#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <err.h>
#include <errno.h>
#include <netinet/in.h>
#include <event.h>
#include <signal.h>

#include "libglouglou.h"
#include "sendbuf.h"

#define error(fmt, ...) \
  if (_verbosity >= 0) \
    printf("libgg: %s: ERROR: " fmt "\n", __func__, ##__VA_ARGS__)
#define verbose(fmt, ...) \
  if (_verbosity >= 1) \
    printf("libgg: %s: " fmt "\n", __func__, ##__VA_ARGS__)
#define debug(fmt, ...) \
  if (_verbosity >= 2) \
    printf("libgg: %s: XXX: " fmt "\n", __func__, ##__VA_ARGS__)

void              cb_srv_receive(evutil_socket_t, short, void *);
struct gg_user   *user_add(struct gg_server *, struct sockaddr_in *);
void              user_del(struct gg_server *, struct gg_user *);
struct gg_user *  user_find(struct gg_server *, struct sockaddr_in *);
int               user_send(struct gg_user *, void *, int);
int               cb_usr_send(void *, int, void *);
int               client_send(struct gg_client *, void *, int);
void              cb_cli_receive(evutil_socket_t, short, void *);
void              cb_cli_timer(evutil_socket_t, short, void *);
int               cb_cli_send(void *, int, void *);
struct gg_packet *pkt_decode(char **, int *);
int               pkt_getsize(struct gg_packet *);
int               pkt_encode(struct gg_packet *, struct gg_packet *);

int _verbosity = 0;

gg_packet_props_t gg_packet_props[] = {
  [PACKET_NEWCONN] = \
    { (PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.newconn) },
  [PACKET_DELCONN] = \
    { (PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.delconn) },
  [PACKET_DATA] = \
    { (PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.data) },
  [PACKET_NAME] = \
    { ((PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.name) - GG_PKTARG_MAX) },
  [PACKET_FORK] = \
    { (PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.fork) },
  [PACKET_EXEC] = \
    { ((PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.exec) - GG_PKTARG_MAX) },
  [PACKET_EXIT] = \
    { (PACKET_HEADER_SIZE + sizeof((struct gg_packet *)0)->pdat.exit) },
};

/*
 * Server
 */

/*
 * start a server
 * For security reasons, do not set handle_packet if you don't need it.
 * Also note that the packet passed by handle_packet is static, so you should
 * not modify it or free it.
 */
struct gg_server *
gg_server_start(struct event_base *ev_base, char *ip, int port,
                int (*handle_conn)(struct gg_server *, struct gg_user *),
                int (*handle_packet)(struct gg_server *, struct gg_user *, struct gg_packet *),
                void *usrdata)
{
  struct gg_server *srv;
  struct sockaddr_in sock_addr;
  struct event *ev;
  int s;
  int sock_on = 1;

  srv = xcalloc(1, sizeof(struct gg_server));
  srv->ev_base = ev_base;
  srv->ip = ip;
  srv->port = port;
  srv->handle_conn = handle_conn;
  srv->handle_packet = handle_packet;
  srv->usrdata = usrdata;

  s = socket(AF_INET, SOCK_DGRAM, 0);
  if (s < 0)
    goto err;
  srv->sock = s;
	setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
		&sock_on, sizeof(sock_on));
	fd_nonblock(s);

	bzero(&sock_addr, sizeof(sock_addr));
	sock_addr.sin_family = AF_INET;
	sock_addr.sin_addr.s_addr = inet_addr(ip);
	sock_addr.sin_port = htons(port);
	addrcpy(&srv->addr, &sock_addr);

	if (bind(s, (struct sockaddr *)&sock_addr,
			sizeof(sock_addr)) != 0)
		goto err;

  ev = event_new(ev_base, s, EV_READ|EV_PERSIST, cb_srv_receive, srv);
  event_add(ev, NULL);
  srv->ev = ev;

  return srv;

err:
  error("%s", strerror(errno));
  gg_server_stop(srv);
  return NULL;
}

void
gg_server_stop(struct gg_server *srv)
{
  struct gg_user *usr;

  while ((usr = LIST_FIRST(&srv->user_list))) {
    user_del(srv, usr);
  }
  if (srv->sock)
    close(srv->sock);
  if (srv->ev)
    event_del(srv->ev);
  free(srv);
}

int
gg_server_send(struct gg_server *srv, struct gg_packet *pkt, struct gg_user *usr)
{
  static struct gg_packet *newpkt;
  static struct gg_packet pktbuf;
  struct gg_user *u;
  int size;
  int res = 0;

  /* optimisation to use sendbuf_gettoken */
  if (!usr && srv->user_count == 1)
    usr = LIST_FIRST(&srv->user_list);

  if (usr) {
    size = pkt_getsize(pkt);
    newpkt = sendbuf_gettoken(usr->sbuf, size);
    if (!newpkt)
      return -1;
    return pkt_encode(pkt, newpkt);
  } else {
    size = pkt_encode(pkt, &pktbuf);
    LIST_FOREACH(u, &srv->user_list, entry) {
      res = res + sendbuf_append(u->sbuf, &pktbuf, size);
    }
  }

  return res;
}

void
gg_server_send_flush(struct gg_server *srv, struct gg_user *usr)
{
  struct gg_user *u;

  if (usr)
    sendbuf_flush(usr->sbuf);
  else
    LIST_FOREACH(u, &srv->user_list, entry)
      sendbuf_flush(u->sbuf);
}

/*
 * Server - private
 */

void cb_srv_receive(evutil_socket_t fd, short what, void *arg)
{
  struct gg_server *srv;
  struct gg_user *usr;
  struct gg_packet *pkt;
	struct sockaddr_in remote;
  socklen_t remote_len;
  char buf[PACKET_BUFFER_SIZE];
  char *buf_p;
	int buf_len;
	int len;

  srv = arg;
  remote_len = sizeof(struct sockaddr_in);
	len = recvfrom(fd, buf, sizeof(buf), 0,
		(struct sockaddr *)&remote, &remote_len);
	if (len < 0) {
		error("recvfrom failed");
		return;
	}

	usr = user_find(srv, &remote);
	if (!usr) {
	  usr = user_add(srv, &remote);
    if (srv->handle_conn)
      srv->handle_conn(srv, usr);
    user_send(usr, "", 0);
  } else {
    debug("Incoming data from existing user !");
    if (len == 0) {
      user_del(srv, usr);
      return;
    }
    if (srv->handle_packet) {
      buf_p = buf;
      buf_len = len;
      while (buf_len > 0 && (pkt = pkt_decode(&buf_p, &buf_len)))
        srv->handle_packet(srv, usr, pkt);
      if (buf_len > 0) {
        /* XXX store incomplete packet for next recv */
        error("incomplete packet, dropped %d bytes !", buf_len);
      }
    }
  }
}

struct gg_user *
user_add(struct gg_server *srv, struct sockaddr_in *remote)
{
  struct gg_user *usr;
  struct sendbuf *sbuf;

  usr = xcalloc(1, sizeof(struct gg_user));
  usr->id = srv->user_id_count;
  srv->user_id_count++;
  srv->user_count++;
  usr->sock = srv->sock;
  addrcpy(&usr->addr, remote);

  sbuf = sendbuf_new(srv->ev_base, PACKET_SNDBUF_MAX, 200, cb_usr_send, usr);
  if (!sbuf)
    goto err;
  usr->sbuf = sbuf;

  LIST_INSERT_HEAD(&srv->user_list, usr, entry);
  verbose("Add user %d !", usr->id);

  return usr;

err:
  user_del(srv, usr);
  return NULL;
}

void
user_del(struct gg_server *srv, struct gg_user *usr)
{
  verbose("Del user %d !", usr->id);
  if (usr->sbuf)
    sendbuf_free(usr->sbuf);
  user_send(usr, "", 0);
  LIST_REMOVE(usr, entry);
  srv->user_count--;
  free(usr);
}

struct gg_user *
user_find(struct gg_server *srv, struct sockaddr_in *remote)
{
	struct gg_user *usr;
	struct sockaddr_in *u;

	LIST_FOREACH(usr, &srv->user_list, entry) {
		u = &usr->addr;
		if (u->sin_addr.s_addr == remote->sin_addr.s_addr &&
			u->sin_port == remote->sin_port)
			return usr;
	}
	return NULL;
}

int
user_send(struct gg_user *usr, void *data, int size)
{
  int sent;

  sent = sendto(usr->sock, data, size, 0, (struct sockaddr *)&usr->addr,
                sizeof(struct sockaddr_in));
  if (sent == -1)
    error("failed: %s", strerror(errno));
  return sent;
}

int
cb_usr_send(void *data, int size, void *usrdata)
{
  struct gg_user *usr;

  usr = usrdata;
  return user_send(usr, data, size);
}

/* 
 * Client
 */

/*
 * connect to a server
 * For security reasons, do not set handle_packet if you don't need it.
 * Also note that the packet passed by handle_packet is static, so you should
 * not modify it or free it.
 */
struct gg_client *
gg_client_connect(struct event_base *ev_base, char *ip, int port,
                  int (*handle_conn)(struct gg_client *),
                  int (*handle_packet)(struct gg_client *, struct gg_packet *),
                  void *usrdata)
{
  struct gg_client *cli;
  struct sockaddr_in sock_addr;
  struct sendbuf *sbuf;
  struct event *ev;
  struct timeval tv;
  int s;
  int sock_on = 1;

  cli = xcalloc(1, sizeof(struct gg_client));
  cli->ev_base = ev_base;
  cli->ip = ip;
  cli->port = port;
  cli->handle_conn = handle_conn;
  cli->handle_packet = handle_packet;
  cli->usrdata = usrdata;
  cli->status = GG_CLIENT_STATUS_CONNECTING;
  s = socket(AF_INET, SOCK_DGRAM, 0);
  if (s < 0)
    goto err;
  cli->sock = s;
	setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
		&sock_on, sizeof(sock_on));
	fd_nonblock(s);

	bzero(&sock_addr, sizeof(sock_addr));
  sock_addr.sin_family = AF_INET;
  sock_addr.sin_addr.s_addr=inet_addr(ip);
  sock_addr.sin_port=htons(port);
  addrcpy(&cli->addr, &sock_addr);

  ev = event_new(ev_base, s, EV_READ|EV_PERSIST, cb_cli_receive, cli);
  event_add(ev, NULL);
  cli->ev = ev;

  ev = evtimer_new(ev_base, cb_cli_timer, cli);
  cli->ev_timer = ev;
  bzero(&tv, sizeof(struct timeval));
  tv.tv_sec = 0;
  evtimer_add(ev, &tv);

  sbuf = sendbuf_new(cli->ev_base, PACKET_SNDBUF_MAX, 200, cb_cli_send, cli);
  if (!sbuf)
    goto err;
  cli->sbuf = sbuf;

  return cli;

err:
  error("Error ! %s", strerror(errno));
  gg_client_disconnect(cli);
  return NULL;
}

void
gg_client_disconnect(struct gg_client *cli)
{
  if (cli->sbuf)
    sendbuf_free(cli->sbuf);
  if (cli->sock) {
    client_send(cli, "", 0);
    close(cli->sock);
  }
  if (cli->ev)
    event_del(cli->ev);
  if (cli->ev_timer)
    event_del(cli->ev_timer);
  free(cli);
}

int
gg_client_send(struct gg_client *cli, struct gg_packet *pkt)
{
  static struct gg_packet *newpkt;
  int size;

  size = pkt_getsize(pkt);
  newpkt = sendbuf_gettoken(cli->sbuf, size);
  if (!newpkt)
    return -1;
  return pkt_encode(pkt, newpkt);
}

void
gg_client_send_flush(struct gg_client *cli)
{
  sendbuf_flush(cli->sbuf);
}

/*
 * Client - private
 */

int
client_send(struct gg_client *cli, void *data, int size)
{
  int sent;

  sent = sendto(cli->sock, data, size, 0, (struct sockaddr *)&cli->addr,
                sizeof(struct sockaddr_in));
  if (sent == -1)
    error("failed: %s", strerror(errno));
  return sent;
}

void cb_cli_receive(evutil_socket_t fd, short what, void *arg)
{
  struct gg_client *cli;
  struct gg_packet *pkt;
  struct sockaddr_in remote;
	socklen_t	remote_len;
  char buf[PACKET_BUFFER_SIZE];
  char *buf_p;
  int buf_len;
  int len;

  cli = arg;
  remote_len = sizeof(struct sockaddr_in);
	len = recvfrom(fd, buf, sizeof(buf), 0,
		(struct sockaddr *)&remote, &remote_len);
	if (addrcmp(&cli->addr, &remote)) {
    error("receiving from stranger !");
    return;
  }
	if (len < 0) {
		error("recvfrom failed");
		return;
	}

  switch (cli->status) {
  case GG_CLIENT_STATUS_CONNECTING:
    verbose("Connected !");
    cli->status = GG_CLIENT_STATUS_CONNECTED;
    if (cli->handle_conn)
      cli->handle_conn(cli);
    break;
  case GG_CLIENT_STATUS_CONNECTED:
    if (len == 0) {
      verbose("libglouglou: cb_cli_receive: recvfrom = 0");
      cli->status = GG_CLIENT_STATUS_CONNECTING;
      return;
    }
    debug("Incoming data !");
    if (cli->handle_packet) {
      buf_p = buf;
      buf_len = len;
      while (buf_len > 0 && (pkt = pkt_decode(&buf_p, &buf_len)))
        cli->handle_packet(cli, pkt);
      if (buf_len > 0) {
        /* XXX store incomplete packet for next recv */
        error("incomplete packet, dropped %d bytes !", buf_len);
      }
    }
    break;
  }
}

void cb_cli_timer(evutil_socket_t fd, short what, void *arg)
{
  struct timeval tv;
  struct gg_client *cli;

  cli = arg;

  switch (cli->status) {
  case GG_CLIENT_STATUS_CONNECTING:
    client_send(cli, "", 0);
    break;
  case GG_CLIENT_STATUS_CONNECTED:
    // XXX send keepalive
    break;
  }

  bzero(&tv, sizeof(struct timeval));
  tv.tv_sec = 2;
  event_add(cli->ev_timer, &tv);
}

int
cb_cli_send(void *data, int size, void *usrdata)
{
  struct gg_client *cli;

  cli = usrdata;
  return client_send(cli, data, size);
}

/*
 * Packets - private
 */

struct gg_packet *
pkt_decode(char **buf, int *buf_len)
{
  static struct gg_packet newpkt;
  struct gg_packet *pkt;
  int len;
  int packet_len;

  len = *buf_len;

#define invalid(msg) \
  { verbose(msg); goto invalid; }
#define incomplete(msg) \
  { verbose(msg); goto incomplete; }

  if (len < PACKET_HEADER_SIZE)
    invalid("len");
  if (len > PACKET_BUFFER_SIZE)
    invalid("len");
  pkt = (struct gg_packet *)*buf;
  if (pkt->ver != PACKET_VERSION)
    invalid("ver");
  if (pkt->type < PACKET_TYPE_MIN || pkt->type > PACKET_TYPE_MAX)
    invalid("type");
  packet_len = gg_packet_props[pkt->type].size; // XXX never overflow ?
  debug("type %d: %d %d", pkt->type, len, packet_len);
  if (len < packet_len)
    invalid("type len");

  newpkt.ver = pkt->ver;
  newpkt.type = pkt->type;
  switch(pkt->type) {
    case PACKET_NEWCONN:
      newpkt.newconn_id = ntohs(pkt->newconn_id);
      newpkt.newconn_src = ntohl(pkt->newconn_src);
      newpkt.newconn_dst = ntohl(pkt->newconn_dst);
      newpkt.newconn_proto = pkt->newconn_proto;
      newpkt.newconn_size = pkt->newconn_size;
      break;
    case PACKET_DELCONN:
      newpkt.delconn_id = ntohs(pkt->delconn_id);
      break;
    case PACKET_DATA:
      newpkt.data_connid = ntohs(pkt->data_connid);
      newpkt.data_size = pkt->data_size;
      break;
    case PACKET_NAME:
      newpkt.name_addr = ntohl(pkt->name_addr);
      newpkt.name_len = pkt->name_len;
      if (newpkt.name_len > GG_PKTARG_MAX)
        invalid("type name name_len");
      if (len < packet_len + newpkt.name_len)
        goto incomplete;
      packet_len = packet_len + newpkt.name_len;
      strncpy((char *)newpkt.name_fqdn, (char *)pkt->name_fqdn,
              newpkt.name_len);
      break;
    case PACKET_FORK:
      newpkt.fork_pid = ntohl(pkt->fork_pid);
      newpkt.fork_ppid = ntohl(pkt->fork_ppid);
      newpkt.fork_cpid = ntohl(pkt->fork_cpid);
      newpkt.fork_tgid = ntohl(pkt->fork_tgid);
      break;
    case PACKET_EXEC:
      newpkt.exec_pid = ntohl(pkt->exec_pid);
      newpkt.exec_cmdlen = pkt->exec_cmdlen;
      if (newpkt.exec_cmdlen > GG_PKTARG_MAX)
        invalid("type exec cmdlen");
      if (len < packet_len + newpkt.exec_cmdlen)
        goto incomplete;
      packet_len = packet_len + newpkt.exec_cmdlen;
      strncpy((char *)newpkt.exec_cmd, (char *)pkt->exec_cmd,
              newpkt.exec_cmdlen);
      break;
    case PACKET_EXIT:
      newpkt.exit_pid = ntohl(pkt->exit_pid);
      newpkt.exit_tgid = ntohl(pkt->exit_tgid);
      newpkt.exit_ecode = pkt->exit_ecode;
      break;
    default:
      goto invalid;
      invalid("type switch");
  }

  *buf = *buf + packet_len;
  *buf_len = len - packet_len;
  return &newpkt;

incomplete:
  error("incomplete packet");
  *buf_len = len;
  return NULL;

invalid:
  error("invalid packet");
  *buf_len = 0;
  return NULL;
}

/*
 * encodes a packet and returns the size before sending it on the wire.
 * it assumes that the packet contains correct content.
 */
int
pkt_encode(struct gg_packet *pkt, struct gg_packet *newpkt)
{
  if (pkt->type < PACKET_TYPE_MIN || pkt->type > PACKET_TYPE_MAX)
    invalid("type");

  newpkt->ver = pkt->ver;
  newpkt->type = pkt->type;
  switch(pkt->type) {
    case PACKET_NEWCONN:
      newpkt->newconn_id = htons(pkt->newconn_id);
      newpkt->newconn_src = htonl(pkt->newconn_src);
      newpkt->newconn_dst = htonl(pkt->newconn_dst);
      newpkt->newconn_proto = pkt->newconn_proto;
      newpkt->newconn_size = pkt->newconn_size;
      break;
    case PACKET_DELCONN:
      newpkt->delconn_id = htons(pkt->delconn_id);
      break;
    case PACKET_DATA:
      newpkt->data_connid = htons(pkt->data_connid);
      newpkt->data_size = pkt->data_size;
      break;
    case PACKET_NAME:
      if (pkt->name_len > GG_PKTARG_MAX)
        goto invalid;
      newpkt->name_addr = htonl(pkt->name_addr);
      newpkt->name_len = pkt->name_len;
      strncpy((char *)newpkt->name_fqdn, (char *)pkt->name_fqdn,
              pkt->name_len);
      break;
    case PACKET_FORK:
      newpkt->fork_pid = htonl(pkt->fork_pid);
      newpkt->fork_ppid = htonl(pkt->fork_ppid);
      newpkt->fork_cpid = htonl(pkt->fork_cpid);
      newpkt->fork_tgid = htonl(pkt->fork_tgid);
      break;
    case PACKET_EXEC:
      if (pkt->exec_cmdlen > GG_PKTARG_MAX)
        goto invalid;
      newpkt->exec_pid = htonl(pkt->exec_pid);
      newpkt->exec_cmdlen = pkt->exec_cmdlen;
      strncpy((char *)newpkt->exec_cmd, (char *)pkt->exec_cmd,
              pkt->exec_cmdlen);
      break;
    case PACKET_EXIT:
      newpkt->exit_pid = htonl(pkt->exit_pid);
      newpkt->exit_tgid = htonl(pkt->exit_tgid);
      newpkt->exit_ecode = pkt->exit_ecode;
      break;
    default:
      error("Unsupported packet type");
      return -1;
  }
  return pkt_getsize(newpkt);

invalid:
  error("invalid packet");
  return -1;
}

int
pkt_getsize(struct gg_packet *pkt)
{
  int packet_len;

  packet_len = gg_packet_props[pkt->type].size; // XXX never overflow ?
  switch(pkt->type) {
    case PACKET_NEWCONN:
    case PACKET_DELCONN:
    case PACKET_DATA:
    case PACKET_FORK:
    case PACKET_EXIT:
      break;
    case PACKET_NAME:
      if (pkt->name_len > GG_PKTARG_MAX)
        goto invalid;
      packet_len = packet_len + pkt->name_len;
      break;
    case PACKET_EXEC:
      if (pkt->exec_cmdlen > GG_PKTARG_MAX)
        goto invalid;
      packet_len = packet_len + pkt->exec_cmdlen;
      break;
    default:
      error("Unsupported packet type");
      return -1;
  }
  return packet_len;

invalid:
  error("invalid packet");
  return -1;
}

/*
 * Verbosity
 */

int
gg_verbosity_get(void)
{
  return _verbosity;
}

void
gg_verbosity_set(int verb)
{
  _verbosity = verb;
}