piwigo_ynh/sources/include/functions.inc.php

<?php
// +-----------------------------------------------------------------------+
// | Piwigo - a PHP based photo gallery                                    |
// +-----------------------------------------------------------------------+
// | Copyright(C) 2008-2016 Piwigo Team                  http://piwigo.org |
// | Copyright(C) 2003-2008 PhpWebGallery Team    http://phpwebgallery.net |
// | Copyright(C) 2002-2003 Pierrick LE GALL   http://le-gall.net/pierrick |
// +-----------------------------------------------------------------------+
// | 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                                          |
// |                                                                       |
// | 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.                                                                  |
// +-----------------------------------------------------------------------+

/**
 * @package functions\___
 */

include_once( PHPWG_ROOT_PATH .'include/functions_plugins.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_user.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_cookie.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_session.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_category.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_html.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_tag.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/functions_url.inc.php' );
include_once( PHPWG_ROOT_PATH .'include/derivative_params.inc.php');
include_once( PHPWG_ROOT_PATH .'include/derivative_std_params.inc.php');
include_once( PHPWG_ROOT_PATH .'include/derivative.inc.php');


/**
 * returns the current microsecond since Unix epoch
 *
 * @return int
 */
function micro_seconds()
{
  $t1 = explode(' ', microtime());
  $t2 = explode('.', $t1[0]);
  $t2 = $t1[1].substr($t2[1], 0, 6);
  return $t2;
}

/**
 * returns a float value coresponding to the number of seconds since
 * the unix epoch (1st January 1970) and the microseconds are precised
 * e.g. 1052343429.89276600
 *
 * @return float
 */
function get_moment()
{
  return microtime(true);
}

/**
 * returns the number of seconds (with 3 decimals precision)
 * between the start time and the end time given
 *
 * @param float $start
 * @param float $end
 * @return string "$TIME s"
 */
function get_elapsed_time($start, $end)
{
  return number_format($end - $start, 3, '.', ' ').' s';
}

/**
 * returns the part of the string after the last "."
 *
 * @param string $filename
 * @return string
 */
function get_extension( $filename )
{
  return substr( strrchr( $filename, '.' ), 1, strlen ( $filename ) );
}

/**
 * returns the part of the string before the last ".".
 * get_filename_wo_extension( 'test.tar.gz' ) = 'test.tar'
 *
 * @param string $filename
 * @return string
 */
function get_filename_wo_extension( $filename )
{
  $pos = strrpos( $filename, '.' );
  return ($pos===false) ? $filename : substr( $filename, 0, $pos);
}

/** no option for mkgetdir() */
define('MKGETDIR_NONE', 0);
/** sets mkgetdir() recursive */
define('MKGETDIR_RECURSIVE', 1);
/** sets mkgetdir() exit script on error */
define('MKGETDIR_DIE_ON_ERROR', 2);
/** sets mkgetdir() add a index.htm file */
define('MKGETDIR_PROTECT_INDEX', 4);
/** sets mkgetdir() add a .htaccess file*/
define('MKGETDIR_PROTECT_HTACCESS', 8);
/** default options for mkgetdir() = MKGETDIR_RECURSIVE | MKGETDIR_DIE_ON_ERROR | MKGETDIR_PROTECT_INDEX */
define('MKGETDIR_DEFAULT', MKGETDIR_RECURSIVE | MKGETDIR_DIE_ON_ERROR | MKGETDIR_PROTECT_INDEX);

/**
 * creates directory if not exists and ensures that directory is writable
 *
 * @param string $dir
 * @param int $flags combination of MKGETDIR_xxx
 * @return bool
 */
function mkgetdir($dir, $flags=MKGETDIR_DEFAULT)
{
  if ( !is_dir($dir) )
  {
    global $conf;
    if (substr(PHP_OS, 0, 3) == 'WIN')
    {
      $dir = str_replace('/', DIRECTORY_SEPARATOR, $dir);
    }
    $umask = umask(0);
    $mkd = @mkdir($dir, $conf['chmod_value'], ($flags&MKGETDIR_RECURSIVE) ? true:false );
    umask($umask);
    if ($mkd==false)
    {
      !($flags&MKGETDIR_DIE_ON_ERROR) or fatal_error( "$dir ".l10n('no write access'));
      return false;
    }
    if( $flags&MKGETDIR_PROTECT_HTACCESS )
    {
      $file = $dir.'/.htaccess';
      file_exists($file) or @file_put_contents( $file, 'deny from all' );
    }
    if( $flags&MKGETDIR_PROTECT_INDEX )
    {
      $file = $dir.'/index.htm';
      file_exists($file) or @file_put_contents( $file, 'Not allowed!' );
    }
  }
  if ( !is_writable($dir) )
  {
    !($flags&MKGETDIR_DIE_ON_ERROR) or fatal_error( "$dir ".l10n('no write access'));
    return false;
  }
  return true;
}

/**
 * finds out if a string is in ASCII, UTF-8 or other encoding
 *
 * @param string $str
 * @return int *0* if _$str_ is ASCII, *1* if UTF-8, *-1* otherwise
 */
function qualify_utf8($Str)
{
  $ret = 0;
  for ($i=0; $i<strlen($Str); $i++)
  {
    if (ord($Str[$i]) < 0x80) continue; # 0bbbbbbb
    $ret = 1;
    if ((ord($Str[$i]) & 0xE0) == 0xC0) $n=1; # 110bbbbb
    elseif ((ord($Str[$i]) & 0xF0) == 0xE0) $n=2; # 1110bbbb
    elseif ((ord($Str[$i]) & 0xF8) == 0xF0) $n=3; # 11110bbb
    elseif ((ord($Str[$i]) & 0xFC) == 0xF8) $n=4; # 111110bb
    elseif ((ord($Str[$i]) & 0xFE) == 0xFC) $n=5; # 1111110b
    else return -1; # Does not match any model
    for ($j=0; $j<$n; $j++)
    { # n bytes matching 10bbbbbb follow ?
      if ((++$i == strlen($Str)) || ((ord($Str[$i]) & 0xC0) != 0x80))
        return -1;
    }
  }
  return $ret;
}

/**
 * Remove accents from a UTF-8 or ISO-8859-1 string (from wordpress)
 *
 * @param string $string
 * @return string
 */
function remove_accents($string)
{
  $utf = qualify_utf8($string);
  if ( $utf == 0 )
  {
    return $string; // ascii
  }

  if ( $utf > 0 )
  {
    $chars = array(
    // Decompositions for Latin-1 Supplement
    "\xc3\x80"=>'A', "\xc3\x81"=>'A',
    "\xc3\x82"=>'A', "\xc3\x83"=>'A',
    "\xc3\x84"=>'A', "\xc3\x85"=>'A',
    "\xc3\x87"=>'C', "\xc3\x88"=>'E',
    "\xc3\x89"=>'E', "\xc3\x8a"=>'E',
    "\xc3\x8b"=>'E', "\xc3\x8c"=>'I',
    "\xc3\x8d"=>'I', "\xc3\x8e"=>'I',
    "\xc3\x8f"=>'I', "\xc3\x91"=>'N',
    "\xc3\x92"=>'O', "\xc3\x93"=>'O',
    "\xc3\x94"=>'O', "\xc3\x95"=>'O',
    "\xc3\x96"=>'O', "\xc3\x99"=>'U',
    "\xc3\x9a"=>'U', "\xc3\x9b"=>'U',
    "\xc3\x9c"=>'U', "\xc3\x9d"=>'Y',
    "\xc3\x9f"=>'s', "\xc3\xa0"=>'a',
    "\xc3\xa1"=>'a', "\xc3\xa2"=>'a',
    "\xc3\xa3"=>'a', "\xc3\xa4"=>'a',
    "\xc3\xa5"=>'a', "\xc3\xa7"=>'c',
    "\xc3\xa8"=>'e', "\xc3\xa9"=>'e',
    "\xc3\xaa"=>'e', "\xc3\xab"=>'e',
    "\xc3\xac"=>'i', "\xc3\xad"=>'i',
    "\xc3\xae"=>'i', "\xc3\xaf"=>'i',
    "\xc3\xb1"=>'n', "\xc3\xb2"=>'o',
    "\xc3\xb3"=>'o', "\xc3\xb4"=>'o',
    "\xc3\xb5"=>'o', "\xc3\xb6"=>'o',
    "\xc3\xb9"=>'u', "\xc3\xba"=>'u',
    "\xc3\xbb"=>'u', "\xc3\xbc"=>'u',
    "\xc3\xbd"=>'y', "\xc3\xbf"=>'y',
    // Decompositions for Latin Extended-A
    "\xc4\x80"=>'A', "\xc4\x81"=>'a',
    "\xc4\x82"=>'A', "\xc4\x83"=>'a',
    "\xc4\x84"=>'A', "\xc4\x85"=>'a',
    "\xc4\x86"=>'C', "\xc4\x87"=>'c',
    "\xc4\x88"=>'C', "\xc4\x89"=>'c',
    "\xc4\x8a"=>'C', "\xc4\x8b"=>'c',
    "\xc4\x8c"=>'C', "\xc4\x8d"=>'c',
    "\xc4\x8e"=>'D', "\xc4\x8f"=>'d',
    "\xc4\x90"=>'D', "\xc4\x91"=>'d',
    "\xc4\x92"=>'E', "\xc4\x93"=>'e',
    "\xc4\x94"=>'E', "\xc4\x95"=>'e',
    "\xc4\x96"=>'E', "\xc4\x97"=>'e',
    "\xc4\x98"=>'E', "\xc4\x99"=>'e',
    "\xc4\x9a"=>'E', "\xc4\x9b"=>'e',
    "\xc4\x9c"=>'G', "\xc4\x9d"=>'g',
    "\xc4\x9e"=>'G', "\xc4\x9f"=>'g',
    "\xc4\xa0"=>'G', "\xc4\xa1"=>'g',
    "\xc4\xa2"=>'G', "\xc4\xa3"=>'g',
    "\xc4\xa4"=>'H', "\xc4\xa5"=>'h',
    "\xc4\xa6"=>'H', "\xc4\xa7"=>'h',
    "\xc4\xa8"=>'I', "\xc4\xa9"=>'i',
    "\xc4\xaa"=>'I', "\xc4\xab"=>'i',
    "\xc4\xac"=>'I', "\xc4\xad"=>'i',
    "\xc4\xae"=>'I', "\xc4\xaf"=>'i',
    "\xc4\xb0"=>'I', "\xc4\xb1"=>'i',
    "\xc4\xb2"=>'IJ', "\xc4\xb3"=>'ij',
    "\xc4\xb4"=>'J', "\xc4\xb5"=>'j',
    "\xc4\xb6"=>'K', "\xc4\xb7"=>'k',
    "\xc4\xb8"=>'k', "\xc4\xb9"=>'L',
    "\xc4\xba"=>'l', "\xc4\xbb"=>'L',
    "\xc4\xbc"=>'l', "\xc4\xbd"=>'L',
    "\xc4\xbe"=>'l', "\xc4\xbf"=>'L',
    "\xc5\x80"=>'l', "\xc5\x81"=>'L',
    "\xc5\x82"=>'l', "\xc5\x83"=>'N',
    "\xc5\x84"=>'n', "\xc5\x85"=>'N',
    "\xc5\x86"=>'n', "\xc5\x87"=>'N',
    "\xc5\x88"=>'n', "\xc5\x89"=>'N',
    "\xc5\x8a"=>'n', "\xc5\x8b"=>'N',
    "\xc5\x8c"=>'O', "\xc5\x8d"=>'o',
    "\xc5\x8e"=>'O', "\xc5\x8f"=>'o',
    "\xc5\x90"=>'O', "\xc5\x91"=>'o',
    "\xc5\x92"=>'OE', "\xc5\x93"=>'oe',
    "\xc5\x94"=>'R', "\xc5\x95"=>'r',
    "\xc5\x96"=>'R', "\xc5\x97"=>'r',
    "\xc5\x98"=>'R', "\xc5\x99"=>'r',
    "\xc5\x9a"=>'S', "\xc5\x9b"=>'s',
    "\xc5\x9c"=>'S', "\xc5\x9d"=>'s',
    "\xc5\x9e"=>'S', "\xc5\x9f"=>'s',
    "\xc5\xa0"=>'S', "\xc5\xa1"=>'s',
    "\xc5\xa2"=>'T', "\xc5\xa3"=>'t',
    "\xc5\xa4"=>'T', "\xc5\xa5"=>'t',
    "\xc5\xa6"=>'T', "\xc5\xa7"=>'t',
    "\xc5\xa8"=>'U', "\xc5\xa9"=>'u',
    "\xc5\xaa"=>'U', "\xc5\xab"=>'u',
    "\xc5\xac"=>'U', "\xc5\xad"=>'u',
    "\xc5\xae"=>'U', "\xc5\xaf"=>'u',
    "\xc5\xb0"=>'U', "\xc5\xb1"=>'u',
    "\xc5\xb2"=>'U', "\xc5\xb3"=>'u',
    "\xc5\xb4"=>'W', "\xc5\xb5"=>'w',
    "\xc5\xb6"=>'Y', "\xc5\xb7"=>'y',
    "\xc5\xb8"=>'Y', "\xc5\xb9"=>'Z',
    "\xc5\xba"=>'z', "\xc5\xbb"=>'Z',
    "\xc5\xbc"=>'z', "\xc5\xbd"=>'Z',
    "\xc5\xbe"=>'z', "\xc5\xbf"=>'s',
    // Decompositions for Latin Extended-B
    "\xc8\x98"=>'S', "\xc8\x99"=>'s',
    "\xc8\x9a"=>'T', "\xc8\x9b"=>'t',
    // Euro Sign
    "\xe2\x82\xac"=>'E',
    // GBP (Pound) Sign
    "\xc2\xa3"=>'');

    $string = strtr($string, $chars);
  }
  else
  {
    // Assume ISO-8859-1 if not UTF-8
    $chars['in'] = chr(128).chr(131).chr(138).chr(142).chr(154).chr(158)
      .chr(159).chr(162).chr(165).chr(181).chr(192).chr(193).chr(194)
      .chr(195).chr(196).chr(197).chr(199).chr(200).chr(201).chr(202)
      .chr(203).chr(204).chr(205).chr(206).chr(207).chr(209).chr(210)
      .chr(211).chr(212).chr(213).chr(214).chr(216).chr(217).chr(218)
      .chr(219).chr(220).chr(221).chr(224).chr(225).chr(226).chr(227)
      .chr(228).chr(229).chr(231).chr(232).chr(233).chr(234).chr(235)
      .chr(236).chr(237).chr(238).chr(239).chr(241).chr(242).chr(243)
      .chr(244).chr(245).chr(246).chr(248).chr(249).chr(250).chr(251)
      .chr(252).chr(253).chr(255);

    $chars['out'] = "EfSZszYcYuAAAAAACEEEEIIIINOOOOOOUUUUYaaaaaaceeeeiiiinoooooouuuuyy";

    $string = strtr($string, $chars['in'], $chars['out']);
    $double_chars['in'] = array(chr(140), chr(156), chr(198), chr(208), chr(222), chr(223), chr(230), chr(240), chr(254));
    $double_chars['out'] = array('OE', 'oe', 'AE', 'DH', 'TH', 'ss', 'ae', 'dh', 'th');
    $string = str_replace($double_chars['in'], $double_chars['out'], $string);
  }

  return $string;
}

if (function_exists('mb_strtolower') && defined('PWG_CHARSET'))
{
  /**
   * removes accents from a string and converts it to lower case
   *
   * @param string $term
   * @return string
   */
  function transliterate($term)
  {
    return remove_accents( mb_strtolower($term, PWG_CHARSET) );
  }
}
else
{
  /**
   * @ignore
   */
  function transliterate($term)
  {
    return remove_accents( strtolower($term) );
  }
}

/**
 * simplify a string to insert it into an URL
 *
 * @param string $str
 * @return string
 */
function str2url($str)
{
  $str = $safe = transliterate($str);
  $str = preg_replace('/[^\x80-\xffa-z0-9_\s\'\:\/\[\],-]/','',$str);
  $str = preg_replace('/[\s\'\:\/\[\],-]+/',' ',trim($str));
  $res = str_replace(' ','_',$str);

  if (empty($res))
  {
    $res = str_replace(' ','_', $safe);
  }

  return $res;
}

/**
 * returns an array with a list of {language_code => language_name}
 *
 * @return string[]
 */
function get_languages()
{
  $query = '
SELECT id, name
  FROM '.LANGUAGES_TABLE.'
  ORDER BY name ASC
;';
  $result = pwg_query($query);

  $languages = array();
  while ($row = pwg_db_fetch_assoc($result))
  {
    if (is_dir(PHPWG_ROOT_PATH.'language/'.$row['id']))
    {
      $languages[ $row['id'] ] = $row['name'];
    }
  }

  return $languages;
}

/**
 * log the visit into history table
 *
 * @param int $image_id
 * @param string $image_type
 * @return bool
 */
function pwg_log($image_id = null, $image_type = null, $format_id = null)
{
  global $conf, $user, $page;

  $do_log = $conf['log'];
  if (is_admin())
  {
    $do_log = $conf['history_admin'];
  }
  if (is_a_guest())
  {
    $do_log = $conf['history_guest'];
  }

  $do_log = trigger_change('pwg_log_allowed', $do_log, $image_id, $image_type);

  if (!$do_log)
  {
    return false;
  }

  $tags_string = null;
  if ('tags'==@$page['section'])
  {
    $tags_string = implode(',', $page['tag_ids']);
  }

  $ip = $_SERVER['REMOTE_ADDR'];
  // In case of "too long" ipv6 address, we take only the 15 first chars.
  //
  // It would be "cleaner" to increase length of history.IP to 50 chars, but
  // the alter table is very long on such a big table. We should plan this
  // for a future version, once history table is kept "smaller".
  if (strpos($ip,':') !== false and strlen($ip) > 15)
  {
    $ip = substr($ip, 0, 15);
  }

  $query = '
INSERT INTO '.HISTORY_TABLE.'
  (
    date,
    time,
    user_id,
    IP,
    section,
    category_id,
    image_id,
    image_type,
    format_id,
    auth_key_id,
    tag_ids
  )
  VALUES
  (
    CURRENT_DATE,
    CURRENT_TIME,
    '.$user['id'].',
    \''.$ip.'\',
    '.(isset($page['section']) ? "'".$page['section']."'" : 'NULL').',
    '.(isset($page['category']['id']) ? $page['category']['id'] : 'NULL').',
    '.(isset($image_id) ? $image_id : 'NULL').',
    '.(isset($image_type) ? "'".$image_type."'" : 'NULL').',
    '.(isset($format_id) ? $format_id : 'NULL').',
    '.(isset($page['auth_key_id']) ? $page['auth_key_id'] : 'NULL').',
    '.(isset($tags_string) ? "'".$tags_string."'" : 'NULL').'
  )
;';
  pwg_query($query);

  return true;
}

/**
 * Computes the difference between two dates.
 * returns a DateInterval object or a stdClass with the same attributes
 * http://stephenharris.info/date-intervals-in-php-5-2
 *
 * @param DateTime $date1
 * @param DateTime $date2
 * @return DateInterval|stdClass
 */
function dateDiff($date1, $date2)
{
  if (version_compare(PHP_VERSION, '5.3.0') >= 0)
  {
    return $date1->diff($date2);
  }

  $diff = new stdClass();

  //Make sure $date1 is ealier
  $diff->invert = $date2 < $date1;
  if ($diff->invert)
  {
    list($date1, $date2) = array($date2, $date1);
  }

  //Calculate R values
  $R = ($date1 <= $date2 ? '+' : '-');
  $r = ($date1 <= $date2 ? '' : '-');

  //Calculate total days
  $diff->days = round(abs($date1->format('U') - $date2->format('U'))/86400);

  //A leap year work around - consistent with DateInterval
  $leap_year = $date1->format('m-d') == '02-29';
  if ($leap_year)
  {
    $date1->modify('-1 day');
  }

  //Years, months, days, hours
  $periods = array('years'=>-1, 'months'=>-1, 'days'=>-1, 'hours'=>-1);

  foreach ($periods as $period => &$i)
  {
    if ($period == 'days' && $leap_year)
    {
      $date1->modify('+1 day');
    }

    while ($date1 <= $date2 )
    {
      $date1->modify('+1 '.$period);
      $i++;
    }

    //Reset date and record increments
    $date1->modify('-1 '.$period);
  }

  list($diff->y, $diff->m, $diff->d, $diff->h) = array_values($periods);

  //Minutes, seconds
  $diff->s = round(abs($date1->format('U') - $date2->format('U')));
  $diff->i = floor($diff->s/60);
  $diff->s = $diff->s - $diff->i*60;

  return $diff;
}

/**
 * converts a string into a DateTime object
 *
 * @param int|string timestamp or datetime string
 * @param string $format input format respecting date() syntax
 * @return DateTime|false
 */
function str2DateTime($original, $format=null)
{
  if (empty($original))
  {
    return false;
  }
  
  if ($original instanceof DateTime)
  {
    return $original;
  }

  if (!empty($format) && version_compare(PHP_VERSION, '5.3.0') >= 0)// from known date format
  {
    return DateTime::createFromFormat('!'.$format, $original); // ! char to reset fields to UNIX epoch
  }
  else
  {
    $t = trim($original, '0123456789');
    if (empty($t)) // from timestamp
    {
      return new DateTime('@'.$original);
    }
    else // from unknown date format (assuming something like Y-m-d H:i:s)
    {
      $ymdhms = array();
      $tok = strtok($original, '- :/');
      while ($tok !== false)
      {
        $ymdhms[] = $tok;
        $tok = strtok('- :/');
      }

      if (count($ymdhms)<3) return false;
      if (!isset($ymdhms[3])) $ymdhms[3] = 0;
      if (!isset($ymdhms[4])) $ymdhms[4] = 0;
      if (!isset($ymdhms[5])) $ymdhms[5] = 0;

      $date = new DateTime();
      $date->setDate($ymdhms[0], $ymdhms[1], $ymdhms[2]);
      $date->setTime($ymdhms[3], $ymdhms[4], $ymdhms[5]);
      return $date;
    }
  }
}

/**
 * returns a formatted and localized date for display
 *
 * @param int|string timestamp or datetime string
 * @param array $show list of components displayed, default is ['day_name', 'day', 'month', 'year']
 *    THIS PARAMETER IS PLANNED TO CHANGE
 * @param string $format input format respecting date() syntax
 * @return string
 */
function format_date($original, $show=null, $format=null)
{
  global $lang;

  $date = str2DateTime($original, $format);

  if (!$date)
  {
    return l10n('N/A');
  }

  if ($show === null || $show === true)
  {
    $show = array('day_name', 'day', 'month', 'year');
  }

  // TODO use IntlDateFormatter for proper i18n

  $print = '';
  if (in_array('day_name', $show))
    $print.= $lang['day'][ $date->format('w') ].' ';

  if (in_array('day', $show))
    $print.= $date->format('j').' ';

  if (in_array('month', $show))
    $print.= $lang['month'][ $date->format('n') ].' ';

  if (in_array('year', $show))
    $print.= $date->format('Y').' ';

  if (in_array('time', $show))
  {
    $temp = $date->format('H:i');
    if ($temp != '00:00')
    {
      $print.= $temp.' ';
    }
  }

  return trim($print);
}

/**
 * Format a "From ... to ..." string from two dates
 * @param string $from
 * @param string $to
 * @param boolean $full
 * @return string
 */
function format_fromto($from, $to, $full=false)
{
  $from = str2DateTime($from);
  $to = str2DateTime($to);

  if ($from->format('Y-m-d') == $to->format('Y-m-d'))
  {
    return format_date($from);
  }
  else
  {
    if ($full || $from->format('Y') != $to->format('Y'))
    {
      $from_str = format_date($from);
    }
    else if ($from->format('m') != $to->format('m'))
    {
      $from_str = format_date($from, array('day_name', 'day', 'month'));
    }
    else
    {
      $from_str = format_date($from, array('day_name', 'day'));
    }
    $to_str = format_date($to);

    return l10n('from %s to %s', $from_str, $to_str);
  }
}

/**
 * Works out the time since the given date
 *
 * @param int|string timestamp or datetime string
 * @param string $stop year,month,week,day,hour,minute,second
 * @param string $format input format respecting date() syntax
 * @param bool $with_text append "ago" or "in the future"
 * @param bool $with_weeks
 * @return string
 */
function time_since($original, $stop='minute', $format=null, $with_text=true, $with_week=true)
{
  $date = str2DateTime($original, $format);

  if (!$date)
  {
    return l10n('N/A');
  }

  $now = new DateTime();
  $diff = dateDiff($now, $date);

  $chunks = array(
    'year' => $diff->y,
    'month' => $diff->m,
    'week' => 0,
    'day' => $diff->d,
    'hour' => $diff->h,
    'minute' => $diff->i,
    'second' => $diff->s,
  );

  // DateInterval does not contain the number of weeks
  if ($with_week)
  {
    $chunks['week'] = (int)floor($chunks['day']/7);
    $chunks['day'] = $chunks['day'] - $chunks['week']*7;
  }

  $j = array_search($stop, array_keys($chunks));

  $print = ''; $i=0;
  foreach ($chunks as $name => $value)
  {
    if ($value != 0)
    {
      $print.= ' '.l10n_dec('%d '.$name, '%d '.$name.'s', $value);
    }
    if (!empty($print) && $i >= $j)
    {
      break;
    }
    $i++;
  }

  $print = trim($print);

  if ($with_text)
  {
    if ($diff->invert)
    {
      $print = l10n('%s ago', $print);
    }
    else
    {
      $print = l10n('%s in the future', $print);
    }
  }

  return $print;
}

/**
 * transform a date string from a format to another (MySQL to d/M/Y for instance)
 *
 * @param string $original
 * @param string $format_in respecting date() syntax
 * @param string $format_out respecting date() syntax
 * @param string $default if _$original_ is empty
 * @return string
 */
function transform_date($original, $format_in, $format_out, $default=null)
{
  if (empty($original)) return $default;
  $date = str2DateTime($original, $format_in);
  return $date->format($format_out);
}

/**
 * append a variable to _$debug_ global
 *
 * @param string $string
 */
function pwg_debug( $string )
{
  global $debug,$t2,$page;

  $now = explode( ' ', microtime() );
  $now2 = explode( '.', $now[0] );
  $now2 = $now[1].'.'.$now2[1];
  $time = number_format( $now2 - $t2, 3, '.', ' ').' s';
  $debug .= '<p>';
  $debug.= '['.$time.', ';
  $debug.= $page['count_queries'].' queries] : '.$string;
  $debug.= "</p>\n";
}

/**
 * Redirects to the given URL (HTTP method).
 * once this function called, the execution doesn't go further
 * (presence of an exit() instruction.
 *
 * @param string $url
 * @return void
 */
function redirect_http( $url )
{
  if (ob_get_length () !== FALSE)
  {
    ob_clean();
  }
  // default url is on html format
  $url = html_entity_decode($url);
  header('Request-URI: '.$url);
  header('Content-Location: '.$url);
  header('Location: '.$url);
  exit();
}

/**
 * Redirects to the given URL (HTML method).
 * once this function called, the execution doesn't go further
 * (presence of an exit() instruction.
 *
 * @param string $url
 * @param string $msg
 * @param integer $refresh_time
 * @return void
 */
function redirect_html( $url , $msg = '', $refresh_time = 0)
{
  global $user, $template, $lang_info, $conf, $lang, $t2, $page, $debug;

  if (!isset($lang_info) || !isset($template) )
  {
    $user = build_user( $conf['guest_id'], true);
    load_language('common.lang');
    trigger_notify('loading_lang');
    load_language('lang', PHPWG_ROOT_PATH.PWG_LOCAL_DIR, array('no_fallback'=>true, 'local'=>true) );
    $template = new Template(PHPWG_ROOT_PATH.'themes', get_default_theme());
  }
	elseif (defined('IN_ADMIN') and IN_ADMIN)
	{
		$template = new Template(PHPWG_ROOT_PATH.'themes', get_default_theme());
	}

  if (empty($msg))
  {
    $msg = nl2br(l10n('Redirection...'));
  }

  $refresh = $refresh_time;
  $url_link = $url;
  $title = 'redirection';

  $template->set_filenames( array( 'redirect' => 'redirect.tpl' ) );

  include( PHPWG_ROOT_PATH.'include/page_header.php' );

  $template->set_filenames( array( 'redirect' => 'redirect.tpl' ) );
  $template->assign('REDIRECT_MSG', $msg);

  $template->parse('redirect');

  include( PHPWG_ROOT_PATH.'include/page_tail.php' );

  exit();
}

/**
 * Redirects to the given URL (automatically choose HTTP or HTML method).
 * once this function called, the execution doesn't go further
 * (presence of an exit() instruction.
 *
 * @param string $url
 * @param string $msg
 * @param integer $refresh_time
 * @return void
 */
function redirect( $url , $msg = '', $refresh_time = 0)
{
  global $conf;

  // with RefeshTime <> 0, only html must be used
  if ($conf['default_redirect_method']=='http'
      and $refresh_time==0
      and !headers_sent()
    )
  {
    redirect_http($url);
  }
  else
  {
    redirect_html($url, $msg, $refresh_time);
  }
}

/**
 * returns available themes
 *
 * @param bool $show_mobile
 * @return array
 */
function get_pwg_themes($show_mobile=false)
{
  global $conf;

  $themes = array();

  $query = '
SELECT
    id,
    name
  FROM '.THEMES_TABLE.'
  ORDER BY name ASC
;';
  $result = pwg_query($query);
  while ($row = pwg_db_fetch_assoc($result))
  {
    if ($row['id'] == $conf['mobile_theme'])
    {
      if (!$show_mobile)
      {
        continue;
      }
      $row['name'] .= ' ('.l10n('Mobile').')';
    }
    if (check_theme_installed($row['id']))
    {
      $themes[ $row['id'] ] = $row['name'];
    }
  }

  // plugins want remove some themes based on user status maybe?
  $themes = trigger_change('get_pwg_themes', $themes);

  return $themes;
}

/**
 * check if a theme is installed (directory exsists)
 *
 * @param string $theme_id
 * @return bool
 */
function check_theme_installed($theme_id)
{
  global $conf;

  return file_exists($conf['themes_dir'].'/'.$theme_id.'/'.'themeconf.inc.php');
}

/**
 * Transforms an original path to its pwg representative
 *
 * @param string $path
 * @param string $representative_ext
 * @return string
 */
function original_to_representative($path, $representative_ext)
{
  $pos = strrpos($path, '/');
  $path = substr_replace($path, 'pwg_representative/', $pos+1, 0);
  $pos = strrpos($path, '.');
  return substr_replace($path, $representative_ext, $pos+1);
}

/**
 * Transforms an original path to its format
 *
 * @param string $path
 * @param string $format_ext
 * @return string
 */
function original_to_format($path, $format_ext)
{
  $pos = strrpos($path, '/');
  $path = substr_replace($path, 'pwg_format/', $pos+1, 0);
  $pos = strrpos($path, '.');
  return substr_replace($path, $format_ext, $pos+1);
}

/**
 * get the full path of an image
 *
 * @param array $element_info element information from db (at least 'path')
 * @return string
 */
function get_element_path($element_info)
{
  $path = $element_info['path'];
  if ( !url_is_remote($path) )
  {
    $path = PHPWG_ROOT_PATH.$path;
  }
  return $path;
}


/**
 * fill the current user caddie with given elements, if not already in caddie
 *
 * @param int[] $elements_id
 */
function fill_caddie($elements_id)
{
  global $user;

  $query = '
SELECT element_id
  FROM '.CADDIE_TABLE.'
  WHERE user_id = '.$user['id'].'
;';
  $in_caddie = query2array($query, null, 'element_id');

  $caddiables = array_diff($elements_id, $in_caddie);

  $datas = array();

  foreach ($caddiables as $caddiable)
  {
    $datas[] = array(
      'element_id' => $caddiable,
      'user_id' => $user['id'],
      );
  }

  if (count($caddiables) > 0)
  {
    mass_inserts(CADDIE_TABLE, array('element_id','user_id'), $datas);
  }
}

/**
 * returns the element name from its filename.
 * removes file extension and replace underscores by spaces
 *
 * @param string $filename
 * @return string name
 */
function get_name_from_file($filename)
{
  return str_replace('_',' ',get_filename_wo_extension($filename));
}

/**
 * translation function.
 * returns the corresponding value from _$lang_ if existing else the key is returned
 * if more than one parameter is provided sprintf is applied
 *
 * @param string $key
 * @param mixed $args,... optional arguments
 * @return string
 */
function l10n($key)
{
  global $lang, $conf;

  if ( ($val=@$lang[$key]) === null)
  {
    if ($conf['debug_l10n'] and !isset($lang[$key]) and !empty($key))
    {
      trigger_error('[l10n] language key "'. $key .'" not defined', E_USER_WARNING);
    }
    $val = $key;
  }

  if (func_num_args() > 1)
  {
    $args = func_get_args();
    $val = vsprintf($val, array_slice($args, 1));
  }

  return $val;
}

/**
 * returns the printf value for strings including %d
 * returned value is concorded with decimal value (singular, plural)
 *
 * @param string $singular_key
 * @param string $plural_key
 * @param int $decimal
 * @return string
 */
function l10n_dec($singular_key, $plural_key, $decimal)
{
  global $lang_info;

  return
    sprintf(
      l10n((
        (($decimal > 1) or ($decimal == 0 and $lang_info['zero_plural']))
          ? $plural_key
          : $singular_key
        )), $decimal);
}

/**
 * returns a single element to use with l10n_args
 *
 * @param string $key translation key
 * @param mixed $args arguments to use on sprintf($key, args)
 *   if args is a array, each values are used on sprintf
 * @return string
 */
function get_l10n_args($key, $args='')
{
  if (is_array($args))
  {
    $key_arg = array_merge(array($key), $args);
  }
  else
  {
    $key_arg = array($key,  $args);
  }
  return array('key_args' => $key_arg);
}

/**
 * returns a string formated with l10n elements.
 * it is usefull to "prepare" a text and translate it later
 * @see get_l10n_args()
 *
 * @param array $key_args one l10n_args element or array of l10n_args elements
 * @param string $sep used when translated elements are concatened
 * @return string
 */
function l10n_args($key_args, $sep = "\n")
{
  if (is_array($key_args))
  {
    foreach ($key_args as $key => $element)
    {
      if (isset($result))
      {
        $result .= $sep;
      }
      else
      {
        $result = '';
      }

      if ($key === 'key_args')
      {
        array_unshift($element, l10n(array_shift($element))); // translate the key
        $result .= call_user_func_array('sprintf', $element);
      }
      else
      {
        $result .= l10n_args($element, $sep);
      }
    }
  }
  else
  {
    fatal_error('l10n_args: Invalid arguments');
  }

  return $result;
}

/**
 * returns the corresponding value from $themeconf if existing or an empty string
 *
 * @param string $key
 * @return string
 */
function get_themeconf($key)
{
  return $GLOBALS['template']->get_themeconf($key);
}

/**
 * Returns webmaster mail address depending on $conf['webmaster_id']
 *
 * @return string
 */
function get_webmaster_mail_address()
{
  global $conf;

  $query = '
SELECT '.$conf['user_fields']['email'].'
  FROM '.USERS_TABLE.'
  WHERE '.$conf['user_fields']['id'].' = '.$conf['webmaster_id'].'
;';
  list($email) = pwg_db_fetch_row(pwg_query($query));

  $email = trigger_change('get_webmaster_mail_address', $email);

  return $email;
}

/**
 * Add configuration parameters from database to global $conf array
 *
 * @param string $condition SQL condition
 * @return void
 */
function load_conf_from_db($condition = '')
{
  global $conf;

  $query = '
SELECT param, value
 FROM '.CONFIG_TABLE.'
 '.(!empty($condition) ? 'WHERE '.$condition : '').'
;';
  $result = pwg_query($query);

  if ((pwg_db_num_rows($result) == 0) and !empty($condition))
  {
    fatal_error('No configuration data');
  }

  while ($row = pwg_db_fetch_assoc($result))
  {
    $val = isset($row['value']) ? $row['value'] : '';
    // If the field is true or false, the variable is transformed into a boolean value.
    if ($val == 'true')
    {
      $val = true;
    }
    elseif ($val == 'false')
    {
      $val = false;
    }
    $conf[ $row['param'] ] = $val;
  }

  trigger_notify('load_conf', $condition);
}

/**
 * Add or update a config parameter
 *
 * @param string $param
 * @param string $value
 * @param boolean $updateGlobal update global *$conf* variable
 * @param callable $parser function to apply to the value before save in database
      (eg: serialize, json_encode) will not be applied to *$conf* if *$parser* is *true*
 */
function conf_update_param($param, $value, $updateGlobal=false, $parser=null)
{
  if ($parser != null)
  {
    $dbValue = call_user_func($parser, $value);
  }
  else if (is_array($value) || is_object($value))
  {
    $dbValue = addslashes(serialize($value));
  }
  else
  {
    $dbValue = boolean_to_string($value);
  }

  $query = '
INSERT INTO
  '.CONFIG_TABLE.' (param, value)
  VALUES(\''.$param.'\', \''.$dbValue.'\')
  ON DUPLICATE KEY UPDATE value = \''.$dbValue.'\'
;';

  pwg_query($query);

  if ($updateGlobal)
  {
    global $conf;
    $conf[$param] = $value;
  }
}

/**
 * Delete one or more config parameters
 * @since 2.6
 *
 * @param string|string[] $params
 */
function conf_delete_param($params)
{
  global $conf;

  if (!is_array($params))
  {
    $params = array($params);
  }
  if (empty($params))
  {
    return;
  }

  $query = '
DELETE FROM '.CONFIG_TABLE.'
  WHERE param IN(\''. implode('\',\'', $params) .'\')
;';
  pwg_query($query);

  foreach ($params as $param)
  {
    unset($conf[$param]);
  }
}

/**
 * Return a default value for a configuration parameter.
 * @since 2.8
 *
 * @param string $param the configuration value to be extracted (if it exists)
 * @param mixed $default_value the default value for the configuration value if it does not exist.
 *
 * @return mixed The configuration value if the variable exists, otherwise the default.
 */
function conf_get_param($param, $default_value=null)
{
  global $conf;
  
  if (isset($conf[$param]))
  {
    return $conf[$param];
  }
  return $default_value;
}


/**
 * Apply *unserialize* on a value only if it is a string
 * @since 2.7
 *
 * @param array|string $value
 * @return array
 */
function safe_unserialize($value)
{
  if (is_string($value))
  {
    return unserialize($value);
  }
  return $value;
}

/**
 * Apply *json_decode* on a value only if it is a string
 * @since 2.7
 *
 * @param array|string $value
 * @return array
 */
function safe_json_decode($value)
{
  if (is_string($value))
  {
    return json_decode($value, true);
  }
  return $value;
}

/**
 * Prepends and appends strings at each value of the given array.
 *
 * @param array $array
 * @param string $prepend_str
 * @param string $append_str
 * @return array
 */
function prepend_append_array_items($array, $prepend_str, $append_str)
{
  array_walk(
    $array,
    create_function('&$s', '$s = "'.$prepend_str.'".$s."'.$append_str.'";')
    );

  return $array;
}

/**
 * creates an simple hashmap based on a SQL query.
 * choose one to be the key, another one to be the value.
 * @deprecated 2.6
 *
 * @param string $query
 * @param string $keyname
 * @param string $valuename
 * @return array
 */
function simple_hash_from_query($query, $keyname, $valuename)
{
	return query2array($query, $keyname, $valuename);
}

/**
 * creates an associative array based on a SQL query.
 * choose one to be the key
 * @deprecated 2.6
 *
 * @param string $query
 * @param string $keyname
 * @return array
 */
function hash_from_query($query, $keyname)
{
	return query2array($query, $keyname);
}

/**
 * creates a numeric array based on a SQL query.
 * if _$fieldname_ is empty the returned value will be an array of arrays
 * if _$fieldname_ is provided the returned value will be a one dimension array
 * @deprecated 2.6
 *
 * @param string $query
 * @param string $fieldname
 * @return array
 */
function array_from_query($query, $fieldname=false)
{
  if (false === $fieldname)
  {
		return query2array($query);
  }
  else
  {
		return query2array($query, null, $fieldname);
  }
}

/**
 * Return the basename of the current script.
 * The lowercase case filename of the current script without extension
 *
 * @return string
 */
function script_basename()
{
  global $conf;

  foreach (array('SCRIPT_NAME', 'SCRIPT_FILENAME', 'PHP_SELF') as $value)
  {
    if (!empty($_SERVER[$value]))
    {
      $filename = strtolower($_SERVER[$value]);
      if ($conf['php_extension_in_urls'] and get_extension($filename)!=='php')
        continue;
      $basename = basename($filename, '.php');
      if (!empty($basename))
      {
        return $basename;
      }
    }
  }
  return '';
}

/**
 * Return $conf['filter_pages'] value for the current page
 *
 * @param string $value_name
 * @return mixed
 */
function get_filter_page_value($value_name)
{
  global $conf;

  $page_name = script_basename();

  if (isset($conf['filter_pages'][$page_name][$value_name]))
  {
    return $conf['filter_pages'][$page_name][$value_name];
  }
  elseif (isset($conf['filter_pages']['default'][$value_name]))
  {
    return $conf['filter_pages']['default'][$value_name];
  }
  else
  {
    return null;
  }
}

/**
 * return the character set used by Piwigo
 * @return string
 */
function get_pwg_charset()
{
  $pwg_charset = 'utf-8';
  if (defined('PWG_CHARSET'))
  {
    $pwg_charset = PWG_CHARSET;
  }
  return $pwg_charset;
}

/**
 * returns the parent (fallback) language of a language.
 * if _$lang_id_ is null it applies to the current language
 * @since 2.6
 *
 * @param string $lang_id
 * @return string|null
 */
function get_parent_language($lang_id=null)
{
  if (empty($lang_id))
  {
    global $lang_info;
    return !empty($lang_info['parent']) ? $lang_info['parent'] : null;
  }
  else
  {
    $f = PHPWG_ROOT_PATH.'language/'.$lang_id.'/common.lang.php';
    if (file_exists($f))
    {
      include($f);
      return !empty($lang_info['parent']) ? $lang_info['parent'] : null;
    }
  }
  return null;
}

/**
 * includes a language file or returns the content of a language file
 *
 * tries to load in descending order:
 *   param language, user language, default language
 *
 * @param string $filename
 * @param string $dirname
 * @param mixed options can contain
 *     @option string language - language to load
 *     @option bool return - if true the file content is returned
 *     @option bool no_fallback - if true do not load default language
 *     @option bool|string force_fallback - force pre-loading of another language
 *        default language if *true* or specified language
 *     @option bool local - if true load file from local directory
 * @return boolean|string
 */
function load_language($filename, $dirname = '', $options = array())
{
  global $user, $language_files;

  // keep trace of plugins loaded files for switch_lang_to() function
  if (!empty($dirname) && !empty($filename) && !@$options['return']
    && !isset($language_files[$dirname][$filename]))
  {
    $language_files[$dirname][$filename] = $options;
  }

  if (!@$options['return'])
  {
    $filename .= '.php';
  }
  if (empty($dirname))
  {
    $dirname = PHPWG_ROOT_PATH;
  }
  $dirname .= 'language/';

  $default_language = defined('PHPWG_INSTALLED') and !defined('UPGRADES_PATH') ?
      get_default_language() : PHPWG_DEFAULT_LANGUAGE;

  // construct list of potential languages
  $languages = array();
  if (!empty($options['language']))
  { // explicit language
    $languages[] = $options['language'];
  }
  if (!empty($user['language']))
  { // use language
    $languages[] = $user['language'];
  }
  if (($parent = get_parent_language()) != null)
  { // parent language
    // this is only for when the "child" language is missing
    $languages[] = $parent;
  }
  if (isset($options['force_fallback']))
  { // fallback language
    // this is only for when the main language is missing
    if ($options['force_fallback'] === true)
    {
      $options['force_fallback'] = $default_language;
    }
    $languages[] = $options['force_fallback'];
  }
  if (!@$options['no_fallback'])
  { // default language
    $languages[] = $default_language;
  }

  $languages = array_unique($languages);

  // find first existing
  $source_file       = '';
  $selected_language = '';
  foreach ($languages as $language)
  {
    $f = @$options['local'] ?
      $dirname.$language.'.'.$filename:
      $dirname.$language.'/'.$filename;

    if (file_exists($f))
    {
      $selected_language = $language;
      $source_file = $f;
      break;
    }
  }
  
  if (!empty($source_file))
  {
    if (!@$options['return'])
    {
      // load forced fallback
      if (isset($options['force_fallback']) && $options['force_fallback'] != $selected_language)
      {
        @include(str_replace($selected_language, $options['force_fallback'], $source_file));
      }

      // load language content
      @include($source_file);
      $load_lang = @$lang;
      $load_lang_info = @$lang_info;

      // access already existing values
      global $lang, $lang_info;
      if (!isset($lang)) $lang = array();
      if (!isset($lang_info)) $lang_info = array();

      // load parent language content directly in global
      if (!empty($load_lang_info['parent']))
        $parent_language = $load_lang_info['parent'];
      else if (!empty($lang_info['parent']))
        $parent_language = $lang_info['parent'];
      else 
        $parent_language = null;

      if (!empty($parent_language) && $parent_language != $selected_language)
      {
        @include(str_replace($selected_language, $parent_language, $source_file));
      }

      // merge contents
      $lang = array_merge($lang, (array)$load_lang);
      $lang_info = array_merge($lang_info, (array)$load_lang_info);
      return true;
    }
    else
    {
      $content = @file_get_contents($source_file);
      //Note: target charset is always utf-8 $content = convert_charset($content, 'utf-8', $target_charset);
      return $content;
    }
  }

  return false;
}

/**
 * converts a string from a character set to another character set
 *
 * @param string $str
 * @param string $source_charset
 * @param string $dest_charset
 */
function convert_charset($str, $source_charset, $dest_charset)
{
  if ($source_charset==$dest_charset)
    return $str;
  if ($source_charset=='iso-8859-1' and $dest_charset=='utf-8')
  {
    return utf8_encode($str);
  }
  if ($source_charset=='utf-8' and $dest_charset=='iso-8859-1')
  {
    return utf8_decode($str);
  }
  if (function_exists('iconv'))
  {
    return iconv($source_charset, $dest_charset.'//TRANSLIT', $str);
  }
  if (function_exists('mb_convert_encoding'))
  {
    return mb_convert_encoding( $str, $dest_charset, $source_charset );
  }
  return $str; // TODO
}

/**
 * makes sure a index.htm protects the directory from browser file listing
 *
 * @param string $dir
 */
function secure_directory($dir)
{
  $file = $dir.'/index.htm';
  if (!file_exists($file))
  {
    @file_put_contents($file, 'Not allowed!');
  }
}

/**
 * returns a "secret key" that is to be sent back when a user posts a form
 *
 * @param int $valid_after_seconds - key validity start time from now
 * @param string $aditionnal_data_to_hash
 * @return string
 */
function get_ephemeral_key($valid_after_seconds, $aditionnal_data_to_hash = '')
{
	global $conf;
	$time = round(microtime(true), 1);
	return $time.':'.$valid_after_seconds.':'
		.hash_hmac(
			'md5',
			$time.substr($_SERVER['REMOTE_ADDR'],0,5).$valid_after_seconds.$aditionnal_data_to_hash,
			$conf['secret_key']);
}

/**
 * verify a key sent back with a form
 *
 * @param string $key
 * @param string $aditionnal_data_to_hash
 * @return bool
 */
function verify_ephemeral_key($key, $aditionnal_data_to_hash = '')
{
	global $conf;
	$time = microtime(true);
	$key = explode( ':', @$key );
	if ( count($key)!=3
		or $key[0]>$time-(float)$key[1] // page must have been retrieved more than X sec ago
		or $key[0]<$time-3600 // 60 minutes expiration
		or hash_hmac(
			  'md5', $key[0].substr($_SERVER['REMOTE_ADDR'],0,5).$key[1].$aditionnal_data_to_hash, $conf['secret_key']
			) != $key[2]
	  )
	{
		return false;
	}
	return true;
}

/**
 * return an array which will be sent to template to display navigation bar
 *
 * @param string $url base url of all links
 * @param int $nb_elements
 * @param int $start
 * @param int $nb_element_page
 * @param bool $clean_url
 * @param string $param_name
 * @return array
 */
function create_navigation_bar($url, $nb_element, $start, $nb_element_page, $clean_url = false, $param_name='start')
{
  global $conf;

  $navbar = array();
  $pages_around = $conf['paginate_pages_around'];
  $start_str = $clean_url ? '/'.$param_name.'-' : (strpos($url, '?')===false ? '?':'&amp;').$param_name.'=';

  if (!isset($start) or !is_numeric($start) or (is_numeric($start) and $start < 0))
  {
    $start = 0;
  }

  // navigation bar useful only if more than one page to display !
  if ($nb_element > $nb_element_page)
  {
    $url_start = $url.$start_str;

    $cur_page = $navbar['CURRENT_PAGE'] = $start / $nb_element_page + 1;
    $maximum = ceil($nb_element / $nb_element_page);

    $start = $nb_element_page * round( $start / $nb_element_page );
    $previous = $start - $nb_element_page;
    $next = $start + $nb_element_page;
    $last = ($maximum - 1) * $nb_element_page;

    // link to first page and previous page?
    if ($cur_page != 1)
    {
      $navbar['URL_FIRST'] = $url;
      $navbar['URL_PREV'] = $previous > 0 ? $url_start.$previous : $url;
    }
    // link on next page and last page?
    if ($cur_page != $maximum)
    {
      $navbar['URL_NEXT'] = $url_start.($next < $last ? $next : $last);
      $navbar['URL_LAST'] = $url_start.$last;
    }

    // pages to display
    $navbar['pages'] = array();
    $navbar['pages'][1] = $url;
    for ($i = max( floor($cur_page) - $pages_around , 2), $stop = min( ceil($cur_page) + $pages_around + 1, $maximum);
         $i < $stop; $i++)
    {
      $navbar['pages'][$i] = $url.$start_str.(($i - 1) * $nb_element_page);
    }
    $navbar['pages'][$maximum] = $url_start.$last;
    $navbar['NB_PAGE']=$maximum;
  }
  return $navbar;
}

/**
 * return an array which will be sent to template to display recent icon
 *
 * @param string $date
 * @param bool $is_child_date
 * @return array
 */
function get_icon($date, $is_child_date = false)
{
  global $cache, $user;

  if (empty($date))
  {
    return false;
  }

  if (!isset($cache['get_icon']['title']))
  {
    $cache['get_icon']['title'] = l10n(
      'photos posted during the last %d days',
      $user['recent_period']
      );
  }

  $icon = array(
    'TITLE' => $cache['get_icon']['title'],
    'IS_CHILD_DATE' => $is_child_date,
    );

  if (isset($cache['get_icon'][$date]))
  {
    return $cache['get_icon'][$date] ? $icon : array();
  }

  if (!isset($cache['get_icon']['sql_recent_date']))
  {
    // Use MySql date in order to standardize all recent "actions/queries"
    $cache['get_icon']['sql_recent_date'] = pwg_db_get_recent_period($user['recent_period']);
  }

  $cache['get_icon'][$date] = $date > $cache['get_icon']['sql_recent_date'];

  return $cache['get_icon'][$date] ? $icon : array();
}

/**
 * check token comming from form posted or get params to prevent csrf attacks.
 * if pwg_token is empty action doesn't require token
 * else pwg_token is compare to server token
 *
 * @return void access denied if token given is not equal to server token
 */
function check_pwg_token()
{
  if (!empty($_REQUEST['pwg_token']))
  {
    if (get_pwg_token() != $_REQUEST['pwg_token'])
    {
      access_denied();
    }
  }
  else
  {
    bad_request('missing token');
  }
}

/**
 * get pwg_token used to prevent csrf attacks
 *
 * @return string
 */
function get_pwg_token()
{
  global $conf;

  return hash_hmac('md5', session_id(), $conf['secret_key']);
}

/*
 * breaks the script execution if the given value doesn't match the given
 * pattern. This should happen only during hacking attempts.
 *
 * @param string $param_name
 * @param array $param_array
 * @param boolean $is_array
 * @param string $pattern
 * @param boolean $mandatory
 */
function check_input_parameter($param_name, $param_array, $is_array, $pattern, $mandatory=false)
{
  $param_value = null;
  if (isset($param_array[$param_name]))
  {
    $param_value = $param_array[$param_name];
  }

  // it's ok if the input parameter is null
  if (empty($param_value))
  {
    if ($mandatory)
    {
      fatal_error('[Hacking attempt] the input parameter "'.$param_name.'" is not valid');
    }
    return true;
  }

  if ($is_array)
  {
    if (!is_array($param_value))
    {
      fatal_error('[Hacking attempt] the input parameter "'.$param_name.'" should be an array');
    }

    foreach ($param_value as $key => $item_to_check)
    {
      if (!preg_match(PATTERN_ID, $key) or !preg_match($pattern, $item_to_check))
      {
        fatal_error('[Hacking attempt] an item is not valid in input parameter "'.$param_name.'"');
      }
    }
  }
  else
  {
    if (!preg_match($pattern, $param_value))
    {
      fatal_error('[Hacking attempt] the input parameter "'.$param_name.'" is not valid');
    }
  }
}

/**
 * get localized privacy level values
 *
 * @return string[]
 */
function get_privacy_level_options()
{
  global $conf;

  $options = array();
  $label = '';
  foreach (array_reverse($conf['available_permission_levels']) as $level)
  {
    if (0 == $level)
    {
      $label = l10n('Everybody');
    }
    else
    {
      if (strlen($label))
      {
        $label .= ', ';
      }
      $label .= l10n( sprintf('Level %d', $level) );
    }
    $options[$level] = $label;
  }
  return $options;
}


/**
 * return the branch from the version. For example version 2.2.4 is for branch 2.2
 *
 * @param string $version
 * @return string
 */
function get_branch_from_version($version)
{
  return implode('.', array_slice(explode('.', $version), 0, 2));
}

/**
 * return the device type: mobile, tablet or desktop
 *
 * @return string
 */
function get_device()
{
  $device = pwg_get_session_var('device');

  if (is_null($device))
  {
    include_once(PHPWG_ROOT_PATH.'include/mdetect.php');
    $uagent_obj = new uagent_info();
    if ($uagent_obj->DetectSmartphone())
    {
      $device = 'mobile';
    }
    elseif ($uagent_obj->DetectTierTablet())
    {
      $device = 'tablet';
    }
    else
    {
      $device = 'desktop';
    }
    pwg_set_session_var('device', $device);
  }

  return $device;
}

/**
 * return true if mobile theme should be loaded
 *
 * @return bool
 */
function mobile_theme()
{
  global $conf;

  if (empty($conf['mobile_theme']))
  {
    return false;
  }

  if (isset($_GET['mobile']))
  {
    $is_mobile_theme = get_boolean($_GET['mobile']);
    pwg_set_session_var('mobile_theme', $is_mobile_theme);
  }
  else
  {
    $is_mobile_theme = pwg_get_session_var('mobile_theme');
  }

  if (is_null($is_mobile_theme))
  {
    $is_mobile_theme = (get_device() == 'mobile');
    pwg_set_session_var('mobile_theme', $is_mobile_theme);
  }

  return $is_mobile_theme;
}

/**
 * check url format
 *
 * @param string $url
 * @return bool
 */
function url_check_format($url)
{
  return filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED | FILTER_FLAG_HOST_REQUIRED)!==false;
}

/**
 * check email format
 *
 * @param string $mail_address
 * @return bool
 */
function email_check_format($mail_address)
{
  return filter_var($mail_address, FILTER_VALIDATE_EMAIL)!==false;
}

/**
 * returns the number of available comments for the connected user
 *
 * @return int
 */
function get_nb_available_comments()
{
  global $user;
  if (!isset($user['nb_available_comments']))
  {
    $where = array();
    if ( !is_admin() )
      $where[] = 'validated=\'true\'';
    $where[] = get_sql_condition_FandF
      (
        array
          (
            'forbidden_categories' => 'category_id',
            'forbidden_images' => 'ic.image_id'
          ),
        '', true
      );

    $query = '
SELECT COUNT(DISTINCT(com.id))
  FROM '.IMAGE_CATEGORY_TABLE.' AS ic
    INNER JOIN '.COMMENTS_TABLE.' AS com
    ON ic.image_id = com.image_id
  WHERE '.implode('
    AND ', $where);
    list($user['nb_available_comments']) = pwg_db_fetch_row(pwg_query($query));

    single_update(USER_CACHE_TABLE,
      array('nb_available_comments'=>$user['nb_available_comments']),
      array('user_id'=>$user['id'])
      );
  }
  return $user['nb_available_comments'];
}

/**
 * Compare two versions with version_compare after having converted
 * single chars to their decimal values.
 * Needed because version_compare does not understand versions like '2.5.c'.
 * @since 2.6
 *
 * @param string $a
 * @param string $b
 * @param string $op
 */
function safe_version_compare($a, $b, $op=null)
{
  $replace_chars = create_function('$m', 'return ord(strtolower($m[1]));');

  // add dot before groups of letters (version_compare does the same thing)
  $a = preg_replace('#([0-9]+)([a-z]+)#i', '$1.$2', $a);
  $b = preg_replace('#([0-9]+)([a-z]+)#i', '$1.$2', $b);

  // apply ord() to any single letter
  $a = preg_replace_callback('#\b([a-z]{1})\b#i', $replace_chars, $a);
  $b = preg_replace_callback('#\b([a-z]{1})\b#i', $replace_chars, $b);

  if (empty($op))
  {
    return version_compare($a, $b);
  }
  else
  {
    return version_compare($a, $b, $op);
  }
}

?>