#include <stdlib.h>
#include <stdio.h>
#include <sys/timerfd.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include "evt_core.h"
#include "net_tools.h"
#include "socks5.h"

struct measlat_ctx {
  int count, size, interval, verbose;
  char *host, *port, *transport;
};

struct measure_conf {
  uint64_t max_measure;
  uint64_t payload_size;
  char* payload;
  uint64_t counter;
};

struct packet_header {
  uint64_t counter;
  struct timespec emit_time;
};

struct measure_conf* create_measure_conf(int max_mes, int plsize) {
  struct measure_conf* mc = malloc(sizeof(struct measure_conf));
  if (mc == NULL) {
    perror("Malloc failed");
    exit(EXIT_FAILURE);
  }

  mc->counter = 0;
  mc->max_measure = max_mes;
  mc->payload_size = plsize;
  mc->payload = malloc(mc->payload_size);
  if (mc->payload == NULL) {
    perror("malloc failed");
    exit(EXIT_FAILURE);
  }
  return mc;
}

void free_mesure_conf(void* v) {
  struct measure_conf* mc = (struct measure_conf*)v;
  free(mc->payload);
  free(mc);
}

int on_udp_err(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  return 1;
}

int on_udp(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  ssize_t res;
  int secs, nsecs;
  uint64_t micro_sec;
  struct timespec curr;
  struct measure_conf* mc = fdinfo->other;
  res = read(fdinfo->fd, mc->payload, mc->payload_size);
  if (res == -1 && errno == EAGAIN) return 1;
  if (res != mc->payload_size) {
    perror("read error");
    exit(EXIT_FAILURE);
  }
  struct packet_header* head = (struct packet_header*) mc->payload;
  if (clock_gettime(CLOCK_MONOTONIC, &curr) == -1){
    perror("clock_gettime error");
    exit(EXIT_FAILURE);
  }

  secs = curr.tv_sec - head->emit_time.tv_sec;
  nsecs = curr.tv_nsec - head->emit_time.tv_nsec;
  micro_sec = secs * 1000000 + nsecs / 1000;
  printf("Packet %llu latency %luµs\n", (unsigned long long)head->counter, micro_sec);

  if (head->counter >= mc->max_measure) {
    printf("Measurement done\n");
    exit(EXIT_SUCCESS);
  }
  return 0;
}

void free_timer_conf(void* v) {
  struct measure_conf* mc = v;
  free(mc->payload);
  free(mc);
}

int on_timer(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  ssize_t s;
  uint64_t ticks;
  struct measure_conf* mc = fdinfo->other;

  s = read(fdinfo->fd, &ticks, sizeof(uint64_t));
  if (s == -1 && errno == EAGAIN) return 1;
  if (s != sizeof(uint64_t)) {
    perror("Read error");
    exit(EXIT_FAILURE);
  }

  if (ticks != 1) {
    fprintf(stderr, "Has ticked %lu times, expected 1 time. This is a bug\n", ticks);
  }
  mc->counter++;

  memset(mc->payload, 0, mc->payload_size);
  struct packet_header* head = (struct packet_header*)mc->payload;
  head->counter = mc->counter;
  if (clock_gettime(CLOCK_MONOTONIC, &head->emit_time) == -1) {
    perror("clock_gettime error");
    exit(EXIT_FAILURE);
  }
  struct evt_core_fdinfo* tgtinfo = evt_core_get_first_from_cat (ctx, "udp-read");
  if (tgtinfo == NULL) tgtinfo = evt_core_get_first_from_cat (ctx, "tcp-read");
  if (tgtinfo == NULL) {
    printf("No connection yet\n");
    return 1;
  }
  s = send(tgtinfo->fd, mc->payload, mc->payload_size, 0);
  if (s < 0) {
    perror("Send error");
    //exit(EXIT_FAILURE);
  }
  return 0;
}


void register_timer(struct evt_core_ctx* evts, int udp, int interval, int count, int size) {
  struct timespec now;
  struct itimerspec timer_config;
  char url[1024];
  struct evt_core_cat cat = {0};
  struct evt_core_fdinfo fdinfo = {0};
  fdinfo.cat = &cat;
  fdinfo.url = url;

  if (clock_gettime(CLOCK_REALTIME, &now) == -1) {
    perror("clock_gettime");
    exit(EXIT_FAILURE);
  }
  uint64_t micro_sec = interval;
  timer_config.it_value.tv_sec = now.tv_sec + 1;
  timer_config.it_value.tv_nsec = now.tv_nsec;
  timer_config.it_interval.tv_sec = micro_sec / 1000;
  timer_config.it_interval.tv_nsec = micro_sec % 1000 * 1000000;

  fdinfo.fd = timerfd_create(CLOCK_REALTIME, 0);
  if (fdinfo.fd == -1) {
    perror("Unable to timerfd_create");
    exit(EXIT_FAILURE);
  }
  if (timerfd_settime (fdinfo.fd, TFD_TIMER_ABSTIME, &timer_config, NULL) == -1) {
    perror("Unable to timerfd_time");
    exit(EXIT_FAILURE);
  }
  fdinfo.cat->name = "timer";
  fdinfo.other = create_measure_conf(count, size);
  fdinfo.free_other = free_timer_conf;
  sprintf(fdinfo.url, "timer:%d:%d", interval, count);
  evt_core_add_fd (evts, &fdinfo);
  printf("--- Timer registered\n");
}

int on_socks5_success_measlat(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  char url[1024];
  struct evt_core_cat cat = {0};
  struct evt_core_fdinfo fdinfo_n = {0};
  struct socks5_ctx* s5ctx = fdinfo->other;
  fdinfo_n.cat = &cat;
  fdinfo_n.url = url;

  struct evt_core_cat* ucat = evt_core_get_from_cat (ctx, "tcp-read");
  if (ucat == NULL) {
    fprintf(stderr, "Category udp-read not found\n");
    exit(EXIT_FAILURE);
  }
  struct measlat_ctx* mctx = ucat->app_ctx;

  fdinfo_n.fd = dup(fdinfo->fd);
  fdinfo_n.cat->name = "tcp-read";
  fdinfo_n.other = create_measure_conf (mctx->count, mctx->size);
  fdinfo_n.free_other = free_mesure_conf;
  sprintf(fdinfo_n.url, "tcp:read:%s:%d", s5ctx->addr, s5ctx->port);

  evt_core_add_fd (ctx, &fdinfo_n);
  printf("--- Tor socket registered\n");

  register_timer(ctx, fdinfo->fd, mctx->interval, mctx->count, mctx->size);
  return 1;
}

void spawn_tor_socket(struct evt_core_ctx* evts) {
  struct evt_core_cat* ucat = evt_core_get_from_cat (evts, "tcp-read");
  if (ucat == NULL) {
    fprintf(stderr, "Category udp-read not found\n");
    exit(EXIT_FAILURE);
  }
  struct measlat_ctx* mctx = ucat->app_ctx;

  socks5_create_dns_client (evts, "127.0.0.1", "9050", mctx->host, atoi(mctx->port));
}

int on_socks5_failed_measlat(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  evt_core_rm_fd (ctx, fdinfo->fd);
  spawn_tor_socket(ctx);

  return 1;
}

void register_categories(struct evt_core_ctx* evts, struct measlat_ctx* mctx) {
  struct evt_core_cat template = {0};
  template.app_ctx = mctx;
  evt_core_init(evts, mctx->verbose);

  template.cb = on_timer;
  template.name = "timer";
  template.flags = EPOLLIN | EPOLLET;
  evt_core_add_cat(evts, &template);

  template.cb = on_udp; // intended but not elegant
  template.err_cb = on_udp_err; // intended but not elegant
  template.name = "tcp-read";
  template.flags = EPOLLIN | EPOLLET;
  evt_core_add_cat(evts, &template);

  template.cb = on_udp;
  template.err_cb = on_udp_err;
  template.name = "udp-read";
  template.flags = EPOLLIN | EPOLLET;
  evt_core_add_cat(evts, &template);

  template.cb = on_socks5_success_measlat;
  template.err_cb = on_socks5_failed_measlat;
  template.name = "socks5-success";
  template.flags = EPOLLET;

  template.cb = on_socks5_failed_measlat;
  template.err_cb = on_socks5_failed_measlat;
  template.name = "socks5-failed";
  template.flags = EPOLLET;

  socks5_init(evts);
  printf("--- Categories registered\n");

}

void spawn_udp_socket(struct evt_core_ctx* evts) {
  struct evt_core_cat* ucat = evt_core_get_from_cat (evts, "udp-read");
  if (ucat == NULL) {
    fprintf(stderr, "Category udp-read not found\n");
    exit(EXIT_FAILURE);
  }
  struct measlat_ctx* mctx = ucat->app_ctx;

  int udp_sock = create_udp_client (mctx->host, mctx->port);
  char url[1024];
  struct evt_core_cat cat = {0};
  struct evt_core_fdinfo fdinfo = {0};
  fdinfo.cat = &cat;
  fdinfo.url = url;

  fdinfo.fd = udp_sock;
  fdinfo.cat->name = "udp-read";
  fdinfo.other = create_measure_conf (mctx->count, mctx->size);
  fdinfo.free_other = free_mesure_conf;
  sprintf(fdinfo.url, "udp:read:%s:%s", mctx->host, mctx->port);
  evt_core_add_fd (evts, &fdinfo);
  printf("--- UDP socket registered\n");

  register_timer(evts, fdinfo.fd, mctx->interval, mctx->count, mctx->size);
}

int main(int argc, char** argv) {
  setvbuf(stdout, NULL, _IONBF, 0);
  printf("~ measlat ~\n");

  int opt;
  struct measlat_ctx mctx = {0};
  struct evt_core_ctx evts = {0};

  // 1. Parse parameters
  while ((opt = getopt(argc, argv, "vh:p:c:s:i:t:")) != -1) {
      switch(opt) {
      case 'v':
        mctx.verbose++;
        break;
      case 'h': // host
        mctx.host = optarg;
        break;
      case 'p': // port
        mctx.port = optarg;
        break;
      case 't': // transport
        mctx.transport = optarg;
        break;
      case 'c': // count
        mctx.count = atoi(optarg);
        break;
      case 's': // size - payload in bytes
        mctx.size = atoi(optarg);
        break;
      case 'i': // interval - every ms
        mctx.interval = atoi(optarg);
        break;
      default:
        goto usage;
      }
  }

  // 2. Check and fix parameters
  size_t header_size = sizeof(struct packet_header);
  if (mctx.interval <= 0) mctx.interval = 1000;
  if (mctx.count <= 0) mctx.count = 1;
  if (mctx.size < header_size) mctx.size = header_size;
  if (mctx.transport == NULL) mctx.transport = "udp";
  if (mctx.host == NULL || mctx.port == NULL) goto usage;

  // 3. Bind events
  register_categories(&evts, &mctx);
  if (strcmp(mctx.transport, "udp") == 0) spawn_udp_socket(&evts);
  else if (strcmp(mctx.transport, "tor") == 0) spawn_tor_socket(&evts);

  // 4. Run main loop
  evt_core_loop(&evts);

  return 0;
usage:
  fprintf(stderr, "Usage: %s -h <host> -p <port> [-t <udp|tor>] [-c <count>] [-i <ms>] [-s <bytes>]\n", argv[0]);
  exit(EXIT_FAILURE);
}