#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
socklen_t get_socket_path(const char *ifname, char *buf, uint size)
{
  int pos = 0;

  if (size < 1)
    return 0;

#ifdef ANDROID
  /* Abstract socket */
  buf[pos++] = 0;
#endif
  bsnprintf(buf+pos, size-pos, SOCKET_PATH "%s.sock", ifname);
  return pos + strlen(buf+pos);
}

bool wg_has_userspace(const char *ifname)
{
  struct stat sb;
  char tmp[sizeof(struct sockaddr_un)];
  socklen_t tmplen = get_socket_path(ifname, tmp, sizeof(tmp));

  if (tmplen > 0 && tmp[0] == 0)
    /* System with abstract socket (Android) always use WireGuard's userspace
       implementation. */
    return true;
  else if (stat(tmp, &sb) == 0)
    return (sb.st_mode & S_IFMT) == S_IFSOCK;
  else
  {
    DBG(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 UNUSED)
{
  DBG(L_TRACE "WG: RX %p %d", sk, size);
  rfree(sk);
  return 1;
}

static
void user_tx_hook(struct birdsock *bs)
{
  DBG(L_TRACE "WG: TX %p %d", bs, bs->tpos - bs->ttx);

  uint size = (uintptr_t)bs->data;

  if (size > 0)
  {
    int res = sk_send(bs, bs->tbsize - size);

    /* Send data, <0=err, >0=ok, 0=sleep */
    log(L_TRACE "WG: send %d", res);

    if (res != 0)
    {
      //rfree(sock);
      //shutdown(sock->fd, SHUT_WR);
    }

    bs->data = NULL;
  }
}

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

  log(L_TRACE "WG: ERR %p %d %s", bs, err, bs->err);
  rfree(bs);
}

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);
  if (dev->flags & WGDEVICE_HAS_PRIVATE_KEY)
    wg_put_key("private_key", dev->private_key, buf, size);
#if 0
  /* Setting listen_port causes dead-lock in wireguard-go. */
  if (dev->flags & WGDEVICE_HAS_LISTEN_PORT)
    wg_put_u16("listen_port", dev->listen_port, buf, size);
#endif
  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)];
  socklen_t pathlen = get_socket_path(ifname, path, sizeof(path));

  struct birdsock *sock = sk_new(pool);
  sock->rx_hook = user_rx_hook;
  sock->tx_hook = user_tx_hook;
  sock->err_hook = user_err_hook;
  sock->fast_rx = 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);

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

  if (len < 0)
  {
    rfree(sock);
    return -1;
  }

  sock->data = (void*)(uintptr_t)size;

  int res = sk_connect_unix(sock, path, pathlen);
  DBG(L_TRACE "WG: socket %d %d %s", res, sock->fd, path);
  if (res < 0)
  {
    rfree(sock);
    return -1;
  }

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