#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"
#include "utils.h"
#include "measure.h"
#include "url.h"
#include "tor_os.h"
#include "tor_ctl.h"

struct measlat_ctx {
  struct measure_conf mc;
  struct sockaddr_in addr;
  socklen_t addrlen;
  int verbose, is_timer_started, is_from_needed, tor_flags;
  char *host, *port, *transport;
};

void register_timer(struct evt_core_ctx* evts, struct timespec* next_tick) {
  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;

  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;
  mctx->is_timer_started = 1;

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

  printf("timer_config: sec=%ld nsec=%ld \n", (uint64_t) timer_config.it_value.tv_sec, (uint64_t) timer_config.it_value.tv_nsec);

  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";
  sprintf(fdinfo.url, "timer:%ld:%ld", mctx->mc.interval, mctx->mc.max_measure);
  evt_core_add_fd (evts, &fdinfo);
  printf("--- Timer registered\n");
}

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

int on_receive_measure_packet(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  ssize_t nread;
  struct measlat_ctx* mctx = fdinfo->cat->app_ctx;

  if (mctx->is_from_needed) nread = recvfrom(fdinfo->fd, mctx->mc.payload, mctx->mc.payload_size, MSG_TRUNC, (struct sockaddr*)&mctx->addr, &mctx->addrlen);
  else nread = recv(fdinfo->fd, mctx->mc.payload, mctx->mc.payload_size, 0);

  if ((nread == -1 && errno == EAGAIN) || nread == 0) return 1;
  // @FIXME logic is wrong for TCP here but would lead (hopefully) to a crash

  // First we parse the packet and exit if needed
  measure_parse (nread, &mctx->mc);

  // Old behaviour where we work in a RTT way and send back the packet
  if (measure_need_reply (&mctx->mc)) {
    ssize_t nwritten;
    if (mctx->is_from_needed) nwritten = sendto(fdinfo->fd, mctx->mc.payload, nread, 0, (struct sockaddr*)&mctx->addr, mctx->addrlen);
    else nwritten = send(fdinfo->fd, mctx->mc.payload, nread, 0);

    // @FIXME don't support EAGAIN on write. Could be intended, you don't think so?
    if (nwritten != nread) {
      fprintf(stderr, "Didn't write the same number of bytes as read. nread=%ld, nwritten=%ld\n", nread, nwritten);
      perror("write errno");
      exit(EXIT_FAILURE);
    }
    return 0;
  }

  // Used to start sending from the server in sync with client
  if (!mctx->is_timer_started) {
    struct timespec next_tick = {0};
    measure_next_tick(&mctx->mc, &next_tick);
    register_timer (ctx, &next_tick);
  }

  return 0;
}


int on_tcp_co(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  int conn_sock1, conn_sock2;
  struct sockaddr_in addr;
  socklen_t in_len;
  char url[1024], port[6];
  struct evt_core_cat local_cat = {0};
  struct evt_core_fdinfo to_fdinfo = {0};
  to_fdinfo.cat = &local_cat;
  to_fdinfo.url = url;

  in_len = sizeof(addr);
  conn_sock1 = accept(fdinfo->fd, (struct sockaddr*)&addr, &in_len);

  if (conn_sock1 == -1 && errno == EAGAIN) return 1;
  if (conn_sock1 == -1) goto co_error;

  url_get_port(port, fdinfo->url);

  to_fdinfo.fd = conn_sock1;
  to_fdinfo.cat->name = "tcp-read";
  sprintf(to_fdinfo.url, "tcp:read:127.0.0.1:%s", port);
  evt_core_add_fd (ctx, &to_fdinfo);

  return 0;

co_error:
  perror("Failed to handle new connection");
  exit(EXIT_FAILURE);
}

int on_timer(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  ssize_t s;
  uint64_t ticks = 0;
  struct measlat_ctx* mctx = fdinfo->cat->app_ctx;

  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);
  }

  struct measure_packet* head = measure_generate(&mctx->mc);
  //printf("send(id=%ld,is_echo=%d)\n", head->counter, head->is_echo);

  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");
    struct evt_core_fdinfo* timer_fd = evt_core_get_first_from_cat (ctx, "timer");
    evt_core_rm_fd(ctx, timer_fd->fd);
    mctx->is_timer_started = 0;
    return 1;
  }
  if (mctx->is_from_needed) s = sendto(tgtinfo->fd, mctx->mc.payload, mctx->mc.payload_size, 0, (struct sockaddr*)&mctx->addr, mctx->addrlen);
  else s = send(tgtinfo->fd, mctx->mc.payload, mctx->mc.payload_size, 0);

  if (s < 0) {
    perror("Send error");
    //exit(EXIT_FAILURE);
  }

  return 0;
}

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";
  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, NULL);
  return 1;
}

void spawn_tor_client(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));
  printf("--- Tor client SOCKS started\n");
}

int on_socks5_failed_measlat(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo) {
  evt_core_rm_fd (ctx, fdinfo->fd);
  spawn_tor_client(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_receive_measure_packet; // intended but not elegant
  template.err_cb = NULL; // intended but not elegant
  template.name = "tcp-read";
  template.flags = EPOLLIN | EPOLLET;
  evt_core_add_cat(evts, &template);

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

  template.cb = on_tcp_co;
  template.err_cb = NULL;
  template.name = "tcp-co";
  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;
  evt_core_add_cat(evts, &template);

  template.cb = on_socks5_failed_measlat;
  template.err_cb = on_socks5_failed_measlat;
  template.name = "socks5-failed";
  template.flags = EPOLLET;
  evt_core_add_cat(evts, &template);

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

}

void spawn_udp_client(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 = &mctx->mc;
  fdinfo.free_other = NULL;
  sprintf(fdinfo.url, "udp:read:%s:%s", mctx->host, mctx->port);
  evt_core_add_fd (evts, &fdinfo);
  printf("--- UDP client registered\n");

  register_timer(evts, NULL);
}

void spawn_udp_server(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_server (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;
  sprintf(url, "udp:rw:127.0.0.1:%s", mctx->port);
  fdinfo.cat->name = "udp-read";
  evt_core_add_fd(evts, &fdinfo);
  printf("--- UDP server is listening\n");
}

void spawn_tor_server(struct evt_core_ctx* evts, uint16_t *ports) {
  char buffer[1024];
  int tcp_serv_sock, err;

  sprintf(buffer, "%d", ports[0]);
  tcp_serv_sock = create_tcp_server ("0.0.0.0", buffer);
  err = listen(tcp_serv_sock, SOMAXCONN);

  struct evt_core_cat cat = {0};
  struct evt_core_fdinfo fdinfo = {0};
  fdinfo.cat = &cat;
  fdinfo.url = buffer;

  fdinfo.fd = tcp_serv_sock;
  sprintf(buffer, "tcp:co:127.0.0.1:%d", ports[0]);
  fdinfo.cat->name = "tcp-co";
  evt_core_add_fd(evts, &fdinfo);
  printf("--- TCP server is listening\n");
}

void measlat_create_onion_services(struct tor_os_str* tos, struct tor_ctl* tctl, uint16_t* ports, int ports_count, enum TOR_ONION_FLAGS tof) {
    tor_os_create (tos, "onion_services.pub", "onion_services.txt", ports_count);
    tor_os_read (tos);

    int err = 0;
    err = tor_ctl_connect (tctl, "127.0.0.1", "9051");
    if (err < 0) {
      fprintf(stderr, "Unable to open Tor Socket\n");
      exit(EXIT_FAILURE);
    }
    err = tor_ctl_add_onion (tctl, tos, ports, tof);
    if (err != 0) {
      fprintf(stderr, "Unable to create Onion Services (error: %d)\n", err);
      exit(EXIT_FAILURE);
    }
}

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:lrn")) != -1) {
      switch(opt) {
      case 'v':
        mctx.verbose++;
        break;
      case 'h': // host
        mctx.host = optarg;
        break;
      case 'p': // port
        mctx.port = optarg;
        break;
      case 'l':
        mctx.mc.is_server = 1;
        break;
      case 't': // transport
        mctx.transport = optarg;
        break;
      case 'c': // count
        mctx.mc.max_measure = atoi(optarg);
        break;
      case 's': // size - payload in bytes
        mctx.mc.payload_size = atoi(optarg);
        break;
      case 'r':
        mctx.mc.is_rtt = 1;
        break;
      case 'n':
        mctx.tor_flags |= TOR_ONION_FLAG_NON_ANONYMOUS;
        break;
      case 'i': // interval - every ms
        mctx.mc.interval = atoi(optarg);
        break;
      default:
        goto usage;
      }
  }

  // 2. Check and fix parameters
  measure_prepare (&mctx.mc);
  mctx.addrlen = sizeof(mctx.addr);
  if (mctx.transport == NULL) mctx.transport = "udp";
  if (mctx.host == NULL) mctx.host = "127.0.0.1";
  if (mctx.port == NULL) mctx.port = strcmp(mctx.transport, "udp") == 0 ? "9000" : "7500";
  printf("[measlat_conf] host=%s, port=%s, listen=%d, transport=%s, count=%ld, size=%ld, interval=%ld, is_rtt=%d\n",
          mctx.host, mctx.port, mctx.mc.is_server, mctx.transport, mctx.mc.max_measure, mctx.mc.payload_size, mctx.mc.interval, mctx.mc.is_rtt);

  // 3. Bind events
  register_categories(&evts, &mctx);

  struct tor_os_str tos = {0};
  struct tor_ctl tctl = {0};
  uint16_t ports[] = {7500};
  int ports_count = sizeof(ports) / sizeof(ports[0]);

  if (mctx.mc.is_server && strcmp(mctx.transport, "udp") == 0) {
    spawn_udp_server (&evts);
    mctx.is_from_needed = 1;

  }
  else if (mctx.mc.is_server && strcmp(mctx.transport, "tor") == 0) {
    spawn_tor_server(&evts, ports);
    measlat_create_onion_services (&tos, &tctl, ports, ports_count, mctx.tor_flags);
    printf("--- Onion services created\n");
  }
  else if (strcmp(mctx.transport, "udp") == 0) spawn_udp_client(&evts);
  else if (strcmp(mctx.transport, "tor") == 0) spawn_tor_client(&evts);
  else exit(EXIT_FAILURE);

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

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