/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2005,2006,2007,2008,2009,2010,2011,2012 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
 * 
 * Deliantra is free software: you can redistribute it and/or modify it under
 * the terms of the Affero GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program 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 Affero GNU General Public License
 * and the GNU General Public License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * The authors can be reached via e-mail to <support@deliantra.net>
 */

/**
 * \file
 * Main client/server loops.
 *
 * \date 2003-12-02
 *
 * loop.c mainly deals with initialization and higher level socket
 * maintanance (checking for lost connections and if data has arrived.)
 */

#include <global.h>
#include <sproto.h>
#include <sockproto.h>

#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#include <unistd.h>
#include <arpa/inet.h>

#define BG_SCRUB_RATE 4 // how often to send a face in the background

#define MAX_QUEUE_DEPTH   50
#define MAX_QUEUE_BACKLOG 3.

void
client::reset_state ()
{
  if (!pl)
    return;

  pl->run_on  = 0;
  pl->fire_on = 0;
}

void
client::queue_command (packet_type *handler, char *data, int datalen)
{
  tstamp stamp = NOW;

  if (cmd_queue.size () >= MAX_QUEUE_DEPTH)
    {
      reset_state ();
      send_packet_printf ("drawinfo %d command queue overflow, ignoring.", NDI_RED);
    }
  else
    {
      cmd_queue.resize (cmd_queue.size () + 1);
      command &cmd = cmd_queue.back ();
      cmd.stamp   = stamp;
      cmd.handler = handler;
      cmd.data    = salloc<char> (datalen + 1, data);
      cmd.datalen = datalen;
    }
}

bool
client::handle_command ()
{
  if (!cmd_queue.empty ()
      && state == ST_PLAYING
      && pl->ob->speed_left > 0.f)
    {
      command &cmd = cmd_queue.front ();

      if (cmd.stamp + MAX_QUEUE_BACKLOG < NOW)
        {
          reset_state (); // the command might actually reset some movement state etc.

          if (pl)
            pl->failmsg (
               "Cannot keep up with your commands, ignoring them! "
               "H<Your character cannot keep up with the instructions you give G<him|her>. "
               "Try issuing commands slower, or, if G<he|she> is incapacitated (paralyzed and so on), "
               "wait till your character can act again.\n\nIf G<he|she> is permanently stuck, then "
               "try the B<suicide> command (or use B<chat> to ask somebody to B<invite> you out).>"
            );
        }
      else
        execute (cmd.handler, cmd.data, cmd.datalen);

      sfree<char> (cmd.data, cmd.datalen + 1);
      cmd_queue.pop_front ();
      return true;
    }
  else
    return false;
}

void
client::tick ()
{
  if (!pl || destroyed ())
    return;

  pl->dirty = true;

  /* Update the players stats once per tick.  More efficient than
   * sending them whenever they change, and probably just as useful
   */
  pl->need_updated_stats ();
  esrv_update_stats (pl);

  if (pl->ns->update_spells)
    esrv_update_spells (pl);

  sint32 weight = pl->ob->client_weight ();

  if (last_weight != weight)
    {
      pl->ob->update_stats ();
      esrv_update_item (UPD_WEIGHT, pl->ob, pl->ob);
    }

  draw_client_map (pl);

  if (update_look)
    esrv_draw_look (pl);

  mapinfo_queue_run ();

#if HAVE_TCP_INFO
  // check time of last ack, and, if too old, kill connection
  socklen_t len = sizeof (tcpi);

  if (!getsockopt (fd, IPPROTO_TCP, TCP_INFO, &tcpi, &len) && len == sizeof (tcpi))
    {
      if (tcpi.tcpi_snd_mss)
        mss = tcpi.tcpi_snd_mss;

#if 0
      fprintf (stderr, "uack %d ack %d lost %d ret %d fack %d sst %d cwnd %d mss %d pmtu %d advmss %d EXC %d\n",
               tcpi.tcpi_unacked,
               tcpi.tcpi_sacked,
               tcpi.tcpi_lost,
               tcpi.tcpi_retrans,
               tcpi.tcpi_fackets,
               tcpi.tcpi_snd_ssthresh, tcpi.tcpi_snd_cwnd, tcpi.tcpi_advmss, tcpi.tcpi_pmtu, tcpi.tcpi_advmss,
               
               tcpi.tcpi_snd_cwnd - (tcpi.tcpi_unacked - tcpi.tcpi_sacked));
#endif

      // fast-time-out a player by checking for missing acks
      // do this only when player is active
      if (pl && pl->active
          && tcpi.tcpi_last_ack_recv > int (socket_timeout * 1000))
        {
          send_msg (NDI_RED | NDI_REPLY, "connection-timeout", "safety disconnect due to tcp/ip timeout (no packets received)");
          write_outputbuffer ();

          LOG (llevDebug, "connection on fd %d closed due to ack timeout (%u/%u/%u)\n", fd,
               (unsigned)tcpi.tcpi_last_ack_recv, (unsigned)tcpi.tcpi_last_data_sent, (unsigned)tcpi.tcpi_unacked);
          destroy ();
        }
    }
#endif

  // limit budget surplus/deficit by one mss, add per-tick budget
  rate_avail = min (rate_avail, mss) + max_rate;

  int max_send = rate_avail;

#if HAVE_TCP_INFO
  // further restrict the available bandwidth by the excess bandwidth available
  min_it (max_send, (tcpi.tcpi_snd_cwnd - tcpi.tcpi_unacked + tcpi.tcpi_sacked) * mss);
#endif

  // round to next-lowest mss
  max_send -= max_send % mss;

  if (ixface.empty ())
    {
      // regularly send a new face when queue is empty
      if (bg_scrub && !--bg_scrub)
        while (scrub_idx < faces.size () - 1)
          {
            ++scrub_idx;

            if (!faces_sent [scrub_idx])
              if (faceinfo *f = face_info (scrub_idx))
                if (f->type == FT_FACE || f->type == FT_SOUND) // only scrub faces and sounds for now
                  {
                    send_face (scrub_idx, -120);
                    flush_fx ();

                    bg_scrub = 1; // send up to one fx per tick, unless an image was requested
                    break;
                  }
          }
    }
  else
    {
      bg_scrub = BG_SCRUB_RATE;

      for (;;)
        {
          int avail = max_send - outputbuffer_len ();

          if (avail <= 0)
            break;

          ixsend &ix = ixface.back ();

          if (facedata *d = face_data (ix.idx, faceset))
            {
              // estimate the packet header overhead "ix " + idx + (new)ofs
              int pktlen = 3 + ber32::encoded_size (ix.idx) + ber32::encoded_size (ix.ofs);
              int chunk = min (avail - packet::hdrlen, MAXSOCKBUF) - pktlen;

              // only transfer something if the amount of data transferred
              // has a healthy relation to the header overhead
              if (chunk < 64)
                break;

              chunk = min (chunk, (int)ix.ofs);

              ix.ofs -= chunk;

              //fprintf (stderr, "i%dx %6d: %5d+%4d   (%4d)\n", fxix, ix.idx,ix.ofs,chunk, ixface.size());//D

              packet sl ("ix");

              sl << ber32 (ix.idx)
                 << ber32 (ix.ofs)
                 << data (d->data + ix.ofs, chunk);

              send_packet (sl);
            }
          else
            ix.ofs = 0;

          if (!ix.ofs)
            {
              ixface.pop_back ();

              if (ixface.empty ())
                break;
            }
        }
    }

  rate_avail -= outputbuffer_len ();
}

void
client::flush_sockets ()
{
  for (sockvec::iterator i = clients.begin (); i != clients.end (); ++i)
    (*i)->flush ();
}

void
client::clock ()
{
  for (sockvec::iterator i = clients.begin (); i != clients.end (); ++i)
    (*i)->tick ();

  // give them all the same chances
  flush_sockets ();

  //TODO: should not be done here, either
  for (unsigned i = 0; i < clients.size (); ++i)
    clients[i]->refcnt_chk ();
}