Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * This file contains the course_enrolment_manager class which is used to interface

 * with the functions that exist in enrollib.php in relation to a single course.

 *

 * @package    core_enrol

 * @copyright  2010 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

use core_user\fields;

defined('MOODLE_INTERNAL') || die();

/**

 * This class provides a targeted tied together means of interfacing the enrolment

 * tasks together with a course.

 *

 * It is provided as a convenience more than anything else.

 *

 * @copyright 2010 Sam Hemelryk

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class course_enrolment_manager {

    /**

     * The course context

     * @var context

     */

    protected $context;

    /**

     * The course we are managing enrolments for

     * @var stdClass

     */

    protected $course = null;

    /**

     * Limits the focus of the manager to one enrolment plugin instance

     * @var string

     */

    protected $instancefilter = null;

    /**

     * Limits the focus of the manager to users with specified role

     * @var int

     */

    protected $rolefilter = 0;

    /**

     * Limits the focus of the manager to users who match search string

     * @var string

     */

    protected $searchfilter = '';

    /**

     * Limits the focus of the manager to users in specified group

     * @var int

     */

    protected $groupfilter = 0;

    /**

     * Limits the focus of the manager to users who match status active/inactive

     * @var int

     */

    protected $statusfilter = -1;

    /**

     * The total number of users enrolled in the course

     * Populated by course_enrolment_manager::get_total_users

     * @var int

     */

    protected $totalusers = null;

    /**

     * An array of users currently enrolled in the course

     * Populated by course_enrolment_manager::get_users

     * @var array

     */

    protected $users = array();

    /**

     * An array of users who have roles within this course but who have not

     * been enrolled in the course

     * @var array

     */

    protected $otherusers = array();

    /**

     * The total number of users who hold a role within the course but who

     * arn't enrolled.

     * @var int

     */

    protected $totalotherusers = null;

    /**

     * The current moodle_page object

     * @var moodle_page

     */

    protected $moodlepage = null;

    /**#@+

     * These variables are used to cache the information this class uses

     * please never use these directly instead use their get_ counterparts.

     * @access private

     * @var array

     */

    private $_instancessql = null;

    private $_instances = null;

    private $_inames = null;

    private $_plugins = null;

    private $_allplugins = null;

    private $_roles = null;

    private $_visibleroles = null;

    private $_assignableroles = null;

    private $_assignablerolesothers = null;

    private $_groups = null;

    /**#@-*/

    /**

     * Constructs the course enrolment manager

     *

     * @param moodle_page $moodlepage

     * @param stdClass $course

     * @param string $instancefilter

     * @param int $rolefilter If non-zero, filters to users with specified role

     * @param string $searchfilter If non-blank, filters to users with search text

     * @param int $groupfilter if non-zero, filter users with specified group

     * @param int $statusfilter if not -1, filter users with active/inactive enrollment.

     */

    public function __construct(moodle_page $moodlepage, $course, $instancefilter = null,

            $rolefilter = 0, $searchfilter = '', $groupfilter = 0, $statusfilter = -1) {

        $this->moodlepage = $moodlepage;

        $this->context = context_course::instance($course->id);

        $this->course = $course;

        $this->instancefilter = $instancefilter;

        $this->rolefilter = $rolefilter;

        $this->searchfilter = $searchfilter;

        $this->groupfilter = $groupfilter;

        $this->statusfilter = $statusfilter;

    }

    /**

     * Returns the current moodle page

     * @return moodle_page

     */

    public function get_moodlepage() {

        return $this->moodlepage;

    }

    /**

     * Returns the total number of enrolled users in the course.

     *

     * If a filter was specificed this will be the total number of users enrolled

     * in this course by means of that instance.

     *

     * @global moodle_database $DB

     * @return int

     */

    public function get_total_users() {

        global $DB;

        if ($this->totalusers === null) {

            list($instancessql, $params, $filter) = $this->get_instance_sql();

            list($filtersql, $moreparams) = $this->get_filter_sql();

            $params += $moreparams;

            $sqltotal = "SELECT COUNT(DISTINCT u.id)

                           FROM {user} u

                           JOIN {user_enrolments} ue ON (ue.userid = u.id  AND ue.enrolid $instancessql)

                           JOIN {enrol} e ON (e.id = ue.enrolid)";

            if ($this->groupfilter) {

                $sqltotal .= " LEFT JOIN ({groups_members} gm JOIN {groups} g ON (g.id = gm.groupid))

                                         ON (u.id = gm.userid AND g.courseid = e.courseid)";

            }

            $sqltotal .= "WHERE $filtersql";

            $this->totalusers = (int)$DB->count_records_sql($sqltotal, $params);

        }

        return $this->totalusers;

    }

    /**

     * Returns the total number of enrolled users in the course.

     *

     * If a filter was specificed this will be the total number of users enrolled

     * in this course by means of that instance.

     *

     * @global moodle_database $DB

     * @return int

     */

    public function get_total_other_users() {

        global $DB;

        if ($this->totalotherusers === null) {

            list($ctxcondition, $params) = $DB->get_in_or_equal($this->context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'ctx');

            $params['courseid'] = $this->course->id;

            $sql = "SELECT COUNT(DISTINCT u.id)

                      FROM {role_assignments} ra

                      JOIN {user} u ON u.id = ra.userid

                      JOIN {context} ctx ON ra.contextid = ctx.id

                 LEFT JOIN (

                           SELECT ue.id, ue.userid

                             FROM {user_enrolments} ue

                        LEFT JOIN {enrol} e ON e.id=ue.enrolid

                            WHERE e.courseid = :courseid

                         ) ue ON ue.userid=u.id

                     WHERE ctx.id $ctxcondition AND

                           ue.id IS NULL";

            $this->totalotherusers = (int)$DB->count_records_sql($sql, $params);

        }

        return $this->totalotherusers;

    }

    /**

     * Gets all of the users enrolled in this course.

     *

     * If a filter was specified this will be the users who were enrolled

     * in this course by means of that instance. If role or search filters were

     * specified then these will also be applied.

     *

     * @global moodle_database $DB

     * @param string $sort

     * @param string $direction ASC or DESC

     * @param int $page First page should be 0

     * @param int $perpage Defaults to 25

     * @return array

     */

    public function get_users($sort, $direction='ASC', $page=0, $perpage=25) {

        global $DB;

        if ($direction !== 'ASC') {

            $direction = 'DESC';

        }

        $key = md5("$sort-$direction-$page-$perpage");

        if (!array_key_exists($key, $this->users)) {

            list($instancessql, $params, $filter) = $this->get_instance_sql();

            list($filtersql, $moreparams) = $this->get_filter_sql();

            $params += $moreparams;

            $userfields = fields::for_identity($this->get_context())->with_userpic()->excluding('lastaccess');

            ['selects' => $fieldselect, 'joins' => $fieldjoin, 'params' => $fieldjoinparams] =

                    (array)$userfields->get_sql('u', true, '', '', false);

            $params += $fieldjoinparams;

            $sql = "SELECT DISTINCT $fieldselect, COALESCE(ul.timeaccess, 0) AS lastcourseaccess

                      FROM {user} u

                      JOIN {user_enrolments} ue ON (ue.userid = u.id  AND ue.enrolid $instancessql)

                      JOIN {enrol} e ON (e.id = ue.enrolid)

                           $fieldjoin

                 LEFT JOIN {user_lastaccess} ul ON (ul.courseid = e.courseid AND ul.userid = u.id)";

            if ($this->groupfilter) {

                $sql .= " LEFT JOIN ({groups_members} gm JOIN {groups} g ON (g.id = gm.groupid))

                                    ON (u.id = gm.userid AND g.courseid = e.courseid)";

            }

            $sql .= "WHERE $filtersql

                  ORDER BY $sort $direction";

            $this->users[$key] = $DB->get_records_sql($sql, $params, $page*$perpage, $perpage);

        }

        return $this->users[$key];

    }

    /**

     * Obtains WHERE clause to filter results by defined search and role filter

     * (instance filter is handled separately in JOIN clause, see

     * get_instance_sql).

     *

     * @return array Two-element array with SQL and params for WHERE clause

     */

    protected function get_filter_sql() {

        global $DB;

        // Search condition.

        // TODO Does not support custom user profile fields (MDL-70456).

        $extrafields = fields::get_identity_fields($this->get_context(), false);

        list($sql, $params) = users_search_sql($this->searchfilter, 'u', USER_SEARCH_CONTAINS, $extrafields);

        // Role condition.

        if ($this->rolefilter) {

            // Get context SQL.

            $contextids = $this->context->get_parent_context_ids();

            $contextids[] = $this->context->id;

            list($contextsql, $contextparams) = $DB->get_in_or_equal($contextids, SQL_PARAMS_NAMED);

            $params += $contextparams;

            // Role check condition.

            $sql .= " AND (SELECT COUNT(1) FROM {role_assignments} ra WHERE ra.userid = u.id " .

                    "AND ra.roleid = :roleid AND ra.contextid $contextsql) > 0";

            $params['roleid'] = $this->rolefilter;

        }

        // Group condition.

        if ($this->groupfilter) {

            if ($this->groupfilter < 0) {

                // Show users who are not in any group.

                $sql .= " AND gm.groupid IS NULL";

            } else {

                $sql .= " AND gm.groupid = :groupid";

                $params['groupid'] = $this->groupfilter;

            }

        }

        // Status condition.

        if ($this->statusfilter === ENROL_USER_ACTIVE) {

            $sql .= " AND ue.status = :active AND e.status = :enabled AND ue.timestart < :now1

                    AND (ue.timeend = 0 OR ue.timeend > :now2)";

            $now = round(time(), -2); // rounding helps caching in DB

            $params += array('enabled' => ENROL_INSTANCE_ENABLED,

                             'active' => ENROL_USER_ACTIVE,

                             'now1' => $now,

                             'now2' => $now);

        } else if ($this->statusfilter === ENROL_USER_SUSPENDED) {

            $sql .= " AND (ue.status = :inactive OR e.status = :disabled OR ue.timestart > :now1

                    OR (ue.timeend <> 0 AND ue.timeend < :now2))";

            $now = round(time(), -2); // rounding helps caching in DB

            $params += array('disabled' => ENROL_INSTANCE_DISABLED,

                             'inactive' => ENROL_USER_SUSPENDED,

                             'now1' => $now,

                             'now2' => $now);

        }

        return array($sql, $params);

    }

    /**

     * Gets and array of other users.

     *

     * Other users are users who have been assigned roles or inherited roles

     * within this course but who have not been enrolled in the course

     *

     * @global moodle_database $DB

     * @param string $sort

     * @param string $direction

     * @param int $page

     * @param int $perpage

     * @return array

     */

    public function get_other_users($sort, $direction='ASC', $page=0, $perpage=25) {

        global $DB;

        if ($direction !== 'ASC') {

            $direction = 'DESC';

        }

        $key = md5("$sort-$direction-$page-$perpage");

        if (!array_key_exists($key, $this->otherusers)) {

            list($ctxcondition, $params) = $DB->get_in_or_equal($this->context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'ctx');

            $params['courseid'] = $this->course->id;

            $params['cid'] = $this->course->id;

            $userfields = fields::for_identity($this->get_context())->with_userpic();

            ['selects' => $fieldselect, 'joins' => $fieldjoin, 'params' => $fieldjoinparams] =

                    (array)$userfields->get_sql('u', true);

            $params += $fieldjoinparams;

            $sql = "SELECT ra.id as raid, ra.contextid, ra.component, ctx.contextlevel, ra.roleid,

                           coalesce(u.lastaccess,0) AS lastaccess

                           $fieldselect

                      FROM {role_assignments} ra

                      JOIN {user} u ON u.id = ra.userid

                      JOIN {context} ctx ON ra.contextid = ctx.id

                           $fieldjoin

                 LEFT JOIN (

                       SELECT ue.id, ue.userid

                         FROM {user_enrolments} ue

                         JOIN {enrol} e ON e.id = ue.enrolid

                        WHERE e.courseid = :courseid

                       ) ue ON ue.userid=u.id

                     WHERE ctx.id $ctxcondition AND

                           ue.id IS NULL

                  ORDER BY $sort $direction, ctx.depth DESC";

            $this->otherusers[$key] = $DB->get_records_sql($sql, $params, $page*$perpage, $perpage);

        }

        return $this->otherusers[$key];

    }

    /**

     * Helper method used by {@link get_potential_users()} and {@link search_other_users()}.

     *

     * @param string $search the search term, if any.

     * @param bool $searchanywhere Can the search term be anywhere, or must it be at the start.

     * @return array with three elements:

     *     string list of fields to SELECT,

     *     string possible database joins for user fields

     *     string contents of SQL WHERE clause,

     *     array query params. Note that the SQL snippets use named parameters.

     */

    protected function get_basic_search_conditions($search, $searchanywhere) {

        global $DB, $CFG;

        // Get custom user field SQL used for querying all the fields we need (identity, name, and

        // user picture).

        $userfields = fields::for_identity($this->context)->with_name()->with_userpic()

                ->excluding('username', 'lastaccess', 'maildisplay');

        ['selects' => $fieldselects, 'joins' => $fieldjoins, 'params' => $params, 'mappings' => $mappings] =

                (array)$userfields->get_sql('u', true, '', '', false);

        // Searchable fields are only the identity and name ones (not userpic, and without exclusions).

        $searchablefields = fields::for_identity($this->context)->with_name();

        $searchable = array_fill_keys($searchablefields->get_required_fields(), true);

        if (array_key_exists('username', $searchable)) {

            // Add the username into the mappings list from the other query, because it was excluded.

            $mappings['username'] = 'u.username';

        }

        // Add some additional sensible conditions

        $tests = array("u.id <> :guestid", 'u.deleted = 0', 'u.confirmed = 1');

        $params['guestid'] = $CFG->siteguest;

        if (!empty($search)) {

            // Include identity and name fields as conditions.

            foreach ($mappings as $fieldname => $fieldsql) {

                if (array_key_exists($fieldname, $searchable)) {

                    $conditions[] = $fieldsql;

                }

            }

            $conditions[] = $DB->sql_fullname('u.firstname', 'u.lastname');

            if ($searchanywhere) {

                $searchparam = '%' . $search . '%';

            } else {

                $searchparam = $search . '%';

            }

            $i = 0;

            foreach ($conditions as $key => $condition) {

                $conditions[$key] = $DB->sql_like($condition, ":con{$i}00", false);

                $params["con{$i}00"] = $searchparam;

                $i++;

            }

            $tests[] = '(' . implode(' OR ', $conditions) . ')';

        }

        $wherecondition = implode(' AND ', $tests);

        $selects = $fieldselects . ', u.username, u.lastaccess, u.maildisplay';

        return [$selects, $fieldjoins, $params, $wherecondition];

    }

    /**

     * Helper method used by {@link get_potential_users()} and {@link search_other_users()}.

     *

     * @param string $search the search string, if any.

     * @param string $fields the first bit of the SQL when returning some users.

     * @param string $countfields fhe first bit of the SQL when counting the users.

     * @param string $sql the bulk of the SQL statement.

     * @param array $params query parameters.

     * @param int $page which page number of the results to show.

     * @param int $perpage number of users per page.

     * @param int $addedenrollment number of users added to enrollment.

     * @param bool $returnexactcount Return the exact total users using count_record or not.

     * @return array with two or three elements:

     *      int totalusers Number users matching the search. (This element only exist if $returnexactcount was set to true)

     *      array users List of user objects returned by the query.

     *      boolean moreusers True if there are still more users, otherwise is False.

     * @throws dml_exception

     */

    protected function execute_search_queries($search, $fields, $countfields, $sql, array $params, $page, $perpage,

            $addedenrollment = 0, $returnexactcount = false) {

        global $DB, $CFG;

        list($sort, $sortparams) = users_order_by_sql('u', $search, $this->get_context());

        $order = ' ORDER BY ' . $sort;

        $totalusers = 0;

        $moreusers = false;

        $results = [];

        $availableusers = $DB->get_records_sql($fields . $sql . $order,

                array_merge($params, $sortparams), ($page * $perpage) - $addedenrollment, $perpage + 1);

        if ($availableusers) {

            $totalusers = count($availableusers);

            $moreusers = $totalusers > $perpage;

            if ($moreusers) {

                // We need to discard the last record.

                array_pop($availableusers);

            }

            if ($returnexactcount && $moreusers) {

                // There is more data. We need to do the exact count.

                $totalusers = $DB->count_records_sql($countfields . $sql, $params);

            }

        }

        $results['users'] = $availableusers;

        $results['moreusers'] = $moreusers;

        if ($returnexactcount) {

            // Include totalusers in result if $returnexactcount flag is true.

            $results['totalusers'] = $totalusers;

        }

        return $results;

    }

    /**

     * Gets an array of the users that can be enrolled in this course.

     *

     * @global moodle_database $DB

     * @param int $enrolid

     * @param string $search

     * @param bool $searchanywhere

     * @param int $page Defaults to 0

     * @param int $perpage Defaults to 25

     * @param int $addedenrollment Defaults to 0

     * @param bool $returnexactcount Return the exact total users using count_record or not.

     * @return array with two or three elements:

     *      int totalusers Number users matching the search. (This element only exist if $returnexactcount was set to true)

     *      array users List of user objects returned by the query.

     *      boolean moreusers True if there are still more users, otherwise is False.

     * @throws dml_exception

     */

    public function get_potential_users($enrolid, $search = '', $searchanywhere = false, $page = 0, $perpage = 25,

            $addedenrollment = 0, $returnexactcount = false) {

        global $DB;

        [$ufields, $joins, $params, $wherecondition] = $this->get_basic_search_conditions($search, $searchanywhere);

        $fields      = 'SELECT '.$ufields;

        $countfields = 'SELECT COUNT(1)';

        $sql = " FROM {user} u

                      $joins

            LEFT JOIN {user_enrolments} ue ON (ue.userid = u.id AND ue.enrolid = :enrolid)

                WHERE $wherecondition

                      AND ue.id IS NULL";

        $params['enrolid'] = $enrolid;

        return $this->execute_search_queries($search, $fields, $countfields, $sql, $params, $page, $perpage, $addedenrollment,

                $returnexactcount);

    }

    /**

     * Searches other users and returns paginated results

     *

     * @global moodle_database $DB

     * @param string $search

     * @param bool $searchanywhere

     * @param int $page Starting at 0

     * @param int $perpage

     * @param bool $returnexactcount Return the exact total users using count_record or not.

     * @return array with two or three elements:

     *      int totalusers Number users matching the search. (This element only exist if $returnexactcount was set to true)

     *      array users List of user objects returned by the query.

     *      boolean moreusers True if there are still more users, otherwise is False.

     * @throws dml_exception

     */

    public function search_other_users($search = '', $searchanywhere = false, $page = 0, $perpage = 25, $returnexactcount = false) {

        global $DB, $CFG;

        [$ufields, $joins, $params, $wherecondition] = $this->get_basic_search_conditions($search, $searchanywhere);

        $fields      = 'SELECT ' . $ufields;

        $countfields = 'SELECT COUNT(u.id)';

        $sql   = " FROM {user} u

                        $joins

              LEFT JOIN {role_assignments} ra ON (ra.userid = u.id AND ra.contextid = :contextid)

                  WHERE $wherecondition

                    AND ra.id IS NULL";

        $params['contextid'] = $this->context->id;

        return $this->execute_search_queries($search, $fields, $countfields, $sql, $params, $page, $perpage, 0, $returnexactcount);

    }

    /**

     * Searches through the enrolled users in this course.

     *

     * @param string $search The search term.

     * @param bool $searchanywhere Can the search term be anywhere, or must it be at the start.

     * @param int $page Starting at 0.

     * @param int $perpage Number of users returned per page.

     * @param bool $returnexactcount Return the exact total users using count_record or not.

     * @param ?int $contextid Context ID we are in - we might use search on activity level and its group mode can be different from course group mode.

     * @return array with two or three elements:

     *      int totalusers Number users matching the search. (This element only exist if $returnexactcount was set to true)

     *      array users List of user objects returned by the query.

     *      boolean moreusers True if there are still more users, otherwise is False.

     */

    public function search_users(string $search = '', bool $searchanywhere = false, int $page = 0, int $perpage = 25,

            bool $returnexactcount = false, ?int $contextid = null) {

        global $USER;

        [$ufields, $joins, $params, $wherecondition] = $this->get_basic_search_conditions($search, $searchanywhere);

        if (isset($contextid)) {

            // If contextid is set, we need to determine the group mode that should be used (module or course).

            [$context, $course, $cm] = get_context_info_array($contextid);

            // If cm instance is returned, then use the group mode from the module, otherwise get the course group mode.

            $groupmode = $cm ? groups_get_activity_groupmode($cm, $course) : groups_get_course_groupmode($this->course);

        } else {

            // Otherwise, default to the group mode of the course.

            $context = $this->context;

            $groupmode = groups_get_course_groupmode($this->course);

        }

        if ($groupmode == SEPARATEGROUPS && !has_capability('moodle/site:accessallgroups', $context)) {

            $groups = groups_get_all_groups($this->course->id, $USER->id, 0, 'g.id');

            $groupids = array_column($groups, 'id');

            if (!$groupids) {

                return ['totalusers' => 0, 'users' => [], 'moreusers' => false];

            }

        } else {

            $groupids = [];

        }

        [$enrolledsql, $enrolledparams] = get_enrolled_sql($context, '', $groupids);

        $fields      = 'SELECT ' . $ufields;

        $countfields = 'SELECT COUNT(u.id)';

        $sql = " FROM {user} u

                      $joins

                 JOIN ($enrolledsql) je ON je.id = u.id

                WHERE $wherecondition";

        $params = array_merge($params, $enrolledparams);

        return $this->execute_search_queries($search, $fields, $countfields, $sql, $params, $page, $perpage, 0, $returnexactcount);

    }

    /**

     * Gets an array containing some SQL to user for when selecting, params for

     * that SQL, and the filter that was used in constructing the sql.

     *

     * @global moodle_database $DB

     * @return array

     */

    protected function get_instance_sql() {

        global $DB;

        if ($this->_instancessql === null) {

            $instances = $this->get_enrolment_instances();

            $filter = $this->get_enrolment_filter();

            if ($filter && array_key_exists($filter, $instances)) {

                $sql = " = :ifilter";

                $params = array('ifilter'=>$filter);

            } else {

                $filter = 0;

                if ($instances) {

                    list($sql, $params) = $DB->get_in_or_equal(array_keys($this->get_enrolment_instances()), SQL_PARAMS_NAMED);

                } else {

                    // no enabled instances, oops, we should probably say something

                    $sql = "= :never";

                    $params = array('never'=>-1);

                }

            }

            $this->instancefilter = $filter;

            $this->_instancessql = array($sql, $params, $filter);

        }

        return $this->_instancessql;

    }

    /**

     * Returns all of the enrolment instances for this course.

     *

     * @param bool $onlyenabled Whether to return data from enabled enrolment instance names only.

     * @return array

     */

    public function get_enrolment_instances($onlyenabled = false) {

        if ($this->_instances === null) {

            $this->_instances = enrol_get_instances($this->course->id, $onlyenabled);

        }

        return $this->_instances;

    }

    /**

     * Returns the names for all of the enrolment instances for this course.

     *

     * @param bool $onlyenabled Whether to return data from enabled enrolment instance names only.

     * @return array

     */

    public function get_enrolment_instance_names($onlyenabled = false) {

        if ($this->_inames === null) {

            $instances = $this->get_enrolment_instances($onlyenabled);

            $plugins = $this->get_enrolment_plugins(false);

            foreach ($instances as $key=>$instance) {

                if (!isset($plugins[$instance->enrol])) {

                    // weird, some broken stuff in plugin

                    unset($instances[$key]);

                    continue;

                }

                $this->_inames[$key] = $plugins[$instance->enrol]->get_instance_name($instance);

            }

        }

        return $this->_inames;

    }

    /**

     * Gets all of the enrolment plugins that are available for this course.

     *

     * @param bool $onlyenabled return only enabled enrol plugins

     * @return array

     */

    public function get_enrolment_plugins($onlyenabled = true) {

        if ($this->_plugins === null) {

            $this->_plugins = enrol_get_plugins(true);

        }

        if ($onlyenabled) {

            return $this->_plugins;

        }

        if ($this->_allplugins === null) {

            // Make sure we have the same objects in _allplugins and _plugins.

            $this->_allplugins = $this->_plugins;

            foreach (enrol_get_plugins(false) as $name=>$plugin) {

                if (!isset($this->_allplugins[$name])) {

                    $this->_allplugins[$name] = $plugin;

                }

            }

        }

        return $this->_allplugins;

    }

    /**

     * Gets all of the roles this course can contain.

     *

     * @return array

     */

    public function get_all_roles() {

        if ($this->_roles === null) {

            $this->_roles = role_fix_names(get_all_roles($this->context), $this->context);

        }

        return $this->_roles;

    }

    /**

     * Gets all of the roles this course can contain.

     *

     * @return array

     */

    public function get_viewable_roles() {

        if ($this->_visibleroles === null) {

            $this->_visibleroles = get_viewable_roles($this->context);

        }

        return $this->_visibleroles;

    }

    /**

     * Gets all of the assignable roles for this course.

     *

     * @return array

     */

    public function get_assignable_roles($otherusers = false) {

        if ($this->_assignableroles === null) {

            $this->_assignableroles = get_assignable_roles($this->context, ROLENAME_ALIAS, false); // verifies unassign access control too

        }

        if ($otherusers) {

            if (!is_array($this->_assignablerolesothers)) {

                $this->_assignablerolesothers = array();

                list($courseviewroles, $ignored) = get_roles_with_cap_in_context($this->context, 'moodle/course:view');

                foreach ($this->_assignableroles as $roleid=>$role) {

                    if (isset($courseviewroles[$roleid])) {

                        $this->_assignablerolesothers[$roleid] = $role;

                    }

                }

            }

            return $this->_assignablerolesothers;

        } else {

            return $this->_assignableroles;

        }

    }

    /**

     * Gets all of the assignable roles for this course, wrapped in an array to ensure

     * role sort order is not lost during json deserialisation.

     *

     * @param boolean $otherusers whether to include the assignable roles for other users

     * @return array

     */

    public function get_assignable_roles_for_json($otherusers = false) {

        $rolesarray = array();

        $assignable = $this->get_assignable_roles($otherusers);

        foreach ($assignable as $id => $role) {

            $rolesarray[] = array('id' => $id, 'name' => $role);

        }

        return $rolesarray;

    }

    /**

     * Gets all of the groups for this course.

     *

     * @return array

     */

    public function get_all_groups() {

        if ($this->_groups === null) {

            $this->_groups = groups_get_all_groups($this->course->id);

            foreach ($this->_groups as $gid=>$group) {

                $this->_groups[$gid]->name = format_string($group->name);

            }

        }

        return $this->_groups;

    }

    /**

     * Unenrols a user from the course given the users ue entry

     *

     * @global moodle_database $DB

     * @param stdClass $ue

     * @return bool

     */

    public function unenrol_user($ue) {

        global $DB;

        list ($instance, $plugin) = $this->get_user_enrolment_components($ue);

        if ($instance && $plugin && $plugin->allow_unenrol_user($instance, $ue) && has_capability("enrol/$instance->enrol:unenrol", $this->context)) {

            $plugin->unenrol_user($instance, $ue->userid);

            return true;

        }

        return false;

    }

    /**

     * Given a user enrolment record this method returns the plugin and enrolment

     * instance that relate to it.

     *

     * @param stdClass|int $userenrolment

     * @return array array($instance, $plugin)

     */

    public function get_user_enrolment_components($userenrolment) {

        global $DB;

        if (is_numeric($userenrolment)) {

            $userenrolment = $DB->get_record('user_enrolments', array('id'=>(int)$userenrolment));

        }

        $instances = $this->get_enrolment_instances();

        $plugins = $this->get_enrolment_plugins(false);

        if (!$userenrolment || !isset($instances[$userenrolment->enrolid])) {

            return array(false, false);

        }

        $instance = $instances[$userenrolment->enrolid];

        $plugin = $plugins[$instance->enrol];

        return array($instance, $plugin);

    }

    /**

     * Removes an assigned role from a user.

     *

     * @global moodle_database $DB

     * @param int $userid

     * @param int $roleid

     * @return bool

     */

    public function unassign_role_from_user($userid, $roleid) {

        global $DB;

        // Admins may unassign any role, others only those they could assign.

        if (!is_siteadmin() and !array_key_exists($roleid, $this->get_assignable_roles())) {

            if (defined('AJAX_SCRIPT')) {

                throw new moodle_exception('invalidrole');

            }

            return false;

        }

        $user = $DB->get_record('user', array('id'=>$userid), '*', MUST_EXIST);

        $ras = $DB->get_records('role_assignments', array('contextid'=>$this->context->id, 'userid'=>$user->id, 'roleid'=>$roleid));

        foreach ($ras as $ra) {

            if ($ra->component) {

                if (strpos($ra->component, 'enrol_') !== 0) {

                    continue;

                }

                if (!$plugin = enrol_get_plugin(substr($ra->component, 6))) {

                    continue;

                }

                if ($plugin->roles_protected()) {

                    continue;

                }

            }

            role_unassign($ra->roleid, $ra->userid, $ra->contextid, $ra->component, $ra->itemid);

        }

        return true;

    }

    /**

     * Assigns a role to a user.

     *

     * @param int $roleid

     * @param int $userid

     * @return int|false

     */

    public function assign_role_to_user($roleid, $userid) {

        require_capability('moodle/role:assign', $this->context);

        if (!array_key_exists($roleid, $this->get_assignable_roles())) {

            if (defined('AJAX_SCRIPT')) {

                throw new moodle_exception('invalidrole');

            }

            return false;

        }

        return role_assign($roleid, $userid, $this->context->id, '', NULL);

    }

    /**

     * Adds a user to a group

     *

     * @param stdClass $user

     * @param int $groupid

     * @return bool

     */

    public function add_user_to_group($user, $groupid) {

        require_capability('moodle/course:managegroups', $this->context);

        $group = $this->get_group($groupid);

        if (!$group) {

            return false;

        }

        return groups_add_member($group->id, $user->id);

    }

    /**

     * Removes a user from a group

     *

     * @global moodle_database $DB

     * @param StdClass $user

     * @param int $groupid

     * @return bool

     */

    public function remove_user_from_group($user, $groupid) {

        global $DB;

        require_capability('moodle/course:managegroups', $this->context);

        $group = $this->get_group($groupid);

        if (!groups_remove_member_allowed($group, $user)) {

            return false;

        }

        if (!$group) {

            return false;

        }

        return groups_remove_member($group, $user);

    }

    /**

     * Gets the requested group

     *

     * @param int $groupid

     * @return stdClass|int

     */

    public function get_group($groupid) {

        $groups = $this->get_all_groups();

        if (!array_key_exists($groupid, $groups)) {

            return false;

        }

        return $groups[$groupid];

    }

    /**

     * Edits an enrolment

     *

     * @param stdClass $userenrolment

     * @param stdClass $data

     * @return bool

     */

    public function edit_enrolment($userenrolment, $data) {

        //Only allow editing if the user has the appropriate capability

        //Already checked in /user/index.php but checking again in case this function is called from elsewhere

        list($instance, $plugin) = $this->get_user_enrolment_components($userenrolment);

        if ($instance && $plugin && $plugin->allow_manage($instance) && has_capability("enrol/$instance->enrol:manage", $this->context)) {

            if (!isset($data->status)) {

                $data->status = $userenrolment->status;

            }

            $plugin->update_user_enrol($instance, $userenrolment->userid, $data->status, $data->timestart, $data->timeend);

            return true;

        }

        return false;

    }

    /**

     * Returns the current enrolment filter that is being applied by this class

     * @return string

     */

    public function get_enrolment_filter() {

        return $this->instancefilter;

    }

    /**

     * Gets the roles assigned to this user that are applicable for this course.

     *

     * @param int $userid

     * @return array

     */

    public function get_user_roles($userid) {

        $roles = array();

        $ras = get_user_roles($this->context, $userid, true, 'c.contextlevel DESC, r.sortorder ASC');

        $plugins = $this->get_enrolment_plugins(false);

        foreach ($ras as $ra) {

            if ($ra->contextid != $this->context->id) {

                if (!array_key_exists($ra->roleid, $roles)) {

                    $roles[$ra->roleid] = null;

                }

                // higher ras, course always takes precedence

                continue;

            }

            if (array_key_exists($ra->roleid, $roles) && $roles[$ra->roleid] === false) {

                continue;

            }

            $changeable = true;

            if ($ra->component) {

                $changeable = false;

                if (strpos($ra->component, 'enrol_') === 0) {

                    $plugin = substr($ra->component, 6);

                    if (isset($plugins[$plugin])) {

                        $changeable = !$plugins[$plugin]->roles_protected();

                    }

                }

            }

            $roles[$ra->roleid] = $changeable;

        }

        return $roles;

    }