/*
 *  sydra
 *
 *  sydra is a toolbox which allows you to set up multiple bidirectional
 *  Video/Audio streams from external locations.
 *  sydra has been written to be used for the Elevate Festival in Graz
 *  Austria in order to involve external locations to present themselves
 *  at the festival.
 *  Sydra is based on GStreamer and is written in C.
 *
 *
 *  Copyright (C) 2014 Christian Pointner <equinox@spreadspace.org>
 *
 *  This file is part of sydra.
 *
 *  sydra is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  sydra is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with sydra. If not, see <http://www.gnu.org/licenses/>.
 *
 *  In addition, as a special exception, the copyright holders hereby
 *  grant permission for non-GPL-compatible GStreamer plugins to be used
 *  and distributed together with GStreamer and sydra.
 *  This permission goes above and beyond the permissions granted by the
 *  GPL license sydra is covered by.
 */

#include "datatypes.h"

#include <string.h>
#include <glib.h>
#include <glib-unix.h>
#include <gio/gio.h>
#include <gst/gst.h>

#include "utils.h"
#include "log.h"


#define UDP_PROTO_MAGIC "SYDRA:"
#define UDP_PROTO_MAGIC_LEN (sizeof(UDP_PROTO_MAGIC)-1)
#define UDP_PROTO_CMD_ADD_CLIENT "add_client\n"
#define UDP_PROTO_CMD_ADD_CLIENT_LEN (sizeof(UDP_PROTO_CMD_ADD_CLIENT)-1)
#define UDP_PROTO_CMD_RM_CLIENT "remove_client\n"
#define UDP_PROTO_CMD_RM_CLIENT_LEN (sizeof(UDP_PROTO_CMD_RM_CLIENT)-1)

static struct udp_client* udp_client_new(struct sockaddr_storage *addr, socklen_t addrlen)
{
  struct udp_client* client = g_new(struct udp_client, 1);
  if(!client) return NULL;

  switch(addr->ss_family)
  {
  case AF_INET: client->host_.type_ = IPv4; client->host_.port_ = ntohs(((struct sockaddr_in*)addr)->sin_port); break;
  case AF_INET6: client->host_.type_ = IPv6; client->host_.port_ = ntohs(((struct sockaddr_in6*)addr)->sin6_port); break;
  default: g_free(client); return NULL;
  }

  int errcode  = getnameinfo((struct sockaddr *)addr, addrlen, client->host_.addr_, sizeof(client->host_.addr_),
                             NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV);
  if (errcode != 0) {
    log_printf(WARNING, "getnameinfo() error: %s", gai_strerror(errcode));
    g_free(client);
    return NULL;
  }
  return client;
}

static void udpsink_add_client(struct sockaddr_storage *addr, socklen_t addrlen, struct udp_sink* sink)
{
  struct udp_client* client = udp_client_new(addr, addrlen);
  if(!client) return;

  GTimeVal now;
  g_get_current_time(&now);
  client->last_seen_ = GST_TIMEVAL_TO_TIME(now);

  GList* entry = g_list_find_custom(sink->clients_, client, cmp_udp_client);
  gchar* name = gst_element_get_name(sink->udp_);
  if(!entry) {
    log_printf(INFO, "adding host %s%c%d to list of receivers for element %s",
               client->host_.addr_, client->host_.type_ == IPv4 ? ':' : '.', client->host_.port_, name);
    g_signal_emit_by_name(G_OBJECT(sink->udp_), "add", client->host_.addr_, client->host_.port_, NULL);
    sink->clients_ = g_list_append(sink->clients_, client);
  } else {
    log_printf(DEBUG, "not adding host %s%c%d to list of receivers for element %s since it already exists",
               client->host_.addr_, client->host_.type_ == IPv4 ? ':' : '.', client->host_.port_, name);
    ((struct udp_client*)(entry->data))->last_seen_ = client->last_seen_;
    g_free(client);
  }
  g_free(name);
}

static void udpsink_remove_client(struct sockaddr_storage *addr, socklen_t addrlen, struct udp_sink* sink)
{
  struct udp_client* client = udp_client_new(addr, addrlen);
  if(!client) return;

  GList* removee = g_list_find_custom(sink->clients_, client, cmp_udp_client);
  gchar* name = gst_element_get_name(sink->udp_);
  if(!removee) {
    log_printf(WARNING, "client %s%c%d not found in client list for %s - nothing removed",
               client->host_.addr_, client->host_.type_ == IPv4 ? ':' : '.', client->host_.port_, name, name);
  } else {
    g_signal_emit_by_name(G_OBJECT(sink->udp_), "remove", client->host_.addr_, client->host_.port_, NULL);
    log_printf(INFO, "client %s%c%d removed from list of receivers for element %s (request)",
               client->host_.addr_, client->host_.type_ == IPv4 ? ':' : '.', client->host_.port_, name, name);
    gpointer rdata = removee->data;
    sink->clients_ = g_list_remove(sink->clients_, removee->data);
    g_free(rdata);
  }
  g_free(name);
  g_free(client);
}

static gboolean on_udp_desc_ready(gint fd, GIOCondition cond, gpointer user_data)
{
  struct udp_sink* sink = (struct udp_sink*)user_data;
  if(!sink || !(sink->udp_)) {
    log_printf(WARNING, "File descriptor %d is ready for reading - but supplied element is NULL removing callback", fd);
    return FALSE;
  }

  struct sockaddr_storage addr;
  socklen_t addrlen = sizeof(addr);
  u_int8_t buf[2048];
  ssize_t bytes = recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *)&addr, &addrlen);
  if(bytes < 1) {
    if(errno == EINTR)
      return TRUE;

    log_printf(WARNING, "Error while receiving UDP data on fd %d, will remove callback", fd);
    return FALSE;
  }

  if(bytes < UDP_PROTO_MAGIC_LEN || memcmp(UDP_PROTO_MAGIC, buf, UDP_PROTO_MAGIC_LEN)) {
    log_printf(DEBUG, "client discovery: ignoring invalid incoming packet");
    return TRUE;
  }

  u_int8_t* cmd = &(buf[UDP_PROTO_MAGIC_LEN]);
  if(bytes == (UDP_PROTO_MAGIC_LEN+UDP_PROTO_CMD_ADD_CLIENT_LEN) &&
     !memcmp(UDP_PROTO_CMD_ADD_CLIENT, cmd, UDP_PROTO_CMD_ADD_CLIENT_LEN)) {
    udpsink_add_client(&addr, addrlen, sink);
  } else if(bytes == (UDP_PROTO_MAGIC_LEN+UDP_PROTO_CMD_RM_CLIENT_LEN) &&
     !memcmp(UDP_PROTO_CMD_RM_CLIENT, cmd, UDP_PROTO_CMD_RM_CLIENT_LEN)) {
    udpsink_remove_client(&addr, addrlen, sink);
  } else {
    log_printf(DEBUG, "client discovery: ignoring invalid command");
  }
  return TRUE;
}

static void check_client_timeout(struct udp_sink* sink, int timeout)
{
  GTimeVal now;
  g_get_current_time(&now);
  GstClockTime timeout_time = GST_TIMEVAL_TO_TIME(now) - (timeout * GST_SECOND);

  GList *c = sink->clients_;
  while(c != NULL) {
    GList *next = c->next;
    struct udp_client* client = (struct udp_client*)c->data;
    if(client->last_seen_ < timeout_time) {
      g_signal_emit_by_name(G_OBJECT(sink->udp_), "remove", client->host_.addr_, client->host_.port_, NULL);
      gchar* name = gst_element_get_name(sink->udp_);
      log_printf(INFO, "client %s%c%d removed from list of receivers for element %s (timeout)",
                 client->host_.addr_, client->host_.type_ == IPv4 ? ':' : '.', client->host_.port_, name, name);
      g_free(name);
      g_free(c->data);
      sink->clients_ = g_list_delete_link(sink->clients_, c);
    }
    c = next;
  }
}

static gboolean check_all_client_timeouts(gpointer user_data)
{
  struct udp_sinks* sinks = (struct udp_sinks*)user_data;
  check_client_timeout(&(sinks->rtp_video_), sinks->client_timeout_);
  check_client_timeout(&(sinks->rtcp_video_), sinks->client_timeout_);
  check_client_timeout(&(sinks->rtp_audio_), sinks->client_timeout_);
  check_client_timeout(&(sinks->rtcp_audio_), sinks->client_timeout_);
  return TRUE;
}

static gboolean attach_udpsink(struct udp_sink* sink, const char* name, const char* prop)
{
  GSocket *sock;
  g_object_get(G_OBJECT(sink->udp_), prop, &sock, NULL);
  int fd = g_socket_get_fd(sock);

  guint id = g_unix_fd_add(fd, G_IO_IN, on_udp_desc_ready, sink);
  if(id <= 0) {
    log_printf(ERROR, "Error while adding %s file descriptor (%d) to main loop", name, fd);
    return FALSE;
  }
  log_printf(DEBUG, "successfully installed callback for %s (fd: %d) for reading (id: %d)", name, fd, id);
  return TRUE;
}

gboolean attach_udpsinks(struct udp_sinks *sinks)
{
  if(!sinks)
    return FALSE;

  if(!attach_udpsink(&(sinks->rtp_video_), "RTP(video) IPv4", "used-socket") ||
     !attach_udpsink(&(sinks->rtp_video_), "RTP(video) IPv6", "used-socket-v6") ||
     !attach_udpsink(&(sinks->rtcp_video_), "RTCP(video) IPv4", "used-socket") ||
     !attach_udpsink(&(sinks->rtcp_video_), "RTCP(video) IPv6", "used-socket-v6") ||
     !attach_udpsink(&(sinks->rtp_audio_), "RTP(audio) IPv4", "used-socket") ||
     !attach_udpsink(&(sinks->rtp_audio_), "RTP(audio) IPv6", "used-socket-v6") ||
     !attach_udpsink(&(sinks->rtcp_audio_), "RTCP(audio) IPv4", "used-socket") ||
     !attach_udpsink(&(sinks->rtcp_audio_), "RTCP(audio) IPv6", "used-socket-v6")) {
    return FALSE;
  }
  if(sinks->client_timeout_ > 0) {
    if(!g_timeout_add_seconds(1, check_all_client_timeouts, sinks))
      return FALSE;
  }

  return TRUE;
}

static gboolean send_keepalives(gpointer user_data)
{
  log_printf(WARNING, "sending keep alives is not yet supporet!");
  return TRUE;
}

gboolean attach_udpsources(struct udp_sources *sources)
{
  if(!sources)
    return FALSE;

  if(sources->keepalive_interval_ > 0) {
    send_keepalives(sources);
    if(!g_timeout_add_seconds(sources->keepalive_interval_, send_keepalives, sources))
      return FALSE;
  }

  return TRUE;
}