#define _USE_MATH_DEFINES
#include <math.h>
#include "dbc.hpp"
#include <print>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <vector>
#include <functional>
#include "shader.hpp"
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "data.hpp"
#include "model.hpp"
#include "camera.hpp"

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

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

struct Config {
  Shader shader;
  Shader lightShader;

  Light light{
    .position={1.2f, 1.0f, 2.0f},
    .ambient={0.2f, 0.2f, 0.2f},
    .diffuse={0.8f, 0.8f, 0.8f},
    .specular={1.0f, 1.0f, 1.0f},
  };

  glm::vec3 cubePos{2.0f, 0.0f, 0.0f};
  Camera camera{.movementSpeed=2.0f};

  Material cubeMaterial{
      .ambient = {1.0f, 0.5f, 0.31f},
      .shininess = 32.0f,
      .diffuseMap = 0,
      .specularMap = 0,
  };

  unsigned int cubeVAO = 0;
  unsigned int lightCubeVAO = 0;
  unsigned int VBO = 0;
  float deltaTime = 0.0f;
  float lastFrame = 0.0f;

  void updateDelta() {
    float currentFrame = glfwGetTime();
    deltaTime = currentFrame - lastFrame;
    lastFrame = currentFrame;
  }
};

void init_glfw() {
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
}

void framebuffer_size_callback(GLFWwindow *, int width, int height) {
  glViewport(0, 0, width, height);
}

void mouse_callback(GLFWwindow *window, double xpos, double ypos) {
  Camera* camera = static_cast<Camera*>(glfwGetWindowUserPointer(window));
  camera->mouse_move(xpos, ypos);
}

void scroll_callback(GLFWwindow *window, double xoffset, double yoffset) {
  Camera* camera = static_cast<Camera*>(glfwGetWindowUserPointer(window));
  camera->mouse_scroll(xoffset, yoffset);
}

GLFWwindow* create_window() {
  GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
  dbc::check(window != NULL, "failed to open window");

  glfwMakeContextCurrent(window);

  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

  auto good = gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
  dbc::check(good, "failed to load GLAD");

  glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
  glfwSetCursorPosCallback(window, mouse_callback);
  glfwSetScrollCallback(window, scroll_callback);

  return window;
}


void processInput(GLFWwindow *window, Camera& camera) {

  if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
    glfwSetWindowShouldClose(window, true);
  }

  if(glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) {
    camera.forward();
  }

  if(glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) {
    camera.back();
  }

  if(glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {
    camera.left();
  }

  if(glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {
    camera.right();
  }
}

unsigned int load_texture(const std::string& image_file) {
  unsigned int texture_id;
  glGenTextures(1, &texture_id);
  glBindTexture(GL_TEXTURE_2D, texture_id);

  // set the texture wrapping parameters
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

  // set texture filtering parameters
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  int width = 0;
  int height = 0;
  int nrChannels = 0;
  stbi_set_flip_vertically_on_load(true);

  unsigned char *data = stbi_load(image_file.c_str(), &width, &height, &nrChannels, 0);

  dbc::check(data != nullptr, std::format("Failed to load texture: {}", image_file));

  dbc::check(nrChannels == 3 || nrChannels == 4,
      std::format("Image {} has invalid channels {} should be 3 or 4.", image_file, nrChannels));

  auto rgb_or_a = nrChannels == 3 ? GL_RGB : GL_RGBA;

  glTexImage2D(GL_TEXTURE_2D, 0, rgb_or_a, width, height, 0, rgb_or_a, GL_UNSIGNED_BYTE, data);
  glGenerateMipmap(GL_TEXTURE_2D);

  stbi_image_free(data);

  return texture_id;
}

Config setup() {
  glEnable(GL_DEPTH_TEST);

  Config config{
    .shader={"shaders/11-vert.glsl", "shaders/11-frag.glsl"},
    .lightShader={"shaders/11-vert.glsl", "shaders/11-lightsource.frag.glsl"},
  };

  unsigned int VBO = 0;
  unsigned int lightCubeVAO = 0;
  unsigned int cubeVAO = 0;

  // cube vao configure, this is the light target
  glGenVertexArrays(1, &cubeVAO);
  glGenBuffers(1, &VBO);

  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  glBindVertexArray(cubeVAO);

  // position attribute
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
  glEnableVertexAttribArray(0);

  glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(3 * sizeof(float)));
  glEnableVertexAttribArray(1);

  glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(6 * sizeof(float)));
  glEnableVertexAttribArray(2);

  // light vao configure, this is the light source
  glGenVertexArrays(1, &lightCubeVAO);
  glBindVertexArray(lightCubeVAO);

  glBindBuffer(GL_ARRAY_BUFFER, VBO);

  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
  glEnableVertexAttribArray(0);

  config.lightCubeVAO = lightCubeVAO;
  config.cubeVAO = cubeVAO;
  config.VBO = VBO;

  config.cubeMaterial.diffuseMap = load_texture("resources/textures/container2.png");
  config.cubeMaterial.specularMap = load_texture("resources/textures/container2_specular.png");

  config.shader.use();
  config.shader.setInt("material.diffuse", 0);
  config.shader.setInt("material.specular", 1);

  return config;
}

void draw_cube(Config& config, glm::mat4& projection, glm::mat4& view) {
  config.shader.use();

  config.shader.applyLight(config.light);

  config.shader.setMat4("view", view);
  config.shader.setMat4("projection", projection);
  config.shader.setVec3("viewPos", config.camera.pos);

  config.shader.applyMaterial(config.cubeMaterial);

  glm::mat4 model = glm::mat4(1.0f);
  model = glm::translate(model, config.cubePos);
  config.shader.setMat4("model", model);

  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D, config.cubeMaterial.diffuseMap);

  glActiveTexture(GL_TEXTURE1);
  glBindTexture(GL_TEXTURE_2D, config.cubeMaterial.specularMap);

  glBindVertexArray(config.cubeVAO);
  glDrawArrays(GL_TRIANGLES, 0, 36);
}

void draw_light(Config& config, glm::mat4& projection, glm::mat4& view) {
  config.lightShader.use();

  config.lightShader.applyLight(config.light);
  config.lightShader.setMat4("projection", projection);
  config.lightShader.setMat4("view", view);

  glm::mat4 model = glm::mat4(1.0f);
  model = glm::translate(model, config.light.position);
  model = glm::scale(model, glm::vec3(0.2f));
  config.lightShader.setMat4("model", model);

  glBindVertexArray(config.lightCubeVAO);
  glDrawArrays(GL_TRIANGLES, 0, 36);
}

void render(GLFWwindow* window, Config& config) {
  glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  config.shader.use();

  // time is used for fake 3d rotation
  float time = glfwGetTime();

  config.camera.update(config.deltaTime);

  glm::mat4 view = config.camera.lookAt();
  glm::mat4 projection = glm::mat4(1.0f);

  // fov, aspect, near plane, far plane
  projection = glm::perspective(glm::radians(config.camera.fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);

  // update light color
  draw_cube(config, projection, view);

  draw_light(config, projection, view);

  glfwSwapBuffers(window);
  glfwPollEvents();
}

void cleanup(Config& config) {
  glDeleteVertexArrays(1, &config.lightCubeVAO);
  glDeleteBuffers(1, &config.lightCubeVAO);
  glDeleteBuffers(1, &config.VBO);
  config.shader.cleanup();
}

int main() {
  init_glfw();

  auto window = create_window();
  auto config = setup();

  glfwSetWindowUserPointer(window, &config.camera);

  while(!glfwWindowShouldClose(window)) {
    processInput(window, config.camera);
    render(window, config);
    config.updateDelta();
  }

  cleanup(config);

  glfwTerminate();

  return 0;
}