#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <alsa/asoundlib.h>

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#define MIDICHK(stmt, msg) if((stmt) < 0) {puts("ERROR: "#msg); exit(1);}

int width = 1920;
int height = 1080;
GLFWwindow* window;
GLuint vertex;
GLuint fragment;
GLuint shaderProgram;
GLuint backbuffer;

typedef struct Shad {
  GLuint id;
  char fragment[40];
  time_t mtime;
  int new;
} Shader;

Shader shader;

typedef struct Img {
  GLuint id;
  char path[40];
  int new;
} Image;

Image images[8];
GLfloat params[4];

static snd_seq_t *midi_seq;
static int midiin;

int ticks =0;
int running = 0;
int program=0;

static void error_callback(int error, const char* description) { fputs(description, stderr); }

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    if (key == GLFW_KEY_Q && action == GLFW_PRESS) glfwSetWindowShouldClose(window, GL_TRUE);
}

const char * readShader(char * path) {
  FILE *file = fopen(path, "r");
  if (!file) { fprintf(stderr,"Cannot read %s\n",path); }
  char source[100000];
  int res = fread(source,1,100000-1,file);
  source[res] = 0;
  fclose(file);
  const char *c_str = source;
  return c_str;
}

GLuint compileShader(const char * source, GLenum type) {
  GLuint sh = glCreateShader(type);
  glShaderSource(sh, 1, &source, NULL);
  glCompileShader(sh);
  int success;
  glGetShaderiv(sh, GL_COMPILE_STATUS, &success);
  if (!success) {
    char infoLog[512];
    glGetShaderInfoLog(sh, 512, NULL, infoLog);
    fprintf(stderr,"Shader compilation failed: %s\n",infoLog);
  }
  else { return sh; }
}

GLuint linkShader(GLuint vertex, GLuint fragment) {
  glUseProgram(0);
  glDeleteProgram(shader.id);
  shader.id = glCreateProgram();
  glAttachShader(shader.id, vertex);
  glAttachShader(shader.id, fragment);
  glLinkProgram(shader.id);
  int success;
  glGetProgramiv(shader.id, GL_LINK_STATUS, &success);
  if (!success) {
    char infoLog[512];
    glGetProgramInfoLog(shader.id, 512, NULL, infoLog);
    fprintf(stderr,"Shader linking failed: %s\n",infoLog);
  }
  glDetachShader(shader.id, vertex); 
  glDetachShader(shader.id, fragment); 
  glDeleteShader(vertex);
  glDeleteShader(fragment);
}

void createShader() {
  static const char vertex_src[] = {
    "#version 450 core\n"
    "const vec2 quadVertices[4] = { vec2(-1.0, -1.0), vec2(1.0, -1.0), vec2(-1.0, 1.0), vec2(1.0, 1.0) };\n"
    "void main() { gl_Position = vec4(quadVertices[gl_VertexID], 0.0, 1.0); }\n"
  };
  vertex = compileShader(vertex_src, GL_VERTEX_SHADER);
  fragment = compileShader(readShader(shader.fragment),GL_FRAGMENT_SHADER);
  linkShader(vertex,fragment);
  struct stat file_stat;
  stat(shader.fragment, &file_stat);
  shader.mtime = file_stat.st_mtime;
  glUseProgram(shader.id);
};

void imageUniforms(int i) {
  glUniform1i(glGetUniformLocation(shader.id, "images")+i,i);
}

void resize_callback(GLFWwindow* window, int w, int h) {
  width = w;
  height = h;
  glUniform2f(glGetUniformLocation(shader.id, "resolution"),width,height); 
}

void readImage(int i) {

  images[i].new = 1;
  int w,h,comp;
  stbi_set_flip_vertically_on_load(1);
  unsigned char* pixels = stbi_load(images[i].path, &w, &h, &comp, STBI_rgb_alpha);
  imageUniforms(i);

  glActiveTexture(GL_TEXTURE0+i);
  glGenTextures(1, &images[i].id);
  glBindTexture(GL_TEXTURE_2D,images[i].id);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
  stbi_image_free(pixels);
}

void *readMidi() {

  MIDICHK(snd_seq_open(&midi_seq, "default", SND_SEQ_OPEN_INPUT, 0), "Could not open sequencer");
  MIDICHK(snd_seq_set_client_name(midi_seq, "SV"), "Could not set client name");
  MIDICHK(midiin = snd_seq_create_simple_port(midi_seq, "sv:in", SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE, SND_SEQ_PORT_TYPE_APPLICATION), "Could not open port");
  
  while(1) {
    snd_seq_event_t *ev = NULL;
    snd_seq_event_input(midi_seq, &ev);
    if (ev->type == SND_SEQ_EVENT_NOTEON) {
      int note = ev->data.note.note;
      if (note >= 36) program = note-36;
    }
    else if(ev->type == SND_SEQ_EVENT_CONTROLLER) {
      int p = ev->data.control.param;
      int v = ev->data.control.value;
      if (p < 4) params[p] = (float)v/127.0;
    }
    else if(ev->type == SND_SEQ_EVENT_SONGPOS)
      ticks = ev->data.control.value*24;
    else if(ev->type == SND_SEQ_EVENT_START)
      running = 1;
    else if(ev->type == SND_SEQ_EVENT_STOP) 
      running = 0;
    else if(ev->type == SND_SEQ_EVENT_CONTINUE)
      running = 1;
    else if(ev->type == SND_SEQ_EVENT_CLOCK)
      if (running) ticks++;
  }
}

void *watchShader() {
  while (1) {
    sleep(0.2);
    struct stat file_stat;
    stat(shader.fragment, &file_stat);
    if (file_stat.st_mtime > shader.mtime) shader.new = 1; 
  }
}

int main(int argc, char **argv) {

  for (int i = optind; i<argc; i++) {
    strncpy(images[i-optind].path, argv[i],40);
    images[i-optind].new = 1;
  }

  // createWindow
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
  glfwWindowHint(GLFW_DECORATED, GL_FALSE);
  const GLFWvidmode * mode = glfwGetVideoMode(glfwGetPrimaryMonitor());
  width = mode->width;
  height = mode->height;
  window = glfwCreateWindow(width,height, "sv", NULL, NULL);
  glfwSetWindowSizeCallback(window, resize_callback);
  glfwMakeContextCurrent(window);
  glfwSetKeyCallback(window, key_callback);
  glfwSetErrorCallback(error_callback);
  glewInit();

  strncpy(shader.fragment,"shader.frag",40);
  shader.new = 1;
  unsigned int VAO;
  glGenVertexArrays(1, &VAO);
  glBindVertexArray(VAO);

  glfwGetWindowSize(window, &width, &height);
  glCreateTextures(GL_TEXTURE_2D,1,&backbuffer);
  glTextureStorage2D(backbuffer,1,GL_RGBA32F,width,height);
  glBindImageTexture(0,backbuffer, 0, GL_FALSE, 0, GL_READ_WRITE, GL_RGBA32F);

  for (int i = 0; i<8; i++) {
    readImage(i);
    images[i].new = 0;
  }
  
  pthread_t midiin_t;
  pthread_create(&midiin_t, NULL, readMidi, NULL);
  pthread_t frag_t;
  pthread_create(&frag_t, NULL, watchShader, NULL);
  
  while (!glfwWindowShouldClose(window)) {

    if (shader.new) {
      createShader();
      glUniform2f(glGetUniformLocation(shader.id, "resolution"),width,height); // important!!
      for (int i = 0; i<8; i++) { imageUniforms(i); }
      shader.new = 0;
    }

    glUniform1f(glGetUniformLocation(shader.id, "time"),glfwGetTime());
    glUniform1f(glGetUniformLocation(shader.id, "ticks"),(float)ticks);
    glUniform1i(glGetUniformLocation(shader.id, "program"),program);
    glUniform1fv(glGetUniformLocation(shader.id, "params"), 8, params);

    if (running) {
      glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
      glfwSwapBuffers(window);
      glfwPollEvents();
    }
  }

  pthread_cancel(midiin_t);
  pthread_cancel(frag_t);
  glfwDestroyWindow(window);
  glfwTerminate();
 
  exit(EXIT_SUCCESS);
}