#include <arpa/inet.h>
#include <errno.h>
#include <ifaddrs.h>
#include <linux/if.h>
#include <linux/net.h>
#include <linux/wireless.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
/* Required for timercmp */
#define __USE_MISC
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

/* Constants */
#define ELEMENT_SEPERATOR "   "

#define STATUS_STRBUF_SZ 512
#define ELEMENT_STRBUF_SZ 128

/* Type definitions */
typedef void (*element_function)(char*);

/* Data structures */
struct element {
  const element_function f;
  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;
  struct {
    char ip4[INET_ADDRSTRLEN];
    char ip6[INET6_ADDRSTRLEN];
  } address;
  char ssid[IW_ESSID_MAX_SIZE + 1];
  char name[IFNAMSIZ];
};

/* Prototypes */
void date(char* buf);
struct battery_status get_battery_status(const char* buf);
void get_battery1_status(char* buf);
void get_battery0_status(char* buf);
void get_all_bat_status(char* buf);
void get_net_link_status(char* buf);

/* Data */
static char* battery_level_icon[] = {
  "", /* "\uf579" */
  "", /* "\uf57a" */
  "", /* "\uf57b" */
  "", /* "\uf57c" */
  "", /* "\uf57d" */
  "", /* "\uf57e" */
  "", /* "\uf57f" */
  "", /* "\uf580" */
  "", /* "\uf581" */
  "", /* "\uf578" */
  "", /* "\uf578" */
};

// Converts milliseconds to nanoseconds
#define MSEC(msec) (msec * 1000 * 1000)
static struct element statusbar[] = {
  /* Add status elements here */
  /*{element_function, {seconds, nanoseconds}, {0}, {0}},*/

  {get_net_link_status,     {15, 0}, {0}, {0}},
  {get_battery0_status,     {60, 0}, {0}, {0}},
  {get_battery1_status,     {60, 0}, {0}, {0}},
  { get_all_bat_status,     {60, 0}, {0}, {0}},
  {               date,   {7, MSEC(500)}, {0}, {0}},
};

struct interface_status interfaces[8]; // surely noone has more than 8 interfaces.

/* Functions */
void
date(char* buf) {
  time_t now = time(NULL);
  struct tm tm;
  tm = *localtime(&now);

  strftime(buf, ELEMENT_STRBUF_SZ, "%Y-%m-%d %H:%M", &tm);
}

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");
  bat_capacity = fopen(capacity_path, "r");

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

void
get_battery1_status(char* buf) {
  struct battery_status s = get_battery_status("BAT1");

  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);
}

void
get_battery0_status(char* buf) {
  struct battery_status s = get_battery_status("BAT0");

  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);
}

/* 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;
  size_t l = strlen(if_name);
  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) {
    close(sock);
    return;
  }

  strncpy(wreq.ifr_name, if_name, l);

  wreq.u.essid.pointer = dst;
  wreq.u.essid.length  = IW_ESSID_MAX_SIZE;
  //printf("#%s#\n", dst);

  // Test if we have wireless on this interface
  if (ioctl(sock, SIOCGIWNAME, &wreq) != -1) {
    // protocol stored in  wreq.u.name
    close(sock);
    return;
  }

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

  close(sock);
}

void
get_net_link_status(char* buf) {
  struct ifaddrs* if_addr;
  size_t n = 0;
  size_t c = 0;

  getifaddrs(&if_addr);

  while (c < 8 && strlen(interfaces[c].name) > 0) {
    c++;
  }

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

    while (i < c && strcmp(name, interfaces[i].name))
      i++;

    //if (i != c) {
    //printf("found %s in %d\n", name, i);
    //}

    /* We're not interested in interfaces that are not "up" */
    if (!(ifa->ifa_flags & IFF_LOWER_UP)) {
      /* Remove it from the list */
      if (i < c) {
        /* Don't memmove if last element */
        if (c - i > 1) {
          memmove(&interfaces[i], &interfaces[i + 1], sizeof(struct interface_status) * (c - i));
        }

        /* "wipe" last element */
        memset(&interfaces[c - 1], 0, sizeof(struct interface_status));

        c--;
      }
      continue;
    }

    /* Ignore loopback interface flag */
    if (ifa->ifa_flags & IFF_LOOPBACK)
      continue;

    ///* Ignore interfaces without an address */
    // if (ifa->ifa_addr == NULL)
    //   continue;

    ///* Ignore everythings not an IPv4 link */
    ///* (AF_PACKET might be usefull if you want to display tx) */
    // if (ifa->ifa_addr->sa_family != AF_INET)
    //   continue;

    /* Find the interface in status, if it exists */
    struct interface_status s; // = &status[c];
    memset(&s, 0, sizeof(struct interface_status));

    s = interfaces[i];

    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     = s.address.ip4;
      } else if (family == AF_INET6) {
        strsize = INET6_ADDRSTRLEN;
        dst     = s.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);
    }

    // Get the ESSID
    get_essid(s.name, s.ssid);

    /* if we got nothing out of it, don't increment */
    if (ifa->ifa_addr == NULL && strlen(s.ssid) == 0)
      continue;

    /* If the interface didn't exist in interfaces before, we should add
     * the name:) */
    if (i == c) {
      strncpy(s.name, name, IFNAMSIZ);
      c++;
    }

    memcpy(&interfaces[i], &s, sizeof(struct interface_status));
  }
  freeifaddrs(if_addr);

  memset(buf, 0, ELEMENT_STRBUF_SZ);
  for (size_t i = 0; i < c; i++) {
    // int i = 0; {
    struct interface_status* s = &interfaces[i];
    // Write the status string to the output buffer
    const size_t namelen = strlen(s->name);
    strncat(buf + n, s->name, namelen);
    n += namelen;

    size_t ssid_len = strlen(s->ssid);
    if (ssid_len > 0) {
      buf[n++] = ' ';
      buf[n++] = '(';
      strncpy(buf + n, s->ssid, ssid_len);
      n += ssid_len;

      buf[n++] = ')';
    }

    //{ // Add the addresses
    //  const size_t addr4_len = strlen(s->address.ip4);
    //  if (addr4_len > 0) {
    //    buf[n++] = ' ';
    //    strncat(buf + n, s->address.ip4, addr4_len);
    //    n += addr4_len;
    //  }

    //  const size_t addr6_len = strlen(s->address.ip6);
    //  if (addr6_len > 0) {
    //    buf[n++] = ' ';
    //    strncat(buf + n, s->address.ip6, addr6_len);
    //    n += addr6_len;
    //  }
    //}

    if (i != c - 1) {
      strncat(buf + n, "  ", 3);
      n += 2;
    }
  }
}

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) {
    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;

  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;
}

int
main(void) {
  const int num_elems = sizeof(statusbar) / sizeof(statusbar[0]);
  struct timespec now;
  const struct timespec one_minute = {60, 0};

  memset(interfaces, 0, sizeof(struct interface_status[8]));

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

    /* Stall updating for at most 1 minute */
    struct timespec next_update = {0};
    now                         = time_add(one_minute, next_update);

    for (i = 0; i < num_elems; i++) {
      struct timespec next_fire = {0};
      statusbar[i].fire_previous = time_add(statusbar[i].fire_interval, next_fire);

      if (time_lt(now, next_fire)) {
        /* Check if this is the next to-be-updated element */
        if (time_lt(next_fire, next_update)) {
          next_update = next_fire;
        }
        continue;
      }

      memset(statusbar[i].buf, 0, ELEMENT_STRBUF_SZ);

      statusbar[i].f(statusbar[i].buf);
      statusbar[i].fire_previous = now;

      /* Check if this element needs to be refreshed next, again */
      statusbar[i].fire_previous = time_add(statusbar[i].fire_interval, next_fire);

      if (time_lt(next_fire, next_update)) {
        next_update = next_fire;
      }

      /* printf("[%ld.%ld]  %s\n",
       * statusbar[i].fire_interval.tv_sec,
       * statusbar[i].fire_interval.tv_usec,
       * (char*)statusbar[i].buf);
       */
    }

    char buf[STATUS_STRBUF_SZ];
    memset(buf, 0, STATUS_STRBUF_SZ);

    for (i = 0; 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);

    next_update = time_sub(now, next_update);

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

  return 0;
}