/* Copyright (C) 2012 Monty Program Ab

   This program 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; version 2 of the License.

   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 GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


#include "my_global.h"
#include <my_sys.h>
#include <mysql/service_logger.h>
#include <my_pthread.h>

#ifdef HAVE_PSI_INTERFACE
/* These belong to the service initialization */
static PSI_mutex_key key_LOCK_logger_service;
static PSI_mutex_info mutex_list[]=
{{ &key_LOCK_logger_service, "logger_service_file_st::lock", PSI_FLAG_GLOBAL}};
#endif

typedef struct logger_handle_st {
  File file;
  char path[FN_REFLEN];
  unsigned long long size_limit;
  unsigned int rotations;
  size_t path_len;
  mysql_mutex_t lock;
} LSFS;


#define LOG_FLAGS (O_APPEND | O_CREAT | O_WRONLY)

static unsigned int n_dig(unsigned int i)
{
  return (i == 0) ? 0 : ((i < 10) ? 1 : ((i < 100) ? 2 : 3));
}


LOGGER_HANDLE *logger_open(const char *path,
                           unsigned long long size_limit,
                           unsigned int rotations)
{
  LOGGER_HANDLE new_log, *l_perm;
  /*
    I don't think we ever need more rotations,
    but if it's so, the rotation procedure should be adapted to it.
  */
  if (rotations > 999)
    return 0;

  new_log.rotations= rotations;
  new_log.size_limit= size_limit;
  new_log.path_len= strlen(fn_format(new_log.path, path,
        mysql_data_home, "", MY_UNPACK_FILENAME));

  if (new_log.path_len+n_dig(rotations)+1 > FN_REFLEN)
  {
    errno= ENAMETOOLONG;
    /* File path too long */
    return 0;
  }
  if ((new_log.file= my_open(new_log.path, LOG_FLAGS, MYF(0))) < 0)
  {
    errno= my_errno;
    /* Check errno for the cause */
    return 0;
  }

  if (!(l_perm= (LOGGER_HANDLE *) my_malloc(sizeof(LOGGER_HANDLE), MYF(0))))
  {
    my_close(new_log.file, MYF(0));
    new_log.file= -1;
    return 0; /* End of memory */
  }
  *l_perm= new_log;
  mysql_mutex_init(key_LOCK_logger_service, &l_perm->lock, MY_MUTEX_INIT_FAST);
  return l_perm;
}

int logger_close(LOGGER_HANDLE *log)
{
  int result;
  File file= log->file;
  mysql_mutex_destroy(&log->lock);
  my_free(log);
  if ((result= my_close(file, MYF(0))))
    errno= my_errno;
  return result;
}


static char *logname(LOGGER_HANDLE *log, char *buf, unsigned int n_log)
{
  sprintf(buf+log->path_len, ".%0*u", n_dig(log->rotations), n_log);
  return buf;
}


static int do_rotate(LOGGER_HANDLE *log)
{
  char namebuf[FN_REFLEN];
  int result;
  unsigned int i;
  char *buf_old, *buf_new, *tmp;

  if (log->rotations == 0)
    return 0;

  memcpy(namebuf, log->path, log->path_len);

  buf_new= logname(log, namebuf, log->rotations);
  buf_old= log->path;
  for (i=log->rotations-1; i>0; i--)
  {
    logname(log, buf_old, i);
    if (!access(buf_old, F_OK) &&
        (result= my_rename(buf_old, buf_new, MYF(0))))
      goto exit;
    tmp= buf_old;
    buf_old= buf_new;
    buf_new= tmp;
  }
  if ((result= my_close(log->file, MYF(0))))
    goto exit;
  namebuf[log->path_len]= 0;
  result= my_rename(namebuf, logname(log, log->path, 1), MYF(0));
  log->file= my_open(namebuf, LOG_FLAGS, MYF(0));
exit:
  errno= my_errno;
  return log->file < 0 || result;
}


int logger_vprintf(LOGGER_HANDLE *log, const char* fmt, va_list ap)
{
  int result;
  my_off_t filesize;
  char cvtbuf[1024];
  size_t n_bytes;

  mysql_mutex_lock(&log->lock);
  if (log->rotations > 0)
    if ((filesize= my_tell(log->file, MYF(0))) == (my_off_t) -1 ||
        ((unsigned long long)filesize >= log->size_limit &&
         do_rotate(log)))
    {
      result= -1;
      errno= my_errno;
      goto exit; /* Log rotation needed but failed */
    }

  n_bytes= my_vsnprintf(cvtbuf, sizeof(cvtbuf), fmt, ap);
  if (n_bytes >= sizeof(cvtbuf))
    n_bytes= sizeof(cvtbuf) - 1;

  result= my_write(log->file, (uchar *) cvtbuf, n_bytes, MYF(0));

exit:
  mysql_mutex_unlock(&log->lock);
  return result;
}


int logger_write(LOGGER_HANDLE *log, const char *buffer, size_t size)
{
  int result;
  my_off_t filesize;

  mysql_mutex_lock(&log->lock);
  if (log->rotations > 0)
    if ((filesize= my_tell(log->file, MYF(0))) == (my_off_t) -1 ||
        ((unsigned long long)filesize >= log->size_limit &&
         do_rotate(log)))
    {
      result= -1;
      errno= my_errno;
      goto exit; /* Log rotation needed but failed */
    }

  result= my_write(log->file, (uchar *) buffer, size, MYF(0));

exit:
  mysql_mutex_unlock(&log->lock);
  return result;
}


int logger_rotate(LOGGER_HANDLE *log)
{
  int result;
  mysql_mutex_lock(&log->lock);
  result= do_rotate(log);
  mysql_mutex_unlock(&log->lock);
  return result;
}


int logger_printf(LOGGER_HANDLE *log, const char *fmt, ...)
{
  int result;
  va_list args;
  va_start(args,fmt);
  result= logger_vprintf(log, fmt, args);
  va_end(args);
  return result;
}

void logger_init_mutexes()
{
#ifdef HAVE_PSI_INTERFACE
  if (PSI_server)
    PSI_server->register_mutex("sql_logger", mutex_list, 1);
#endif
}