// Include Config header generated by GNU autotools
#include <GL/glew.h>
// Make sure Glew is loaded first
#include <GL/gl.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_opengl.h>
// Not used yet
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
// File reader
#include <fstream>
#include <iostream>
#include <string>
// Shader
#include "ShaderLoader.h"
// Camera
#include "PlayerCamera.h"

// Include error class
#include "Error.h"
Error error("main");

int main(int argc, char **argv) {
  // Initialise SDL2
  if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
    error.crash("Unable to initialise SDL: ", SDL_GetError());
    return 1;
  }

  // Make OpenGL use double buffering (Render game first then shove to output)
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

  // TODO: Understand what a depth buffer is
  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);

  // TODO: Discover if this is necessary for linux and what values they need be
  // SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
  // SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
  // SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
  // SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);

  // Create Window
  SDL_Window *window =
      SDL_CreateWindow("Game", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                       800, 600, SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL);
  if (window == NULL) {
    error.crash("Unable to initialise SDL Window: ", SDL_GetError());
    return 1;
  }

  // Create glContext
  SDL_GLContext glContext = SDL_GL_CreateContext(window);
  // TODO: Test that glContext was created successfully

  // Tell us the number of vertex attributes allowed in bug reports
  //
  int nrAttributes;
  glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &nrAttributes);
  error.log("Maximum num of vertex attributes supported: " +
            std::to_string(nrAttributes));

  // Initialise Glew
  if (glewInit() != GLEW_OK) {
    error.crash("Unable to initialise GLEW (OpenGL Extention Wrangler)");
  }

  // Create event handling struct
  SDL_Event input;

  ShaderLoader shader("./data/shaders"
                      "/vertex.glsl",
                      "./data/shaders"
                      "/fragment.glsl");

  float vertices[] = {
      // positions        // texture Co-ords
      0.5f,  0.5f,  0.0f, 1.0f, 1.0f, // top right
      0.5f,  -0.5f, 0.0f, 1.0f, 0.0f, // bottom right
      -0.5f, -0.5f, 0.0f, 0.0f, 0.0f, // bottom left
      -0.5f, 0.5f,  0.0f, 0.0f, 1.0f  // top left
  };

  unsigned int indices[] = {
      0, 1, 3, // First triangle
      1, 2, 3  // Second triangle
  };

  unsigned int VBO, VAO, EBO;
  glGenVertexArrays(1, &VAO);
  glGenBuffers(1, &VBO);
  glGenBuffers(1, &EBO);
  // bind the Vertex Array Object first, then bind and set vertex buffer(s), and
  // then configure vertex attributes(s).
  glBindVertexArray(VAO);

  // Bind VBO
  glBindBuffer(GL_ARRAY_BUFFER, VBO);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
  // Bind EBO
  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
  glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,
               GL_STATIC_DRAW);

  // position attribute
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void *)0);
  glEnableVertexAttribArray(0);
  // texture attribute
  glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float),
                        (void *)(3 * sizeof(float)));
  glEnableVertexAttribArray(1);

  // You can unbind the VAO afterwards so other VAO calls won't accidentally
  // modify this VAO, but this rarely happens. Modifying other VAOs requires a
  // call to glBindVertexArray anyways so we generally don't unbind VAOs (nor
  // VBOs) when it's not directly necessary. glBindVertexArray(0);

  // Determine how we handle textures
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
  // Determine border colour for incorrectly sized textures
  float borderColor[] = {0.5f, 0.5f, 0.5f, 1.0f};
  glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
  // Texture aliasing
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  // Load texture image
  SDL_Surface *image = IMG_Load("./data"
                                "/container.jpg");
  if (image == nullptr) {
    error.crash("SDL2_image was unable to load a texture", IMG_GetError());
  }

  // create and bind texture object
  unsigned int texture;
  glGenTextures(1, &texture);
  glBindTexture(GL_TEXTURE_2D, texture);

  // Handle different SDL Surface data types
  int mode = GL_RGB;
  if (image->format->BytesPerPixel == 4) {
    mode = GL_RGBA;
  }

  // Generate texture and mipmap from image
  glTexImage2D(GL_TEXTURE_2D, 0, mode, image->w, image->h, 0, mode,
               GL_UNSIGNED_BYTE, image->pixels);
  glGenerateMipmap(GL_TEXTURE_2D);

  // remove image surface now it's no longer needed to create texture
  SDL_FreeSurface(image);
  image = nullptr;

  // Mess with perspective
  // Projection matrix : 45° Field of View, 4:3 ratio, display range : 0.1
  // unit <-> 100 units
  float width = 800;
  float height = 600;
  glm::mat4 Projection = glm::perspective(
      glm::radians(45.0f), (float)width / (float)height, 0.1f, 100.0f);

  //// Camera matrix
  // glm::mat4 View = glm::lookAt(
  //     glm::vec3(4, 3, 3), // Camera is at (4,3,3), in World Space
  //     glm::vec3(0, 0, 0), // and looks at the origin
  //     glm::vec3(0, 1, 0)  // Head is up (set to 0,-1,0 to look upside-down)
  //);
  //// Model matrix : an identity matrix (model will be at the origin)
  // glm::mat4 Model = glm::mat4(1.0f);

  //// Our ModelViewProjection : multiplication of our 3 matrices
  // glm::mat4 mvp =
  //     Projection * View *
  //     Model; // Remember, matrix multiplication is the other way around

  PlayerCamera camera;

  // Game loop
  bool running = true;
  while (running) {
    // SDL Event handling loop
    while (SDL_PollEvent(&input) > 0) {
      // Handle SDL quit event
      if (input.type == SDL_QUIT) {
        running = false;
      }
      // TODO: Do something with keys lol
    };
    camera.tick();

    // Clear screen ready for next loop
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    // Make every shader/rendering call from this point on use our shader
    // glUseProgram(shaderProgram);

    // Send our glsl shader our mvp
    shader.setMat4("MVP", camera.getMVP());
    shader.use();

    // I think this is meant to be here but it breaks...
    // shove vertex array into buffer
    glBindVertexArray(VAO);

    // TODO: Run game here lol
    // Draw triangle
    // glDrawArrays(GL_TRIANGLES, 0, 3);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    // glBindVertexArray(0);

    SDL_GL_SwapWindow(window);
  };

  // Escaped Game loop

  // On close also destroy window
  SDL_DestroyWindow(window);

  // Close all leftover SDL systems
  SDL_Quit();

  return 0;
}