#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#include <wayland-client-protocol.h>
#include <wayland-client.h>

#include "xdg-shell.h"

struct wl_display *display = NULL;
struct wl_registry *registry = NULL;
struct wl_compositor *compositor = NULL;
struct wl_surface *surface = NULL;

struct wl_shm *shm = NULL;
struct wl_buffer *buffer = NULL;
void *shm_data;

struct xdg_wm_base *xdg_wm_base = NULL;
struct xdg_surface *xdg_surface = NULL;
struct xdg_toplevel *xdg_toplevel = NULL;

//=================
// Shared Memory
//=================
static int set_cloexec_or_close(int fd) {
  if (fd == -1)
    return -1;

  long flags = fcntl(fd, F_GETFD);
  if (flags == -1)
    goto err;

  if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1)
    goto err;

  return fd;

err:
  close(fd);
  return -1;
}

static int create_tmpfile_cloexec(char *tmpname) {
  int fd;

#ifdef HAVE_MKOSTEMP
  fd = mkostemp(tmpname, O_CLOEXEC);
  if (fd >= 0)
    unlink(tmpname);
#else
  fd = mkstemp(tmpname);
  if (fd >= 0) {
    fd = set_cloexec_or_close(fd);
    unlink(tmpname);
  }
#endif

  return fd;
}

/*
 * Create a new, unique, anonymous file of the given size, and
 * return the file descriptor for it. The file descriptor is set
 * CLOEXEC. The file is immediately suitable for mmap()'ing
 * the given size at offset zero.
 *
 * The file should not have a permanent backing store like a disk,
 * but may have if XDG_RUNTIME_DIR is not properly implemented in OS.
 *
 * The file name is deleted from the file system.
 *
 * The file is suitable for buffer sharing between processes by
 * transmitting the file descriptor over Unix sockets using the
 * SCM_RIGHTS methods.
 */
int os_create_anonymous_file(off_t size) {
  static const char template[] = "/a404m-shared-XXXXXX";

  const char *path = getenv("XDG_RUNTIME_DIR");
  if (!path) {
    errno = ENOENT;
    return -1;
  }

  char *name = malloc(strlen(path) + sizeof(template));
  if (!name)
    return -1;
  strcpy(name, path);
  strcat(name, template);

  int fd = create_tmpfile_cloexec(name);

  free(name);

  if (fd < 0)
    return -1;

  if (ftruncate(fd, size) < 0) {
    close(fd);
    return -1;
  }

  return fd;
}

//=============
// Shm
//=============
static void shm_format_handler(void *data, struct wl_shm *shm,
                               uint32_t format) {
  (void)data;
  (void)shm;

  fprintf(stderr, "Format %d\n", format);
}

static const struct wl_shm_listener shm_listener = {
    .format = shm_format_handler,
};

//==============
// XDG
//==============
static void xdg_wm_base_ping_handler(void *data, struct xdg_wm_base *wm_base,
                                     uint32_t serial) {
  (void)data;

  xdg_wm_base_pong(wm_base, serial);
}

static const struct xdg_wm_base_listener xdg_wm_base_listener = {
    .ping = xdg_wm_base_ping_handler,
};

static void xdg_surface_configure_handler(void *data,
                                          struct xdg_surface *xdg_surface,
                                          uint32_t serial) {
  (void)data;

  xdg_surface_ack_configure(xdg_surface, serial);
}

static const struct xdg_surface_listener xdg_surface_listener = {
    .configure = xdg_surface_configure_handler,
};

static void xdg_toplevel_configure_handler(void *data,
                                           struct xdg_toplevel *toplevel,
                                           int32_t width, int32_t height,
                                           struct wl_array *states) {
  (void)data;
  (void)toplevel;
  (void)states;

  fprintf(stderr, "XDG toplevel configure: %dx%d\n", width, height);
}

static void xdg_toplevel_close_handler(void *data,
                                       struct xdg_toplevel *toplevel) {
  (void)data;
  (void)toplevel;
}

static const struct xdg_toplevel_listener xdg_toplevel_listener = {
    .configure = xdg_toplevel_configure_handler,
    .close = xdg_toplevel_close_handler,
};

//==============
// Global
//==============
static void global_registry_handler(void *data, struct wl_registry *registry,
                                    uint32_t id, const char *interface,
                                    uint32_t version) {
  printf("Got a registry event for <%s>, id: %d, version: %d.\n", interface, id,
         version);
  if (strcmp(interface, "wl_compositor") == 0) {
    compositor = wl_registry_bind(registry, id, &wl_compositor_interface, 4);
  } else if (strcmp(interface, "xdg_wm_base") == 0) {
    xdg_wm_base = wl_registry_bind(registry, id, &xdg_wm_base_interface, 1);
  } else if (strcmp(interface, "wl_shm") == 0) {
    shm = wl_registry_bind(registry, id, &wl_shm_interface, 1);
    wl_shm_add_listener(shm, &shm_listener, NULL);
  }
}

static void global_registry_remove_handler(void *data,
                                           struct wl_registry *registry,
                                           uint32_t id) {
  printf("Got a registry losing event for <%d>\n", id);
}

static const struct wl_registry_listener registry_listener = {
    .global = global_registry_handler,
    .global_remove = global_registry_remove_handler,
};

//==========
// Buffer
//==========
static struct wl_buffer *create_buffer(int width, int height) {
  struct wl_shm_pool *pool;
  int stride = width * 4; // 4 bytes per pixel in our ARGB8888 format.
  int size = stride * height;
  int fd;
  struct wl_buffer *buff;

  fd = os_create_anonymous_file(size);
  if (fd < 0) {
    fprintf(stderr, "Failed to create a buffer. size: %d\n", size);
    exit(1);
  }

  shm_data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (shm_data == MAP_FAILED) {
    fprintf(stderr, "mmap failed!\n");
    close(fd);
    exit(1);
  }

  pool = wl_shm_create_pool(shm, fd, size);
  buff = wl_shm_pool_create_buffer(pool, 0, width, height, stride,
                                   WL_SHM_FORMAT_ARGB8888);
  wl_shm_pool_destroy(pool);

  return buff;
}

//=========
// A404M
//=========

static const int width = 480, height = 360;
static int last_frame = 0;

static int cube_pos_x = 0;
static int cube_pos_y = 0;
static bool cube_flag_x = true;
static bool cube_flag_y = true;
static constexpr int cube_size = 50;
static uint32_t cube_color = 0xff22aaff;
static constexpr uint32_t back_color = 0xaa222222;

static void collide() {
  cube_color = (0xff000000 | (0xffffff & rand()));
}

static void draw() {
  uint32_t *pixel = shm_data;

  const int cube_end_pos_x = cube_pos_x + cube_size;
  const int cube_end_pos_y = cube_pos_y + cube_size;

  int cube_begin_loop_x = cube_pos_x - 1;
  int cube_begin_loop_y = cube_pos_y - 1;

  if (cube_begin_loop_x < 0) {
    cube_begin_loop_x = 0;
  }
  if (cube_begin_loop_y < 0) {
    cube_begin_loop_y = 0;
  }

  int cube_end_loop_x = cube_pos_x + cube_size + 1;
  int cube_end_loop_y = cube_pos_y + cube_size + 1;

  if (cube_end_loop_x > width) {
    cube_end_loop_x = width;
  }
  if (cube_end_loop_y > height) {
    cube_end_loop_y = height;
  }

  for (int x = cube_begin_loop_x; x < cube_end_loop_x; ++x) {
    for (int y = cube_begin_loop_y; y < cube_end_loop_y; ++y) {
      if (cube_pos_x < x && x < cube_end_pos_x && cube_pos_y < y &&
          y < cube_end_pos_y) {
        pixel[x + y * width] = cube_color;
      } else {
        // *pixel = (rand() << 3 * 8) | (0xffffff & rand());
        pixel[x + y * width] = back_color;
      }
    }
  }

  if (cube_flag_x) {
    ++cube_pos_x;
  } else {
    --cube_pos_x;
  }
  if (cube_flag_y) {
    ++cube_pos_y;
  } else {
    --cube_pos_y;
  }

  if (cube_pos_x < 0) {
    cube_flag_x = true;
    collide();
  } else if (cube_pos_x + cube_size >= width) {
    cube_flag_x = false;
    collide();
  }

  if (cube_pos_y < 0) {
    cube_flag_y = true;
    collide();
  } else if (cube_pos_y + cube_size >= height) {
    cube_flag_y = false;
    collide();
  }

  wl_surface_attach(surface, buffer, 0, 0);
  wl_surface_damage_buffer(surface, cube_begin_loop_x, cube_begin_loop_y, cube_end_loop_x, cube_end_loop_y);
  wl_surface_commit(surface);
}

static const struct wl_callback_listener surface_frame_listener;

static void surface_frame_done(void *data, struct wl_callback *callback,
                               uint32_t time) {
  // printf("frame %d\n", time - last_frame);
  last_frame = time;
  wl_callback_destroy(callback);

  wl_callback_add_listener(wl_surface_frame(surface), &surface_frame_listener,
                           data);

  draw();
}

static const struct wl_callback_listener surface_frame_listener = {
    .done = surface_frame_done,
};
//==========
// Main
//==========

int main(int argc, char *argv[]) {
  (void)argc;
  (void)argv;

  srand(time(NULL));

  cube_pos_x = rand() % width;
  cube_pos_y = rand() % height;

  display = wl_display_connect(NULL);
  if (display == NULL) {
    fprintf(stderr, "Failed to connect to display.\n");
    exit(1);
  }
  printf("Connected to display.\n");

  registry = wl_display_get_registry(display);
  wl_registry_add_listener(registry, &registry_listener, NULL);

  wl_display_dispatch(display);
  wl_display_roundtrip(display);

  // Check compositor.
  fprintf(stderr, " - Checking compositor...\n");
  if (compositor == NULL) {
    fprintf(stderr, "Can't find compositor.\n");
    exit(1);
  } else {
    printf("Found compositor!\n");
  }

  // Surface
  surface = wl_compositor_create_surface(compositor);
  if (surface == NULL) {
    exit(1);
  }

  // XDG.
  xdg_wm_base_add_listener(xdg_wm_base, &xdg_wm_base_listener, NULL);

  xdg_surface = xdg_wm_base_get_xdg_surface(xdg_wm_base, surface);
  xdg_surface_add_listener(xdg_surface, &xdg_surface_listener, NULL);

  xdg_toplevel = xdg_surface_get_toplevel(xdg_surface);
  xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, NULL);

  // This step is important on Weston.
  wl_surface_commit(surface);
  wl_display_roundtrip(display);

  struct wl_callback *fcb = wl_surface_frame(surface);

  wl_callback_add_listener(fcb, &surface_frame_listener, NULL);

  // Create a buffer.
  buffer = create_buffer(width, height);

  wl_surface_attach(surface, buffer, 0, 0);
  wl_surface_commit(surface);

  // Drawing pixels.
  draw();

  /*
  wl_surface_attach(surface, buffer, 0, 0);
  wl_surface_damage_buffer(surface, 0, 0, width, height);
  wl_surface_commit(surface);
  */

  // Display loop.
  while (true) {
    int cond = wl_display_dispatch(display);
    // printf("%d\n", cond);

    if (cond == -1) {
      break;
    }
  }

  // Free resources.
  xdg_toplevel_destroy(xdg_toplevel);

  xdg_surface_destroy(xdg_surface);

  wl_surface_destroy(surface);

  wl_display_disconnect(display);
  printf("Disconnected from display.\n");

  return 0;
}