#include <arpa/inet.h>
#include <errno.h>
#include <ifaddrs.h>
#include <linux/if.h>
#include <linux/wireless.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <mqueue.h>
#include <signal.h>
#include <assert.h>

#include <time.h>
#include <unistd.h>

#include "config.h"

/* Constants */
#define ELEMENT_SEPERATOR "   "

#define STATUS_STRBUF_SZ 512
#define ELEMENT_STRBUF_SZ 128

#define MAX(a, b) ((a) > (b) ? (a) : (b))

/* Type definitions */
typedef int (update_func_t)(char*, char*);

/* Data structures */
struct element {
  update_func_t* f;
  char* a;
  const struct timespec fire_interval;
  struct timespec fire_previous;
  char buf[ELEMENT_STRBUF_SZ];
};

enum battery_status_charge {
  bat_unknown,
  bat_not_charging,
  bat_charging,
  bat_discharging
};

struct battery_status {
  enum battery_status_charge status;
  float charge;
};

#define ADDRSTRLEN                                                             \
  (INET_ADDRSTRLEN > INET6_ADDRSTRLEN) ? INET_ADDRSTRLEN : INET6_ADDRSTRLEN
struct interface_status {
  enum { loopback, ethernet, wifi, wan } type;
  bool up;
  struct {
    char ip4[INET_ADDRSTRLEN];
    char ip6[INET6_ADDRSTRLEN];
  } address;
  char ssid[IW_ESSID_MAX_SIZE + 1];
  char name[IFNAMSIZ + 1];
};



/* Prototypes */
int element_date(char* buf, char* fmt);
struct battery_status get_battery_status(const char* buf);
int element_battery(char* buf, char* bat);
void get_all_bat_status(char* buf);
void get_net_link_status(char* buf);
int element_wifi(char* buf, char* link_name);
static void update_statusbuffer(char* buf);

/* Data */
static char* battery_level_icon[] = {
  "󰂎", /* '\Uf008e' */
  "󰁺", /* '\Uf007a' */
  "󰁻", /* '\Uf007b' */
  "󰁼", /* '\Uf007c' */
  "󰁽", /* '\Uf007d' */
  "󰁾", /* '\Uf007e' */
  "󰁿", /* '\Uf007f' */
  "󰂀", /* '\Uf0080' */
  "󰂁", /* '\Uf0081' */
  "󰂂", /* '\Uf0082' */
  "󰁹", /* '\Uf0079' */
};

static struct element statusbar[] = {
  /* Add status elements here */
  /*{update_func_t, {minutes, seconds}, {0}, {0}},*/
  [ELEMENT_INVALID] = {NULL, NULL, {0}, {0}, {0}},

#define ELEMENT(name, arg, minutes, seconds) \
  [ELEMENT_##name] = {element_##name, arg, {(minutes * 60) + ((int)seconds), (long)(seconds * 1000000) % 1000000}, {0}, {0}},
#include "config.def.h"
#undef ELEMENT
};

// "fail fast strcmp", neat to find inequalities between strings
static int ffast_strcmp(char* a, const char *const b) {
  int i = 0;

  while (a[i] == b[i]) {
    if (a[i] == '\0') break;
    i++;
  }

  return a[i] - b[i];
}
/* Functions */
int
element_date(char* buf, char* fmt) {
  //if (!ffast_strcmp(fmt, "NULL")) fmt = "%Y-%m-%d %H:%M";
  if (fmt == NULL) fmt = "%Y-%m-%d %H:%M";

  time_t now = time(NULL);
  struct tm *tm = localtime(&now);

  strftime(buf, ELEMENT_STRBUF_SZ, fmt, tm);
  return 0;
}

struct battery_status
get_battery_status(const char* buf) {
  const char path_prefix[] = "/sys/class/power_supply/";

  char charge_path[128];
  char capacity_path[128];

  char charge_str[512];
  char capacity_str[512];

  int charge   = 0;
  int capacity = 0;

  FILE* bat_charge;
  FILE* bat_capacity;

  memset(charge_path, 0, 128);
  memset(capacity_path, 0, 128);

  strcat(charge_path, path_prefix);
  strcat(charge_path, buf);
  strcat(charge_path, "/energy_now");

  strcat(capacity_path, path_prefix);
  strcat(capacity_path, buf);
  strcat(capacity_path, "/energy_full");

  bat_charge   = fopen(charge_path, "r");
  if (!bat_charge) {
    printf("%d: \"%s\" %s\n", errno, charge_path, strerror(errno));
    return (struct battery_status){bat_unknown, -1};
  }

  bat_capacity = fopen(capacity_path, "r");
  if (!bat_capacity) {
    printf("%d: \"%s\" %s\n", errno, capacity_path, strerror(errno));
    fclose(bat_charge);
    return (struct battery_status){bat_unknown, -1};
  }

  fread(charge_str, sizeof(char), 512, bat_charge);
  fread(capacity_str, sizeof(char), 512, bat_capacity);

  fclose(bat_charge);
  fclose(bat_capacity);

  charge   = atoi(charge_str);
  capacity = atoi(capacity_str);

  return (struct battery_status){bat_unknown, (float)charge / capacity};
}

int
element_battery(char* buf, char* bat) {
  struct battery_status s = get_battery_status(bat);

  int batlvl              = (int)(s.charge * 100.f) / 10;
  char* batlvl_icon       = battery_level_icon[batlvl];

  snprintf(buf, ELEMENT_STRBUF_SZ, "%s %.1f%%", batlvl_icon, 100.f * s.charge);
  return 0;
}

/* todo, remake this to enumerate all possible batteries */
void
get_all_bat_status(char* buf) {
  struct battery_status s = get_battery_status("BAT0");
  struct battery_status t = get_battery_status("BAT1");

  s.charge                = (s.charge + t.charge) / 2.f;

  int batlvl              = (int)(s.charge * 100.f) / 10;
  char* batlvl_icon       = battery_level_icon[batlvl];

  /*snprintf(buf, ELEMENT_STRBUF_SZ, "%.1f%%", 100.f * s.charge);*/
  snprintf(buf, ELEMENT_STRBUF_SZ, "%s %.1f%%", batlvl_icon, 100.f * s.charge);
}

void
get_essid(char* if_name, char* dst) {
  /* Get the SSID */
  struct iwreq wreq;
  const size_t if_namelen = strlen(if_name);
  const size_t l          = if_namelen > IFNAMSIZ ? IFNAMSIZ : if_namelen;
  int sock                = socket(AF_INET, SOCK_DGRAM, 0);

  if (sock == -1) {
    return;
  }

  memset(&wreq, 0, sizeof(struct iwreq));

  if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, if_name, l) == -1) {
    printf("Err: %s\n", strerror(errno));
    close(sock);
    return;
  }

  strncpy(wreq.ifr_name, if_name, l);

  wreq.u.essid.pointer = dst;
  wreq.u.essid.length  = IW_ESSID_MAX_SIZE;

  // May need to open a new socket, rebind, or something in-between to get both
  // wireless capabilities and essid??



  // Test if we have wireless on this interface
  //if (ioctl(sock, SIOCGIWNAME, &wreq) < 0) {
  //  // protocol stored in  wreq.u.name
  //  close(sock);
  //  return;
  //}

  if (ioctl(sock, SIOCGIWESSID, &wreq) < 0) {
    dst[0] = '\0';
  }

  close(sock);
}

int element_wifi(char* buf, char* link_name) {
  struct interface_status if_status;
  struct ifaddrs* if_addr;
  struct ifaddrs* ifa;

  memset(&if_status, 0, sizeof(struct interface_status));
  const int nlen = strlen(link_name) > IFNAMSIZ + 1 ? IFNAMSIZ : strlen(link_name);
  strncpy(if_status.name, link_name, nlen);

  getifaddrs(&if_addr);

  for (ifa = if_addr; ifa != NULL; ifa = ifa->ifa_next) {
    size_t i         = 0;
    const char* name = ifa->ifa_name;

    if (ffast_strcmp(if_status.name, name)) continue;

    if (ifa->ifa_flags & IFF_LOWER_UP) {
      if_status.up = true;

      if (ifa->ifa_addr != NULL) {
      const int family = ifa->ifa_addr->sa_family;

      size_t strsize   = 0;
      char* dst        = NULL;

      if (family == AF_INET) {
        strsize = INET_ADDRSTRLEN;
        dst     = if_status.address.ip4;
      } else if (family == AF_INET6) {
        strsize = INET6_ADDRSTRLEN;
        dst     = if_status.address.ip6;
      } else if (family == AF_PACKET) {
        continue;
      } else
        /* In this case, there's probably something horribly wrong */
        continue;

      /* Get the IP address */
      inet_ntop(family, (void*)&((struct sockaddr_in*)ifa->ifa_addr)->sin_addr,
                dst, strsize);
      }
    }

  }

  freeifaddrs(if_addr);

  // print interface
  if (!if_status.up) return 0;

  get_essid(if_status.name, if_status.ssid);

  strcat(buf, if_status.name);

  if (if_status.ssid[0] != 0) {
    strcat(buf, " (");
    strcat(buf, if_status.ssid);
    strcat(buf, ")");
  }
  //if (if_status.address.ip4[0] != 0 || if_status.address.ip6[0] != 0) {
  //  strcat(buf, " ");
  //  if (if_status.address.ip4[0] != 0) {
  //    strcat(buf, "⁴");
  //  }
  //  if (if_status.address.ip6[0] != 0) {
  //    strcat(buf, "⁶");
  //  }
  //}
  return 0;
}

/* external commands */
/* I just couldn't be bothered to learn pipewire */

static struct timespec
time_add(struct timespec a, struct timespec b) {
  struct timespec dst;
  dst.tv_sec  = a.tv_sec + b.tv_sec;
  dst.tv_nsec = a.tv_nsec + b.tv_nsec;

  /* larger than 1 second in μsec */
  if (dst.tv_nsec >= 1000000 * 1000) {
    dst.tv_nsec -= 1000000 * 1000;
    dst.tv_sec++;
  }

  return dst;
}

/* Assume that time_t and time64_t are signed (they are on my machine) */
static struct timespec
time_sub(struct timespec a, struct timespec b) {
  struct timespec dst;

  dst.tv_sec  = a.tv_sec - b.tv_sec;
  dst.tv_nsec = a.tv_nsec - b.tv_nsec;

  // Subtract a second if nanoseconds are negative
  if (dst.tv_nsec < 0) {
    dst.tv_nsec += 1000000 * 1000;
    dst.tv_sec--;
  }

  return dst;
}

static bool
time_lt(struct timespec a, struct timespec b) {
  if (a.tv_sec == b.tv_sec) {
    return a.tv_nsec < b.tv_nsec;
  }

  return a.tv_sec < b.tv_sec;
}

struct mq_data {
  mqd_t mqfd;
  struct timespec next_update;
  char* dstbuffer;
};

static void
update_element_thread(union sigval sv) {
  struct mq_attr attr;
  ssize_t nr;
  struct message_t msg;
  struct mq_data mq_data = *((struct mq_data*)sv.sival_ptr);

  char* buf = mq_data.dstbuffer;
  if (mq_getattr(mq_data.mqfd, &attr) == -1) {
    fprintf(stderr, "Failed to get mq attributes: %s\n", strerror(errno));
    return;
  }

  if (attr.mq_msgsize != sizeof(struct message_t)) {
    fprintf(stderr, "Misconfigured message queue!\n");
    return;
  }

  // It is apparently the way to ensure continued notifications to register for
  // further notifications before emptying the queue.
  // Makes you wonder if you should've used a named pipe + signals instead :)
  struct sigevent sev = (struct sigevent){
    .sigev_notify = SIGEV_THREAD,
    .sigev_notify_function = update_element_thread,
    .sigev_notify_attributes = NULL,
    .sigev_value = sv,
  };

  if (mq_notify(mq_data.mqfd, &sev) == -1) {
    fprintf(stderr, "Failed to register mq_notify: %s\n", strerror(errno));
  }

  // Empty queue
  while (mq_receive(mq_data.mqfd, (char*)&msg, sizeof(struct message_t), NULL) != -1) {
    fprintf(stderr, "%d on %d\n", msg.action, msg.element);
    if (msg.action != update || msg.element <= ELEMENT_INVALID || msg.element >= ELEMENT_MAX) {
      fprintf(stderr, "Invalid action/element\n");
      continue;
    }

    struct element* e = &statusbar[msg.element];
    assert(e->f != NULL);
    struct timespec now;
    struct timespec next_fire = time_add(e->fire_previous, e->fire_interval);
    clock_gettime(CLOCK_REALTIME, &now);

    memset(e->buf, 0, ELEMENT_STRBUF_SZ);

    e->f(e->buf, e->a);
    e->fire_previous = now;

    /* Check if this element needs to be refreshed next, again */
    next_fire = time_add(now, e->fire_interval);
    if (time_lt(next_fire, ((struct mq_data*)(sv.sival_ptr))->next_update)) {
      ((struct mq_data*)(sv.sival_ptr))->next_update = next_fire;
    }

  }
    update_statusbuffer(mq_data.dstbuffer);
  // EAGAIN indicates the queue is empty
  if (errno != EAGAIN) {
    fprintf(stderr, "Failed to receive mq message: %s\n", strerror(errno));
  }
}

static void update_statusbuffer(char* buf) {
  static const int num_elems = sizeof(statusbar) / sizeof(statusbar[0]);

  /* Copy the statusbar buffers into the final buffer */
  memset(buf, 0, STATUS_STRBUF_SZ);

  for (int i = 1; i < num_elems; i++) {
    if (!strlen(statusbar[i].buf))
      continue;

    strcat(buf, statusbar[i].buf);
    if (i != num_elems - 1)
      strcat(buf, ELEMENT_SEPERATOR);
  }

  /* strcat(buf, "\0"); */

  puts(buf);
  fflush(stdout);
}

int
main(void) {
  char buf[STATUS_STRBUF_SZ];
  //struct message_t *ipc_message;
  //// ("/status", max(argv[identifier], XDG_SEAT, DISPLAY, WAYLAND_DISPLAY))
  const char* queue_identifier = "/status";
  const struct timespec one_minute = {60, 0};
  struct timespec now;
  clock_gettime(CLOCK_REALTIME, &now);

  struct mq_attr attr = {
    .mq_flags   = 0, // ignored for mq_open
    .mq_maxmsg  = 10, // must be [1;10], default value can be read from /proc/sys/fs/mqueue/msg_default
    .mq_msgsize = sizeof(struct message_t),
    .mq_curmsgs = 0, // ignored for mq_open
  };

  //printf("Attempting setting msg-size to %ld\n", sizeof(struct message_t));

  struct mq_data mq_data;
  mq_data.dstbuffer = buf;
  mq_data.next_update = time_add(now, one_minute);;

  mq_data.mqfd = mq_open(queue_identifier,
      O_RDONLY | O_CREAT | O_EXCL | O_CLOEXEC | O_NONBLOCK,
      // 600
      S_IRUSR | S_IWUSR,
      &attr); // O_NONBLOCK
  if (mq_data.mqfd == -1) {
    fprintf(stderr, "Failed to open mq: %s\n", strerror(errno));
    // Make this check a flag
    if (errno == EEXIST) {
      if (mq_unlink(queue_identifier) == -1) {
        fprintf(stderr, "Failed to unlink mq: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
      } else {
        fprintf(stderr, "Unlinked %s\n", queue_identifier);

        // Retry
        mq_data.mqfd = mq_open(queue_identifier,
            O_RDONLY | O_CREAT | O_EXCL | O_CLOEXEC | O_NONBLOCK,
            S_IRUSR | S_IWUSR,
            &attr);
        if (mq_data.mqfd == -1) {
          fprintf(stderr, "Failed to open mq: %s\n", strerror(errno));
          exit(EXIT_FAILURE);
        }
      }
    } else {
      exit(EXIT_FAILURE);
    }
  }

  struct sigevent sev = (struct sigevent){
    .sigev_notify = SIGEV_THREAD,
    .sigev_notify_function = update_element_thread,
    .sigev_notify_attributes = NULL,
    .sigev_value.sival_ptr = &mq_data,
  };

  // We need to run update_element_thread in the first place to make sure we
  // empty the queue
  update_element_thread((union sigval){.sival_ptr = &mq_data});



  const int num_elems = sizeof(statusbar) / sizeof(statusbar[0]);

  while (true) {
    clock_gettime(CLOCK_REALTIME, &now);
    unsigned i;

    /* Stall updating for at most 1 minute */
    mq_data.next_update = time_add(now, one_minute);

    for (i = 1; i < num_elems; i++) {
      struct element* e = &statusbar[i];
      assert(e->f != NULL);
      // Next time this element updates
      struct timespec next_fire = time_add(e->fire_previous, e->fire_interval);

      /* test if this is not to be updated yet */
      if (time_lt(now, next_fire)) {
        /* test if this element is to be updated next */
        if (time_lt(next_fire, mq_data.next_update)) {
          mq_data.next_update = next_fire;
        }
        continue;
      }

      /* Otherwise update this element */
      memset(e->buf, 0, ELEMENT_STRBUF_SZ);

      e->f(e->buf, e->a);
      e->fire_previous = now;

      /* Check if this element needs to be refreshed next, again */
      next_fire = time_add(now, e->fire_interval);
      if (time_lt(next_fire, mq_data.next_update)) {
        mq_data.next_update = next_fire;
      }

      /* printf("[%ld.%ld]  %s\n",
       * e->fire_interval.tv_sec,
       * e->fire_interval.tv_nsec,
       * (char*)e->buf);
       */
    }

    update_statusbuffer(buf);

    struct timespec sleep_for = time_sub(mq_data.next_update, now);
    // why the fuck are we adding 500 nanoseconds here
    //sleep_for                 = time_add(sleep_for, (struct timespec){0, 500});

    /* Replace NULL to get "remaining time", in case we got
     * interrupted / signaled */
    nanosleep(&sleep_for, NULL);
  }

  return 0;
}