#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>

#include <ft2build.h>
#include FT_FREETYPE_H

#include <SDL3/SDL.h>

#include "timer.h"
#include "bufsize.h"
#include "packet.h"
#include "timespec.h"
#include "ping_pong.h"
#include "gpio.h"

#define DEST_PORT 4321
#define DEST_ADDR "fd00::2"

#define PORT 1234

struct glyph {
  int32_t width;
  int32_t height;

  int32_t horiBearingX;
  int32_t horiBearingY;
  int32_t horiAdvance;

  SDL_Texture * texture;
};

static struct glyph glyphs[0x80 - 0x20] = {0};
int32_t face_height;

int
load_outline_char(SDL_Renderer * renderer,
		  const FT_Face face,
                  const FT_Int32 load_flags,
                  const FT_Render_Mode render_mode,
                  const FT_ULong char_code)
{
  FT_Error error;
  FT_UInt glyph_index = FT_Get_Char_Index(face, char_code);

  error = FT_Load_Glyph(face, glyph_index, load_flags);
  if (error) {
    printf("FT_Load_Glyph %s\n", FT_Error_String(error));
    return -1;
  }

  error = FT_Render_Glyph(face->glyph, render_mode);
  if (error) {
    printf("FT_Render_Glyph %s\n", FT_Error_String(error));
    return -1;
  }

  struct glyph * glyph = &glyphs[char_code - 0x20];

  glyph->width = face->glyph->bitmap.width;
  glyph->height = face->glyph->bitmap.rows;
  glyph->horiBearingX = face->glyph->metrics.horiBearingX;
  glyph->horiBearingY = face->glyph->metrics.horiBearingY;
  glyph->horiAdvance = face->glyph->metrics.horiAdvance;

  if (face->glyph->bitmap.pitch != 0) {
    SDL_Surface * surface = SDL_CreateSurface(face->glyph->bitmap.width,
					      face->glyph->bitmap.rows,
					      SDL_PIXELFORMAT_RGBA8888);

    SDL_LockSurface(surface);

    for (int y = 0; y < face->glyph->bitmap.rows; y++) {
      for (int x = 0; x < face->glyph->bitmap.width; x++) {
	int s_ix = y * face->glyph->bitmap.pitch + x;
	int d_ix = y * surface->pitch + x * 4;
	uint8_t gray = face->glyph->bitmap.buffer[s_ix];
	((uint8_t *)surface->pixels)[d_ix + 0] = gray;
	((uint8_t *)surface->pixels)[d_ix + 1] = gray;
	((uint8_t *)surface->pixels)[d_ix + 2] = gray;
	((uint8_t *)surface->pixels)[d_ix + 3] = 255;
      }
    }

    SDL_UnlockSurface(surface);

    if (glyph->texture != NULL)
      SDL_DestroyTexture(glyph->texture);
    glyph->texture = SDL_CreateTextureFromSurface(renderer, surface);
    if (glyph->texture == NULL) {
      printf("%s\n", SDL_GetError());
    }
    assert(glyph->texture != NULL);

    SDL_DestroySurface(surface);
  }

  return 0;
}

int load_font(SDL_Renderer * renderer, int font_size)
{
  FT_Library library;
  FT_Face face;
  FT_Error error;

  error = FT_Init_FreeType(&library);
  if (error) {
    printf("FT_Init_FreeType\n");
    return -1;
  }

  error = FT_New_Face(library, "/home/bilbo/timer/DejaVuSansMono.ttf", 0, &face);
  if (error) {
    printf("FT_New_Face\n");
    return -1;
  }

  error = FT_Set_Pixel_Sizes(face, 0, font_size);
  if (error) {
    printf("FT_Set_Pixel_Sizes: %s %d\n", FT_Error_String(error), error);
    return -1;
  }

  for (int char_code = 0x20; char_code <= 0x7f; char_code++) {
    load_outline_char(renderer, face, FT_LOAD_DEFAULT, FT_RENDER_MODE_NORMAL, char_code);
  }

  printf("loaded size %ld\n", face->size->metrics.height >> 6);
  face_height = face->size->metrics.height;

  return 0;
}

void render(SDL_Renderer * renderer, int window_width, int window_height, const char * s, int length)
{
  int32_t advance = (window_width - (window_width * 5 / 100)) << 6;
  for (int i = (length - 1); i >= 0; i--) {
    char c = s[i];
    struct glyph * glyph = &glyphs[c - 0x20];
    advance -= glyph->horiAdvance;
    if (glyph->texture != NULL) {
      double x = (double)(advance + glyph->horiBearingX) / 64.f;
      double y = (window_height / 2) + (face_height >> 6) / 3 + ((double)glyph->horiBearingY / -64.f);
      SDL_FRect srect = {
	.x = 0.f,
	.y = 0.f,
	.w = glyph->width,
	.h = glyph->height
      };
      SDL_FRect drect = {
	.x = x,
	.y = y,
	.w = glyph->width,
	.h = glyph->height
      };
      SDL_RenderTexture(renderer, glyph->texture, &srect, &drect);
    }
  }
}

int max(int a, int b) {
  return a > b ? a : b;
}

int handle_buf(int sockfd,
               void * buf, ssize_t length,
               struct timer_state * timer_state,
               struct link_state * link_state)
{
  struct event * evt = (struct event *)buf;

  if (evt->sequence != 0) {
    if (evt->sequence == link_state->recv_sequence) {
      printf("ignore duplicate seq %d; recv %ld type %d\n", evt->sequence, link_state->recv_sequence, evt->type);
      return 0;
    } else {
      printf("type %d seq %d\n", evt->sequence, evt->type);
      link_state->recv_sequence = evt->sequence;
    }
  }

  switch (evt->type) {
  case EVENT_TYPE__TIME_STOP:
    {
      if (length != (sizeof (struct packet_stopwatch))) {
	printf("handle_buf: packet_stopwatch: invalid length\n");
	return 0;
      }

      struct packet_stopwatch * time_pkt = (struct packet_stopwatch *)buf;
      memcpy(&timer_state->time, &time_pkt->stopwatch_time, (sizeof (struct stopwatch_time)));
      timer_state->status = TIMER_STOPPED;
      packet_send_ack(sockfd, &link_state->dest_addr, evt->sequence);
    }
    break;
  case EVENT_TYPE__TIME_START:
    {
      if (length != (sizeof (struct packet_start))) {
	printf("handle_buf: time start: invalid length\n");
	return 0;
      }

      int ret = clock_gettime(CLOCK_MONOTONIC_RAW, &timer_state->counter.start);
      assert(ret != -1);
      timer_state->counter.offset = timespec_div(&link_state->remote_average_rtt, 2);
      printf("counter_offset %ld.%09ld\n", timer_state->counter.offset.tv_sec, timer_state->counter.offset.tv_nsec);
      timer_state->status = TIMER_RUNNING;
      packet_send_ack(sockfd, &link_state->dest_addr, evt->sequence);
    }
    break;
  case EVENT_TYPE__TIME_RESUME:
    {
      if (length != (sizeof (struct packet_resume))) {
	printf("handle_buf: time resume: invalid length\n");
	return 0;
      }
      struct packet_resume * resume_pkt = (struct packet_resume *)buf;
      printf("resume offset %ld.%09ld\n", resume_pkt->offset.tv_sec, resume_pkt->offset.tv_nsec);
      int ret = clock_gettime(CLOCK_MONOTONIC_RAW, &timer_state->counter.start);
      assert(ret != -1);
      timer_state->counter.offset = timespec_div(&link_state->remote_average_rtt, 2);
      timer_state->counter.offset = timespec_add(&timer_state->counter.offset, &resume_pkt->offset);
      printf("counter offset %ld.%09ld\n", timer_state->counter.offset.tv_sec, timer_state->counter.offset.tv_nsec);
      timer_state->status = TIMER_RUNNING;
      packet_send_ack(sockfd, &link_state->dest_addr, evt->sequence);
    }
    break;
  case EVENT_TYPE__PING: [[fallthrough]];
  case EVENT_TYPE__PONG: [[fallthrough]];
  case EVENT_TYPE__AVERAGE_RTT:
    {
      int ret = handle_ping_pong(sockfd,
                                 buf, length,
                                 link_state);
      if (ret == -1) {
        return -1;
      }
    }
    break;
  default:
    printf("unhandled event %d\n", evt->type);
    break;
  }

  return 0;
}

int handle_sockfd(int sockfd,
                  struct timer_state * timer_state,
                  struct link_state * link_state)
{
  char buf[BUFSIZE];
  struct sockaddr_in6 src_addr;
  socklen_t addrlen = (sizeof (struct sockaddr_in6));

  while (1) {
    ssize_t recv_len = recvfrom(sockfd,
				buf, (sizeof (buf)),
				0,
				(struct sockaddr *)&src_addr, &addrlen);
    if (recv_len == -1) {
      if (errno == EAGAIN || errno == EWOULDBLOCK) {
	//perror("sock eagain");
	return 0;
      } else {
	perror("recvfrom sock");
	return -1;
      }
    }

    //char src_addr_str[INET6_ADDRSTRLEN];
    //inet_ntop(AF_INET6, &src_addr.sin6_addr, src_addr_str, INET6_ADDRSTRLEN);
    //printf("received packet from %s:%d\n", src_addr_str, ntohs(src_addr.sin6_port));
    //printf("length: %ld\n", recv_len);

    int ret = handle_buf(sockfd, buf, recv_len, timer_state, link_state);
    if (ret == -1) {
      return -1;
    }
  }

  return 0;
}

char * format_base10(char * buf, int value, int digits)
{
  static int table[10] = {
    1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000
  };

  if (digits <= 0)
    return buf;

  int power = table[digits - 1];
  for (int i = 0; i < digits; i++) {
    buf[i] = '0' + ((value / power) % 10);
    power /= 10;
  }

  return buf + digits;
}

int main()
{
  int ret;
  SDL_Window * window;
  SDL_Renderer * renderer;

  ret = SDL_Init(SDL_INIT_VIDEO);
  assert(ret == 0);

  window = SDL_CreateWindow("timer",
			    512, // w
			    512, // h
			    SDL_WINDOW_RESIZABLE);// | SDL_WINDOW_MAXIMIZED);

  int num_drivers = SDL_GetNumRenderDrivers();
  printf("available drivers:\n");
  for (int i = 0; i < num_drivers; i++) {
    const char * s = SDL_GetRenderDriver(i);
    printf("  %s\n", s);
  }
  renderer = SDL_CreateRenderer(window, "opengles2");
  SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);

  SDL_PropertiesID props = SDL_GetRendererProperties(renderer);

  const char * name = SDL_GetRendererName(renderer);
  assert(name != NULL);
  printf("renderer: %s\n", name);
  const SDL_PixelFormatEnum * formats = SDL_GetProperty(props, SDL_PROP_RENDERER_TEXTURE_FORMATS_POINTER, NULL);
  assert(formats != NULL);
  while (*formats != SDL_PIXELFORMAT_UNKNOWN) {
    printf("%s\n", SDL_GetPixelFormatName(*formats++));
  }

  int last_width = -1;

  uint64_t ticks = SDL_GetTicks();
  uint64_t last_ping_tick = 0;
  const int min_length = 5;
  int max_length = min_length;

  /*
    socket
  */

  int sockfd = socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, IPPROTO_UDP);
  if (sockfd == -1) {
    perror("socket");
    return -1;
  }

  struct sockaddr_in6 sockaddr;
  sockaddr.sin6_family = AF_INET6;
  sockaddr.sin6_port = htons(PORT);
  sockaddr.sin6_addr = in6addr_any;

  ret = bind(sockfd, (struct sockaddr *)&sockaddr, (sizeof (struct sockaddr_in6)));
  if (ret == -1) {
    perror("bind");
    return -1;
  }

  /*
   */

  struct timer_state timer_state = {0};
  struct link_state link_state = {0};
  struct gpio_state gpio_state = {0};

  link_state.dest_addr.sin6_family = AF_INET6;
  link_state.dest_addr.sin6_port = htons(DEST_PORT);
  ret = inet_pton(AF_INET6, DEST_ADDR, &link_state.dest_addr.sin6_addr);
  assert(ret == 1);

  gpio_open("/dev/gpiochip0", &gpio_state);
  // ignored gpio_open error

  while (1) {
    handle_sockfd(sockfd, &timer_state, &link_state);

    char str_buf[20 * 2 + 1 + 1];
    switch (timer_state.status) {
    case TIMER_STOPPED:
      {
        char * bufi = str_buf;
        bufi = format_base10(bufi,
                             timer_state.time.integer_value,
                             timer_state.time.integer_digits);
        *bufi++ = '.';
        bufi = format_base10(bufi,
                             timer_state.time.fraction_value,
                             timer_state.time.fraction_digits);
        *bufi = 0;
      }
      break;
    case TIMER_RUNNING:
      {
	struct timespec now;
	int ret = clock_gettime(CLOCK_MONOTONIC_RAW, &now);
	assert(ret != -1);

	struct timespec real_start = timespec_sub(&timer_state.counter.start, &timer_state.counter.offset);
	struct timespec duration = timespec_sub(&now, &real_start);

	snprintf(str_buf, (sizeof (str_buf)) - 1,
                 "%ld.%02ld",
                 duration.tv_sec,
                 duration.tv_nsec / (1000000000 / 100)); // 2 digits
      }
      break;
    default:
      str_buf[0] = 0;
      break;
    }
    int length = strlen(str_buf);

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);
    int window_width;
    int window_height;
    ret = SDL_GetWindowSizeInPixels(window, &window_width, &window_height);
    assert(ret == 0);
     if ((window_width != last_width) || (length > max_length)) {
      max_length = max(min_length, length);
      last_width = window_width;

      int divisor = max(1, max_length);
      int font_size = (window_width * 150 / 100) / divisor;
      printf("fs %d %d max_length: %d\n", font_size, window_width, max_length);
      load_font(renderer, font_size);
    }

    render(renderer, window_width, window_height, str_buf, length);

    while (SDL_GetTicks() - ticks < (1000 / 60)) { SDL_Delay(1); }
    SDL_RenderPresent(renderer);
    ticks = SDL_GetTicks();
    if (ticks - last_ping_tick > PING_INTERVAL * 1000) {
      //printf("send ping\n");
      int ret = packet_send_ping(sockfd, &link_state.dest_addr);
      if (ret == -1) {
	return -1;
      }
      last_ping_tick = ticks;
      gpio_set_values_from_link_states(&gpio_state,
				       &link_state,
				       1);
    }

    SDL_Event event;
    while (SDL_PollEvent(&event)) {
      switch (event.type) {
      case SDL_EVENT_QUIT:
	goto exit;
      case SDL_EVENT_KEY_DOWN:
	if (event.key.keysym.sym == SDLK_ESCAPE)
	  goto exit;
	break;
      default:
	break;
      }
    }
  }

 exit:
  SDL_DestroyRenderer(renderer);
  SDL_DestroyWindow(window);
  SDL_Quit();
  close(sockfd);
}