' . "\n";
            $mail->SMTPDebug = true;
        }
        $mail->Host = $CFG->smtphosts;               // specify main and backup servers

        if ($CFG->smtpuser) {                          // Use SMTP authentication
            $mail->SMTPAuth = true;
            $mail->Username = $CFG->smtpuser;
            $mail->Password = $CFG->smtppass;
        }
    }

    $adminuser = get_admin();

    $mail->Sender   = $adminuser->email;

    if (is_string($from)) { // So we can pass whatever we want if there is need
        $mail->From     = $CFG->noreplyaddress;
        $mail->FromName = $from;
    } else if ($usetrueaddress and $from->maildisplay) {
        $mail->From     = $from->email;
        $mail->FromName = fullname($from);
    } else {
        $mail->From     = $CFG->noreplyaddress;
        $mail->FromName = fullname($from);
    }
    $mail->Subject  =  stripslashes($subject);

    $mail->AddAddress($user->email, fullname($user) );

    $mail->WordWrap = 79;                               // set word wrap

    if (!empty($from->customheaders)) {                 // Add custom headers
        if (is_array($from->customheaders)) {
            foreach ($from->customheaders as $customheader) {
                $mail->AddCustomHeader($customheader);
            }
        } else {
            $mail->AddCustomHeader($from->customheaders);
        }
    }

    if ($messagehtml) {
        $mail->IsHTML(true);
        $mail->Encoding = 'quoted-printable';           // Encoding to use
        $mail->Body    =  $messagehtml;
        $mail->AltBody =  "\n$messagetext\n";
    } else {
        $mail->IsHTML(false);
        $mail->Body =  "\n$messagetext\n";
    }

    if ($attachment && $attachname) {
        if (ereg( "\\.\\." ,$attachment )) {    // Security check for ".." in dir path
            $mail->AddAddress($adminuser->email, fullname($adminuser) );
            $mail->AddStringAttachment('Error in attachment.  User attempted to attach a filename with a unsafe name.', 'error.txt', '8bit', 'text/plain');
        } else {
            include_once($CFG->dirroot .'/files/mimetypes.php');
            $mimetype = mimeinfo('type', $attachname);
            $mail->AddAttachment($CFG->dataroot .'/'. $attachment, $attachname, 'base64', $mimetype);
        }
    }

    if ($mail->Send()) {
        return true;
    } else {
        mtrace('ERROR: '. $mail->ErrorInfo);
        add_to_log(SITEID, 'library', 'mailer', $FULLME, 'ERROR: '. $mail->ErrorInfo);
        return false;
    }
}

/**
 * Resets specified user's password and send the new password to the user via email.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return boolean|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function reset_password_and_mail($user) {

    global $CFG;

    $site  = get_site();
    $from = get_admin();

    $newpassword = generate_password();

    if (! set_field('user', 'password', md5($newpassword), 'id', $user->id) ) {
        error('Could not set user password!');
    }

    $a->firstname = $user->firstname;
    $a->sitename = $site->fullname;
    $a->username = $user->username;
    $a->newpassword = $newpassword;
    $a->link = $CFG->wwwroot .'/login/change_password.php';
    $a->signoff = fullname($from, true).' ('. $from->email .')';

    $message = get_string('newpasswordtext', '', $a);

    $subject  = $site->fullname .': '. get_string('changedpassword');

    return email_to_user($user, $from, $subject, $message);

}

/**
 * Send email to specified user with confirmation text and activation link.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return boolean|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
 function send_confirmation_email($user) {

    global $CFG;

    $site = get_site();
    $from = get_admin();

    $data->firstname = fullname($user);
    $data->sitename = $site->fullname;
    $data->link = $CFG->wwwroot .'/login/confirm.php?p='. $user->secret .'&s='. $user->username;
    $data->admin = fullname($from) .' ('. $from->email .')';

    $message = get_string('emailconfirmation', '', $data);
    $subject = get_string('emailconfirmationsubject', '', $site->fullname);

    $messagehtml = text_to_html($message, false, false, true);

    return email_to_user($user, $from, $subject, $message, $messagehtml);

}

/**
 * send_password_change_confirmation_email.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return boolean|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 * @todo Finish documenting this function
 */
function send_password_change_confirmation_email($user) {

    global $CFG;

    $site = get_site();
    $from = get_admin();

    $data->firstname = $user->firstname;
    $data->sitename = $site->fullname;
    $data->link = $CFG->wwwroot .'/login/forgot_password.php?p='. $user->secret .'&s='. $user->username;
    $data->admin = fullname($from).' ('. $from->email .')';

    $message = get_string('emailpasswordconfirmation', '', $data);
    $subject = get_string('emailpasswordconfirmationsubject', '', $site->fullname);

    return email_to_user($user, $from, $subject, $message);

}

/**
 * Check that an email is allowed.  It returns an error message if there
 * was a problem.
 *
 * @param    type description
 * @todo Finish documenting this function
 */
function email_is_not_allowed($email) {

    global $CFG;

    if (!empty($CFG->allowemailaddresses)) {
        $allowed = explode(' ', $CFG->allowemailaddresses);
        foreach ($allowed as $allowedpattern) {
            $allowedpattern = trim($allowedpattern);
            if (!$allowedpattern) {
                continue;
            }
            if (strpos($email, $allowedpattern) !== false) {  // Match!
                return false;
            }
        }
        return get_string('emailonlyallowed', '', $CFG->allowemailaddresses);

    } else if (!empty($CFG->denyemailaddresses)) {
        $denied = explode(' ', $CFG->denyemailaddresses);
        foreach ($denied as $deniedpattern) {
            $deniedpattern = trim($deniedpattern);
            if (!$deniedpattern) {
                continue;
            }
            if (strpos($email, $deniedpattern) !== false) {   // Match!
                return get_string('emailnotallowed', '', $CFG->denyemailaddresses);
            }
        }
    }

    return false;
}


/// FILE HANDLING  /////////////////////////////////////////////

/**
 * Create a directory.
 *
 * @uses $CFG
 * @param string $directory  a string of directory names under $CFG->dataroot eg  stuff/assignment/1
 * param boolean $shownotices If true then notification messages will be printed out on error.
 * @return string|false Returns full path to directory if successful, false if not
 */
function make_upload_directory($directory, $shownotices=true) {

    global $CFG;

    $currdir = $CFG->dataroot;

    umask(0000);

    if (!file_exists($currdir)) {
        if (! mkdir($currdir, $CFG->directorypermissions)) {
            if ($shownotices) {
                notify('ERROR: You need to create the directory '. $currdir .' with web server write access');
            }
            return false;
        }
        if ($handle = fopen($currdir.'/.htaccess', 'w')) {   // For safety
            @fwrite($handle, "deny from all\r\n");
            @fclose($handle); 
        }
    }

    $dirarray = explode('/', $directory);

    foreach ($dirarray as $dir) {
        $currdir = $currdir .'/'. $dir;
        if (! file_exists($currdir)) {
            if (! mkdir($currdir, $CFG->directorypermissions)) {
                if ($shownotices) {
                    notify('ERROR: Could not find or create a directory ('. $currdir .')');
                }
                return false;
            }
            //@chmod($currdir, $CFG->directorypermissions);  // Just in case mkdir didn't do it
        }
    }

    return $currdir;
}

/**
 * Makes an upload directory for a particular module.
 *
 * @uses $CFG
 * @param int $courseid The id of the course in question - maps to id field of 'course' table.
 * @return string|false Returns full path to directory if successful, false if not
 * @todo Finish documenting this function
 */
function make_mod_upload_directory($courseid) {
    global $CFG;

    if (! $moddata = make_upload_directory($courseid .'/'. $CFG->moddata)) {
        return false;
    }

    $strreadme = get_string('readme');

    if (file_exists($CFG->dirroot .'/lang/'. $CFG->lang .'/docs/module_files.txt')) {
        copy($CFG->dirroot .'/lang/'. $CFG->lang .'/docs/module_files.txt', $moddata .'/'. $strreadme .'.txt');
    } else {
        copy($CFG->dirroot .'/lang/en/docs/module_files.txt', $moddata .'/'. $strreadme .'.txt');
    }
    return $moddata;
}

/**
 * Returns current name of file on disk if it exists.
 *
 * @param string $newfile File to be verified
 * @return string Current name of file on disk if true
 * @todo Finish documenting this function
 */
function valid_uploaded_file($newfile) {
    if (empty($newfile)) {
        return '';
    }
    if (is_uploaded_file($newfile['tmp_name']) and $newfile['size'] > 0) {
        return $newfile['tmp_name'];
    } else {
        return '';
    }
}

/**
 * Returns the maximum size for uploading files.
 *
 * There are seven possible upload limits:
 * 1. in Apache using LimitRequestBody (no way of checking or changing this)
 * 2. in php.ini for 'upload_max_filesize' (can not be changed inside PHP)
 * 3. in .htaccess for 'upload_max_filesize' (can not be changed inside PHP)
 * 4. in php.ini for 'post_max_size' (can not be changed inside PHP)
 * 5. by the Moodle admin in $CFG->maxbytes
 * 6. by the teacher in the current course $course->maxbytes
 * 7. by the teacher for the current module, eg $assignment->maxbytes
 *
 * These last two are passed to this function as arguments (in bytes).
 * Anything defined as 0 is ignored.
 * The smallest of all the non-zero numbers is returned.
 *
 * @param int $sizebytes ?
 * @param int $coursebytes Current course $course->maxbytes (in bytes)
 * @param int $modulebytes Current module ->maxbytes (in bytes)
 * @return int The maximum size for uploading files.
 * @todo Finish documenting this function
 */
function get_max_upload_file_size($sitebytes=0, $coursebytes=0, $modulebytes=0) {

    if (! $filesize = ini_get('upload_max_filesize')) {
        $filesize = '5M';
    }
    $minimumsize = get_real_size($filesize);

    if ($postsize = ini_get('post_max_size')) {
        $postsize = get_real_size($postsize);
        if ($postsize < $minimumsize) {
            $minimumsize = $postsize;
        }
    }

    if ($sitebytes and $sitebytes < $minimumsize) {
        $minimumsize = $sitebytes;
    }

    if ($coursebytes and $coursebytes < $minimumsize) {
        $minimumsize = $coursebytes;
    }

    if ($modulebytes and $modulebytes < $minimumsize) {
        $minimumsize = $modulebytes;
    }

    return $minimumsize;
}

/**
 * Related to the above function - this function returns an
 * array of possible sizes in an array, translated to the
 * local language.
 *
 * @uses SORT_NUMERIC
 * @param int $sizebytes ?
 * @param int $coursebytes Current course $course->maxbytes (in bytes)
 * @param int $modulebytes Current module ->maxbytes (in bytes)
 * @return int
 * @todo Finish documenting this function
 */
function get_max_upload_sizes($sitebytes=0, $coursebytes=0, $modulebytes=0) {

    if (!$maxsize = get_max_upload_file_size($sitebytes, $coursebytes, $modulebytes)) {
        return array();
    }

    $filesize[$maxsize] = display_size($maxsize);

    $sizelist = array(10240, 51200, 102400, 512000, 1048576, 2097152,
                      5242880, 10485760, 20971520, 52428800, 104857600);

    foreach ($sizelist as $sizebytes) {
       if ($sizebytes < $maxsize) {
           $filesize[$sizebytes] = display_size($sizebytes);
       }
    }

    krsort($filesize, SORT_NUMERIC);

    return $filesize;
}

/**
 * If there has been an error uploading a file, print the appropriate error message
 * Numerical constants used as constant definitions not added until PHP version 4.2.0
 *
 * $filearray is a 1-dimensional sub-array of the $_FILES array
 * eg $filearray = $_FILES['userfile1']
 * If left empty then the first element of the $_FILES array will be used
 *
 * @uses $_FILES
 * @param array $filearray  A 1-dimensional sub-array of the $_FILES array
 * @param boolean $returnerror ?
 * @return boolean
 * @todo Finish documenting this function
 */
function print_file_upload_error($filearray = '', $returnerror = false) {

    if ($filearray == '' or !isset($filearray['error'])) {

        if (empty($_FILES)) return false;

        $files = $_FILES; /// so we don't mess up the _FILES array for subsequent code
        $filearray = array_shift($files); /// use first element of array
    }

    switch ($filearray['error']) {

        case 0: // UPLOAD_ERR_OK
            if ($filearray['size'] > 0) {
                $errmessage = get_string('uploadproblem', $filearray['name']);
            } else {
                $errmessage = get_string('uploadnofilefound'); /// probably a dud file name
            }
            break;

        case 1: // UPLOAD_ERR_INI_SIZE
            $errmessage = get_string('uploadserverlimit');
            break;

        case 2: // UPLOAD_ERR_FORM_SIZE
            $errmessage = get_string('uploadformlimit');
            break;

        case 3: // UPLOAD_ERR_PARTIAL
            $errmessage = get_string('uploadpartialfile');
            break;

        case 4: // UPLOAD_ERR_NO_FILE
            $errmessage = get_string('uploadnofilefound');
            break;

        default:
            $errmessage = get_string('uploadproblem', $filearray['name']);
    }

    if ($returnerror) {
        return $errmessage;
    } else {
        notify($errmessage);
        return true;
    }

}

/**
 * Returns an array with all the filenames in
 * all subdirectories, relative to the given rootdir.
 * If excludefile is defined, then that file/directory is ignored
 * If getdirs is true, then (sub)directories are included in the output
 * If getfiles is true, then files are included in the output
 * (at least one of these must be true!)
 *
 * @param string $rootdir  ?
 * @param string $excludefile  If defined then the specified file/directory is ignored
 * @param boolean $descend  ?
 * @param boolean $getdirs  If true then (sub)directories are included in the output
 * @param boolean $getfiles  If true then files are included in the output
 * @return array An array with all the filenames in
 * all subdirectories, relative to the given rootdir
 * @todo Finish documenting this function. Add examples of $excludefile usage.
 */
function get_directory_list($rootdir, $excludefile='', $descend=true, $getdirs=false, $getfiles=true) {

    $dirs = array();

    if (!$getdirs and !$getfiles) {   // Nothing to show
        return $dirs;
    }

    if (!is_dir($rootdir)) {          // Must be a directory
        return $dirs;
    }

    if (!$dir = opendir($rootdir)) {  // Can't open it for some reason
        return $dirs;
    }

    while (false !== ($file = readdir($dir))) {
        $firstchar = substr($file, 0, 1);
        if ($firstchar == '.' or $file == 'CVS' or $file == $excludefile) {
            continue;
        }
        $fullfile = $rootdir .'/'. $file;
        if (filetype($fullfile) == 'dir') {
            if ($getdirs) {
                $dirs[] = $file;
            }
            if ($descend) {
                $subdirs = get_directory_list($fullfile, $excludefile, $descend, $getdirs, $getfiles);
                foreach ($subdirs as $subdir) {
                    $dirs[] = $file .'/'. $subdir;
                }
            }
        } else if ($getfiles) {
            $dirs[] = $file;
        }
    }
    closedir($dir);

    asort($dirs);

    return $dirs;
}

/**
 * Adds up all the files in a directory and works out the size.
 *
 * @param string $rootdir  ?
 * @param string $excludefile  ?
 * @return array
 * @todo Finish documenting this function
 */
function get_directory_size($rootdir, $excludefile='') {

    $size = 0;

    if (!is_dir($rootdir)) {          // Must be a directory
        return $dirs;
    }

    if (!$dir = @opendir($rootdir)) {  // Can't open it for some reason
        return $dirs;
    }

    while (false !== ($file = readdir($dir))) {
        $firstchar = substr($file, 0, 1);
        if ($firstchar == '.' or $file == 'CVS' or $file == $excludefile) {
            continue;
        }
        $fullfile = $rootdir .'/'. $file;
        if (filetype($fullfile) == 'dir') {
            $size += get_directory_size($fullfile, $excludefile);
        } else {
            $size += filesize($fullfile);
        }
    }
    closedir($dir);

    return $size;
}

/**
 * Converts numbers like 10M into bytes.
 *
 * @param mixed $size The size to be converted
 * @return mixed
 */
function get_real_size($size=0) {
    if (!$size) {
        return 0;
    }
    $scan['MB'] = 1048576;
    $scan['Mb'] = 1048576;
    $scan['M'] = 1048576;
    $scan['m'] = 1048576;
    $scan['KB'] = 1024;
    $scan['Kb'] = 1024;
    $scan['K'] = 1024;
    $scan['k'] = 1024;

    while (list($key) = each($scan)) {
        if ((strlen($size)>strlen($key))&&(substr($size, strlen($size) - strlen($key))==$key)) {
            $size = substr($size, 0, strlen($size) - strlen($key)) * $scan[$key];
            break;
        }
    }
    return $size;
}

/**
 * Converts bytes into display form
 *
 * @param string $size  ?
 * @return string
 * @staticvar string $gb Localized string for size in gigabytes
 * @staticvar string $mb Localized string for size in megabytes
 * @staticvar string $kb Localized string for size in kilobytes
 * @staticvar string $b Localized string for size in bytes
 * @todo Finish documenting this function. Verify return type.
 */
function display_size($size) {

    static $gb, $mb, $kb, $b;

    if (empty($gb)) {
        $gb = get_string('sizegb');
        $mb = get_string('sizemb');
        $kb = get_string('sizekb');
        $b  = get_string('sizeb');
    }

    if ($size >= 1073741824) {
        $size = round($size / 1073741824 * 10) / 10 . $gb;
    } else if ($size >= 1048576) {
        $size = round($size / 1048576 * 10) / 10 . $mb;
    } else if ($size >= 1024) {
        $size = round($size / 1024 * 10) / 10 . $kb;
    } else {
        $size = $size .' '. $b;
    }
    return $size;
}

/**
 * Cleans a given filename by removing suspicious or troublesome characters
 * Only these are allowed:
 *    alphanumeric _ - .
 *
 * @param string $string  ?
 * @return string
 * @todo Finish documenting this function
 */
function clean_filename($string) {
    $string = eregi_replace("\.\.+", '', $string);
    $string = preg_replace('/[^\.a-zA-Z\d\_-]/','_', $string ); // only allowed chars
    $string = eregi_replace("_+", '_', $string);
    return $string;
}


/// STRING TRANSLATION  ////////////////////////////////////////

/**
 * Returns the code for the current language
 *
 * @uses $CFG
 * @param $USER
 * @param $SESSION
 * @return string
 */
function current_language() {
    global $CFG, $USER, $SESSION;

    if (!empty($CFG->courselang)) {    // Course language can override all other settings for this page
        return $CFG->courselang;

    } else if (!empty($SESSION->lang)) {    // Session language can override other settings
        return $SESSION->lang;

    } else if (!empty($USER->lang)) {    // User language can override site language
        return $USER->lang;

    } else {
        return $CFG->lang;
    }
}

/**
 * Prints out a translated string.
 *
 * Prints out a translated string using the return value from the {@link get_string()} function.
 *
 * Example usage of this function when the string is in the moodle.php file:

 * 
 * echo '';
 * print_string('wordforstudent');
 * echo '';
 * 
 *
 * Example usage of this function when the string is not in the moodle.php file:

 * 
 * echo '
';
 * print_string('typecourse', 'calendar');
 * echo '
';
 * 
 *
 * @param string $identifier The key identifier for the localized string
 * @param string $module The module where the key identifier is stored. If none is specified then moodle.php is used.
 * @param mixed $a An object, string or number that can be used
 * within translation strings
 */
function print_string($identifier, $module='', $a=NULL) {
    echo get_string($identifier, $module, $a);
}

/**
 * Returns a localized string.
 *
 * Returns the translated string specified by $identifier as
 * for $module.  Uses the same format files as STphp.
 * $a is an object, string or number that can be used
 * within translation strings
 *
 * eg "hello \$a->firstname \$a->lastname"
 * or "hello \$a"
 *
 * If you would like to directly echo the localized string use
 * the function {@link print_string()}
 *
 * Example usage of this function involves finding the string you would
 * like a local equivalent of and using its identifier and module information
 * to retrive it.

 * If you open moodle/lang/en/moodle.php and look near line 1031
 * you will find a string to prompt a user for their word for student
 * 
 * $string['wordforstudent'] = 'Your word for Student';
 * 
 * So if you want to display the string 'Your word for student'
 * in any language that supports it on your site
 * you just need to use the identifier 'wordforstudent'
 * 
 * $mystring = ''. get_string('wordforstudent') .'';
or
 * 
 * If the string you want is in another file you'd take a slightly
 * different approach. Looking in moodle/lang/en/calendar.php you find
 * around line 75:
 * 
 * $string['typecourse'] = 'Course event';
 * 
 * If you want to display the string "Course event" in any language
 * supported you would use the identifier 'typecourse' and the module 'calendar'
 * (because it is in the file calendar.php):
 * 
 * $mystring = '
'. get_string('typecourse', 'calendar') .'
';
 * 
 *
 * As a last resort, should the identifier fail to map to a string
 * the returned string will be [[ $identifier ]]
 *
 * @uses $CFG
 * @param string $identifier The key identifier for the localized string
 * @param string $module The module where the key identifier is stored. If none is specified then moodle.php is used.
 * @param mixed $a An object, string or number that can be used
 * within translation strings
 * @return string The localized string.
 */
function get_string($identifier, $module='', $a=NULL) {

    global $CFG;

    global $course;     /// Not a nice hack, but quick
    if (empty($CFG->courselang)) {
        if (!empty($course->lang)) {
            $CFG->courselang = $course->lang;
        }
    }

    $lang = current_language();

    if ($module == '') {
        $module = 'moodle';
    }

/// Define the two or three major locations of language strings for this module

    $locations = array( $CFG->dataroot.'/lang/',  $CFG->dirroot.'/lang/' );
    if ($module != 'moodle') {
        $locations[] =  $CFG->dirroot .'/mod/'.$module.'/lang/';
    }

/// First check all the normal locations for the string in the current language

    foreach ($locations as $location) {
        $langfile = $location.$lang.'/'.$module.'.php';
        if (file_exists($langfile)) {
            if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }
    }

/// If the preferred language was English we can abort now
    if ($lang == 'en') {
        return '[['. $identifier .']]';
    }

/// Is a parent language defined?  If so, try to find this string in a parent language file

    foreach ($locations as $location) {
        $langfile = $location.$lang.'/moodle.php';
        if (file_exists($langfile)) {
            if ($result = get_string_from_file('parentlanguage', $langfile, "\$parentlang")) {
                eval($result);
                if (!empty($parentlang)) {   // found it!
                    $langfile = $location.$parentlang.'/'.$module.'.php';
                    if (file_exists($langfile)) {
                        if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                            eval($result);
                            return $resultstring;
                        }
                    }
                }
            }
        }
    }

/// Our only remaining option is to try English

    foreach ($locations as $location) {
        $langfile = $location.'en/'.$module.'.php';

        if (file_exists($langfile)) {
            if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }
    }

    return '[['.$identifier.']]';  // Last resort
}

/**
 * This function is only used from {@link get_string()}.
 *
 * @internal Only used from get_string, not meant to be public API
 * @param string $identifier ?
 * @param string $langfile ?
 * @param string $destination ?
 * @return string|false ?
 * @staticvar array $strings Localized strings
 * @access private
 * @todo Finish documenting this function.
 */
function get_string_from_file($identifier, $langfile, $destination) {

    static $strings;    // Keep the strings cached in memory.

    if (empty($strings[$langfile])) {
        $string = array();
        include ($langfile);
        $strings[$langfile] = $string;
    } else {
        $string = &$strings[$langfile];
    }

    if (!isset ($string[$identifier])) {
        return false;
    }

    return $destination .'= sprintf("'. $string[$identifier] .'");';
}

/**
 * Converts an array of strings to their localized value.
 *
 * @param array $array An array of strings
 * @param string $module The language module that these strings can be found in.
 * @return string
 */
function get_strings($array, $module='') {

   $string = NULL;
   foreach ($array as $item) {
       $string->$item = get_string($item, $module);
   }
   return $string;
}

/**
 * Returns a list of language codes and their full names
 *
 * @uses $CFG
 * @return array An associative array with contents in the form of LanguageCode => LanguageName
 * @todo Finish documenting this function
 */
function get_list_of_languages() {
    global $CFG;

    $languages = array();

    if (!empty($CFG->langlist)) {       // use admin's list of languages
        $langlist = explode(',', $CFG->langlist);
        foreach ($langlist as $lang) {
            if (file_exists($CFG->dirroot .'/lang/'. $lang .'/moodle.php')) {
                include($CFG->dirroot .'/lang/'. $lang .'/moodle.php');
                $languages[$lang] = $string['thislanguage'].' ('. $lang .')';
                unset($string);
            }
        }
    } else {
        if (!$langdirs = get_list_of_plugins('lang')) {
            return false;
        }
        foreach ($langdirs as $lang) {
            @include($CFG->dirroot .'/lang/'. $lang .'/moodle.php');
            $languages[$lang] = $string['thislanguage'] .' ('. $lang .')';
            unset($string);
        }
    }

    return $languages;
}

/**
 * Returns a list of country names in the current language
 *
 * @uses $CFG
 * @uses $USER
 * @return string?
 * @todo Finish documenting this function.
 */
function get_list_of_countries() {
    global $CFG, $USER;

    $lang = current_language();

    if (!file_exists($CFG->dirroot .'/lang/'. $lang .'/countries.php')) {
        if ($parentlang = get_string('parentlanguage')) {
            if (file_exists($CFG->dirroot .'/lang/'. $parentlang .'/countries.php')) {
                $lang = $parentlang;
            } else {
                $lang = 'en';  // countries.php must exist in this pack
            }
        } else {
            $lang = 'en';  // countries.php must exist in this pack
        }
    }

    include($CFG->dirroot .'/lang/'. $lang .'/countries.php');

    if (!empty($string)) {
        asort($string);
    }

    return $string;
}

/**
 * Returns a list of picture names in the current language
 *
 * @uses $CFG
 * @return string?
 * @todo Finish documenting this function.
 */
function get_list_of_pixnames() {
    global $CFG;

    $lang = current_language();

    if (!file_exists($CFG->dirroot .'/lang/'. $lang .'/pix.php')) {
        if ($parentlang = get_string('parentlanguage')) {
            if (file_exists($CFG->dirroot .'/lang/'. $parentlang .'/pix.php')) {
                $lang = $parentlang;
            } else {
                $lang = 'en';  // countries.php must exist in this pack
            }
        } else {
            $lang = 'en';  // countries.php must exist in this pack
        }
    }

    include_once($CFG->dirroot .'/lang/'. $lang .'/pix.php');

    return $string;
}

/**
 * Can include a given document file (depends on second
 * parameter) or just return info about it.
 *
 * @uses $CFG
 * @param string $file ?
 * @param boolean $include ?
 * @return ?
 * @todo Finish documenting this function
 */
function document_file($file, $include=true) {
    global $CFG;

    $file = clean_filename($file);

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

    $langs = array(current_language(), get_string('parentlanguage'), 'en');

    foreach ($langs as $lang) {
        $info->filepath = $CFG->dirroot .'/lang/'. $lang .'/docs/'. $file;
        $info->urlpath  = $CFG->wwwroot .'/lang/'. $lang .'/docs/'. $file;

        if (file_exists($info->filepath)) {
            if ($include) {
                include($info->filepath);
            }
            return $info;
        }
    }

    return false;
}

/**
* Function to raise the memory limit to a new value.
* Will respect the memory limit if it is higher, thus allowing
* settings in php.ini, apache conf or command line switches
* to override it
*
* The memory limit should be expressed with a string (eg:'64M')
*
* Return boolean
*
* @param    value    string with the new memory limit
*/
function raise_memory_limit ($newlimit) {

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

    $cur = @ini_get('memory_limit');
    if (empty($cur)) {
        // if php is compiled without --enable-memory-limits
        // apparently memory_limit is set to ''
        $cur=0;
    } else {
        if ($cur == -1){
            return true; // unlimited mem!
        }
      $cur = get_real_size($cur);
    }

    $new = get_real_size($newlimit);
    if ($new > $cur) {
        ini_set('memory_limit', $newlimit);
        return true;
    }
    return false;
}

/// ENCRYPTION  ////////////////////////////////////////////////

/**
 * rc4encrypt
 *
 * @param string $data ?
 * @return string
 * @todo Finish documenting this function
 */
function rc4encrypt($data) {
    $password = 'nfgjeingjk';
    return endecrypt($password, $data, '');
}

/**
 * rc4decrypt
 *
 * @param string $data ?
 * @return string
 * @todo Finish documenting this function
 */
function rc4decrypt($data) {
    $password = 'nfgjeingjk';
    return endecrypt($password, $data, 'de');
}

/**
 * Based on a class by Mukul Sabharwal [mukulsabharwal @ yahoo.com]
 *
 * @param string $pwd ?
 * @param string $data ?
 * @param string $case ?
 * @return string
 * @todo Finish documenting this function
 */
function endecrypt ($pwd, $data, $case) {

    if ($case == 'de') {
        $data = urldecode($data);
    }

    $key[] = '';
    $box[] = '';
    $temp_swap = '';
    $pwd_length = 0;

    $pwd_length = strlen($pwd);

    for ($i = 0; $i <= 255; $i++) {
        $key[$i] = ord(substr($pwd, ($i % $pwd_length), 1));
        $box[$i] = $i;
    }

    $x = 0;

    for ($i = 0; $i <= 255; $i++) {
        $x = ($x + $box[$i] + $key[$i]) % 256;
        $temp_swap = $box[$i];
        $box[$i] = $box[$x];
        $box[$x] = $temp_swap;
    }

    $temp = '';
    $k = '';

    $cipherby = '';
    $cipher = '';

    $a = 0;
    $j = 0;

    for ($i = 0; $i < strlen($data); $i++) {
        $a = ($a + 1) % 256;
        $j = ($j + $box[$a]) % 256;
        $temp = $box[$a];
        $box[$a] = $box[$j];
        $box[$j] = $temp;
        $k = $box[(($box[$a] + $box[$j]) % 256)];
        $cipherby = ord(substr($data, $i, 1)) ^ $k;
        $cipher .= chr($cipherby);
    }

    if ($case == 'de') {
        $cipher = urldecode(urlencode($cipher));
    } else {
        $cipher = urlencode($cipher);
    }

    return $cipher;
}


/// CALENDAR MANAGEMENT  ////////////////////////////////////////////////////////////////


/**
 * Call this function to add an event to the calendar table
 *  and to call any calendar plugins
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field. The object event should include the following:
 *  

 *    
$event->name - Name for the event
 *    
$event->description - Description of the event (defaults to '')
 *    
$event->format - Format for the description (using formatting types defined at the top of weblib.php)
 *    
$event->courseid - The id of the course this event belongs to (0 = all courses)
 *    
$event->groupid - The id of the group this event belongs to (0 = no group)
 *    
$event->userid - The id of the user this event belongs to (0 = no user)
 *    
$event->modulename - Name of the module that creates this event
 *    
$event->instance - Instance of the module that owns this event
 *    
$event->eventtype - The type info together with the module info could
 *             be used by calendar plugins to decide how to display event
 *    
$event->timestart- Timestamp for start of event
 *    
$event->timeduration - Duration (defaults to zero)
 *    
$event->visible - 0 if the event should be hidden (e.g. because the activity that created it is hidden)
 *  
 * @return int The id number of the resulting record
 * @todo Finish documenting this function
 */
 function add_event($event) {

    global $CFG;

    $event->timemodified = time();

    if (!$event->id = insert_record('event', $event)) {
        return false;
    }

    if (!empty($CFG->calendar)) { // call the add_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_add_event = $CFG->calendar.'_add_event';
            if (function_exists($calendar_add_event)) {
                $calendar_add_event($event);
            }
        }
    }

    return $event->id;
}

/**
 * Call this function to update an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return boolean
 * @todo Finish documenting this function
 */
function update_event($event) {

    global $CFG;

    $event->timemodified = time();

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_update_event = $CFG->calendar.'_update_event';
            if (function_exists($calendar_update_event)) {
                $calendar_update_event($event);
            }
        }
    }
    return update_record('event', $event);
}

/**
 * Call this function to delete the event with id $id from calendar table.
 *
  * @uses $CFG
 * @param int $id The id of an event from the 'calendar' table.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function delete_event($id) {

    global $CFG;

    if (!empty($CFG->calendar)) { // call the delete_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_delete_event = $CFG->calendar.'_delete_event';
            if (function_exists($calendar_delete_event)) {
                $calendar_delete_event($id);
            }
        }
    }
    return delete_records('event', 'id', $id);
}

/**
 * Call this function to hide an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function hide_event($event) {
    global $CFG;

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_hide_event = $CFG->calendar.'_hide_event';
            if (function_exists($calendar_hide_event)) {
                $calendar_hide_event($event);
            }
        }
    }
    return set_field('event', 'visible', 0, 'id', $event->id);
}

/**
 * Call this function to unhide an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function show_event($event) {
    global $CFG;

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_show_event = $CFG->calendar.'_show_event';
            if (function_exists($calendar_show_event)) {
                $calendar_show_event($event);
            }
        }
    }
    return set_field('event', 'visible', 1, 'id', $event->id);
}


/// ENVIRONMENT CHECKING  ////////////////////////////////////////////////////////////

/**
 * Lists plugin directories within some directory
 *
 * @uses $CFG
 * @param string $plugin ?
 * @param string $exclude ?
 * @return array
 * @todo Finish documenting this function
 */
function get_list_of_plugins($plugin='mod', $exclude='') {

    global $CFG;

    $basedir = opendir($CFG->dirroot .'/'. $plugin);
    while ($dir = readdir($basedir)) {
        $firstchar = substr($dir, 0, 1);
        if ($firstchar == '.' or $dir == 'CVS' or $dir == '_vti_cnf' or $dir == $exclude) {
            continue;
        }
        if (filetype($CFG->dirroot .'/'. $plugin .'/'. $dir) != 'dir') {
            continue;
        }
        $plugins[] = $dir;
    }
    if ($plugins) {
        asort($plugins);
    }
    return $plugins;
}

/**
 * Returns true if the current version of PHP is greater that the specified one.
 *
 * @param string $version The version of php being tested.
 * @return boolean
 * @todo Finish documenting this function
 */
function check_php_version($version='4.1.0') {
    $minversion = intval(str_replace('.', '', $version));
    $curversion = intval(str_replace('.', '', phpversion()));
    return ($curversion >= $minversion);
}


/**
 * Checks to see if is a browser matches the specified
 * brand and is equal or better version.
 *
 * @uses $_SERVER
 * @param string $brand The browser identifier being tested
 * @param int $version The version of the browser
 * @return boolean
 * @todo Finish documenting this function
 */
 function check_browser_version($brand='MSIE', $version=5.5) {
    $agent = $_SERVER['HTTP_USER_AGENT'];

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

    switch ($brand) {

      case 'Gecko':   /// Gecko based browsers

          if (substr_count($agent, 'Camino')) {
              // MacOS X Camino support
              $version = 20041110;
          }

          // the proper string - Gecko/CCYYMMDD Vendor/Version
          if (ereg("^([a-zA-Z]+)/([0-9]+\.[0-9]+) \((.*)\) (.*)$", $agent, $match)) {
              if (ereg("^([Gecko]+)/([0-9]+)",$match[4], $reldate)) {
                  if ($reldate[2] > $version) {
                      return true;
                  }
              }
          }
          break;


      case 'MSIE':   /// Internet Explorer

          if (strpos($agent, 'Opera')) {     // Reject Opera
              return false;
          }
          $string = explode(';', $agent);
          if (!isset($string[1])) {
              return false;
          }
          $string = explode(' ', trim($string[1]));
          if (!isset($string[0]) and !isset($string[1])) {
              return false;
          }
          if ($string[0] == $brand and (float)$string[1] >= $version ) {
              return true;
          }
          break;

    }

    return false;
}

/**
 * This function makes the return value of ini_get consistent if you are
 * setting server directives through the .htaccess file in apache.
 * Current behavior for value set from php.ini On = 1, Off = [blank]
 * Current behavior for value set from .htaccess On = On, Off = Off
 * Contributed by jdell @ unr.edu
 *
 * @param string $ini_get_arg ?
 * @return boolean
 * @todo Finish documenting this function
 */
function ini_get_bool($ini_get_arg) {
    $temp = ini_get($ini_get_arg);

    if ($temp == '1' or strtolower($temp) == 'on') {
        return true;
    }
    return false;
}

/**
 * Compatibility stub to provide backward compatibility
 *
 * Determines if the HTML editor is enabled.
 * @deprecated Use {@link can_use_html_editor()} instead.
 */
 function can_use_richtext_editor() {
    return can_use_html_editor();
}

/**
 * Determines if the HTML editor is enabled.
 *
 * This depends on site and user
 * settings, as well as the current browser being used.
 *
 * @return string|false Returns false if editor is not being used, otherwise
 * returns 'MSIE' or 'Gecko'.
 * @todo Finish documenting this function
 */
 function can_use_html_editor() {
    global $USER, $CFG;

    if (!empty($USER->htmleditor) and !empty($CFG->htmleditor)) {
        if (check_browser_version('MSIE', 5.5)) {
            return 'MSIE';
        } else if (check_browser_version('Gecko', 20030516)) {
            return 'Gecko';
        }
    }
    return false;
}

/**
 * Hack to find out the GD version by parsing phpinfo output
 *
 * @return int GD version (1, 2, or 0)
 */
function check_gd_version() {
    $gdversion = 0;

    if (function_exists('gd_info')){
        $gd_info = gd_info();
        if (substr_count($gd_info['GD Version'], '2.')) {
            $gdversion = 2;
        } else if (substr_count($gd_info['GD Version'], '1.')) {
            $gdversion = 1;
        }

    } else {
        ob_start();
        phpinfo(8);
        $phpinfo = ob_get_contents();
        ob_end_clean();

        $phpinfo = explode("\n", $phpinfo);


        foreach ($phpinfo as $text) {
            $parts = explode('', $text);
            foreach ($parts as $key => $val) {
                $parts[$key] = trim(strip_tags($val));
            }
            if ($parts[0] == 'GD Version') {
                if (substr_count($parts[1], '2.0')) {
                    $parts[1] = '2.0';
                }
                $gdversion = intval($parts[1]);
            }
        }
    }

    return $gdversion;   // 1, 2 or 0
}

/**
 * Determine if moodle installation requires update
 *
 * Checks version numbers of main code and all modules to see
 * if there are any mismatches
 *
 * @uses $CFG
 * @return boolean
 * @todo Finish documenting this function
 */
function moodle_needs_upgrading() {
    global $CFG;

    include_once($CFG->dirroot .'/version.php');  # defines $version and upgrades
    if ($CFG->version) {
        if ($version > $CFG->version) {
            return true;
        }
        if ($mods = get_list_of_plugins('mod')) {
            foreach ($mods as $mod) {
                $fullmod = $CFG->dirroot .'/mod/'. $mod;
                unset($module);
                if (!is_readable($fullmod .'/version.php')) {
                    notify('Module "'. $mod .'" is not readable - check permissions');
                    continue;
                }
                include_once($fullmod .'/version.php');  # defines $module with version etc
                if ($currmodule = get_record('modules', 'name', $mod)) {
                    if ($module->version > $currmodule->version) {
                        return true;
                    }
                }
            }
        }
    } else {
        return true;
    }
    return false;
}


/// MISCELLANEOUS ////////////////////////////////////////////////////////////////////

/**
 * Notify admin users or admin user of any failed logins (since last notification).
 *
 * @uses $CFG
 * @uses $db
 * @uses HOURSECS
 * @todo Finish documenting this function. Add long description with more detail on what it does.
 */
function notify_login_failures() {
    global $CFG, $db;

    switch ($CFG->notifyloginfailures) {
        case 'mainadmin' :
            $recip = array(get_admin());
            break;
        case 'alladmins':
            $recip = get_admins();
            break;
    }

    if (empty($CFG->lastnotifyfailure)) {
        $CFG->lastnotifyfailure=0;
    }

    // we need to deal with the threshold stuff first.
    if (empty($CFG->notifyloginthreshold)) {
        $CFG->notifyloginthreshold = 10; // default to something sensible.
    }

    $notifyipsrs = $db->Execute('SELECT ip FROM '. $CFG->prefix .'log WHERE time > '. $CFG->lastnotifyfailure .'
                          AND module=\'login\' AND action=\'error\' GROUP BY ip HAVING count(*) > '. $CFG->notifyloginthreshold);

    $notifyusersrs = $db->Execute('SELECT info FROM '. $CFG->prefix .'log WHERE time > '. $CFG->lastnotifyfailure .'
                          AND module=\'login\' AND action=\'error\' GROUP BY info HAVING count(*) > '. $CFG->notifyloginthreshold);

    if ($notifyipsrs) {
        $ipstr = '';
        while ($row = $notifyipsrs->FetchRow()) {
            $ipstr .= "'". $row['ip'] ."',";
        }
        $ipstr = substr($ipstr,0,strlen($ipstr)-1);
    }
    if ($notifyusersrs) {
        $userstr = '';
        while ($row = $notifyusersrs->FetchRow()) {
            $userstr .= "'". $row['info'] ."',";
        }
        $userstr = substr($userstr,0,strlen($userstr)-1);
    }

    if (strlen($userstr) > 0 || strlen($ipstr) > 0) {
        $count = 0;
        $logs = get_logs('time > '. $CFG->lastnotifyfailure .' AND module=\'login\' AND action=\'error\' '
                 .((strlen($ipstr) > 0 && strlen($userstr) > 0) ? ' AND ( ip IN ('. $ipstr .') OR info IN ('. $userstr .') ) '
                 : ((strlen($ipstr) != 0) ? ' AND ip IN ('. $ipstr .') ' : ' AND info IN ('. $userstr .') ')), 'l.time DESC', '', '', $count);

        // if we haven't run in the last hour and we have something useful to report and we are actually supposed to be reporting to somebody
        if (is_array($recip) and count($recip) > 0 and ((time() - HOURSECS) > $CFG->lastnotifyfailure)
            and is_array($logs) and count($logs) > 0) {

            $message = '';
            $site = get_site();
            $subject = get_string('notifyloginfailuressubject', '', $site->fullname);
            $message .= get_string('notifyloginfailuresmessagestart', '', $CFG->wwwroot)
                 .(($CFG->lastnotifyfailure != 0) ? '('.userdate($CFG->lastnotifyfailure).')' : '')."\n\n";
            foreach ($logs as $log) {
                $log->time = userdate($log->time);
                $message .= get_string('notifyloginfailuresmessage','',$log)."\n";
            }
            $message .= "\n\n".get_string('notifyloginfailuresmessageend','',$CFG->wwwroot)."\n\n";
            foreach ($recip as $admin) {
                mtrace('Emailing '. $admin->username .' about '. count($logs) .' failed login attempts');
                email_to_user($admin,get_admin(),$subject,$message);
            }
            $conf->name = 'lastnotifyfailure';
            $conf->value = time();
            if ($current = get_record('config', 'name', 'lastnotifyfailure')) {
                $conf->id = $current->id;
                if (! update_record('config', $conf)) {
                    mtrace('Could not update last notify time');
                }

            } else if (! insert_record('config', $conf)) {
                mtrace('Could not set last notify time');
            }
        }
    }
}

/**
 * moodle_setlocale
 *
 * @uses $CFG
 * @uses $USER
 * @uses $SESSION
 * @param string $locale ?
 * @todo Finish documenting this function
 */
function moodle_setlocale($locale='') {

    global $SESSION, $USER, $CFG;

    if ($locale) {
        $CFG->locale = $locale;
    } else if (!empty($CFG->courselang) and ($CFG->courselang != $CFG->lang) ) {
        $CFG->locale = get_string('locale');
    } else if (!empty($SESSION->lang) and ($SESSION->lang != $CFG->lang) ) {
        $CFG->locale = get_string('locale');
    } else if (!empty($USER->lang) and ($USER->lang != $CFG->lang) ) {
        $CFG->locale = get_string('locale');
    } else if (empty($CFG->locale)) {
        $CFG->locale = get_string('locale');
        set_config('locale', $CFG->locale);   // cache it to save lookups in future
    }
    setlocale (LC_TIME, $CFG->locale);
    setlocale (LC_COLLATE, $CFG->locale);

    if ($CFG->locale != 'tr_TR') {            // To workaround a well-known PHP bug with Turkish
        setlocale (LC_CTYPE, $CFG->locale);
    }
}

/**
 * Converts string to lowercase using most compatible function available.
 *
 * @param string $string The string to convert to all lowercase characters.
 * @param string $encoding The encoding on the string.
 * @return string
 * @todo Add examples of calling this function with/without encoding types
 */
function moodle_strtolower ($string, $encoding='') {
    if (function_exists('mb_strtolower')) {
        if($encoding===''){
           return mb_strtolower($string);          //use multibyte support with default encoding
        } else {
           return mb_strtolower($string, $encoding); //use given encoding
        }
    } else {
        return strtolower($string);                // use common function what rely on current locale setting
    }
}

/**
 * Count words in a string.
 *
 * Words are defined as things between whitespace.
 *
 * @param string $string The text to be searched for words.
 * @return int The count of words in the specified string
 */
function count_words($string) {
    $string = strip_tags($string);
    return count(preg_split("/\w\b/", $string)) - 1;
}

/**
 * Generate and return a random string of the specified length.
 *
 * @param int $length The length of the string to be created.
 * @return string
 */
function random_string ($length=15) {
    $pool  = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $pool .= 'abcdefghijklmnopqrstuvwxyz';
    $pool .= '0123456789';
    $poollen = strlen($pool);
    mt_srand ((double) microtime() * 1000000);
    $string = '';
    for ($i = 0; $i < $length; $i++) {
        $string .= substr($pool, (mt_rand()%($poollen)), 1);
    }
    return $string;
}

/**
 * Given dates in seconds, how many weeks is the date from startdate
 * The first week is 1, the second 2 etc ...
 *
 * @uses WEEKSECS
 * @param ? $startdate ?
 * @param ? $thedate ?
 * @return string
 * @todo Finish documenting this function
 */
function getweek ($startdate, $thedate) {
    if ($thedate < $startdate) {   // error
        return 0;
    }

    return floor(($thedate - $startdate) / WEEKSECS) + 1;
}

/**
 * returns a randomly generated password of length $maxlen.  inspired by
 * {@link http://www.phpbuilder.com/columns/jesus19990502.php3}
 *
 * @param int $maxlength  The maximum size of the password being generated.
 * @return string
 * @todo Finish documenting this function
 */
function generate_password($maxlen=10) {
    global $CFG;

    $fillers = '1234567890!$-+';
    $wordlist = file($CFG->wordlist);

    srand((double) microtime() * 1000000);
    $word1 = trim($wordlist[rand(0, count($wordlist) - 1)]);
    $word2 = trim($wordlist[rand(0, count($wordlist) - 1)]);
    $filler1 = $fillers[rand(0, strlen($fillers) - 1)];

    return substr($word1 . $filler1 . $word2, 0, $maxlen);
}

/**
 * Given a float, prints it nicely
 *
 * @param float $num The float to print
 * @param int $places The number of decimal places to print.
 * @return string
 */
function format_float($num, $places=1) {
    return sprintf("%.$places"."f", $num);
}

/**
 * Given a simple array, this shuffles it up just like shuffle()
 * Unlike PHP's shuffle() ihis function works on any machine.
 *
 * @param array $array The array to be rearranged
 * @return array
 */
function swapshuffle($array) {

    srand ((double) microtime() * 10000000);
    $last = count($array) - 1;
    for ($i=0;$i<=$last;$i++) {
        $from = rand(0,$last);
        $curr = $array[$i];
        $array[$i] = $array[$from];
        $array[$from] = $curr;
    }
    return $array;
}

/**
 * Like {@link swapshuffle()}, but works on associative arrays
 *
 * @param array $array The associative array to be rearranged
 * @return array
 */
function swapshuffle_assoc($array) {
///

    $newkeys = swapshuffle(array_keys($array));
    foreach ($newkeys as $newkey) {
        $newarray[$newkey] = $array[$newkey];
    }
    return $newarray;
}

/**
 * Given an arbitrary array, and a number of draws,
 * this function returns an array with that amount
 * of items.  The indexes are retained.
 *
 * @param array $array ?
 * @param ? $draws ?
 * @return ?
 * @todo Finish documenting this function
 */
function draw_rand_array($array, $draws) {
    srand ((double) microtime() * 10000000);

    $return = array();

    $last = count($array);

    if ($draws > $last) {
        $draws = $last;
    }

    while ($draws > 0) {
        $last--;

        $keys = array_keys($array);
        $rand = rand(0, $last);

        $return[$keys[$rand]] = $array[$keys[$rand]];
        unset($array[$keys[$rand]]);

        $draws--;
    }

    return $return;
}

/**
 * microtime_diff
 *
 * @param string $a ?
 * @param string $b ?
 * @return string
 * @todo Finish documenting this function
 */
function microtime_diff($a, $b) {
    list($a_dec, $a_sec) = explode(' ', $a);
    list($b_dec, $b_sec) = explode(' ', $b);
    return $b_sec - $a_sec + $b_dec - $a_dec;
}

/**
 * Given a list (eg a,b,c,d,e) this function returns
 * an array of 1->a, 2->b, 3->c etc
 *
 * @param array $list ?
 * @param string $separator ?
 * @todo Finish documenting this function
 */
function make_menu_from_list($list, $separator=',') {

    $array = array_reverse(explode($separator, $list), true);
    foreach ($array as $key => $item) {
        $outarray[$key+1] = trim($item);
    }
    return $outarray;
}

/**
 * Creates an array that represents all the current grades that
 * can be chosen using the given grading type.  Negative numbers
 * are scales, zero is no grade, and positive numbers are maximum
 * grades.
 *
 * @param int $gradingtype ?
 * return int
 * @todo Finish documenting this function
 */
function make_grades_menu($gradingtype) {
    $grades = array();
    if ($gradingtype < 0) {
        if ($scale = get_record('scale', 'id', - $gradingtype)) {
            return make_menu_from_list($scale->scale);
        }
    } else if ($gradingtype > 0) {
        for ($i=$gradingtype; $i>=0; $i--) {
            $grades[$i] = $i .' / '. $gradingtype;
        }
        return $grades;
    }
    return $grades;
}

/**
 * This function returns the nummber of activities
 * using scaleid in a courseid
 *
 * @param int $courseid ?
 * @param int $scaleid ?
 * @return int
 * @todo Finish documenting this function
 */
function course_scale_used($courseid, $scaleid) {

    global $CFG;

    $return = 0;

    if (!empty($scaleid)) {
        if ($cms = get_course_mods($courseid)) {
            foreach ($cms as $cm) {
                //Check cm->name/lib.php exists
                if (file_exists($CFG->dirroot.'/mod/'.$cm->modname.'/lib.php')) {
                    include_once($CFG->dirroot.'/mod/'.$cm->modname.'/lib.php');
                    $function_name = $cm->modname.'_scale_used';
                    if (function_exists($function_name)) {
                        if ($function_name($cm->instance,$scaleid)) {
                            $return++;
                        }
                    }
                }
            }
        }
    }
    return $return;
}

/**
 * This function returns the nummber of activities
 * using scaleid in the entire site
 *
 * @param int $scaleid ?
 * @return int
 * @todo Finish documenting this function. Is return type correct?
 */
function site_scale_used($scaleid,&$courses) {

    global $CFG;

    $return = 0;

    if (!is_array($courses) || count($courses) == 0) {
        $courses = get_courses("all",false,"c.id,c.shortname");
    }

    if (!empty($scaleid)) {
        if (is_array($courses) && count($courses) > 0) {
            foreach ($courses as $course) {
                $return += course_scale_used($course->id,$scaleid);
            }
        }
    }
    return $return;
}

/**
 * make_unique_id_code
 *
 * @param string $extra ?
 * @return string
 * @todo Finish documenting this function
 */
function make_unique_id_code($extra='') {

    $hostname = 'unknownhost';
    if (!empty($_SERVER['HTTP_HOST'])) {
        $hostname = $_SERVER['HTTP_HOST'];
    } else if (!empty($_ENV['HTTP_HOST'])) {
        $hostname = $_ENV['HTTP_HOST'];
    } else if (!empty($_SERVER['SERVER_NAME'])) {
        $hostname = $_SERVER['SERVER_NAME'];
    } else if (!empty($_ENV['SERVER_NAME'])) {
        $hostname = $_ENV['SERVER_NAME'];
    }

    $date = gmdate("ymdHis");

    $random =  random_string(6);

    if ($extra) {
        return $hostname .'+'. $date .'+'. $random .'+'. $extra;
    } else {
        return $hostname .'+'. $date .'+'. $random;
    }
}


/**
 * Function to check the passed address is within the passed subnet
 *
 * The parameter is a comma separated string of subnet definitions.
 * Subnet strings can be in one of two formats:
 *   1: xxx.xxx.xxx.xxx/xx
 *   2: xxx.xxx
 * Code for type 1 modified from user posted comments by mediator at
 * {@link http://au.php.net/manual/en/function.ip2long.php}
 *
 * @param string $addr    The address you are checking
 * @param string $subnetstr    The string of subnet addresses
 * @return boolean
 */
function address_in_subnet($addr, $subnetstr) {

    $subnets = explode(',', $subnetstr);
    $found = false;
    $addr = trim($addr);

    foreach ($subnets as $subnet) {
        $subnet = trim($subnet);
        if (strpos($subnet, '/') !== false) { /// type 1

            list($ip, $mask) = explode('/', $subnet);
            $mask = 0xffffffff << (32 - $mask);
            $found = ((ip2long($addr) & $mask) == (ip2long($ip) & $mask));

        } else { /// type 2
            $found = (strpos($addr, $subnet) === 0);
        }

        if ($found) {
            continue;
        }
    }

    return $found;
}

/**
 * For outputting debugging info
 *
 * @uses STDOUT
 * @param string $string ?
 * @param string $eol ?
 * @todo Finish documenting this function
 */
function mtrace($string, $eol="\n") {

    if (defined('STDOUT')) {
        fwrite(STDOUT, $string.$eol);
    } else {
        echo $string . $eol;
    }

    flush();
}

//Replace 1 or more slashes or backslashes to 1 slash
function cleardoubleslashes ($path) {
    return preg_replace('/(\/|\\\){1,}/','/',$path);
}

function zip_files ($originalfiles, $destination) {
//Zip an array of files/dirs to a destination zip file
//Both parameters must be FULL paths to the files/dirs

    global $CFG;

    //Extract everything from destination
    $path_parts = pathinfo(cleardoubleslashes($destination));
    $destpath = $path_parts["dirname"];       //The path of the zip file
    $destfilename = $path_parts["basename"];  //The name of the zip file
    $extension = $path_parts["extension"];    //The extension of the file

    //If no file, error
    if (empty($destfilename)) {
        return false;
    }

    //If no extension, add it
    if (empty($extension)) {
        $extension = 'zip';
        $destfilename = $destfilename.'.'.$extension;
    }

    //Check destination path exists
    if (!is_dir($destpath)) {
        return false;
    }

    //Check destination path is writable. TODO!!

    //Clean destination filename
    $destfilename = clean_filename($destfilename);

    //Now check and prepare every file
    $files = array();
    $origpath = NULL;

    foreach ($originalfiles as $file) {  //Iterate over each file
        //Check for every file
        $tempfile = cleardoubleslashes($file); // no doubleslashes!
        //Calculate the base path for all files if it isn't set
        if ($origpath === NULL) {
            $origpath = rtrim(cleardoubleslashes(dirname($tempfile)), "/");
        }
        //See if the file is readable
        if (!is_readable($tempfile)) {  //Is readable
            continue;
        }
        //See if the file/dir is in the same directory than the rest
        if (rtrim(cleardoubleslashes(dirname($tempfile)), "/") != $origpath) {
            continue;
        }
        //Add the file to the array
        $files[] = $tempfile;
    }

    //Everything is ready:
    //    -$origpath is the path where ALL the files to be compressed reside (dir).
    //    -$destpath is the destination path where the zip file will go (dir).
    //    -$files is an array of files/dirs to compress (fullpath)
    //    -$destfilename is the name of the zip file (without path)

    //print_object($files);                  //Debug

    if (empty($CFG->zip)) {    // Use built-in php-based zip function

        include_once("$CFG->libdir/pclzip/pclzip.lib.php");
        $archive = new PclZip(cleardoubleslashes("$destpath/$destfilename"));
        if (($list = $archive->create($files, PCLZIP_OPT_REMOVE_PATH,$origpath) == 0)) {
            notice($archive->errorInfo(true));
            return false;
        }

    } else {                   // Use external zip program

        $filestozip = "";
        foreach ($files as $filetozip) {
            $filestozip .= escapeshellarg(basename($filetozip));
            $filestozip .= " ";
        }
        //Construct the command
        $separator = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? ' &' : ' ;';
        $command = 'cd '.escapeshellarg($origpath).$separator.
                    escapeshellarg($CFG->zip).' -r '.
                    escapeshellarg(cleardoubleslashes("$destpath/$destfilename")).' '.$filestozip;
        //All converted to backslashes in WIN
        if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
            $command = str_replace('/','\\',$command);
        }
        Exec($command);
    }
    return true;
}

function unzip_file ($zipfile, $destination = '', $showstatus = true) {
//Unzip one zip file to a destination dir
//Both parameters must be FULL paths
//If destination isn't specified, it will be the
//SAME directory where the zip file resides.

    global $CFG;

    //Extract everything from zipfile
    $path_parts = pathinfo(cleardoubleslashes($zipfile));
    $zippath = $path_parts["dirname"];       //The path of the zip file
    $zipfilename = $path_parts["basename"];  //The name of the zip file
    $extension = $path_parts["extension"];    //The extension of the file

    //If no file, error
    if (empty($zipfilename)) {
        return false;
    }

    //If no extension, error
    if (empty($extension)) {
        return false;
    }

    //If no destination, passed let's go with the same directory
    if (empty($destination)) {
        $destination = $zippath;
    }

    //Clear $destination
    $destpath = rtrim(cleardoubleslashes($destination), "/");

    //Check destination path exists
    if (!is_dir($destpath)) {
        return false;
    }

    //Check destination path is writable. TODO!!

    //Everything is ready:
    //    -$zippath is the path where the zip file resides (dir)
    //    -$zipfilename is the name of the zip file (without path)
    //    -$destpath is the destination path where the zip file will uncompressed (dir)

    if (empty($CFG->unzip)) {    // Use built-in php-based unzip function

        include_once("$CFG->libdir/pclzip/pclzip.lib.php");
        $archive = new PclZip(cleardoubleslashes("$zippath/$zipfilename"));
        if (!$list = $archive->extract(PCLZIP_OPT_PATH, $destpath,
                                       PCLZIP_CB_PRE_EXTRACT, 'unzip_cleanfilename')) {
            notice($archive->errorInfo(true));
            return false;
        }

    } else {                     // Use external unzip program

        $separator = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? ' &' : ' ;';
        $redirection = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? '' : ' 2>&1';

        $command = 'cd '.escapeshellarg($zippath).$separator.
                    escapeshellarg($CFG->unzip).' -o '.
                    escapeshellarg(cleardoubleslashes("$zippath/$zipfilename")).' -d '.
                    escapeshellarg($destpath).$redirection;
        //All converted to backslashes in WIN
        if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
            $command = str_replace('/','\\',$command);
        }
        Exec($command,$list);
    }

    //Display some info about the unzip execution
    if ($showstatus) {
        unzip_show_status($list,$destpath);
    }

    return true;
}

function unzip_cleanfilename ($p_event, &$p_header) {
//This function is used as callback in unzip_file() function
//to clean illegal characters for given platform and to prevent directory traversal.
//Produces the same result as info-zip unzip.
    $p_header['filename'] = ereg_replace('[[:cntrl:]]', '', $p_header['filename']); //strip control chars first!
    $p_header['filename'] = ereg_replace('\.\.+', '', $p_header['filename']); //directory traversal protection
    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
        $p_header['filename'] = ereg_replace('[:*"?<>|]', '_', $p_header['filename']); //replace illegal chars
        $p_header['filename'] = ereg_replace('^([a-zA-Z])_', '\1:', $p_header['filename']); //repair drive letter
    } else {
        //Add filtering for other systems here
        // BSD: none (tested)
        // Linux: ??
        // MacosX: ??
    }
    $p_header['filename'] = cleardoubleslashes($p_header['filename']); //normalize the slashes/backslashes
    return 1;
}

function unzip_show_status ($list,$removepath) {
//This function shows the results of the unzip execution
//depending of the value of the $CFG->zip, results will be
//text or an array of files.

    global $CFG;

    if (empty($CFG->unzip)) {    // Use built-in php-based zip function
        $strname = get_string("name");
        $strsize = get_string("size");
        $strmodified = get_string("modified");
        $strstatus = get_string("status");
        echo "";
        echo "";
        echo "";
        echo "";
        echo "";
        foreach ($list as $item) {
            echo "";
            $item['filename'] = str_replace(cleardoubleslashes($removepath).'/', "", $item['filename']);
            print_cell("left", $item['filename']);
            if (! $item['folder']) {
                print_cell("right", display_size($item['size']));
            } else {
                echo "";
            }
            $filedate  = userdate($item['mtime'], get_string("strftimedatetime"));
            print_cell("right", $filedate);
            print_cell("right", $item['status']);
            echo "";
        }
        echo "
$strname
$strsize
$strmodified
$strstatus
 
";

    } else {                   // Use external zip program
        print_simple_box_start("center");
        echo "
";
        foreach ($list as $item) {
            echo str_replace(cleardoubleslashes($removepath.'/'), '', $item).'
';
        }
        echo "
";
        print_simple_box_end();
    }
}

/**
 * Returns most reliable client address
 *
 * @return string The remote IP address
 */
 function getremoteaddr() {
    if (getenv('HTTP_CLIENT_IP')) $ip = getenv('HTTP_CLIENT_IP');
    else if(getenv('HTTP_X_FORWARDED_FOR')) $ip = getenv('HTTP_X_FORWARDED_FOR');
    else if(getenv('REMOTE_ADDR')) $ip = getenv('REMOTE_ADDR');
    else $ip = false; //just in case
    return $ip;
}

/**
 * html_entity_decode is only supported by php 4.3.0 and higher
 * so if it is not predefined, define it here
 *
 * @param string $string ?
 * @return string
 * @todo Finish documenting this function
 */
if(!function_exists('html_entity_decode')) {
     function html_entity_decode($string) {
        $trans_tbl = get_html_translation_table(HTML_ENTITIES);
        $trans_tbl = array_flip($trans_tbl);
        return strtr($string, $trans_tbl);
    }
}

/**
 * If new messages are waiting for the current user, then return 
 * Javascript code to create a popup window
 *
 * @return string Javascript code
 */
function message_popup_window() {
    global $USER;

    $popuplimit = 30;     // Minimum seconds between popups

    if (!defined('MESSAGE_WINDOW')) {
        if (isset($USER->id)) {
            if (!isset($USER->message_lastpopup)) {
                $USER->message_lastpopup = 0;
            }
            if ((time() - $USER->message_lastpopup) > $popuplimit) {  /// It's been long enough
                if (get_user_preferences('message_showmessagewindow', 1) == 1) {
                    if (count_records_select('message', 'useridto = \''.$USER->id.'\' AND timecreated > \''.$USER->message_lastpopup.'\'')) {
                        $USER->message_lastpopup = time();
                        return '";
                    }
                }
            }
        }
    }

    return '';
}

// Used to make sure that $min <= $value <= $max
function bounded_number($min, $value, $max) {
    if($value < $min) {
        return $min;
    }
    if($value > $max) {
        return $max;
    }
    return $value;
}

// vim:autoindent:expandtab:shiftwidth=4:tabstop=4:tw=140:
?>