/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2005,2006,2007,2008 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
 * Copyright (©) 2002,2007 Mark Wedel & Crossfire Development Team
 * Copyright (©) 1992,2007 Frank Tore Johansen
 * 
 * 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>
 */

#include <cstdarg>
#include <cstring>

#include <vector>

#include <sys/uio.h>
#include <pthread.h>

#include "global.h"
#include "dynbuf.h"
#include "util.h"

struct logline
{
  struct timeval tv;
  char *buf; // includes PREFIX_LEN garbage bytes
  int len;
  int flags;
};

static SMUTEX(mutex);
static SCOND(cond);
static int logfd = STDERR_FILENO;
static int logsync = 1;
static std::vector<logline, slice_allocator<logline> > queue;

void set_logfd (int fd)
{
  SMUTEX_LOCK (mutex);
  logfd = fd < 0 ? STDERR_FILENO : fd;
  SMUTEX_UNLOCK (mutex);
}

#define PREFIX_LEN sizeof ("0000-00-00 00:00:00.0000+") - 1

static void
log_sync (logline &line)
{
  struct tm lt;
  char pfx [PREFIX_LEN];

  localtime_r (&line.tv.tv_sec, &lt);

  sprintf (pfx, "%04d-%02d-%02d %02d:%02d:%02d.%04d",
    lt.tm_year + 1900,
    lt.tm_mon + 1,
    lt.tm_mday,
    lt.tm_hour,
    lt.tm_min,
    lt.tm_sec,
    (int)(line.tv.tv_usec / 100)
  );

  pfx [PREFIX_LEN - 1] = line.flags & logSync ? '=' : ' ';

  struct iovec iov [2];

  iov [0].iov_base = pfx;
  iov [0].iov_len = PREFIX_LEN;

  char *buf = line.buf;

  while (char *end = strchr (buf, '\n'))
    {
      iov [1].iov_base = buf;
      iov [1].iov_len = end - buf + 1;

      writev (STDERR_FILENO, iov, 2);
      if (logfd != STDERR_FILENO)
        writev (logfd, iov, 2);

      buf = end + 1;

      if (buf == line.buf + line.len)
        break;

      pfx [PREFIX_LEN - 1] = '+';
    }

  sfree (line.buf, line.len);
}

static void *
logthread_proc (void *arg)
{
  int idx = 0;

  for (;;)
    {
      logline line;

      SMUTEX_LOCK (mutex);

      while (queue.empty ())
        SCOND_WAIT (cond, mutex);

      line = queue [idx++];

      // this algorithm could result in an ever-increasing vector
      // size if we log faster than we can write, but if that happens
      // we have bigger problems.
      if (idx == queue.size ())
        {
          queue.clear ();
          idx = 0;
        }

      SMUTEX_UNLOCK (mutex);

      log_sync (line);
    }
}

void
log_cleanup ()
{
  logsync = 1;

  for (;;)
    {
      int done;

      SMUTEX_LOCK (mutex);
      done = queue.empty ();
      SMUTEX_UNLOCK (mutex);

      if (done)
        break;

      usleep (10000);
    }
}

static void
af_child ()
{
  logsync = 1;
}

static struct logthread : thread
{
  logthread ()
  {
    pthread_atfork (0, 0, af_child);
    start (logthread_proc);
    logsync = 0;
  }
} logthread;

void
LOG (int flags, const char *format, ...)
{
  int level = flags & 15;

  if (level > settings.debug)
    return;

  logline line;
  gettimeofday (&line.tv, 0);

  static dynbuf_text buf;

  va_list ap;
  va_start (ap, format);
  buf.vprintf (format, ap);
  va_end (ap);

  buf << '\n';

  line.buf = buf.linearise ();
  line.len = buf.size ();

  if (line.buf [line.len - 2] == '\n')
    --line.len;

  line.buf = salloc<char> (line.len, line.buf);

  buf.clear ();

  if (logsync)
    flags |= logSync;

  if (flags & logBacktrace)
    {
      line.buf [line.len - 1] = 0;
      log_backtrace (line.buf);
      line.buf [line.len - 1] = '\n';
    }

  line.flags = flags;

  if (line.flags & logSync)
    log_sync (line);
  else
    {
      SMUTEX_LOCK (mutex);
      queue.push_back (line);
      SMUTEX_UNLOCK (mutex);
      SCOND_SIGNAL (cond);
    }
}