source: trunk/include/functions_user.inc.php @ 29111

<?php
// +-----------------------------------------------------------------------+
// | Piwigo - a PHP based photo gallery                                    |
// +-----------------------------------------------------------------------+
// | Copyright(C) 2008-2014 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\user
 */


/**
 * Checks if an email is well formed and not already in use.
 *
 * @param int $user_id
 * @param string $mail_address
 * @return string|void error message or nothing
 */
function validate_mail_address($user_id, $mail_address)
{
  global $conf;

  if (empty($mail_address) and
      !($conf['obligatory_user_mail_address'] and
      in_array(script_basename(), array('register', 'profile'))))
  {
    return '';
  }

  if ( !email_check_format($mail_address) )
  {
    return l10n('mail address must be like xxx@yyy.eee (example : jack@altern.org)');
  }

  if (defined("PHPWG_INSTALLED") and !empty($mail_address))
  {
    $query = '
SELECT count(*)
FROM '.USERS_TABLE.'
WHERE upper('.$conf['user_fields']['email'].') = upper(\''.$mail_address.'\')
'.(is_numeric($user_id) ? 'AND '.$conf['user_fields']['id'].' != \''.$user_id.'\'' : '').'
;';
    list($count) = pwg_db_fetch_row(pwg_query($query));
    if ($count != 0)
    {
      return l10n('this email address is already in use');
    }
  }
}

/**
 * Checks if a login is not already in use.
 * Comparision is case insensitive.
 *
 * @param string $login
 * @return string|void error message or nothing
 */
function validate_login_case($login)
{
  global $conf;

  if (defined("PHPWG_INSTALLED"))
  {
    $query = "
SELECT ".$conf['user_fields']['username']."
FROM ".USERS_TABLE."
WHERE LOWER(".stripslashes($conf['user_fields']['username']).") = '".strtolower($login)."'
;";

    $count = pwg_db_num_rows(pwg_query($query));

    if ($count > 0)
    {
      return l10n('this login is already used');
    }
  }
}
/**
 * Searches for user with the same username in different case.
 *
 * @param string $username typically typed in by user for identification
 * @return string $username found in database
 */
function search_case_username($username)
{
  global $conf;

  $username_lo = strtolower($username);

  $SCU_users = array();

  $q = pwg_query("
    SELECT ".$conf['user_fields']['username']." AS username
    FROM `".USERS_TABLE."`;
  ");
  while ($r = pwg_db_fetch_assoc($q))
   $SCU_users[$r['username']] = strtolower($r['username']);
   // $SCU_users is now an associative table where the key is the account as
   // registered in the DB, and the value is this same account, in lower case

  $users_found = array_keys($SCU_users, $username_lo);
  // $users_found is now a table of which the values are all the accounts
  // which can be written in lowercase the same way as $username
  if (count($users_found) != 1) // If ambiguous, don't allow lowercase writing
   return $username; // but normal writing will work
  else
   return $users_found[0];
}

/**
 * Creates a new user.
 *
 * @param string $login
 * @param string $password
 * @param string $mail_adress
 * @param bool $notify_admin
 * @param array &$errors populated with error messages
 * @param bool $notify_user
 * @return int|false user id or false
 */
function register_user($login, $password, $mail_address, $notify_admin=true, &$errors = array(), $notify_user=false)
{
  global $conf;

  if ($login == '')
  {
    $errors[] = l10n('Please, enter a login');
  }
  if (preg_match('/^.* $/', $login))
  {
    $errors[] = l10n('login mustn\'t end with a space character');
  }
  if (preg_match('/^ .*$/', $login))
  {
    $errors[] = l10n('login mustn\'t start with a space character');
  }
  if (get_userid($login))
  {
    $errors[] = l10n('this login is already used');
  }
  if ($login != strip_tags($login))
  {
    $errors[] = l10n('html tags are not allowed in login');
  }
  $mail_error = validate_mail_address(null, $mail_address);
  if ('' != $mail_error)
  {
    $errors[] = $mail_error;
  }

  if ($conf['insensitive_case_logon'] == true)
  {
    $login_error = validate_login_case($login);
    if ($login_error != '')
    {
      $errors[] = $login_error;
    }
  }

  $errors = trigger_change(
    'register_user_check',
    $errors,
    array(
      'username'=>$login,
      'password'=>$password,
      'email'=>$mail_address,
      )
    );

  // if no error until here, registration of the user
  if (count($errors) == 0)
  {
    $insert = array(
      $conf['user_fields']['username'] => pwg_db_real_escape_string($login),
      $conf['user_fields']['password'] => $conf['password_hash']($password),
      $conf['user_fields']['email'] => $mail_address
      );

    single_insert(USERS_TABLE, $insert);
    $user_id = pwg_db_insert_id();

    // Assign by default groups
    $query = '
SELECT id
  FROM '.GROUPS_TABLE.'
  WHERE is_default = \''.boolean_to_string(true).'\'
  ORDER BY id ASC
;';
    $result = pwg_query($query);

    $inserts = array();
    while ($row = pwg_db_fetch_assoc($result))
    {
      $inserts[] = array(
        'user_id' => $user_id,
        'group_id' => $row['id']
        );
    }

    if (count($inserts) != 0)
    {
      mass_inserts(USER_GROUP_TABLE, array('user_id', 'group_id'), $inserts);
    }

    $override = null;
    if ($notify_admin and $conf['browser_language'])
    {
      if (!get_browser_language($override['language']))
      {
        $override=null;
      }
    }
    create_user_infos($user_id, $override);

    if ($notify_admin and $conf['email_admin_on_new_user'])
    {
      include_once(PHPWG_ROOT_PATH.'include/functions_mail.inc.php');
      $admin_url = get_absolute_root_url().'admin.php?page=user_list&username='.$login;

      $keyargs_content = array(
        get_l10n_args('User: %s', stripslashes($login) ),
        get_l10n_args('Email: %s', $_POST['mail_address']),
        get_l10n_args(''),
        get_l10n_args('Admin: %s', $admin_url),
        );

      pwg_mail_notification_admins(
        get_l10n_args('Registration of %s', stripslashes($login) ),
        $keyargs_content
        );
    }

    if ($notify_user and email_check_format($mail_address))
    {
      include_once(PHPWG_ROOT_PATH.'include/functions_mail.inc.php');

      $keyargs_content = array(
        get_l10n_args('Hello %s,', stripslashes($login)),
        get_l10n_args('Thank you for registering at %s!', $conf['gallery_title']),
        get_l10n_args('', ''),
        get_l10n_args('Here are your connection settings', ''),
        get_l10n_args('', ''),
        get_l10n_args('Link: %s', get_absolute_root_url()),
        get_l10n_args('Username: %s', stripslashes($login)),
        get_l10n_args('Password: %s', stripslashes($password)),
        get_l10n_args('Email: %s', $mail_address),
        get_l10n_args('', ''),
        get_l10n_args('If you think you\'ve received this email in error, please contact us at %s', get_webmaster_mail_address()),
        );

      pwg_mail(
        $mail_address,
        array(
          'subject' => '['.$conf['gallery_title'].'] '.l10n('Registration'),
          'content' => l10n_args($keyargs_content),
          'content_format' => 'text/plain',
          )
        );
    }

    trigger_notify(
      'register_user',
      array(
        'id'=>$user_id,
        'username'=>$login,
        'email'=>$mail_address,
        )
      );

    return $user_id;
  }
  else
  {
    return false;
  }
}

/**
 * Fetches user data from database.
 * Same that getuserdata() but with additional tests for guest.
 *
 * @param int $user_id
 * @param boolean $user_cache
 * @return array
 */
function build_user($user_id, $use_cache=true)
{
  global $conf;

  $user['id'] = $user_id;
  $user = array_merge( $user, getuserdata($user_id, $use_cache) );

  if ($user['id'] == $conf['guest_id'] and $user['status'] <> 'guest')
  {
    $user['status'] = 'guest';
    $user['internal_status']['guest_must_be_guest'] = true;
  }

  // Check user theme
  if (!isset($user['theme_name']))
  {
    $user['theme'] = get_default_theme();
  }

  return $user;
}

/**
 * Finds informations related to the user identifier.
 *
 * @param int $user_id
 * @param boolean $use_cache
 * @return array
 */
function getuserdata($user_id, $use_cache=false)
{
  global $conf;

  // retrieve basic user data
  $query = '
SELECT ';
  $is_first = true;
  foreach ($conf['user_fields'] as $pwgfield => $dbfield)
  {
    if ($is_first)
    {
      $is_first = false;
    }
    else
    {
      $query.= '
     , ';
    }
    $query.= $dbfield.' AS '.$pwgfield;
  }
  $query.= '
  FROM '.USERS_TABLE.'
  WHERE '.$conf['user_fields']['id'].' = \''.$user_id.'\'';

  $row = pwg_db_fetch_assoc(pwg_query($query));

  // retrieve additional user data ?
  if ($conf['external_authentification'])
  {
    $query = '
SELECT
    COUNT(1) AS counter
  FROM '.USER_INFOS_TABLE.' AS ui
    LEFT JOIN '.USER_CACHE_TABLE.' AS uc ON ui.user_id = uc.user_id
    LEFT JOIN '.THEMES_TABLE.' AS t ON t.id = ui.theme
  WHERE ui.user_id = '.$user_id.'
  GROUP BY ui.user_id
;';
    list($counter) = pwg_db_fetch_row(pwg_query($query));
    if ($counter != 1)
    {
      create_user_infos($user_id);
    }
  }

  // retrieve user info
  $query = '
SELECT
    ui.*,
    uc.*,
    t.name AS theme_name
  FROM '.USER_INFOS_TABLE.' AS ui
    LEFT JOIN '.USER_CACHE_TABLE.' AS uc ON ui.user_id = uc.user_id
    LEFT JOIN '.THEMES_TABLE.' AS t ON t.id = ui.theme
  WHERE ui.user_id = '.$user_id.'
;';

  $result = pwg_query($query);
  $user_infos_row = pwg_db_fetch_assoc($result);

  // then merge basic + additional user data
  $userdata = array_merge($row, $user_infos_row);

  foreach ($userdata as &$value)
  {
      // If the field is true or false, the variable is transformed into a boolean value.
      if ($value == 'true')
      {
        $value = true;
      }
      elseif ($value == 'false')
      {
        $value = false;
      }
  }
  unset($value);

  if ($use_cache)
  {
    if (!isset($userdata['need_update'])
        or !is_bool($userdata['need_update'])
        or $userdata['need_update'] == true)
    {
      $userdata['cache_update_time'] = time();

      // Set need update are done
      $userdata['need_update'] = false;

      $userdata['forbidden_categories'] =
        calculate_permissions($userdata['id'], $userdata['status']);

      /* now we build the list of forbidden images (this list does not contain
      images that are not in at least an authorized category)*/
      $query = '
SELECT DISTINCT(id)
  FROM '.IMAGES_TABLE.' INNER JOIN '.IMAGE_CATEGORY_TABLE.' ON id=image_id
  WHERE category_id NOT IN ('.$userdata['forbidden_categories'].')
    AND level>'.$userdata['level'];
      $forbidden_ids = query2array($query,null, 'id');

      if ( empty($forbidden_ids) )
      {
        $forbidden_ids[] = 0;
      }
      $userdata['image_access_type'] = 'NOT IN'; //TODO maybe later
      $userdata['image_access_list'] = implode(',',$forbidden_ids);


      $query = '
SELECT COUNT(DISTINCT(image_id)) as total
  FROM '.IMAGE_CATEGORY_TABLE.'
  WHERE category_id NOT IN ('.$userdata['forbidden_categories'].')
    AND image_id '.$userdata['image_access_type'].' ('.$userdata['image_access_list'].')';
      list($userdata['nb_total_images']) = pwg_db_fetch_row(pwg_query($query));


      // now we update user cache categories
      $user_cache_cats = get_computed_categories($userdata, null);
      if ( !is_admin($userdata['status']) )
      { // for non admins we forbid categories with no image (feature 1053)
        $forbidden_ids = array();
        foreach ($user_cache_cats as $cat)
        {
          if ($cat['count_images']==0)
          {
            $forbidden_ids[] = $cat['cat_id'];
            remove_computed_category($user_cache_cats, $cat);
          }
        }
        if ( !empty($forbidden_ids) )
        {
          if ( empty($userdata['forbidden_categories']) )
          {
            $userdata['forbidden_categories'] = implode(',', $forbidden_ids);
          }
          else
          {
            $userdata['forbidden_categories'] .= ','.implode(',', $forbidden_ids);
          }
        }
      }

      // delete user cache
      $query = '
DELETE FROM '.USER_CACHE_CATEGORIES_TABLE.'
  WHERE user_id = '.$userdata['id'];
      pwg_query($query);

      // Due to concurrency issues, we ask MySQL to ignore errors on
      // insert. This may happen when cache needs refresh and that Piwigo is
      // called "very simultaneously".
      mass_inserts(
        USER_CACHE_CATEGORIES_TABLE,
        array(
          'user_id', 'cat_id',
          'date_last', 'max_date_last', 'nb_images', 'count_images', 'nb_categories', 'count_categories'
          ),
        $user_cache_cats,
        array('ignore' => true)
      );


      // update user cache
      $query = '
DELETE FROM '.USER_CACHE_TABLE.'
  WHERE user_id = '.$userdata['id'];
      pwg_query($query);

      // for the same reason as user_cache_categories, we ignore error on
      // this insert
      $query = '
INSERT IGNORE INTO '.USER_CACHE_TABLE.'
  (user_id, need_update, cache_update_time, forbidden_categories, nb_total_images,
    last_photo_date,
    image_access_type, image_access_list)
  VALUES
  ('.$userdata['id'].',\''.boolean_to_string($userdata['need_update']).'\','
  .$userdata['cache_update_time'].',\''
  .$userdata['forbidden_categories'].'\','.$userdata['nb_total_images'].','.
  (empty($userdata['last_photo_date']) ? 'NULL': '\''.$userdata['last_photo_date'].'\'').
  ',\''.$userdata['image_access_type'].'\',\''.$userdata['image_access_list'].'\')';
      pwg_query($query);
    }
  }

  return $userdata;
}

/**
 * Deletes favorites of the current user if he's not allowed to see them.
 */
function check_user_favorites()
{
  global $user;

  if ($user['forbidden_categories'] == '')
  {
    return;
  }

  // $filter['visible_categories'] and $filter['visible_images']
  // must be not used because filter <> restriction
  // retrieving images allowed : belonging to at least one authorized
  // category
  $query = '
SELECT DISTINCT f.image_id
  FROM '.FAVORITES_TABLE.' AS f INNER JOIN '.IMAGE_CATEGORY_TABLE.' AS ic
    ON f.image_id = ic.image_id
  WHERE f.user_id = '.$user['id'].'
  '.get_sql_condition_FandF(
      array(
        'forbidden_categories' => 'ic.category_id',
        ),
      'AND'
    ).'
;';
  $authorizeds = query2array($query,null, 'image_id');

  $query = '
SELECT image_id
  FROM '.FAVORITES_TABLE.'
  WHERE user_id = '.$user['id'].'
;';
  $favorites = query2array($query,null, 'image_id');

  $to_deletes = array_diff($favorites, $authorizeds);
  if (count($to_deletes) > 0)
  {
    $query = '
DELETE FROM '.FAVORITES_TABLE.'
  WHERE image_id IN ('.implode(',', $to_deletes).')
    AND user_id = '.$user['id'].'
;';
    pwg_query($query);
  }
}

/**
 * Calculates the list of forbidden categories for a given user.
 *
 * Calculation is based on private categories minus categories authorized to
 * the groups the user belongs to minus the categories directly authorized
 * to the user. The list contains at least 0 to be compliant with queries
 * such as "WHERE category_id NOT IN ($forbidden_categories)"
 *
 * @param int $user_id
 * @param string $user_status
 * @return string comma separated ids
 */
function calculate_permissions($user_id, $user_status)
{
  $query = '
SELECT id
  FROM '.CATEGORIES_TABLE.'
  WHERE status = \'private\'
;';
  $private_array = query2array($query,null, 'id');

  // retrieve category ids directly authorized to the user
  $query = '
SELECT cat_id
  FROM '.USER_ACCESS_TABLE.'
  WHERE user_id = '.$user_id.'
;';
  $authorized_array = query2array($query,null, 'cat_id');

  // retrieve category ids authorized to the groups the user belongs to
  $query = '
SELECT cat_id
  FROM '.USER_GROUP_TABLE.' AS ug INNER JOIN '.GROUP_ACCESS_TABLE.' AS ga
    ON ug.group_id = ga.group_id
  WHERE ug.user_id = '.$user_id.'
;';
  $authorized_array =
    array_merge(
      $authorized_array,
      query2array($query,null, 'cat_id')
      );

  // uniquify ids : some private categories might be authorized for the
  // groups and for the user
  $authorized_array = array_unique($authorized_array);

  // only unauthorized private categories are forbidden
  $forbidden_array = array_diff($private_array, $authorized_array);

  // if user is not an admin, locked categories are forbidden
  if (!is_admin($user_status))
  {
    $query = '
SELECT id
  FROM '.CATEGORIES_TABLE.'
  WHERE visible = \'false\'
;';
    $forbidden_array = array_merge($forbidden_array, query2array($query, null, 'id') );
    $forbidden_array = array_unique($forbidden_array);
  }

  if ( empty($forbidden_array) )
  {// at least, the list contains 0 value. This category does not exists so
   // where clauses such as "WHERE category_id NOT IN(0)" will always be
   // true.
    $forbidden_array[] = 0;
  }

  return implode(',', $forbidden_array);
}

/**
 * Returns user identifier thanks to his name.
 *
 * @param string $username
 * @param int|false
 */
function get_userid($username)
{
  global $conf;

  $username = pwg_db_real_escape_string($username);

  $query = '
SELECT '.$conf['user_fields']['id'].'
  FROM '.USERS_TABLE.'
  WHERE '.$conf['user_fields']['username'].' = \''.$username.'\'
;';
  $result = pwg_query($query);

  if (pwg_db_num_rows($result) == 0)
  {
    return false;
  }
  else
  {
    list($user_id) = pwg_db_fetch_row($result);
    return $user_id;
  }
}

/**
 * Returns user identifier thanks to his email.
 *
 * @param string $email
 * @param int|false
 */
function get_userid_by_email($email)
{
  global $conf;

  $email = pwg_db_real_escape_string($email);

  $query = '
SELECT
    '.$conf['user_fields']['id'].'
  FROM '.USERS_TABLE.'
  WHERE UPPER('.$conf['user_fields']['email'].') = UPPER(\''.$email.'\')
;';
  $result = pwg_query($query);

  if (pwg_db_num_rows($result) == 0)
  {
    return false;
  }
  else
  {
    list($user_id) = pwg_db_fetch_row($result);
    return $user_id;
  }
}

/**
 * Returns a array with default user valuees.
 *
 * @param convert_str ceonferts 'true' and 'false' into booleans
 * @return array
 */
function get_default_user_info($convert_str=true)
{
  global $cache, $conf;

  if (!isset($cache['default_user']))
  {
    $query = '
SELECT *
  FROM '.USER_INFOS_TABLE.'
  WHERE user_id = '.$conf['default_user_id'].'
;';

    $result = pwg_query($query);

    if (pwg_db_num_rows($result) > 0)
    {
      $cache['default_user'] = pwg_db_fetch_assoc($result);

      unset($cache['default_user']['user_id']);
      unset($cache['default_user']['status']);
      unset($cache['default_user']['registration_date']);
    }
    else
    {
      $cache['default_user'] = false;
    }
  }

  if (is_array($cache['default_user']) and $convert_str)
  {
    $default_user = $cache['default_user'];
    foreach ($default_user as &$value)
    {
      // If the field is true or false, the variable is transformed into a boolean value.
      if ($value == 'true')
      {
        $value = true;
      }
      elseif ($value == 'false')
      {
        $value = false;
      }
    }
    return $default_user;
  }
  else
  {
    return $cache['default_user'];
  }
}

/**
 * Returns a default user value.
 *
 * @param string $value_name
 * @param mixed $default
 * @return mixed
 */
function get_default_user_value($value_name, $default)
{
  $default_user = get_default_user_info(true);
  if ($default_user === false or empty($default_user[$value_name]))
  {
    return $default;
  }
  else
  {
   return $default_user[$value_name];
  }
}

/**
 * Returns the default theme.
 * If the default theme is not available it returns the first available one.
 *
 * @return string
 */
function get_default_theme()
{
  $theme = get_default_user_value('theme', PHPWG_DEFAULT_TEMPLATE);
  if (check_theme_installed($theme))
  {
    return $theme;
  }

  // let's find the first available theme
  $active_themes = array_keys(get_pwg_themes());
  return $active_themes[0];
}

/**
 * Returns the default language.
 *
 * @return string
 */
function get_default_language()
{
  return get_default_user_value('language', PHPWG_DEFAULT_LANGUAGE);
}

/**
 * Tries to find the browser language among available languages.
 * @todo : try to match 'fr_CA' before 'fr'
 *
 * @param string &$lang
 * @return bool
 */
function get_browser_language(&$lang)
{
  $browser_language = substr(@$_SERVER["HTTP_ACCEPT_LANGUAGE"], 0, 2);
  foreach (get_languages() as $language_code => $language_name)
  {
    if (substr($language_code, 0, 2) == $browser_language)
    {
      $lang = $language_code;
      return true;
    }
  }
  return false;
}

/**
 * Creates user informations based on default values.
 *
 * @param int|int[] $user_ids
 * @param array $override_values values used to override default user values
 */
function create_user_infos($user_ids, $override_values=null)
{
  global $conf;

  if (!is_array($user_ids))
  {
    $user_ids = array($user_ids);
  }

  if (!empty($user_ids))
  {
    $inserts = array();
    list($dbnow) = pwg_db_fetch_row(pwg_query('SELECT NOW();'));

    $default_user = get_default_user_info(false);
    if ($default_user === false)
    {
      // Default on structure are used
      $default_user = array();
    }

    if (!is_null($override_values))
    {
      $default_user = array_merge($default_user, $override_values);
    }

    foreach ($user_ids as $user_id)
    {
      $level= isset($default_user['level']) ? $default_user['level'] : 0;
      if ($user_id == $conf['webmaster_id'])
      {
        $status = 'webmaster';
        $level = max( $conf['available_permission_levels'] );
      }
      elseif (($user_id == $conf['guest_id']) or
               ($user_id == $conf['default_user_id']))
      {
        $status = 'guest';
      }
      else
      {
        $status = 'normal';
      }

      $insert = array_merge(
        $default_user,
        array(
          'user_id' => $user_id,
          'status' => $status,
          'registration_date' => $dbnow,
          'level' => $level
          ));

      $inserts[] = $insert;
    }

    mass_inserts(USER_INFOS_TABLE, array_keys($inserts[0]), $inserts);
  }
}

/**
 * Returns the auto login key for an user or false if the user is not found.
 *
 * @param int $user_id
 * @param int $time
 * @param string &$username fille with corresponding username
 * @return string|false
 */
function calculate_auto_login_key($user_id, $time, &$username)
{
  global $conf;
  $query = '
SELECT '.$conf['user_fields']['username'].' AS username
  , '.$conf['user_fields']['password'].' AS password
FROM '.USERS_TABLE.'
WHERE '.$conf['user_fields']['id'].' = '.$user_id;
  $result = pwg_query($query);
  if (pwg_db_num_rows($result) > 0)
  {
    $row = pwg_db_fetch_assoc($result);
    $username = stripslashes($row['username']);
    $data = $time.$user_id.$username;
    $key = base64_encode( hash_hmac('sha1', $data, $conf['secret_key'].$row['password'],true) );
    return $key;
  }
  return false;
}

/**
 * Performs all required actions for user login.
 *
 * @param int $user_id
 * @param bool $remember_me
 */
function log_user($user_id, $remember_me)
{
  global $conf, $user;

  if ($remember_me and $conf['authorize_remembering'])
  {
    $now = time();
    $key = calculate_auto_login_key($user_id, $now, $username);
    if ($key!==false)
    {
      $cookie = $user_id.'-'.$now.'-'.$key;
      setcookie($conf['remember_me_name'],
        $cookie,
        time()+$conf['remember_me_length'],
        cookie_path(),ini_get('session.cookie_domain'),ini_get('session.cookie_secure'),
        ini_get('session.cookie_httponly')
        );
    }
  }
  else
  { // make sure we clean any remember me ...
    setcookie($conf['remember_me_name'], '', 0, cookie_path(),ini_get('session.cookie_domain'));
  }
  if ( session_id()!="" )
  { // we regenerate the session for security reasons
    // see http://www.acros.si/papers/session_fixation.pdf
    session_regenerate_id(true);
  }
  else
  {
    session_start();
  }
  $_SESSION['pwg_uid'] = (int)$user_id;

  $user['id'] = $_SESSION['pwg_uid'];
  trigger_notify('user_login', $user['id']);
}

/**
 * Performs auto-connection when cookie remember_me exists.
 *
 * @return bool
 */
function auto_login()
{
  global $conf;

  if ( isset( $_COOKIE[$conf['remember_me_name']] ) )
  {
    $cookie = explode('-', stripslashes($_COOKIE[$conf['remember_me_name']]));
    if ( count($cookie)===3
        and is_numeric(@$cookie[0]) /*user id*/
        and is_numeric(@$cookie[1]) /*time*/
        and time()-$conf['remember_me_length']<=@$cookie[1]
        and time()>=@$cookie[1] /*cookie generated in the past*/ )
    {
      $key = calculate_auto_login_key( $cookie[0], $cookie[1], $username );
      if ($key!==false and $key===$cookie[2])
      {
        log_user($cookie[0], true);
        trigger_notify('login_success', stripslashes($username));
        return true;
      }
    }
    setcookie($conf['remember_me_name'], '', 0, cookie_path(),ini_get('session.cookie_domain'));
  }
  return false;
}

/**
 * Hashes a password with the PasswordHash class from phpass security library.
 * @since 2.5
 *
 * @param string $password plain text
 * @return string
 */
function pwg_password_hash($password)
{
  global $pwg_hasher;

  if (empty($pwg_hasher))
  {
    require_once(PHPWG_ROOT_PATH.'include/passwordhash.class.php');

    // We use the portable hash feature from phpass because we can't be sure
    // Piwigo runs on PHP 5.3+ (and won't run on an older version in the
    // future)
    $pwg_hasher = new PasswordHash(13, true);
  }

  return $pwg_hasher->HashPassword($password);
}

/**
 * Verifies a password, with the PasswordHash class from phpass security library.
 * If the hash is 'old' (assumed MD5) the hash is updated in database, used for
 * migration from Piwigo 2.4.
 * @since 2.5
 *
 * @param string $password plain text
 * @param string $hash may be md5 or phpass hashed password
 * @param integer $user_id only useful to update password hash from md5 to phpass
 * @return bool
 */
function pwg_password_verify($password, $hash, $user_id=null)
{
  global $conf, $pwg_hasher;

  // If the password has not been hashed with the current algorithm.
  if (strpos($hash, '$P') !== 0)
  {
    if (!empty($conf['pass_convert']))
    {
      $check = ($hash == $conf['pass_convert']($password));
    }
    else
    {
      $check = ($hash == md5($password));
    }

    if ($check)
    {
      if (!isset($user_id) or $conf['external_authentification'])
      {
        return true;
      }

      // Rehash using new hash.
      $hash = pwg_password_hash($password);

      single_update(
        USERS_TABLE,
        array('password' => $hash),
        array('id' => $user_id)
        );
    }
  }

  // If the stored hash is longer than an MD5, presume the
  // new style phpass portable hash.
  if (empty($pwg_hasher))
  {
    require_once(PHPWG_ROOT_PATH.'include/passwordhash.class.php');

    // We use the portable hash feature
    $pwg_hasher = new PasswordHash(13, true);
  }

  return $pwg_hasher->CheckPassword($password, $hash);
}

/**
 * Tries to login a user given username and password (must be MySql escaped).
 *
 * @param string $username
 * @param string $password
 * @param bool $remember_me
 * @return bool
 */
function try_log_user($username, $password, $remember_me)
{
  return trigger_change('try_log_user', false, $username, $password, $remember_me);
}

add_event_handler('try_log_user', 'pwg_login');

/**
 * Default method for user login, can be overwritten with 'try_log_user' trigger.
 * @see try_log_user()
 *
 * @param string $username
 * @param string $password
 * @param bool $remember_me
 * @return bool
 */
function pwg_login($success, $username, $password, $remember_me)
{
  if ($success===true)
  {
    return true;
  }

  // we force the session table to be clean
  pwg_session_gc();

  global $conf;
  // retrieving the encrypted password of the login submitted
  $query = '
SELECT '.$conf['user_fields']['id'].' AS id,
       '.$conf['user_fields']['password'].' AS password
  FROM '.USERS_TABLE.'
  WHERE '.$conf['user_fields']['username'].' = \''.pwg_db_real_escape_string($username).'\'
;';
  $row = pwg_db_fetch_assoc(pwg_query($query));
  if ($conf['password_verify']($password, $row['password'], $row['id']))
  {
    log_user($row['id'], $remember_me);
    trigger_notify('login_success', stripslashes($username));
    return true;
  }
  trigger_notify('login_failure', stripslashes($username));
  return false;
}

/**
 * Performs all the cleanup on user logout.
 */
function logout_user()
{
  global $conf;

  trigger_notify('user_logout', @$_SESSION['pwg_uid']);

  $_SESSION = array();
  session_unset();
  session_destroy();
  setcookie(session_name(),'',0,
      ini_get('session.cookie_path'),
      ini_get('session.cookie_domain')
    );
  setcookie($conf['remember_me_name'], '', 0, cookie_path(),ini_get('session.cookie_domain'));
}

/**
 * Return user status.
 *
 * @param string $user_status used if $user not initialized
 * @return string
 */
function get_user_status($user_status='')
{
  global $user;

  if (empty($user_status))
  {
    if (isset($user['status']))
    {
      $user_status = $user['status'];
    }
    else
    {
      // swicth to default value
      $user_status = '';
    }
  }
  return $user_status;
}

/**
 * Return ACCESS_* value for a given $status.
 *
 * @param string $user_status used if $user not initialized
 * @return int one of ACCESS_* constants
 */
function get_access_type_status($user_status='')
{
  global $conf;

  switch (get_user_status($user_status))
  {
    case 'guest':
    {
      $access_type_status =
        ($conf['guest_access'] ? ACCESS_GUEST : ACCESS_FREE);
      break;
    }
    case 'generic':
    {
      $access_type_status = ACCESS_GUEST;
      break;
    }
    case 'normal':
    {
      $access_type_status = ACCESS_CLASSIC;
      break;
    }
    case 'admin':
    {
      $access_type_status = ACCESS_ADMINISTRATOR;
      break;
    }
    case 'webmaster':
    {
      $access_type_status = ACCESS_WEBMASTER;
      break;
    }
    default:
    {
      $access_type_status = ACCESS_FREE;
      break;
    }
  }

  return $access_type_status;
}

/**
 * Returns if user has access to a particular ACCESS_*
 *
 * @return int $access_type one of ACCESS_* constants
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_autorize_status($access_type, $user_status='')
{
  return (get_access_type_status($user_status) >= $access_type);
}

/**
 * Abord script if user has no access to a particular ACCESS_*
 *
 * @return int $access_type one of ACCESS_* constants
 * @param string $user_status used if $user not initialized
 */
function check_status($access_type, $user_status='')
{
  if (!is_autorize_status($access_type, $user_status))
  {
    access_denied();
  }
}

/**
 * Returns if user is generic.
 *
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_generic($user_status='')
{
  return get_user_status($user_status) == 'generic';
}

/**
 * Returns if user is a guest.
 *
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_a_guest($user_status='')
{
  return get_user_status($user_status) == 'guest';
}

/**
 * Returns if user is, at least, a classic user.
 *
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_classic_user($user_status='')
{
  return is_autorize_status(ACCESS_CLASSIC, $user_status);
}

/**
 * Returns if user is, at least, an administrator.
 *
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_admin($user_status='')
{
  return is_autorize_status(ACCESS_ADMINISTRATOR, $user_status);
}

/**
 * Returns if user is a webmaster.
 *
 * @param string $user_status used if $user not initialized
 * @return bool
 */
function is_webmaster($user_status='')
{
  return is_autorize_status(ACCESS_WEBMASTER, $user_status);
}

/**
 * Returns if current user can edit/delete/validate a comment.
 *
 * @param string $action edit/delete/validate
 * @param int $comment_author_id
 * @return bool
 */
function can_manage_comment($action, $comment_author_id)
{
  global $user, $conf;

  if (is_a_guest())
  {
    return false;
  }

  if (!in_array($action, array('delete','edit', 'validate')))
  {
    return false;
  }

  if (is_admin())
  {
    return true;
  }

  if ('edit' == $action and $conf['user_can_edit_comment'])
  {
    if ($comment_author_id == $user['id']) {
      return true;
    }
  }

  if ('delete' == $action and $conf['user_can_delete_comment'])
  {
    if ($comment_author_id == $user['id']) {
      return true;
    }
  }

  return false;
}

/**
 * Compute sql WHERE condition with restrict and filter data.
 * "FandF" means Forbidden and Filters.
 *
 * @param array $condition_fields one witch fields apply each filter
 *    - forbidden_categories
 *    - visible_categories
 *    - forbidden_images
 *    - visible_images
 * @param string $prefix_condition prefixes query if condition is not empty
 * @param boolean $force_one_condition use at least "1 = 1"
 * @return string
 */
function get_sql_condition_FandF(
  $condition_fields,
  $prefix_condition = null,
  $force_one_condition = false
  )
{
  global $user, $filter;

  $sql_list = array();

  foreach ($condition_fields as $condition => $field_name)
  {
    switch($condition)
    {
      case 'forbidden_categories':
      {
        if (!empty($user['forbidden_categories']))
        {
          $sql_list[] =
            $field_name.' NOT IN ('.$user['forbidden_categories'].')';
        }
        break;
      }
      case 'visible_categories':
      {
        if (!empty($filter['visible_categories']))
        {
          $sql_list[] =
            $field_name.' IN ('.$filter['visible_categories'].')';
        }
        break;
      }
      case 'visible_images':
        if (!empty($filter['visible_images']))
        {
          $sql_list[] =
            $field_name.' IN ('.$filter['visible_images'].')';
        }
        // note there is no break - visible include forbidden
      case 'forbidden_images':
        if (
            !empty($user['image_access_list'])
            or $user['image_access_type']!='NOT IN'
            )
        {
          $table_prefix=null;
          if ($field_name=='id')
          {
            $table_prefix = '';
          }
          elseif ($field_name=='i.id')
          {
            $table_prefix = 'i.';
          }
          if ( isset($table_prefix) )
          {
            $sql_list[]=$table_prefix.'level<='.$user['level'];
          }
          elseif ( !empty($user['image_access_list']) and !empty($user['image_access_type']) )
          {
            $sql_list[]=$field_name.' '.$user['image_access_type']
                .' ('.$user['image_access_list'].')';
          }
        }
        break;
      default:
      {
        die('Unknow condition');
        break;
      }
    }
  }

  if (count($sql_list) > 0)
  {
    $sql = '('.implode(' AND ', $sql_list).')';
  }
  else
  {
    $sql = $force_one_condition ? '1 = 1' : '';
  }

  if (isset($prefix_condition) and !empty($sql))
  {
    $sql = $prefix_condition.' '.$sql;
  }

  return $sql;
}

/**
 * Returns sql WHERE condition for recent photos/albums for current user.
 *
 * @param string $db_field
 * @return string
 */
function get_recent_photos_sql($db_field)
{
  global $user;
  if (!isset($user['last_photo_date']))
  {
    return '0=1';
  }
  return $db_field.'>=LEAST('
    .pwg_db_get_recent_period_expression($user['recent_period'])
    .','.pwg_db_get_recent_period_expression(1,$user['last_photo_date']).')';
}
?>