Failed to initialize GLAD" << std::endl;
    return -1;
  }

  // 设置视口
  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

  // 创建着色器程序
  Shader shader = Shader("src/simple.vs", "src/uniformcolor.fs");


  unsigned int VAO, VBO, EBO;
  // 创建顶点数组对象
  glGenVertexArrays(1, &VAO);
  glBindVertexArray(VAO);

  // 创建顶点缓冲对象
  glGenBuffers(1, &VBO);
  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  // 创建索引缓冲对象
  glGenBuffers(1, &EBO);
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
  glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,
               GL_STATIC_DRAW);

  // 设置顶点属性指针
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
  glEnableVertexAttribArray(0);

  // 循环渲染
  while (!glfwWindowShouldClose(window)) {
    // 处理输入
    processInput(window);

    // 设置为白色
    glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // 激活着色器
    shader.use();

    // 更新uniform颜色
    float timeValue = glfwGetTime();
    float greenValue = (sin(timeValue) / 2.0f) + 0.5f;
    shader.setFloat4("ourColor", 1.0f, greenValue, 0.0f, 0.0f);
    shader.setFloat1("xOffset", cos(timeValue) / 2.0f);
    shader.setFloat1("yOffset", sin(timeValue) / 2.0f);

    // 绘制三角形
    glBindVertexArray(VAO);
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);

    // 检查并调用事件，交换缓冲
    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  // 释放资源
  glfwTerminate();
  return 0;
}

// 处理输入
void processInput(GLFWwindow *window) {
  if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
    glfwSetWindowShouldClose(window, true);
}

// 窗口大小改变时回调该函数
void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
  glViewport(0, 0, width, height);
}