accesslib.php MDL-19236 added phpdocs and copyrights

[moodle.git] / lib / adminlib.php

<?php  //$Id$

/**
 * adminlib.php - Contains functions that only administrators will ever need to use
 *
 * @author Martin Dougiamas and many others
 * @version  $Id$
 * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
 * @package moodlecore
 */

/// Add libraries
require_once($CFG->libdir.'/ddllib.php');
require_once($CFG->libdir.'/xmlize.php');
require_once($CFG->libdir.'/messagelib.php');      // Messagelib functions

define('INSECURE_DATAROOT_WARNING', 1);
define('INSECURE_DATAROOT_ERROR', 2);

/**
 * Delete all plugin tables
 * @name string name of plugin, used as table prefix
 * @file string path to install.xml file
 * @feedback boolean
 */
function drop_plugin_tables($name, $file, $feedback=true) {
    global $CFG, $DB;

    // first try normal delete
    if (file_exists($file) and $DB->get_manager()->delete_tables_from_xmldb_file($file)) {
        return true;
    }

    // then try to find all tables that start with name and are not in any xml file
    $used_tables = get_used_table_names();

    $tables = $DB->get_tables();

    /// Iterate over, fixing id fields as necessary
    foreach ($tables as $table) {
        if (in_array($table, $used_tables)) {
            continue;
        }

        if (strpos($table, $name) !== 0) {
            continue;
        }

        // found orphan table --> delete it
        if ($DB->get_manager()->table_exists($table)) {
            $xmldb_table = new xmldb_table($table);
            $DB->get_manager()->drop_table($xmldb_table);
        }
    }

    return true;
}

/**
 * Returns names of all known tables == tables that moodle knowns about.
 * @return array of lowercase table names
 */
function get_used_table_names() {
    $table_names = array();
    $dbdirs = get_db_directories();

    foreach ($dbdirs as $dbdir) {
        $file = $dbdir.'/install.xml';

        $xmldb_file = new xmldb_file($file);

        if (!$xmldb_file->fileExists()) {
            continue;
        }

        $loaded    = $xmldb_file->loadXMLStructure();
        $structure = $xmldb_file->getStructure();

        if ($loaded and $tables = $structure->getTables()) {
            foreach($tables as $table) {
                $table_names[] = strtolower($table->name);
            }
        }
    }

    return $table_names;
}

/**
 * Lists all plugin types
 * @return array of strings - name=>location
 */
function get_plugin_types() {
    global $CFG;

    return array('mod'           => 'mod',
                 'qtype'         => 'question/type',
                 'block'         => 'blocks',
                 'auth'          => 'auth',
                 'enrol'         => 'enrol',
                 'format'        => 'course/format',
                 'editor'        => 'lib/editor',
                 'gradeexport'   => 'grade/export',
                 'gradeimport'   => 'grade/import',
                 'gradereport'   => 'grade/report',
                 'message'       => 'message/output',
                 'coursereport'  => 'course/report',
                 'report'        => $CFG->admin.'/report',
                 'portfolio'     => 'portfolio/type',
                 'repository'    => 'repository',

        // following types a very ugly hacks - we should not make exceptions like this - all plugins should be equal;
        // these plugins may cause problems such as when wanting to uninstall them
                 'quizreport'      => 'mod/quiz/report',
                 'assignment_type' => 'mod/assignment/type',
                );
}

/**
 * Returns list of all directories where we expect install.xml files
 * @return array of paths
 */
function get_db_directories() {
    global $CFG;

    $dbdirs = array();

/// First, the main one (lib/db)
    $dbdirs[] = $CFG->libdir.'/db';

/// Now, activity modules (mod/xxx/db)
    if ($plugins = get_list_of_plugins('mod')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/mod/'.$plugin.'/db';
        }
    }

/// Now, assignment submodules (mod/assignment/type/xxx/db)
    if ($plugins = get_list_of_plugins('mod/assignment/type')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/mod/assignment/type/'.$plugin.'/db';
        }
    }

/// Now, question types (question/type/xxx/db)
    if ($plugins = get_list_of_plugins('question/type')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/question/type/'.$plugin.'/db';
        }
    }

/// Now, blocks (blocks/xxx/db)
    if ($plugins = get_list_of_plugins('blocks', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/blocks/'.$plugin.'/db';
        }
    }

/// Now, course formats (course/format/xxx/db)
    if ($plugins = get_list_of_plugins('course/format', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/course/format/'.$plugin.'/db';
        }
    }

/// Now, enrolment plugins (enrol/xxx/db)
    if ($plugins = get_list_of_plugins('enrol', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/enrol/'.$plugin.'/db';
        }
    }

/// Now admin report plugins (admin/report/xxx/db)
    if ($plugins = get_list_of_plugins($CFG->admin.'/report', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/'.$CFG->admin.'/report/'.$plugin.'/db';
        }
    }

/// Now quiz report plugins (mod/quiz/report/xxx/db)
    if ($plugins = get_list_of_plugins('mod/quiz/report', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot.'/mod/quiz/report/'.$plugin.'/db';
        }
    }

    if ($plugins = get_list_of_plugins('portfolio/type', 'db')) {
        foreach ($plugins as $plugin) {
            $dbdirs[] = $CFG->dirroot . '/portfolio/type/' . $plugin . '/db';
        }
    }

/// Local database changes, if the local folder exists.
    if (file_exists($CFG->dirroot . '/local')) {
        $dbdirs[] = $CFG->dirroot.'/local/db';
    }

    return $dbdirs;
}

/**
 * Try to obtain or release the cron lock.
 *
 * @param string  $name  name of lock
 * @param int  $until timestamp when this lock considered stale, null means remove lock unconditionaly
 * @param bool $ignorecurrent ignore current lock state, usually entend previous lock
 * @return bool true if lock obtained
 */
function set_cron_lock($name, $until, $ignorecurrent=false) {
    global $DB;
    if (empty($name)) {
        debugging("Tried to get a cron lock for a null fieldname");
        return false;
    }

    // remove lock by force == remove from config table
    if (is_null($until)) {
        set_config($name, null);
        return true;
    }

    if (!$ignorecurrent) {
        // read value from db - other processes might have changed it
        $value = $DB->get_field('config', 'value', array('name'=>$name));

        if ($value and $value > time()) {
            //lock active
            return false;
        }
    }

    set_config($name, $until);
    return true;
}

/**
 * Test if and critical warnings are present
 * @return bool
 */
function admin_critical_warnings_present() {
    global $SESSION;

    if (!has_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM))) {
        return 0;
    }

    if (!isset($SESSION->admin_critical_warning)) {
        $SESSION->admin_critical_warning = 0;
        if (is_dataroot_insecure(true) === INSECURE_DATAROOT_ERROR) {
            $SESSION->admin_critical_warning = 1;
        }
    }

    return $SESSION->admin_critical_warning;
}

/**
 * Detects if float support at least 10 deciman digits
 * and also if float-->string conversion works as expected.
 * @return bool true if problem found
 */
function is_float_problem() {
    $num1 = 2009010200.01;
    $num2 = 2009010200.02;

    return ((string)$num1 === (string)$num2 or $num1 === $num2 or $num2 <= (string)$num1);
}

/**
 * Try to verify that dataroot is not accessible from web.
 * It is not 100% correct but might help to reduce number of vulnerable sites.
 *
 * Protection from httpd.conf and .htaccess is not detected properly.
 * @param bool $fetchtest try to test public access by fetching file
 * @return mixed empty means secure, INSECURE_DATAROOT_ERROR found a critical problem, INSECURE_DATAROOT_WARNING migth be problematic
 */
function is_dataroot_insecure($fetchtest=false) {
    global $CFG;

    $siteroot = str_replace('\\', '/', strrev($CFG->dirroot.'/')); // win32 backslash workaround

    $rp = preg_replace('|https?://[^/]+|i', '', $CFG->wwwroot, 1);
    $rp = strrev(trim($rp, '/'));
    $rp = explode('/', $rp);
    foreach($rp as $r) {
        if (strpos($siteroot, '/'.$r.'/') === 0) {
            $siteroot = substr($siteroot, strlen($r)+1); // moodle web in subdirectory
        } else {
            break; // probably alias root
        }
    }

    $siteroot = strrev($siteroot);
    $dataroot = str_replace('\\', '/', $CFG->dataroot.'/');

    if (strpos($dataroot, $siteroot) !== 0) {
        return false;
    }

    if (!$fetchtest) {
        return INSECURE_DATAROOT_WARNING;
    }

    // now try all methods to fetch a test file using http protocol

    $httpdocroot = str_replace('\\', '/', strrev($CFG->dirroot.'/'));
    preg_match('|(https?://[^/]+)|i', $CFG->wwwroot, $matches);
    $httpdocroot = $matches[1];
    $datarooturl = $httpdocroot.'/'. substr($dataroot, strlen($siteroot));
    if (make_upload_directory('diag', false) === false) {
        return INSECURE_DATAROOT_WARNING;
    }
    $testfile = $CFG->dataroot.'/diag/public.txt';
    if (!file_exists($testfile)) {
        file_put_contents($testfile, 'test file, do not delete');
    }
    $teststr = trim(file_get_contents($testfile));
    if (empty($teststr)) {
        // hmm, strange
        return INSECURE_DATAROOT_WARNING;
    }

    $testurl = $datarooturl.'/diag/public.txt';
    if (extension_loaded('curl') and
        !(stripos(ini_get('disable_functions'), 'curl_init') !== FALSE) and
        !(stripos(ini_get('disable_functions'), 'curl_setop') !== FALSE) and
        ($ch = @curl_init($testurl)) !== false) {
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HEADER, false);
        $data = curl_exec($ch);
        if (!curl_errno($ch)) {
            $data = trim($data);
            if ($data === $teststr) {
                curl_close($ch);
                return INSECURE_DATAROOT_ERROR;
            }
        }
        curl_close($ch);
    }

    if ($data = @file_get_contents($testurl)) {
        $data = trim($data);
        if ($data === $teststr) {
            return INSECURE_DATAROOT_ERROR;
        }
    }

    preg_match('|https?://([^/]+)|i', $testurl, $matches);
    $sitename = $matches[1];
    $error = 0;
    if ($fp = @fsockopen($sitename, 80, $error)) {
        preg_match('|https?://[^/]+(.*)|i', $testurl, $matches);
        $localurl = $matches[1];
        $out = "GET $localurl HTTP/1.1\r\n";
        $out .= "Host: $sitename\r\n";
        $out .= "Connection: Close\r\n\r\n";
        fwrite($fp, $out);
        $data = '';
        $incoming = false;
        while (!feof($fp)) {
            if ($incoming) {
                $data .= fgets($fp, 1024);
            } else if (@fgets($fp, 1024) === "\r\n") {
                $incoming = true;
            }
        }
        fclose($fp);
        $data = trim($data);
        if ($data === $teststr) {
            return INSECURE_DATAROOT_ERROR;
        }
    }

    return INSECURE_DATAROOT_WARNING;
}

/// =============================================================================================================
/// administration tree classes and functions


// n.b. documentation is still in progress for this code

/// INTRODUCTION

/// This file performs the following tasks:
///  -it defines the necessary objects and interfaces to build the Moodle
///   admin hierarchy
///  -it defines the admin_externalpage_setup(), admin_externalpage_print_header(),
///   and admin_externalpage_print_footer() functions used on admin pages

/// ADMIN_SETTING OBJECTS

/// Moodle settings are represented by objects that inherit from the admin_setting
/// class. These objects encapsulate how to read a setting, how to write a new value
/// to a setting, and how to appropriately display the HTML to modify the setting.

/// ADMIN_SETTINGPAGE OBJECTS

/// The admin_setting objects are then grouped into admin_settingpages. The latter
/// appear in the Moodle admin tree block. All interaction with admin_settingpage
/// objects is handled by the admin/settings.php file.

/// ADMIN_EXTERNALPAGE OBJECTS

/// There are some settings in Moodle that are too complex to (efficiently) handle
/// with admin_settingpages. (Consider, for example, user management and displaying
/// lists of users.) In this case, we use the admin_externalpage object. This object
/// places a link to an external PHP file in the admin tree block.

/// If you're using an admin_externalpage object for some settings, you can take
/// advantage of the admin_externalpage_* functions. For example, suppose you wanted
/// to add a foo.php file into admin. First off, you add the following line to
/// admin/settings/first.php (at the end of the file) or to some other file in
/// admin/settings:

///    $ADMIN->add('userinterface', new admin_externalpage('foo', get_string('foo'),
///        $CFG->wwwdir . '/' . '$CFG->admin . '/foo.php', 'some_role_permission'));

/// Next, in foo.php, your file structure would resemble the following:

///        require_once('.../config.php');
///        require_once($CFG->libdir.'/adminlib.php');
///        admin_externalpage_setup('foo');
///        // functionality like processing form submissions goes here
///        admin_externalpage_print_header();
///        // your HTML goes here
///        admin_externalpage_print_footer();

/// The admin_externalpage_setup() function call ensures the user is logged in,
/// and makes sure that they have the proper role permission to access the page.

/// The admin_externalpage_print_header() function prints the header (it figures
/// out what category and subcategories the page is classified under) and ensures
/// that you're using the admin pagelib (which provides the admin tree block and
/// the admin bookmarks block).

/// The admin_externalpage_print_footer() function properly closes the tables
/// opened up by the admin_externalpage_print_header() function and prints the
/// standard Moodle footer.

/// ADMIN_CATEGORY OBJECTS

/// Above and beyond all this, we have admin_category objects. These objects
/// appear as folders in the admin tree block. They contain admin_settingpage's,
/// admin_externalpage's, and other admin_category's.

/// OTHER NOTES

/// admin_settingpage's, admin_externalpage's, and admin_category's all inherit
/// from part_of_admin_tree (a pseudointerface). This interface insists that
/// a class has a check_access method for access permissions, a locate method
/// used to find a specific node in the admin tree and find parent path.

/// admin_category's inherit from parentable_part_of_admin_tree. This pseudo-
/// interface ensures that the class implements a recursive add function which
/// accepts a part_of_admin_tree object and searches for the proper place to
/// put it. parentable_part_of_admin_tree implies part_of_admin_tree.

/// Please note that the $this->name field of any part_of_admin_tree must be
/// UNIQUE throughout the ENTIRE admin tree.

/// The $this->name field of an admin_setting object (which is *not* part_of_
/// admin_tree) must be unique on the respective admin_settingpage where it is
/// used.


/// CLASS DEFINITIONS /////////////////////////////////////////////////////////

/**
 * Pseudointerface for anything appearing in the admin tree
 *
 * The pseudointerface that is implemented by anything that appears in the admin tree
 * block. It forces inheriting classes to define a method for checking user permissions
 * and methods for finding something in the admin tree.
 *
 * @author Vincenzo K. Marcovecchio
 * @package admin
 */
interface part_of_admin_tree {

    /**
     * Finds a named part_of_admin_tree.
     *
     * Used to find a part_of_admin_tree. If a class only inherits part_of_admin_tree
     * and not parentable_part_of_admin_tree, then this function should only check if
     * $this->name matches $name. If it does, it should return a reference to $this,
     * otherwise, it should return a reference to NULL.
     *
     * If a class inherits parentable_part_of_admin_tree, this method should be called
     * recursively on all child objects (assuming, of course, the parent object's name
     * doesn't match the search criterion).
     *
     * @param string $name The internal name of the part_of_admin_tree we're searching for.
     * @return mixed An object reference or a NULL reference.
     */
    public function locate($name);

    /**
     * Removes named part_of_admin_tree.
     *
     * @param string $name The internal name of the part_of_admin_tree we want to remove.
     * @return bool success.
     */
    public function prune($name);

    /**
     * Search using query
     * @param strin query
     * @return mixed array-object structure of found settings and pages
     */
    public function search($query);

    /**
     * Verifies current user's access to this part_of_admin_tree.
     *
     * Used to check if the current user has access to this part of the admin tree or
     * not. If a class only inherits part_of_admin_tree and not parentable_part_of_admin_tree,
     * then this method is usually just a call to has_capability() in the site context.
     *
     * If a class inherits parentable_part_of_admin_tree, this method should return the
     * logical OR of the return of check_access() on all child objects.
     *
     * @return bool True if the user has access, false if she doesn't.
     */
    public function check_access();

    /**
     * Mostly usefull for removing of some parts of the tree in admin tree block.
     *
     * @return True is hidden from normal list view
     */
    public function is_hidden();
}

/**
 * Pseudointerface implemented by any part_of_admin_tree that has children.
 *
 * The pseudointerface implemented by any part_of_admin_tree that can be a parent
 * to other part_of_admin_tree's. (For now, this only includes admin_category.) Apart
 * from ensuring part_of_admin_tree compliancy, it also ensures inheriting methods
 * include an add method for adding other part_of_admin_tree objects as children.
 *
 * @author Vincenzo K. Marcovecchio
 * @package admin
 */
interface parentable_part_of_admin_tree extends part_of_admin_tree {

    /**
     * Adds a part_of_admin_tree object to the admin tree.
     *
     * Used to add a part_of_admin_tree object to this object or a child of this
     * object. $something should only be added if $destinationname matches
     * $this->name. If it doesn't, add should be called on child objects that are
     * also parentable_part_of_admin_tree's.
     *
     * @param string $destinationname The internal name of the new parent for $something.
     * @param part_of_admin_tree $something The object to be added.
     * @return bool True on success, false on failure.
     */
    public function add($destinationname, $something);

}

/**
 * The object used to represent folders (a.k.a. categories) in the admin tree block.
 *
 * Each admin_category object contains a number of part_of_admin_tree objects.
 *
 * @author Vincenzo K. Marcovecchio
 * @package admin
 */
class admin_category implements parentable_part_of_admin_tree {

    /**
     * @var mixed An array of part_of_admin_tree objects that are this object's children
     */
    public $children;

    /**
     * @var string An internal name for this category. Must be unique amongst ALL part_of_admin_tree objects
     */
    public $name;

    /**
     * @var string The displayed name for this category. Usually obtained through get_string()
     */
    public $visiblename;

    /**
     * @var bool Should this category be hidden in admin tree block?
     */
    public $hidden;

    /**
     * paths
     */
    public $path;
    public $visiblepath;

    /**
     * Constructor for an empty admin category
     *
     * @param string $name The internal name for this category. Must be unique amongst ALL part_of_admin_tree objects
     * @param string $visiblename The displayed named for this category. Usually obtained through get_string()
     * @param bool $hidden hide category in admin tree block
     */
    public function __construct($name, $visiblename, $hidden=false) {
        $this->children    = array();
        $this->name        = $name;
        $this->visiblename = $visiblename;
        $this->hidden      = $hidden;
    }

    /**
     * Returns a reference to the part_of_admin_tree object with internal name $name.
     *
     * @param string $name The internal name of the object we want.
     * @param bool $findpath initialize path and visiblepath arrays
     * @return mixed A reference to the object with internal name $name if found, otherwise a reference to NULL.
     */
    public function locate($name, $findpath=false) {
        if ($this->name == $name) {
            if ($findpath) {
                $this->visiblepath[] = $this->visiblename;
                $this->path[]        = $this->name;
            }
            return $this;
        }

        $return = NULL;
        foreach($this->children as $childid=>$unused) {
            if ($return = $this->children[$childid]->locate($name, $findpath)) {
                break;
            }
        }

        if (!is_null($return) and $findpath) {
            $return->visiblepath[] = $this->visiblename;
            $return->path[]        = $this->name;
        }

        return $return;
    }

    /**
     * Search using query
     * @param strin query
     * @return mixed array-object structure of found settings and pages
     */
    public function search($query) {
        $result = array();
        foreach ($this->children as $child) {
            $subsearch = $child->search($query);
            if (!is_array($subsearch)) {
                debugging('Incorrect search result from '.$child->name);
                continue;
            }
            $result = array_merge($result, $subsearch);
        }
        return $result;
    }

    /**
     * Removes part_of_admin_tree object with internal name $name.
     *
     * @param string $name The internal name of the object we want to remove.
     * @return bool success
     */
    public function prune($name) {

        if ($this->name == $name) {
            return false;  //can not remove itself
        }

        foreach($this->children as $precedence => $child) {
            if ($child->name == $name) {
                // found it!
                unset($this->children[$precedence]);
                return true;
            }
            if ($this->children[$precedence]->prune($name)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Adds a part_of_admin_tree to a child or grandchild (or great-grandchild, and so forth) of this object.
     *
     * @param string $destinationame The internal name of the immediate parent that we want for $something.
     * @param mixed $something A part_of_admin_tree or setting instanceto be added.
     * @return bool True if successfully added, false if $something can not be added.
     */
    public function add($parentname, $something) {
        $parent = $this->locate($parentname);
        if (is_null($parent)) {
            debugging('parent does not exist!');
            return false;
        }

        if ($something instanceof part_of_admin_tree) {
            if (!($parent instanceof parentable_part_of_admin_tree)) {
                debugging('error - parts of tree can be inserted only into parentable parts');
                return false;
            }
            $parent->children[] = $something;
            return true;

        } else {
            debugging('error - can not add this element');
            return false;
        }

    }

    /**
     * Checks if the user has access to anything in this category.
     *
     * @return bool True if the user has access to atleast one child in this category, false otherwise.
     */
    public function check_access() {
        foreach ($this->children as $child) {
            if ($child->check_access()) {
                return true;
            }
        }
        return false;
    }

    /**
     * Is this category hidden in admin tree block?
     *
     * @return bool True if hidden
     */
    public function is_hidden() {
        return $this->hidden;
    }
}

class admin_root extends admin_category {
    /** list of errors */
    public $errors;

    /** search query */
    public $search;

    /** full tree flag - true means all settings required, false onlypages required */
    public $fulltree;

    /** flag indicating loaded tree */
    public $loaded;

    /** site custom defaults overriding defaults in setings files */
    public $custom_defaults;

    public function __construct($fulltree) {
        global $CFG;

        parent::__construct('root', get_string('administration'), false);
        $this->errors   = array();
        $this->search   = '';
        $this->fulltree = $fulltree;
        $this->loaded   = false;

        // load custom defaults if found
        $this->custom_defaults = null;
        $defaultsfile = "$CFG->dirroot/local/defaults.php";
        if (is_readable($defaultsfile)) {
            $defaults = array();
            include($defaultsfile);
            if (is_array($defaults) and count($defaults)) {
                $this->custom_defaults = $defaults;
            }
        }
    }

    public function purge_children($requirefulltree) {
        $this->children = array();
        $this->fulltree = ($requirefulltree || $this->fulltree);
        $this->loaded   = false;
    }
}

/**
 * Links external PHP pages into the admin tree.
 *
 * See detailed usage example at the top of this document (adminlib.php)
 *
 * @author Vincenzo K. Marcovecchio
 * @package admin
 */
class admin_externalpage implements part_of_admin_tree {

    /**
     * @var string An internal name for this external page. Must be unique amongst ALL part_of_admin_tree objects
     */
    public $name;

    /**
     * @var string The displayed name for this external page. Usually obtained through get_string().
     */
    public $visiblename;

    /**
     * @var string The external URL that we should link to when someone requests this external page.
     */
    public $url;

    /**
     * @var string The role capability/permission a user must have to access this external page.
     */
    public $req_capability;

    /**
     * @var object The context in which capability/permission should be checked, default is site context.
     */
    public $context;

    /**
     * @var bool hidden in admin tree block.
     */
    public $hidden;

    /**
     * visible path
     */
    public $path;
    public $visiblepath;

    /**
     * Constructor for adding an external page into the admin tree.
     *
     * @param string $name The internal name for this external page. Must be unique amongst ALL part_of_admin_tree objects.
     * @param string $visiblename The displayed name for this external page. Usually obtained through get_string().
     * @param string $url The external URL that we should link to when someone requests this external page.
     * @param mixed $req_capability The role capability/permission a user must have to access this external page. Defaults to 'moodle/site:config'.
     * @param boolean $hidden Is this external page hidden in admin tree block? Default false.
     * @param context $context The context the page relates to. Not sure what happens
     *      if you specify something other than system or front page. Defaults to system.
     */
    public function __construct($name, $visiblename, $url, $req_capability='moodle/site:config', $hidden=false, $context=NULL) {
        $this->name        = $name;
        $this->visiblename = $visiblename;
        $this->url         = $url;
        if (is_array($req_capability)) {
            $this->req_capability = $req_capability;
        } else {
            $this->req_capability = array($req_capability);
        }
        $this->hidden = $hidden;
        $this->context = $context;
    }

    /**
     * Returns a reference to the part_of_admin_tree object with internal name $name.
     *
     * @param string $name The internal name of the object we want.
     * @return mixed A reference to the object with internal name $name if found, otherwise a reference to NULL.
     */
    public function locate($name, $findpath=false) {
        if ($this->name == $name) {
            if ($findpath) {
                $this->visiblepath = array($this->visiblename);
                $this->path        = array($this->name);
            }
            return $this;
        } else {
            $return = NULL;
            return $return;
        }
    }

    public function prune($name) {
        return false;
    }

    /**
     * Search using query
     * @param strin query
     * @return mixed array-object structure of found settings and pages
     */
    public function search($query) {
        $textlib = textlib_get_instance();

        $found = false;
        if (strpos(strtolower($this->name), $query) !== false) {
            $found = true;
        } else if (strpos($textlib->strtolower($this->visiblename), $query) !== false) {
            $found = true;
        }
        if ($found) {
            $result = new object();
            $result->page     = $this;
            $result->settings = array();
            return array($this->name => $result);
        } else {
            return array();
        }
    }

    /**
     * Determines if the current user has access to this external page based on $this->req_capability.
     * @return bool True if user has access, false otherwise.
     */
    public function check_access() {
        global $CFG;
        $context = empty($this->context) ? get_context_instance(CONTEXT_SYSTEM) : $this->context;
        foreach($this->req_capability as $cap) {
            if (is_valid_capability($cap) and has_capability($cap, $context)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Is this external page hidden in admin tree block?
     *
     * @return bool True if hidden
     */
    public function is_hidden() {
        return $this->hidden;
    }

}

/**
 * Used to group a number of admin_setting objects into a page and add them to the admin tree.
 *
 * @author Vincenzo K. Marcovecchio
 * @package admin
 */
class admin_settingpage implements part_of_admin_tree {

    /**
     * @var string An internal name for this external page. Must be unique amongst ALL part_of_admin_tree objects
     */
    public $name;

    /**
     * @var string The displayed name for this external page. Usually obtained through get_string().
     */
    public $visiblename;
    /**
     * @var mixed An array of admin_setting objects that are part of this setting page.
     */
    public $settings;

    /**
     * @var string The role capability/permission a user must have to access this external page.
     */
    public $req_capability;

    /**
     * @var object The context in which capability/permission should be checked, default is site context.
     */
    public $context;

    /**
     * @var bool hidden in admin tree block.
     */
    public $hidden;

    /**
     * paths
     */
    public $path;
    public $visiblepath;

    // see admin_externalpage
    public function __construct($name, $visiblename, $req_capability='moodle/site:config', $hidden=false, $context=NULL) {
        $this->settings    = new object();
        $this->name        = $name;
        $this->visiblename = $visiblename;
        if (is_array($req_capability)) {
            $this->req_capability = $req_capability;
        } else {
            $this->req_capability = array($req_capability);
        }
        $this->hidden      = $hidden;
        $this->context     = $context;
    }

    // see admin_category
    public function locate($name, $findpath=false) {
        if ($this->name == $name) {
            if ($findpath) {
                $this->visiblepath = array($this->visiblename);
                $this->path        = array($this->name);
            }
            return $this;
        } else {
            $return = NULL;
            return $return;
        }
    }

    public function search($query) {
        $found = array();

        foreach ($this->settings as $setting) {
            if ($setting->is_related($query)) {
                $found[] = $setting;
            }
        }

        if ($found) {
            $result = new object();
            $result->page     = $this;
            $result->settings = $found;
            return array($this->name => $result);
        }

        $textlib = textlib_get_instance();

        $found = false;
        if (strpos(strtolower($this->name), $query) !== false) {
            $found = true;
        } else if (strpos($textlib->strtolower($this->visiblename), $query) !== false) {
            $found = true;
        }
        if ($found) {
            $result = new object();
            $result->page     = $this;
            $result->settings = array();
            return array($this->name => $result);
        } else {
            return array();
        }
    }

    public function prune($name) {
        return false;
    }

    /**
     * not the same as add for admin_category. adds an admin_setting to this admin_settingpage. settings appear (on the settingpage) in the order in which they're added
     * n.b. each admin_setting in an admin_settingpage must have a unique internal name
     * @param object $setting is the admin_setting object you want to add
     * @return true if successful, false if not
     */
    public function add($setting) {
        if (!($setting instanceof admin_setting)) {
            debugging('error - not a setting instance');
            return false;
        }

        $this->settings->{$setting->name} = $setting;
        return true;
    }

    // see admin_externalpage
    public function check_access() {
        global $CFG;
        $context = empty($this->context) ? get_context_instance(CONTEXT_SYSTEM) : $this->context;
        foreach($this->req_capability as $cap) {
            if (is_valid_capability($cap) and has_capability($cap, $context)) {
                return true;
            }
        }
        return false;
    }

    /**
     * outputs this page as html in a table (suitable for inclusion in an admin pagetype)
     * returns a string of the html
     */
    public function output_html() {
        $adminroot = admin_get_root();
        $return = '<fieldset>'."\n".'<div class="clearer"><!-- --></div>'."\n";
        foreach($this->settings as $setting) {
            $fullname = $setting->get_full_name();
            if (array_key_exists($fullname, $adminroot->errors)) {
                $data = $adminroot->errors[$fullname]->data;
            } else {
                $data = $setting->get_setting();
                // do not use defaults if settings not available - upgrdesettings handles the defaults!
            }
            $return .= $setting->output_html($data);
        }
        $return .= '</fieldset>';
        return $return;
    }

    /**
     * Is this settigns page hidden in admin tree block?
     *
     * @return bool True if hidden
     */
    public function is_hidden() {
        return $this->hidden;
    }

}


/**
 * Admin settings class. Only exists on setting pages.
 * Read & write happens at this level; no authentication.
 */
abstract class admin_setting {

    public $name;
    public $visiblename;
    public $description;
    public $defaultsetting;
    public $updatedcallback;
    public $plugin; // null means main config table

    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised name
     * @param string $description localised long description
     * @param mixed $defaultsetting string or array depending on implementation
     */
    public function __construct($name, $visiblename, $description, $defaultsetting) {
        $this->parse_setting_name($name);
        $this->visiblename    = $visiblename;
        $this->description    = $description;
        $this->defaultsetting = $defaultsetting;
    }

    /**
     * Set up $this->name and possibly $this->plugin based on whether $name looks
     * like 'settingname' or 'plugin/settingname'. Also, do some sanity checking
     * on the names, that is, output a developer debug warning if the name
     * contains anything other than [a-zA-Z0-9_]+.
     *
     * @param string $name the setting name passed in to the constructor.
     */
    private function parse_setting_name($name) {
        $bits = explode('/', $name);
        if (count($bits) > 2) {
            throw new moodle_exception('invalidadminsettingname', '', '', $name);
        }
        $this->name = array_pop($bits);
        if (!preg_match('/^[a-zA-Z0-9_]+$/', $this->name)) {
            throw new moodle_exception('invalidadminsettingname', '', '', $name);
        }
        if (!empty($bits)) {
            $this->plugin = array_pop($bits);
            if ($this->plugin === 'moodle') {
                $this->plugin = null;
            } else if (!preg_match('/^[a-zA-Z0-9_]+$/', $this->plugin)) {
                throw new moodle_exception('invalidadminsettingname', '', '', $name);
            }
        }
    }

    public function get_full_name() {
        return 's_'.$this->plugin.'_'.$this->name;
    }

    public function get_id() {
        return 'id_s_'.$this->plugin.'_'.$this->name;
    }

    public function config_read($name) {
        global $CFG;
        if (!empty($this->plugin)) {
            $value = get_config($this->plugin, $name);
            return $value === false ? NULL : $value;

        } else {
            if (isset($CFG->$name)) {
                return $CFG->$name;
            } else {
                return NULL;
            }
        }
    }

    /**
     *
     * @param <type> $name
     * @param <type> $value
     * @return <type> Write setting to confix table
     */
    public function config_write($name, $value) {
        global $DB, $USER, $CFG;

        // make sure it is a real change
        $oldvalue = get_config($this->plugin, $name);
        $oldvalue = ($oldvalue === false) ? null : $oldvalue; // normalise
        $value = is_null($value) ? null : (string)$value;

        if ($oldvalue === $value) {
            return true;
        }

        // store change
        set_config($name, $value, $this->plugin);


        // log change
        $log = new object();
        $log->userid       = empty($CFG->rolesactive) ? 0 :$USER->id; // 0 as user id during install
        $log->timemodified = time();
        $log->plugin       = $this->plugin;
        $log->name         = $name;
        $log->value        = $value;
        $log->oldvalue     = $oldvalue;
        $DB->insert_record('config_log', $log);

        return true; // BC only
    }

    /**
     * Returns current value of this setting
     * @return mixed array or string depending on instance, NULL means not set yet
     */
    public abstract function get_setting();

    /**
     * Returns default setting if exists
     * @return mixed array or string depending on instance; NULL means no default, user must supply
     */
    public function get_defaultsetting() {
        $adminroot =  admin_get_root(false, false);
        if (!empty($adminroot->custom_defaults)) {
            $plugin = is_null($this->plugin) ? 'moodle' : $this->plugin;
            if (isset($adminroot->custom_defaults[$plugin])) {
                if (array_key_exists($this->name, $adminroot->custom_defaults[$plugin])) { // null is valid valie here ;-)
                    return $adminroot->custom_defaults[$plugin][$this->name];
                }
            }
        }
        return $this->defaultsetting;
    }

    /**
     * Store new setting
     * @param mixed string or array, must not be NULL
     * @return '' if ok, string error message otherwise
     */
    public abstract function write_setting($data);

    /**
     * Return part of form with setting
     * @param mixed data array or string depending on setting
     * @return string
     */
    public function output_html($data, $query='') {
        // should be overridden
        return;
    }

    /**
     * function called if setting updated - cleanup, cache reset, etc.
     */
    public function set_updatedcallback($functionname) {
        $this->updatedcallback = $functionname;
    }

    /**
     * Is setting related to query text - used when searching
     * @param string $query
     * @return bool
     */
    public function is_related($query) {
        if (strpos(strtolower($this->name), $query) !== false) {
            return true;
        }
        $textlib = textlib_get_instance();
        if (strpos($textlib->strtolower($this->visiblename), $query) !== false) {
            return true;
        }
        if (strpos($textlib->strtolower($this->description), $query) !== false) {
            return true;
        }
        $current = $this->get_setting();
        if (!is_null($current)) {
            if (is_string($current)) {
                if (strpos($textlib->strtolower($current), $query) !== false) {
                    return true;
                }
            }
        }
        $default = $this->get_defaultsetting();
        if (!is_null($default)) {
            if (is_string($default)) {
                if (strpos($textlib->strtolower($default), $query) !== false) {
                    return true;
                }
            }
        }
        return false;
    }
}

/**
 * No setting - just heading and text.
 */
class admin_setting_heading extends admin_setting {
    /**
     * not a setting, just text
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $heading heading
     * @param string $information text in box
     */
    public function __construct($name, $heading, $information) {
        parent::__construct($name, $heading, $information, '');
    }

    public function get_setting() {
        return true;
    }

    public function get_defaultsetting() {
        return true;
    }

    public function write_setting($data) {
        // do not write any setting
        return '';
    }

    public function output_html($data, $query='') {
        $return = '';
        if ($this->visiblename != '') {
            $return .= print_heading('<a name="'.$this->name.'">'.highlightfast($query, $this->visiblename).'</a>', '', 3, 'main', true);
        }
        if ($this->description != '') {
            $return .= print_box(highlight($query, $this->description), 'generalbox formsettingheading', '', true);
        }
        return $return;
    }
}

/**
 * The most flexibly setting, user is typing text
 */
class admin_setting_configtext extends admin_setting {

    public $paramtype;
    public $size;

    /**
     * config text contructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param string $defaultsetting
     * @param mixed $paramtype int means PARAM_XXX type, string is a allowed format in regex
     * @param int $size default field size
     */
    public function __construct($name, $visiblename, $description, $defaultsetting, $paramtype=PARAM_RAW, $size=null) {
        $this->paramtype = $paramtype;
        if (!is_null($size)) {
            $this->size  = $size;
        } else {
            $this->size  = ($paramtype == PARAM_INT) ? 5 : 30;
        }
        parent::__construct($name, $visiblename, $description, $defaultsetting);
    }

    public function get_setting() {
        return $this->config_read($this->name);
    }

    public function write_setting($data) {
        if ($this->paramtype === PARAM_INT and $data === '') {
            // do not complain if '' used instead of 0
            $data = 0;
        }
        // $data is a string
        $validated = $this->validate($data);
        if ($validated !== true) {
            return $validated;
        }
        return ($this->config_write($this->name, $data) ? '' : get_string('errorsetting', 'admin'));
    }

    /**
     * Validate data before storage
     * @param string data
     * @return mixed true if ok string if error found
     */
    public function validate($data) {
        if (is_string($this->paramtype)) {
            if (preg_match($this->paramtype, $data)) {
                return true;
            } else {
                return get_string('validateerror', 'admin');
            }

        } else if ($this->paramtype === PARAM_RAW) {
            return true;

        } else {
            $cleaned = clean_param($data, $this->paramtype);
            if ("$data" == "$cleaned") { // implicit conversion to string is needed to do exact comparison
                return true;
            } else {
                return get_string('validateerror', 'admin');
            }
        }
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-text defaultsnext"><input type="text" size="'.$this->size.'" id="'.$this->get_id().'" name="'.$this->get_full_name().'" value="'.s($data).'" /></div>',
                $this->description, true, '', $default, $query);
    }
}

/**
 * General text area without html editor.
 */
class admin_setting_configtextarea extends admin_setting_configtext {
    public $rows;
    public $cols;

    public function __construct($name, $visiblename, $description, $defaultsetting, $paramtype=PARAM_RAW, $cols='60', $rows='8') {
        $this->rows = $rows;
        $this->cols = $cols;
        parent::__construct($name, $visiblename, $description, $defaultsetting, $paramtype);
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        $defaultinfo = $default;
        if (!is_null($default) and $default !== '') {
            $defaultinfo = "\n".$default;
        }

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-textarea form-textarea-advanced" ><textarea rows="'. $this->rows .'" cols="'. $this->cols .'" id="'. $this->get_id() .'" name="'. $this->get_full_name() .'">'. s($data) .'</textarea></div>',
                $this->description, true, '', $defaultinfo, $query);
    }
}

/**
 * Password field, allows unmasking of password
 */
class admin_setting_configpasswordunmask extends admin_setting_configtext {
    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param string $defaultsetting default password
     */
    public function __construct($name, $visiblename, $description, $defaultsetting) {
        parent::__construct($name, $visiblename, $description, $defaultsetting, PARAM_RAW, 30);
    }

    public function output_html($data, $query='') {
        $id = $this->get_id();
        $unmask = get_string('unmaskpassword', 'form');
        $unmaskjs = '<script type="text/javascript">
//<![CDATA[
var is_ie = (navigator.userAgent.toLowerCase().indexOf("msie") != -1);

document.getElementById("'.$id.'").setAttribute("autocomplete", "off");

var unmaskdiv = document.getElementById("'.$id.'unmaskdiv");

var unmaskchb = document.createElement("input");
unmaskchb.setAttribute("type", "checkbox");
unmaskchb.setAttribute("id", "'.$id.'unmask");
unmaskchb.onchange = function() {unmaskPassword("'.$id.'");};
unmaskdiv.appendChild(unmaskchb);

var unmasklbl = document.createElement("label");
unmasklbl.innerHTML = "'.addslashes_js($unmask).'";
if (is_ie) {
  unmasklbl.setAttribute("htmlFor", "'.$id.'unmask");
} else {
  unmasklbl.setAttribute("for", "'.$id.'unmask");
}
unmaskdiv.appendChild(unmasklbl);

if (is_ie) {
  // ugly hack to work around the famous onchange IE bug
  unmaskchb.onclick = function() {this.blur();};
  unmaskdiv.onclick = function() {this.blur();};
}
//]]>
</script>';
        return format_admin_setting($this, $this->visiblename,
                '<div class="form-password"><input type="password" size="'.$this->size.'" id="'.$id.'" name="'.$this->get_full_name().'" value="'.s($data).'" /><div class="unmask" id="'.$id.'unmaskdiv"></div>'.$unmaskjs.'</div>',
                $this->description, true, '', NULL, $query);
    }
}

/**
 * Path to directory
 */
class admin_setting_configfile extends admin_setting_configtext {
    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param string $defaultdirectory default directory location
     */
    public function __construct($name, $visiblename, $description, $defaultdirectory) {
        parent::__construct($name, $visiblename, $description, $defaultdirectory, PARAM_RAW, 50);
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        if ($data) {
            if (file_exists($data)) {
                $executable = '<span class="pathok">&#x2714;</span>';
            } else {
                $executable = '<span class="patherror">&#x2718;</span>';
            }
        } else {
            $executable = '';
        }

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-file defaultsnext"><input type="text" size="'.$this->size.'" id="'.$this->get_id().'" name="'.$this->get_full_name().'" value="'.s($data).'" />'.$executable.'</div>',
                $this->description, true, '', $default, $query);
    }
}

/**
 * Path to executable file
 */
class admin_setting_configexecutable extends admin_setting_configfile {

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        if ($data) {
            if (file_exists($data) and is_executable($data)) {
                $executable = '<span class="pathok">&#x2714;</span>';
            } else {
                $executable = '<span class="patherror">&#x2718;</span>';
            }
        } else {
            $executable = '';
        }

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-file defaultsnext"><input type="text" size="'.$this->size.'" id="'.$this->get_id().'" name="'.$this->get_full_name().'" value="'.s($data).'" />'.$executable.'</div>',
                $this->description, true, '', $default, $query);
    }
}

/**
 * Path to directory
 */
class admin_setting_configdirectory extends admin_setting_configfile {
    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        if ($data) {
            if (file_exists($data) and is_dir($data)) {
                $executable = '<span class="pathok">&#x2714;</span>';
            } else {
                $executable = '<span class="patherror">&#x2718;</span>';
            }
        } else {
            $executable = '';
        }

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-file defaultsnext"><input type="text" size="'.$this->size.'" id="'.$this->get_id().'" name="'.$this->get_full_name().'" value="'.s($data).'" />'.$executable.'</div>',
                $this->description, true, '', $default, $query);
    }
}

/**
 * Checkbox
 */
class admin_setting_configcheckbox extends admin_setting {
    public $yes;
    public $no;

    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param string $defaultsetting
     * @param string $yes value used when checked
     * @param string $no value used when not checked
     */
    public function __construct($name, $visiblename, $description, $defaultsetting, $yes='1', $no='0') {
        parent::__construct($name, $visiblename, $description, $defaultsetting);
        $this->yes = (string)$yes;
        $this->no  = (string)$no;
    }

    public function get_setting() {
        return $this->config_read($this->name);
    }

    public function write_setting($data) {
        if ((string)$data === $this->yes) { // convert to strings before comparison
            $data = $this->yes;
        } else {
            $data = $this->no;
        }
        return ($this->config_write($this->name, $data) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        if (!is_null($default)) {
            if ((string)$default === $this->yes) {
                $defaultinfo = get_string('checkboxyes', 'admin');
            } else {
                $defaultinfo = get_string('checkboxno', 'admin');
            }
        } else {
            $defaultinfo = NULL;
        }

        if ((string)$data === $this->yes) { // convert to strings before comparison
            $checked = 'checked="checked"';
        } else {
            $checked = '';
        }

        return format_admin_setting($this, $this->visiblename,
                '<div class="form-checkbox defaultsnext" ><input type="hidden" name="'.$this->get_full_name().'" value="'.s($this->no).'" /> '
                .'<input type="checkbox" id="'.$this->get_id().'" name="'.$this->get_full_name().'" value="'.s($this->yes).'" '.$checked.' /></div>',
                $this->description, true, '', $defaultinfo, $query);
    }
}

/**
 * Multiple checkboxes, each represents different value, stored in csv format
 */
class admin_setting_configmulticheckbox extends admin_setting {
    public $choices;

    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param array $defaultsetting array of selected
     * @param array $choices array of $value=>$label for each checkbox
     */
    public function __construct($name, $visiblename, $description, $defaultsetting, $choices) {
        $this->choices = $choices;
        parent::__construct($name, $visiblename, $description, $defaultsetting);
    }

    /**
     * This public function may be used in ancestors for lazy loading of choices
     * @return true if loaded, false if error
     */
    public function load_choices() {
        /*
        if (is_array($this->choices)) {
            return true;
        }
        .... load choices here
        */
        return true;
    }

    /**
     * Is setting related to query text - used when searching
     * @param string $query
     * @return bool
     */
    public function is_related($query) {
        if (!$this->load_choices() or empty($this->choices)) {
            return false;
        }
        if (parent::is_related($query)) {
            return true;
        }

        $textlib = textlib_get_instance();
        foreach ($this->choices as $desc) {
            if (strpos($textlib->strtolower($desc), $query) !== false) {
                return true;
            }
        }
        return false;
    }

    public function get_setting() {
        $result = $this->config_read($this->name);

        if (is_null($result)) {
            return NULL;
        }
        if ($result === '') {
            return array();
        }
        $enabled = explode(',', $result);
        $setting = array();
        foreach ($enabled as $option) {
            $setting[$option] = 1;
        }
        return $setting;
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return ''; // ignore it
        }
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }
        unset($data['xxxxx']);
        $result = array();
        foreach ($data as $key => $value) {
            if ($value and array_key_exists($key, $this->choices)) {
                $result[] = $key;
            }
        }
        return $this->config_write($this->name, implode(',', $result)) ? '' : get_string('errorsetting', 'admin');
    }

    public function output_html($data, $query='') {
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }
        $default = $this->get_defaultsetting();
        if (is_null($default)) {
            $default = array();
        }
        if (is_null($data)) {
            $data = array();
        }
        $options = array();
        $defaults = array();
        foreach ($this->choices as $key=>$description) {
            if (!empty($data[$key])) {
                $checked = 'checked="checked"';
            } else {
                $checked = '';
            }
            if (!empty($default[$key])) {
                $defaults[] = $description;
            }

            $options[] = '<input type="checkbox" id="'.$this->get_id().'_'.$key.'" name="'.$this->get_full_name().'['.$key.']" value="1" '.$checked.' />'
                         .'<label for="'.$this->get_id().'_'.$key.'">'.highlightfast($query, $description).'</label>';
        }

        if (is_null($default)) {
            $defaultinfo = NULL;
        } else if (!empty($defaults)) {
            $defaultinfo = implode(', ', $defaults);
        } else {
            $defaultinfo = get_string('none');
        }

        $return = '<div class="form-multicheckbox">';
        $return .= '<input type="hidden" name="'.$this->get_full_name().'[xxxxx]" value="1" />'; // something must be submitted even if nothing selected
        if ($options) {
            $return .= '<ul>';
            foreach ($options as $option) {
                $return .= '<li>'.$option.'</li>';
            }
            $return .= '</ul>';
        }
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', $defaultinfo, $query);

    }
}

/**
 * Multiple checkboxes 2, value stored as string 00101011
 */
class admin_setting_configmulticheckbox2 extends admin_setting_configmulticheckbox {
    public function get_setting() {
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        if (!$this->load_choices()) {
            return NULL;
        }
        $result = str_pad($result, count($this->choices), '0');
        $result = preg_split('//', $result, -1, PREG_SPLIT_NO_EMPTY);
        $setting = array();
        foreach ($this->choices as $key=>$unused) {
            $value = array_shift($result);
            if ($value) {
                $setting[$key] = 1;
            }
        }
        return $setting;
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return ''; // ignore it
        }
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }
        $result = '';
        foreach ($this->choices as $key=>$unused) {
            if (!empty($data[$key])) {
                $result .= '1';
            } else {
                $result .= '0';
            }
        }
        return $this->config_write($this->name, $result) ? '' : get_string('errorsetting', 'admin');
    }
}

/**
 * Select one value from list
 */
class admin_setting_configselect extends admin_setting {
    public $choices;

    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param string $defaultsetting
     * @param array $choices array of $value=>$label for each selection
     */
    public function __construct($name, $visiblename, $description, $defaultsetting, $choices) {
        $this->choices = $choices;
        parent::__construct($name, $visiblename, $description, $defaultsetting);
    }

    /**
     * This function may be used in ancestors for lazy loading of choices
     * @return true if loaded, false if error
     */
    public function load_choices() {
        /*
        if (is_array($this->choices)) {
            return true;
        }
        .... load choices here
        */
        return true;
    }

    public function is_related($query) {
        if (parent::is_related($query)) {
            return true;
        }
        if (!$this->load_choices()) {
            return false;
        }
        $textlib = textlib_get_instance();
        foreach ($this->choices as $key=>$value) {
            if (strpos($textlib->strtolower($key), $query) !== false) {
                return true;
            }
            if (strpos($textlib->strtolower($value), $query) !== false) {
                return true;
            }
        }
        return false;
    }

    public function get_setting() {
        return $this->config_read($this->name);
    }

    public function write_setting($data) {
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }
        if (!array_key_exists($data, $this->choices)) {
            return ''; // ignore it
        }

        return ($this->config_write($this->name, $data) ? '' : get_string('errorsetting', 'admin'));
    }

    /**
     * Ensure the options are loaded, and generate the HTML for the select
     * element and any warning message. Separating this out from output_html
     * makes it easier to subclass this class.
     *
     * @param string $data the option to show as selected.
     * @param string $current the currently selected option in the database, null if none.
     * @param string $default the default selected option.
     * @return array the HTML for the select element, and a warning message.
     */
    public function output_select_html($data, $current, $default, $extraname = '') {
        if (!$this->load_choices() or empty($this->choices)) {
            return array('', '');
        }

        $warning = '';
        if (is_null($current)) {
            // first run
        } else if (empty($current) and (array_key_exists('', $this->choices) or array_key_exists(0, $this->choices))) {
            // no warning
        } else if (!array_key_exists($current, $this->choices)) {
            $warning = get_string('warningcurrentsetting', 'admin', s($current));
            if (!is_null($default) and $data == $current) {
                $data = $default; // use default instead of first value when showing the form
            }
        }

        $selecthtml = '<select id="'.$this->get_id().'" name="'.$this->get_full_name().$extraname.'">';
        foreach ($this->choices as $key => $value) {
            // the string cast is needed because key may be integer - 0 is equal to most strings!
            $selecthtml .= '<option value="'.$key.'"'.((string)$key==$data ? ' selected="selected"' : '').'>'.$value.'</option>';
        }
        $selecthtml .= '</select>';
        return array($selecthtml, $warning);
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();
        $current = $this->get_setting();

        list($selecthtml, $warning) = $this->output_select_html($data, $current, $default);
        if (!$selecthtml) {
            return '';
        }

        if (!is_null($default) and array_key_exists($default, $this->choices)) {
            $defaultinfo = $this->choices[$default];
        } else {
            $defaultinfo = NULL;
        }

        $return = '<div class="form-select defaultsnext">' . $selecthtml . '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, true, $warning, $defaultinfo, $query);
    }
}

/**
 * Select multiple items from list
 */
class admin_setting_configmultiselect extends admin_setting_configselect {
    /**
     * Constructor
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param array $defaultsetting array of selected items
     * @param array $choices array of $value=>$label for each list item
     */
    public function __construct($name, $visiblename, $description, $defaultsetting, $choices) {
        parent::__construct($name, $visiblename, $description, $defaultsetting, $choices);
    }

    public function get_setting() {
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        if ($result === '') {
            return array();
        }
        return explode(',', $result);
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return ''; //ignore it
        }
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }

        unset($data['xxxxx']);

        $save = array();
        foreach ($data as $value) {
            if (!array_key_exists($value, $this->choices)) {
                continue; // ignore it
            }
            $save[] = $value;
        }

        return ($this->config_write($this->name, implode(',', $save)) ? '' : get_string('errorsetting', 'admin'));
    }

    /**
     * Is setting related to query text - used when searching
     * @param string $query
     * @return bool
     */
    public function is_related($query) {
        if (!$this->load_choices() or empty($this->choices)) {
            return false;
        }
        if (parent::is_related($query)) {
            return true;
        }

        $textlib = textlib_get_instance();
        foreach ($this->choices as $desc) {
            if (strpos($textlib->strtolower($desc), $query) !== false) {
                return true;
            }
        }
        return false;
    }

    public function output_html($data, $query='') {
        if (!$this->load_choices() or empty($this->choices)) {
            return '';
        }
        $choices = $this->choices;
        $default = $this->get_defaultsetting();
        if (is_null($default)) {
            $default = array();
        }
        if (is_null($data)) {
            $data = array();
        }

        $defaults = array();
        $size = min(10, count($this->choices));
        $return = '<div class="form-select"><input type="hidden" name="'.$this->get_full_name().'[xxxxx]" value="1" />'; // something must be submitted even if nothing selected
        $return .= '<select id="'.$this->get_id().'" name="'.$this->get_full_name().'[]" size="'.$size.'" multiple="multiple">';
        foreach ($this->choices as $key => $description) {
            if (in_array($key, $data)) {
                $selected = 'selected="selected"';
            } else {
                $selected = '';
            }
            if (in_array($key, $default)) {
                $defaults[] = $description;
            }

            $return .= '<option value="'.s($key).'" '.$selected.'>'.$description.'</option>';
        }

        if (is_null($default)) {
            $defaultinfo = NULL;
        } if (!empty($defaults)) {
            $defaultinfo = implode(', ', $defaults);
        } else {
            $defaultinfo = get_string('none');
        }

        $return .= '</select></div>';
        return format_admin_setting($this, $this->visiblename, $return, $this->description, true, '', $defaultinfo, $query);
    }
}

/**
 * Time selector
 * this is a liiitle bit messy. we're using two selects, but we're returning
 * them as an array named after $name (so we only use $name2 internally for the setting)
 */
class admin_setting_configtime extends admin_setting {
    public $name2;

    /**
     * Constructor
     * @param string $hoursname setting for hours
     * @param string $minutesname setting for hours
     * @param string $visiblename localised
     * @param string $description long localised info
     * @param array $defaultsetting array representing default time 'h'=>hours, 'm'=>minutes
     */
    public function __construct($hoursname, $minutesname, $visiblename, $description, $defaultsetting) {
        $this->name2 = $minutesname;
        parent::__construct($hoursname, $visiblename, $description, $defaultsetting);
    }

    public function get_setting() {
        $result1 = $this->config_read($this->name);
        $result2 = $this->config_read($this->name2);
        if (is_null($result1) or is_null($result2)) {
            return NULL;
        }

        return array('h' => $result1, 'm' => $result2);
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return '';
        }

        $result = $this->config_write($this->name, (int)$data['h']) && $this->config_write($this->name2, (int)$data['m']);
        return ($result ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();

        if (is_array($default)) {
            $defaultinfo = $default['h'].':'.$default['m'];
        } else {
            $defaultinfo = NULL;
        }

        $return = '<div class="form-time defaultsnext">'.
                  '<select id="'.$this->get_id().'h" name="'.$this->get_full_name().'[h]">';
        for ($i = 0; $i < 24; $i++) {
            $return .= '<option value="'.$i.'"'.($i == $data['h'] ? ' selected="selected"' : '').'>'.$i.'</option>';
        }
        $return .= '</select>:<select id="'.$this->get_id().'m" name="'.$this->get_full_name().'[m]">';
        for ($i = 0; $i < 60; $i += 5) {
            $return .= '<option value="'.$i.'"'.($i == $data['m'] ? ' selected="selected"' : '').'>'.$i.'</option>';
        }
        $return .= '</select></div>';
        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', $defaultinfo, $query);
    }

}

class admin_setting_configiplist extends admin_setting_configtextarea {
    public function validate($data) {
        if(!empty($data)) {
            $ips = explode("\n", $data);
        } else {
            return true;
        }
        $result = true;
        foreach($ips as $ip) {
            $ip = trim($ip);
            if(preg_match('#^(\d{1,3})(\.\d{1,3}){0,3}$#', $ip, $match) ||
                   preg_match('#^(\d{1,3})(\.\d{1,3}){0,3}(\/\d{1,2})$#', $ip, $match) ||
                   preg_match('#^(\d{1,3})(\.\d{1,3}){3}(-\d{1,3})$#', $ip, $match)) {
                $result = true;
            } else {
                $result = false;
                break;
            }
        }
        if($result){
            return true;
        } else {
            return get_string('validateerror', 'admin');
        }
    }
}

/**
 * An admin setting for selecting one or more users, who have a particular capability
 * in the system context. Warning, make sure the list will never be too long. There is
 * no paging or searching of this list.
 *
 * To correctly get a list of users from this config setting, you need to call the
 * get_users_from_config($CFG->mysetting, $capability); function in moodlelib.php.
 */
class admin_setting_users_with_capability extends admin_setting_configmultiselect {
    protected $capability;

    /**
     * Constructor.
     *
     * @param string $name unique ascii name, either 'mysetting' for settings that in config, or 'myplugin/mysetting' for ones in config_plugins.
     * @param string $visiblename localised name
     * @param string $description localised long description
     * @param array $defaultsetting array of usernames
     * @param string $capability string capability name.
     */
    function __construct($name, $visiblename, $description, $defaultsetting, $capability) {
        $this->capability = $capability;
        parent::__construct($name, $visiblename, $description, $defaultsetting, NULL);
    }

    function load_choices() {
        if (is_array($this->choices)) {
            return true;
        }
        $users = get_users_by_capability(get_context_instance(CONTEXT_SYSTEM),
                $this->capability, 'u.id,u.username,u.firstname,u.lastname', 'u.lastname,u.firstname');
        $this->choices = array(
            '$@NONE@$' => get_string('nobody'),
            '$@ALL@$' => get_string('everyonewhocan', 'admin', get_capability_string($this->capability)),
        );
        foreach ($users as $user) {
            $this->choices[$user->username] = fullname($user);
        }
        return true;
    }

    public function get_defaultsetting() {
        $this->load_choices();
        $defaultsetting = parent::get_defaultsetting();
        if (empty($defaultsetting)) {
            return array('$@NONE@$');
        } else if (array_key_exists($defaultsetting, $this->choices)) {
            return $defaultsetting;
        } else {
            return '';
        }
    }

    public function get_setting() {
        $result = parent::get_setting();
        if (empty($result)) {
            $result = array('$@NONE@$');
        }
        return $result;
    }

    public function write_setting($data) {
        // If all is selected, remove any explicit options.
        if (in_array('$@ALL@$', $data)) {
            $data = array('$@ALL@$');
        }
        // None never needs to be writted to the DB.
        if (in_array('$@NONE@$', $data)) {
            unset($data[array_search('$@NONE@$', $data)]);
        }
        return parent::write_setting($data);
    }
}

/**
 * Special checkbox for calendar - resets SESSION vars.
 */
class admin_setting_special_adminseesall extends admin_setting_configcheckbox {
    public function __construct() {
        parent::__construct('calendar_adminseesall', get_string('adminseesall', 'admin'),
                            get_string('helpadminseesall', 'admin'), '0');
    }

    public function write_setting($data) {
        global $SESSION;
        unset($SESSION->cal_courses_shown);
        return parent::write_setting($data);
    }
}

/**
 * Special select for settings that are altered in setup.php and can not be altered on the fly
 */
class admin_setting_special_selectsetup extends admin_setting_configselect {
    public function get_setting() {
        // read directly from db!
        return get_config(NULL, $this->name);
    }

    public function write_setting($data) {
        global $CFG;
        // do not change active CFG setting!
        $current = $CFG->{$this->name};
        $result = parent::write_setting($data);
        $CFG->{$this->name} = $current;
        return $result;
    }
}

/**
 * Special select for frontpage - stores data in course table
 */
class admin_setting_sitesetselect extends admin_setting_configselect {
    public function get_setting() {
        $site = get_site();
        return $site->{$this->name};
    }

    public function write_setting($data) {
        global $DB, $SITE;
        if (!in_array($data, array_keys($this->choices))) {
            return get_string('errorsetting', 'admin');
        }
        $record = new stdClass();
        $record->id           = SITEID;
        $temp                 = $this->name;
        $record->$temp        = $data;
        $record->timemodified = time();
        // update $SITE
        $SITE->{$this->name} = $data;
        return ($DB->update_record('course', $record) ? '' : get_string('errorsetting', 'admin'));
    }
}

/**
 * Special select - lists on the frontpage - hacky
 */
class admin_setting_courselist_frontpage extends admin_setting {
    public $choices;

    public function __construct($loggedin) {
        global $CFG;
        require_once($CFG->dirroot.'/course/lib.php');
        $name        = 'frontpage'.($loggedin ? 'loggedin' : '');
        $visiblename = get_string('frontpage'.($loggedin ? 'loggedin' : ''),'admin');
        $description = get_string('configfrontpage'.($loggedin ? 'loggedin' : ''),'admin');
        $defaults    = array(FRONTPAGECOURSELIST);
        parent::__construct($name, $visiblename, $description, $defaults);
    }

    public function load_choices() {
        global $DB;
        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = array(FRONTPAGENEWS          => get_string('frontpagenews'),
                               FRONTPAGECOURSELIST    => get_string('frontpagecourselist'),
                               FRONTPAGECATEGORYNAMES => get_string('frontpagecategorynames'),
                               FRONTPAGECATEGORYCOMBO => get_string('frontpagecategorycombo'),
                               'none'                 => get_string('none'));
        if ($this->name == 'frontpage' and $DB->count_records('course') > FRONTPAGECOURSELIMIT) {
            unset($this->choices[FRONTPAGECOURSELIST]);
        }
        return true;
    }
    public function get_setting() {
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        if ($result === '') {
            return array();
        }
        return explode(',', $result);
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return '';
        }
        $this->load_choices();
        $save = array();
        foreach($data as $datum) {
            if ($datum == 'none' or !array_key_exists($datum, $this->choices)) {
                continue;
            }
            $save[$datum] = $datum; // no duplicates
        }
        return ($this->config_write($this->name, implode(',', $save)) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        $this->load_choices();
        $currentsetting = array();
        foreach ($data as $key) {
            if ($key != 'none' and array_key_exists($key, $this->choices)) {
                $currentsetting[] = $key; // already selected first
            }
        }

        $return = '<div class="form-group">';
        for ($i = 0; $i < count($this->choices) - 1; $i++) {
            if (!array_key_exists($i, $currentsetting)) {
                $currentsetting[$i] = 'none'; //none
            }
            $return .='<select class="form-select" id="'.$this->get_id().$i.'" name="'.$this->get_full_name().'[]">';
            foreach ($this->choices as $key => $value) {
                $return .= '<option value="'.$key.'"'.("$key" == $currentsetting[$i] ? ' selected="selected"' : '').'>'.$value.'</option>';
            }
            $return .= '</select>';
            if ($i !== count($this->choices) - 2) {
                $return .= '<br />';
            }
        }
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);
    }
}

/**
 * Special checkbox for frontpage - stores data in course table
 */
class admin_setting_sitesetcheckbox extends admin_setting_configcheckbox {
    public function get_setting() {
        $site = get_site();
        return $site->{$this->name};
    }

    public function write_setting($data) {
        global $DB, $SITE;
        $record = new object();
        $record->id            = SITEID;
        $record->{$this->name} = ($data == '1' ? 1 : 0);
        $record->timemodified  = time();
        // update $SITE
        $SITE->{$this->name} = $data;
        return ($DB->update_record('course', $record) ? '' : get_string('errorsetting', 'admin'));
    }
}

/**
 * Special text for frontpage - stores data in course table.
 * Empty string means not set here. Manual setting is required.
 */
class admin_setting_sitesettext extends admin_setting_configtext {
    public function get_setting() {
        $site = get_site();
        return $site->{$this->name} != '' ? $site->{$this->name} : NULL;
    }

    public function validate($data) {
        $cleaned = clean_param($data, PARAM_MULTILANG);
        if ($cleaned === '') {
            return get_string('required');
        }
        if ("$data" == "$cleaned") { // implicit conversion to string is needed to do exact comparison
            return true;
        } else {
            return get_string('validateerror', 'admin');
        }
    }

    public function write_setting($data) {
        global $DB, $SITE;
        $data = trim($data);
        $validated = $this->validate($data);
        if ($validated !== true) {
            return $validated;
        }

        $record = new object();
        $record->id            = SITEID;
        $record->{$this->name} = $data;
        $record->timemodified  = time();
        // update $SITE
        $SITE->{$this->name} = $data;
        return ($DB->update_record('course', $record) ? '' : get_string('dbupdatefailed', 'error'));
    }
}

/**
 * Special text editor for site description.
 */
class admin_setting_special_frontpagedesc extends admin_setting {
    public function __construct() {
        parent::__construct('summary', get_string('frontpagedescription'), get_string('frontpagedescriptionhelp'), NULL);
    }

    public function get_setting() {
        $site = get_site();
        return $site->{$this->name};
    }

    public function write_setting($data) {
        global $DB, $SITE;
        $record = new object();
        $record->id            = SITEID;
        $record->{$this->name} = $data;
        $record->timemodified  = time();
        $SITE->{$this->name} = $data;
        return ($DB->update_record('course', $record) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        global $CFG;

        $CFG->adminusehtmleditor = can_use_html_editor();
        $return = '<div class="form-htmlarea">'.print_textarea($CFG->adminusehtmleditor, 15, 60, 0, 0, $this->get_full_name(), $data, 0, true, 'summary') .'</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);
    }
}

class admin_setting_special_editorfontlist extends admin_setting {

    public $items;

    public function __construct() {
        global $CFG;
        $name = 'editorfontlist';
        $visiblename = get_string('editorfontlist', 'admin');
        $description = get_string('configeditorfontlist', 'admin');
        $defaults = array('k0' => 'Trebuchet',
                          'v0' => 'Trebuchet MS,Verdana,Arial,Helvetica,sans-serif',
                          'k1' => 'Arial',
                          'v1' => 'arial,helvetica,sans-serif',
                          'k2' => 'Courier New',
                          'v2' => 'courier new,courier,monospace',
                          'k3' => 'Georgia',
                          'v3' => 'georgia,times new roman,times,serif',
                          'k4' => 'Tahoma',
                          'v4' => 'tahoma,arial,helvetica,sans-serif',
                          'k5' => 'Times New Roman',
                          'v5' => 'times new roman,times,serif',
                          'k6' => 'Verdana',
                          'v6' => 'verdana,arial,helvetica,sans-serif',
                          'k7' => 'Impact',
                          'v7' => 'impact',
                          'k8' => 'Wingdings',
                          'v8' => 'wingdings');
        parent::__construct($name, $visiblename, $description, $defaults);
    }

    public function get_setting() {
        global $CFG;
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        $i = 0;
        $currentsetting = array();
        $items = explode(';', $result);
        foreach ($items as $item) {
          $item = explode(':', $item);
          $currentsetting['k'.$i] = $item[0];
          $currentsetting['v'.$i] = $item[1];
          $i++;
        }
        return $currentsetting;
    }

    public function write_setting($data) {

        // there miiight be an easier way to do this :)
        // if this is changed, make sure the $defaults array above is modified so that this
        // function processes it correctly

        $keys = array();
        $values = array();

        foreach ($data as $key => $value) {
            if (substr($key,0,1) == 'k') {
                $keys[substr($key,1)] = $value;
            } elseif (substr($key,0,1) == 'v') {
                $values[substr($key,1)] = $value;
            }
        }

        $result = array();
        for ($i = 0; $i < count($keys); $i++) {
            if (($keys[$i] !== '') && ($values[$i] !== '')) {
                $result[] = clean_param($keys[$i],PARAM_NOTAGS).':'.clean_param($values[$i], PARAM_NOTAGS);
            }
        }

        return ($this->config_write($this->name, implode(';', $result)) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        $fullname = $this->get_full_name();
        $return = '<div class="form-group">';
        for ($i = 0; $i < count($data) / 2; $i++) {
            $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.$i.']" value="'.$data['k'.$i].'" />';
            $return .= '&nbsp;&nbsp;';
            $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.$i.']" value="'.$data['v'.$i].'" /><br />';
        }
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.$i.']" value="" />';
        $return .= '&nbsp;&nbsp;';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.$i.']" value="" /><br />';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.($i + 1).']" value="" />';
        $return .= '&nbsp;&nbsp;';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.($i + 1).']" value="" />';
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);
    }

}

class admin_setting_emoticons extends admin_setting {

    public $items;

    public function __construct() {
        global $CFG;
        $name = 'emoticons';
        $visiblename = get_string('emoticons', 'admin');
        $description = get_string('configemoticons', 'admin');
        $defaults = array('k0' => ':-)',
                          'v0' => 'smiley',
                          'k1' => ':)',
                          'v1' => 'smiley',
                          'k2' => ':-D',
                          'v2' => 'biggrin',
                          'k3' => ';-)',
                          'v3' => 'wink',
                          'k4' => ':-/',
                          'v4' => 'mixed',
                          'k5' => 'V-.',
                          'v5' => 'thoughtful',
                          'k6' => ':-P',
                          'v6' => 'tongueout',
                          'k7' => 'B-)',
                          'v7' => 'cool',
                          'k8' => '^-)',
                          'v8' => 'approve',
                          'k9' => '8-)',
                          'v9' => 'wideeyes',
                          'k10' => ':o)',
                          'v10' => 'clown',
                          'k11' => ':-(',
                          'v11' => 'sad',
                          'k12' => ':(',
                          'v12' => 'sad',
                          'k13' => '8-.',
                          'v13' => 'shy',
                          'k14' => ':-I',
                          'v14' => 'blush',
                          'k15' => ':-X',
                          'v15' => 'kiss',
                          'k16' => '8-o',
                          'v16' => 'surprise',
                          'k17' => 'P-|',
                          'v17' => 'blackeye',
                          'k18' => '8-[',
                          'v18' => 'angry',
                          'k19' => 'xx-P',
                          'v19' => 'dead',
                          'k20' => '|-.',
                          'v20' => 'sleepy',
                          'k21' => '}-]',
                          'v21' => 'evil',
                          'k22' => '(h)',
                          'v22' => 'heart',
                          'k23' => '(heart)',
                          'v23' => 'heart',
                          'k24' => '(y)',
                          'v24' => 'yes',
                          'k25' => '(n)',
                          'v25' => 'no',
                          'k26' => '(martin)',
                          'v26' => 'martin',
                          'k27' => '( )',
                          'v27' => 'egg');
        parent::__construct($name, $visiblename, $description, $defaults);
    }

    public function get_setting() {
        global $CFG;
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        $i = 0;
        $currentsetting = array();
        $items = explode('{;}', $result);
        foreach ($items as $item) {
          $item = explode('{:}', $item);
          $currentsetting['k'.$i] = $item[0];
          $currentsetting['v'.$i] = $item[1];
          $i++;
        }
        return $currentsetting;
    }

    public function write_setting($data) {

        // there miiight be an easier way to do this :)
        // if this is changed, make sure the $defaults array above is modified so that this
        // function processes it correctly

        $keys = array();
        $values = array();

        foreach ($data as $key => $value) {
            if (substr($key,0,1) == 'k') {
                $keys[substr($key,1)] = $value;
            } elseif (substr($key,0,1) == 'v') {
                $values[substr($key,1)] = $value;
            }
        }

        $result = array();
        for ($i = 0; $i < count($keys); $i++) {
            if (($keys[$i] !== '') && ($values[$i] !== '')) {
                $result[] = clean_param($keys[$i],PARAM_NOTAGS).'{:}'.clean_param($values[$i], PARAM_NOTAGS);
            }
        }

        return ($this->config_write($this->name, implode('{;}', $result)) ? '' : get_string('errorsetting', 'admin').$this->visiblename.'<br />');
    }

    public function output_html($data, $query='') {
        $fullname = $this->get_full_name();
        $return = '<div class="form-group">';
        for ($i = 0; $i < count($data) / 2; $i++) {
            $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.$i.']" value="'.$data['k'.$i].'" />';
            $return .= '&nbsp;&nbsp;';
            $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.$i.']" value="'.$data['v'.$i].'" /><br />';
        }
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.$i.']" value="" />';
        $return .= '&nbsp;&nbsp;';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.$i.']" value="" /><br />';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[k'.($i + 1).']" value="" />';
        $return .= '&nbsp;&nbsp;';
        $return .= '<input type="text" class="form-text" name="'.$fullname.'[v'.($i + 1).']" value="" />';
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);
    }

}

class admin_setting_special_editorhidebuttons extends admin_setting {
    public $items;

    public function __construct() {
        parent::__construct('editorhidebuttons', get_string('editorhidebuttons', 'admin'),
                            get_string('confeditorhidebuttons', 'admin'), array());
        // weird array... buttonname => buttonimage (assume proper path appended). if you leave buttomimage blank, text will be printed instead
        $this->items = array('fontname' => '',
                         'fontsize' => '',
                         'formatblock' => '',
                         'bold' => 'ed_format_bold.gif',
                         'italic' => 'ed_format_italic.gif',
                         'underline' => 'ed_format_underline.gif',
                         'strikethrough' => 'ed_format_strike.gif',
                         'subscript' => 'ed_format_sub.gif',
                         'superscript' => 'ed_format_sup.gif',
                         'copy' => 'ed_copy.gif',
                         'cut' => 'ed_cut.gif',
                         'paste' => 'ed_paste.gif',
                         'clean' => 'ed_wordclean.gif',
                         'undo' => 'ed_undo.gif',
                         'redo' => 'ed_redo.gif',
                         'justifyleft' => 'ed_align_left.gif',
                         'justifycenter' => 'ed_align_center.gif',
                         'justifyright' => 'ed_align_right.gif',
                         'justifyfull' => 'ed_align_justify.gif',
                         'lefttoright' => 'ed_left_to_right.gif',
                         'righttoleft' => 'ed_right_to_left.gif',
                         'insertorderedlist' => 'ed_list_num.gif',
                         'insertunorderedlist' => 'ed_list_bullet.gif',
                         'outdent' => 'ed_indent_less.gif',
                         'indent' => 'ed_indent_more.gif',
                         'forecolor' => 'ed_color_fg.gif',
                         'hilitecolor' => 'ed_color_bg.gif',
                         'inserthorizontalrule' => 'ed_hr.gif',
                         'createanchor' => 'ed_anchor.gif',
                         'createlink' => 'ed_link.gif',
                         'unlink' => 'ed_unlink.gif',
                         'insertimage' => 'ed_image.gif',
                         'inserttable' => 'insert_table.gif',
                         'insertsmile' => 'em.icon.smile.gif',
                         'insertchar' => 'icon_ins_char.gif',
                         'spellcheck' => 'spell-check.gif',
                         'htmlmode' => 'ed_html.gif',
                         'popupeditor' => 'fullscreen_maximize.gif',
                         'search_replace' => 'ed_replace.gif');
    }

    public function get_setting() {
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        if ($result === '') {
            return array();
        }
        return explode(' ', $result);
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return ''; // ignore it
        }
        unset($data['xxxxx']);
        $result = array();

        foreach ($data as $key => $value) {
            if (!isset($this->items[$key])) {
                return get_string('errorsetting', 'admin');
            }
            if ($value == '1') {
                $result[] = $key;
            }
        }
        return ($this->config_write($this->name, implode(' ', $result)) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {

        global $CFG;

        // checkboxes with input name="$this->name[$key]" value="1"
        // we do 15 fields per column

        $return = '<div class="form-group">';
        $return .= '<table><tr><td valign="top" align="right">';
        $return .= '<input type="hidden" name="'.$this->get_full_name().'[xxxxx]" value="1" />'; // something must be submitted even if nothing selected

        $count = 0;

        foreach($this->items as $key => $value) {
            if ($count % 15 == 0 and $count != 0) {
                $return .= '</td><td valign="top" align="right">';
            }

            $return .= '<label for="'.$this->get_id().$key.'">';
            $return .= ($value == '' ? get_string($key,'editor') : '<img width="18" height="18" src="'.$CFG->wwwroot.'/lib/editor/htmlarea/images/'.$value.'" alt="'.get_string($key,'editor').'" title="'.get_string($key,'editor').'" />').'&nbsp;';
            $return .= '<input type="checkbox" class="form-checkbox" value="1" id="'.$this->get_id().$key.'" name="'.$this->get_full_name().'['.$key.']"'.(in_array($key,$data) ? ' checked="checked"' : '').' />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
            $return .= '</label>';
            $count++;
            if ($count % 15 != 0) {
                $return .= '<br /><br />';
            }
        }

        $return .= '</td></tr>';
        $return .= '</table>';
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);
    }
}

/**
 * Special setting for limiting of the list of available languages.
 */
class admin_setting_langlist extends admin_setting_configtext {
    public function __construct() {
        parent::__construct('langlist', get_string('langlist', 'admin'), get_string('configlanglist', 'admin'), '', PARAM_NOTAGS);
    }

    public function write_setting($data) {
        $return = parent::write_setting($data);
        get_list_of_languages(true);//refresh the list
        return $return;
    }
}

/**
 * Course category selection
 */
class admin_settings_coursecat_select extends admin_setting_configselect {
    public function __construct($name, $visiblename, $description, $defaultsetting) {
        parent::__construct($name, $visiblename, $description, $defaultsetting, NULL);
    }

    public function load_choices() {
        global $CFG;
        require_once($CFG->dirroot.'/course/lib.php');
        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = make_categories_options();
        return true;
    }
}

class admin_setting_special_backupdays extends admin_setting_configmulticheckbox2 {
    public function __construct() {
        parent::__construct('backup_sche_weekdays', get_string('schedule'), get_string('backupschedulehelp'), array(), NULL);
        $this->plugin = 'backup';
    }

    public function load_choices() {
        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = array();
        $days = array('sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday');
        foreach ($days as $day) {
            $this->choices[$day] = get_string($day, 'calendar');
        }
        return true;
    }
}

/**
 * Special debug setting
 */
class admin_setting_special_debug extends admin_setting_configselect {
    public function __construct() {
        parent::__construct('debug', get_string('debug', 'admin'), get_string('configdebug', 'admin'), DEBUG_NONE, NULL);
    }

    public function load_choices() {
        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = array(DEBUG_NONE      => get_string('debugnone', 'admin'),
                               DEBUG_MINIMAL   => get_string('debugminimal', 'admin'),
                               DEBUG_NORMAL    => get_string('debugnormal', 'admin'),
                               DEBUG_ALL       => get_string('debugall', 'admin'),
                               DEBUG_DEVELOPER => get_string('debugdeveloper', 'admin'));
        return true;
    }
}


class admin_setting_special_calendar_weekend extends admin_setting {
    public function __construct() {
        $name = 'calendar_weekend';
        $visiblename = get_string('calendar_weekend', 'admin');
        $description = get_string('helpweekenddays', 'admin');
        $default = array ('0', '6'); // Saturdays and Sundays
        parent::__construct($name, $visiblename, $description, $default);
    }

    public function get_setting() {
        $result = $this->config_read($this->name);
        if (is_null($result)) {
            return NULL;
        }
        if ($result === '') {
            return array();
        }
        $settings = array();
        for ($i=0; $i<7; $i++) {
            if ($result & (1 << $i)) {
                $settings[] = $i;
            }
        }
        return $settings;
    }

    public function write_setting($data) {
        if (!is_array($data)) {
            return '';
        }
        unset($data['xxxxx']);
        $result = 0;
        foreach($data as $index) {
            $result |= 1 << $index;
        }
        return ($this->config_write($this->name, $result) ? '' : get_string('errorsetting', 'admin'));
    }

    public function output_html($data, $query='') {
        // The order matters very much because of the implied numeric keys
        $days = array('sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday');
        $return = '<table><thead><tr>';
        $return .= '<input type="hidden" name="'.$this->get_full_name().'[xxxxx]" value="1" />'; // something must be submitted even if nothing selected
        foreach($days as $index => $day) {
            $return .= '<td><label for="'.$this->get_id().$index.'">'.get_string($day, 'calendar').'</label></td>';
        }
        $return .= '</tr></thead><tbody><tr>';
        foreach($days as $index => $day) {
            $return .= '<td><input type="checkbox" class="form-checkbox" id="'.$this->get_id().$index.'" name="'.$this->get_full_name().'[]" value="'.$index.'" '.(in_array("$index", $data) ? 'checked="checked"' : '').' /></td>';
        }
        $return .= '</tr></tbody></table>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, false, '', NULL, $query);

    }
}


/**
 * Admin setting that allows a user to pick appropriate roles for something.
 */
class admin_setting_pickroles extends admin_setting_configmulticheckbox {
    private $types;

    /**
     * @param string $name Name of config variable
     * @param string $visiblename Display name
     * @param string $description Description
     * @param array $types Array of capabilities (usually moodle/legacy:something)
     *   which identify roles that will be enabled by default. Default is the
     *   student role
     */
    public function __construct($name, $visiblename, $description, $types) {
        parent::__construct($name, $visiblename, $description, NULL, NULL);
        $this->types = $types;
    }

    public function load_choices() {
        global $CFG, $DB;
        if (empty($CFG->rolesactive)) {
            return false;
        }
        if (is_array($this->choices)) {
            return true;
        }
        if ($roles = get_all_roles()) {
            $this->choices = array();
            foreach($roles as $role) {
                $this->choices[$role->id] = format_string($role->name);
            }
            return true;
        } else {
            return false;
        }
    }

    public function get_defaultsetting() {
        global $CFG;

        if (empty($CFG->rolesactive)) {
            return null;
        }
        $result = array();
        foreach($this->types as $capability) {
            if ($caproles = get_roles_with_capability($capability, CAP_ALLOW)) {
                foreach ($caproles as $caprole) {
                    $result[$caprole->id] = 1;
                }
            }
        }
        return $result;
    }
}

/**
 * Text field with an advanced checkbox, that controls a additional "fix_$name" setting.
 */
class admin_setting_text_with_advanced extends admin_setting_configtext {
    public function __construct($name, $visiblename, $description, $defaultsetting, $paramtype) {
        parent::__construct($name, $visiblename, $description,
                $defaultsetting, $paramtype);
    }

    public function get_setting() {
        $value = parent::get_setting();
        $fix = $this->config_read('fix_' . $this->name);
        if (is_null($value) or is_null($fix)) {
            return NULL;
        }
        return array('value' => $value, 'fix' => $fix);
    }

    public function write_setting($data) {
        $error = parent::write_setting($data['value']);
        if (!$error) {
            if (empty($data['fix'])) {
                $ok = $this->config_write('fix_' . $this->name, 0);
            } else {
                $ok = $this->config_write('fix_' . $this->name, 1);
            }
            if (!$ok) {
                $error = get_string('errorsetting', 'admin');
            }
        }
        return $error;
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();
        $defaultinfo = array();
        if (isset($default['value'])) {
            if ($default['value'] === '') {
                $defaultinfo[] = "''";
            } else {
                $defaultinfo[] = $default['value'];
            }
        }
        if (!empty($default['fix'])) {
            $defaultinfo[] = get_string('advanced');
        }
        $defaultinfo = implode(', ', $defaultinfo);

        $fix = !empty($data['fix']);
        $return = '<div class="form-text defaultsnext">' .
                '<input type="text" size="' . $this->size . '" id="' . $this->get_id() .
                '" name="' . $this->get_full_name() . '[value]" value="' . s($data['value']) . '" />' .
                ' <input type="checkbox" class="form-checkbox" id="' .
                $this->get_id() . '_fix" name="' . $this->get_full_name() .
                '[fix]" value="1" ' . ($fix ? 'checked="checked"' : '') . ' />' .
                ' <label for="' . $this->get_id() . '_fix">' .
                get_string('advanced') . '</label></div>';

        return format_admin_setting($this, $this->visiblename, $return,
                $this->description, true, '', $defaultinfo, $query);
    }
}

/**
 * Dropdown menu with an advanced checkbox, that controls a additional "fix_$name" setting.
 */
class admin_setting_combo_with_advanced extends admin_setting_configselect {
    public function __construct($name, $visiblename, $description, $defaultsetting, $choices) {
        parent::__construct($name, $visiblename, $description, $defaultsetting, $choices);
    }

    public function get_setting() {
        $value = parent::get_setting();
        $fix = $this->config_read('fix_' . $this->name);
        if (is_null($value) or is_null($fix)) {
            return NULL;
        }
        return array('value' => $value, 'fix' => $fix);
    }

    public function write_setting($data) {
        $error = parent::write_setting($data['value']);
        if (!$error) {
            if (empty($data['fix'])) {
                $ok = $this->config_write('fix_' . $this->name, 0);
            } else {
                $ok = $this->config_write('fix_' . $this->name, 1);
            }
            if (!$ok) {
                $error = get_string('errorsetting', 'admin');
            }
        }
        return $error;
    }

    public function output_html($data, $query='') {
        $default = $this->get_defaultsetting();
        $current = $this->get_setting();

        list($selecthtml, $warning) = $this->output_select_html($data['value'],
                $current['value'], $default['value'], '[value]');
        if (!$selecthtml) {
            return '';
        }

        if (!is_null($default) and array_key_exists($default['value'], $this->choices)) {
            $defaultinfo = array();
            if (isset($this->choices[$default['value']])) {
                $defaultinfo[] = $this->choices[$default['value']];
            }
            if (!empty($default['fix'])) {
                $defaultinfo[] = get_string('advanced');
            }
            $defaultinfo = implode(', ', $defaultinfo);
        } else {
            $defaultinfo = '';
        }

        $fix = !empty($data['fix']);
        $return = '<div class="form-select defaultsnext">' . $selecthtml .
                ' <input type="checkbox" class="form-checkbox" id="' .
                $this->get_id() . '_fix" name="' . $this->get_full_name() .
                '[fix]" value="1" ' . ($fix ? 'checked="checked"' : '') . ' />' .
                ' <label for="' . $this->get_id() . '_fix">' .
                get_string('advanced') . '</label></div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, true, $warning, $defaultinfo, $query);
    }
}

/**
 * Specialisation of admin_setting_combo_with_advanced for easy yes/no choices.
 */
class admin_setting_yesno_with_advanced extends admin_setting_combo_with_advanced {
    public function __construct($name, $visiblename, $description, $defaultsetting) {
        parent::__construct($name, $visiblename, $description,
                $defaultsetting, array(get_string('no'), get_string('yes')));
    }
}

/**
 * Graded roles in gradebook
 */
class admin_setting_special_gradebookroles extends admin_setting_pickroles {
    public function __construct() {
        parent::__construct('gradebookroles', get_string('gradebookroles', 'admin'),
                                              get_string('configgradebookroles', 'admin'),
                                              array('moodle/legacy:student'));
    }
}


class admin_setting_regradingcheckbox extends admin_setting_configcheckbox {
    public function write_setting($data) {
        global $CFG, $DB;

        $oldvalue  = $this->config_read($this->name);
        $return    = parent::write_setting($data);
        $newvalue  = $this->config_read($this->name);

        if ($oldvalue !== $newvalue) {
            // force full regrading
            $DB->set_field('grade_items', 'needsupdate', 1, array('needsupdate'=>0));
        }

        return $return;
    }
}

/**
 * Which roles to show on course decription page
 */
class admin_setting_special_coursemanager extends admin_setting_pickroles {
    public function __construct() {
        parent::__construct('coursemanager', get_string('coursemanager', 'admin'),
                                             get_string('configcoursemanager', 'admin'),
                                             array('moodle/legacy:editingteacher'));
    }
}

class admin_setting_special_gradelimiting extends admin_setting_configcheckbox {
    function admin_setting_special_gradelimiting() {
        parent::__construct('unlimitedgrades', get_string('unlimitedgrades', 'grades'),
                                                  get_string('configunlimitedgrades', 'grades'), '0', '1', '0');
    }

    function regrade_all() {
        global $CFG;
        require_once("$CFG->libdir/gradelib.php");
        grade_force_site_regrading();
    }

    function write_setting($data) {
        $previous = $this->get_setting();

        if ($previous === null) {
            if ($data) {
                $this->regrade_all();
            }
        } else {
            if ($data != $previous) {
                $this->regrade_all();
            }
        }
        return ($this->config_write($this->name, $data) ? '' : get_string('errorsetting', 'admin'));
    }

}

/**
 * Primary grade export plugin - has state tracking.
 */
class admin_setting_special_gradeexport extends admin_setting_configmulticheckbox {
    public function __construct() {
        parent::__construct('gradeexport', get_string('gradeexport', 'admin'),
                            get_string('configgradeexport', 'admin'), array(), NULL);
    }

    public function load_choices() {
        if (is_array($this->choices)) {
            return true;
        }
        $this->choices = array();

        if ($plugins = get_list_of_plugins('grade/export')) {
            foreach($plugins as $plugin) {
                $this->choices[$plugin] = get_string('modulename', 'gradeexport_'.$plugin);
            }
        }
        return true;
    }
}

/**
 * Grade category settings
 */
class admin_setting_gradecat_combo extends admin_setting {

    public $choices;

    public function __construct($name, $visiblename, $description, $defaultsetting, $choices) {
        $this->choices = $choices;
        parent::__construct($name, $visiblename, $description, $defaultsetting);
    }

    public function get_setting() {
        global $CFG;

        $value = $this->config_read($this->name);
        $flag  = $this->config_read($this->name.'_flag');

        if (is_null($value) or is_null($flag)) {
            return NULL;
        }

        $flag   = (int)$flag;
        $forced = (boolean)(1 & $flag); // first bit
        $adv    = (boolean)(2 & $flag); // second bit

        return array('value' => $value, 'forced' => $forced, 'adv' => $adv);
    }

    public function write_setting($data) {
        global $CFG;

        $value  = $data['value'];
        $forced = empty($data['forced']) ? 0 : 1;
        $adv    = empty($data['adv'])    ? 0 : 2;
        $flag   = ($forced | $adv); //bitwise or

        if (!in_array($value, array_keys($this->choices))) {
            return 'Error setting ';
        }

        $oldvalue  = $this->config_read($this->name);
        $oldflag   = (int)$this->config_read($this->name.'_flag');
        $oldforced = (1 & $oldflag); // first bit

        $result1 = $this->config_write($this->name, $value);
        $result2 = $this->config_write($this->name.'_flag', $flag);

        // force regrade if needed
        if ($oldforced != $forced or ($forced and $value != $oldvalue)) {
           require_once($CFG->libdir.'/gradelib.php');
           grade_category::updated_forced_settings();
        }

        if ($result1 and $result2) {
            return '';
        } else {
            return get_string('errorsetting', 'admin');
        }
    }

    public function output_html($data, $query='') {
        $value  = $data['value'];
        $forced = !empty($data['forced']);
        $adv    = !empty($data['adv']);

        $default = $this->get_defaultsetting();
        if (!is_null($default)) {
            $defaultinfo = array();
            if (isset($this->choices[$default['value']])) {
                $defaultinfo[] = $this->choices[$default['value']];
            }
            if (!empty($default['forced'])) {
                $defaultinfo[] = get_string('force');
            }
            if (!empty($default['adv'])) {
                $defaultinfo[] = get_string('advanced');
            }
            $defaultinfo = implode(', ', $defaultinfo);

        } else {
            $defaultinfo = NULL;
        }


        $return = '<div class="form-group">';
        $return .= '<select class="form-select" id="'.$this->get_id().'" name="'.$this->get_full_name().'[value]">';
        foreach ($this->choices as $key => $val) {
            // the string cast is needed because key may be integer - 0 is equal to most strings!
            $return .= '<option value="'.$key.'"'.((string)$key==$value ? ' selected="selected"' : '').'>'.$val.'</option>';
        }
        $return .= '</select>';
        $return .= '<input type="checkbox" class="form-checkbox" id="'.$this->get_id().'force" name="'.$this->get_full_name().'[forced]" value="1" '.($forced ? 'checked="checked"' : '').' />'
                  .'<label for="'.$this->get_id().'force">'.get_string('force').'</label>';
        $return .= '<input type="checkbox" class="form-checkbox" id="'.$this->get_id().'adv" name="'.$this->get_full_name().'[adv]" value="1" '.($adv ? 'checked="checked"' : '').' />'
                  .'<label for="'.$this->get_id().'adv">'.get_string('advanced').'</label>';
        $return .= '</div>';

        return format_admin_setting($this, $this->visiblename, $return, $this->description, true, '', $defaultinfo, $query);
    }
}