#include <stdio.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
#include "lib/lists.h"
#include "lib/ip.h"
#include "lib/socket.h"
#include "nest/iface.h"
#include "sysdep/unix/unix.h"
#include "sysdep/unix/wg_user.h"
#include "sysdep/linux/wireguard.h"

static
char *get_socket_path(const char *ifname, char *buf, uint size)
{
  bsnprintf(buf, size, SOCKET_PATH "%s.sock", ifname);
  return buf;
}

bool wg_has_userspace(const char *ifname)
{
  struct stat sb;
  char tmp[sizeof(struct sockaddr_un)];

  if (stat(get_socket_path(ifname, tmp, sizeof(tmp)), &sb) == 0)
    return (sb.st_mode & S_IFMT) == S_IFSOCK;
  else
    {
      log(L_TRACE "WG: no socket %s", tmp);
      return false;
    }
}

/* NULL=receiving turned off, returns 1 to clear rx buffer */
static
int user_rx_hook(struct birdsock *sk UNUSED, uint size)
{
  log(L_TRACE "WG: RX %d", size);
  return 1;
}

static
void user_tx_hook(struct birdsock *bs UNUSED)
{
  log(L_TRACE "WG: TX");
}

/* errno or zero if EOF */
static
void user_err_hook(struct birdsock *bs, int err)
{
  /* if (err == 0) */
  /*   return; */

  log(L_TRACE "WG: ERR %d %s", err, bs->err);
  if (bs->fd >= 0)
    close(bs->fd);
  bs->fd = -1;
}

static void
wg_puts(const char *str, byte **buf, uint *size)
{
  int len = strlen(str);
  if (0 < len && len < (int)*size)
    {
      strcpy(*buf, str);
      *size -= len;
      *buf += len;
    }
  else
    *size = 0;
}

static void
wg_put_str(const char *key, const char *value, byte **buf, uint *size)
{
  char tmp[128];

  int len = snprintf(tmp, sizeof(tmp), "%s=%s\n", key, value);
  if (0 < len && len < (int)*size)
    {
      strcpy(*buf, tmp);
      *size -= len;
      *buf += len;
    }
  else
    *size = 0;
}

static void
wg_put_u16(const char *key, u16 value, byte **buf, uint *size)
{
  char tmp[64];

  int len = snprintf(tmp, sizeof(tmp), "%u", value);
  if (len > 0)
    wg_put_str(key, tmp, buf, size);
  else
    *size = 0;
}

static void
wg_put_bool(const char *key, bool value, byte **buf, uint *size)
{
  if (value)
    wg_put_str(key, "true", buf, size);
}

static void
wg_put_key(const char *key, wg_key value, byte **buf, uint *size)
{
  char tmp[128];

  for (uint i=0; i < sizeof(wg_key); i++)
    bsnprintf(tmp+2*i, sizeof(tmp)-2*i, "%02x", value[i]);

  wg_put_str(key, tmp, buf, size);
}

static void
wg_put_endpoint(const wg_endpoint *endpoint, byte **buf, uint *size)
{
  char tmp[INET6_ADDRSTRLEN + 16];
  ip_addr ip;
  struct iface *ifa = NULL;
  uint port = 0;

  if (sockaddr_read((sockaddr*)&endpoint->addr, endpoint->addr.sa_family,
		    &ip, &ifa, &port) == 0)
    {
      char *pos = NULL;

      if (ipa_is_ip4(ip))
	pos = ip4_ntop(ipa_to_ip4(ip), tmp);
      else
	{
	  tmp[0] = '[';
	  pos = ip6_ntop(ipa_to_ip6(ip), tmp + 1);
	  if (ifa)
	    pos += bsprintf(pos, "%%%u", ifa->index);
	  *pos++ = ']';
	}

      bsprintf(pos, ":%u", port);
      wg_put_str("endpoint", tmp, buf, size);
    }
}

static void
wg_put_allowedip(wg_allowedip *allowedip, byte **buf, uint *size)
{
  char tmp[INET6_ADDRSTRLEN + 10];
  ip_addr ip = IP6_NONE;

  switch (allowedip->family)
    {
    case AF_INET:
      ip = ipa_from_in4(allowedip->ip4);
      break;
    case AF_INET6:
      ip = ipa_from_in6(allowedip->ip6);
      break;
    default:
      return;
    }

  int res = bsnprintf(tmp, sizeof(tmp), "%I/%u", ip, allowedip->cidr);

  if (res < 0)
    {
      *size = 0;
      return;
    }

  wg_put_str("allowed_ip", tmp, buf, size);
}

static int
user_put_device(wg_device *dev, byte **buf, uint *size)
{
  wg_put_u16("set", 1, buf, size);
  wg_put_key("private_key", dev->private_key, buf, size);
  wg_put_u16("listen_port", dev->listen_port, buf, size);
  wg_put_bool("replace_peers", dev->flags & WGDEVICE_REPLACE_PEERS, buf, size);

  wg_peer *peer = NULL;
  wg_for_each_peer(dev, peer)
    {
      wg_put_key("public_key", peer->public_key, buf, size);
      wg_put_endpoint(&peer->endpoint, buf, size);
      wg_put_bool("replace_allowed_ips", peer->flags & WGPEER_REPLACE_ALLOWEDIPS, buf, size);

      wg_allowedip *allowedip = NULL;
      wg_for_each_allowedip(peer, allowedip)
	{
	  wg_put_allowedip(allowedip, buf, size);
	}
    }
  wg_puts("\n", buf, size);

  if (*size > 0)
    return 0;
  else
    return -1;
}

int
wg_user_set_device(struct pool *pool,
		   const char *ifname,
		   struct wg_device *dev)
{
  char path[sizeof(struct sockaddr_un)];

  bsnprintf(path, sizeof(path), SOCKET_PATH "%s.sock", ifname);

  struct birdsock *sock = sk_new(pool);
  sock->rx_hook = user_rx_hook;
  sock->tx_hook = user_tx_hook;
  sock->err_hook = user_err_hook;
  int res = sk_connect_unix(sock, path);
  log(L_TRACE "WG: socket %d %d %s", res, sock->fd, path);
  if (res < 0)
    return -1;

  uint tbsize = 8192;
  sk_set_tbsize(sock, tbsize);
  sk_set_rbsize(sock, 16);
  byte *pos = sock->tbuf;
  uint size = tbsize;
  int len = user_put_device(dev, &pos, &size);

  log(L_TRACE "WG: put %d %s", size, sock->tbuf);

  if (len < 0)
    {
      /* FIXME close */
      return -1;
    }
  res = sk_send(sock, tbsize - size);
  /* Send data, <0=err, >0=ok, 0=sleep */
  log(L_TRACE "WG: send %d", res);

  /* abort(); */
  return -1;
}