<?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/>.

/**
 * Local stuff for cohort enrolment plugin.
 *
 * @package    enrol
 * @subpackage cohort
 * @copyright  2010 Petr Skoda {@link http://skodak.org}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

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

/**
 * Event handler for cohort enrolment plugin.
 *
 * We try to keep everything in sync via listening to events,
 * it may fail sometimes, so we always do a full sync in cron too.
 */
class enrol_cohort_handler {
    public function member_added($ca) {
        global $DB;

        if (!enrol_is_enabled('cohort')) {
            return true;
        }

        // does anything want to sync with this parent?
        //TODO: add join to role table to make sure that roleid actually exists
        if (!$enrols = $DB->get_records('enrol', array('customint1'=>$ca->cohortid, 'enrol'=>'cohort'), 'id ASC')) {
            return true;
        }

        $plugin = enrol_get_plugin('cohort');
        foreach ($enrols as $enrol) {
            // no problem if already enrolled
            $plugin->enrol_user($enrol, $ca->userid, $enrol->roleid);
        }

        return true;
    }

    public function member_removed($ca) {
        global $DB;

        // does anything want to sync with this parent?
        if (!$enrols = $DB->get_records('enrol', array('customint1'=>$ca->cohortid, 'enrol'=>'cohort'), 'id ASC')) {
            return true;
        }

        $plugin = enrol_get_plugin('cohort');
        foreach ($enrols as $enrol) {
            // no problem if already enrolled
            $plugin->unenrol_user($enrol, $ca->userid);
        }

        return true;
    }

    public function deleted($cohort) {
        global $DB;

        // does anything want to sync with this parent?
        if (!$enrols = $DB->get_records('enrol', array('customint1'=>$cohort->id, 'enrol'=>'cohort'), 'id ASC')) {
            return true;
        }

        $plugin = enrol_get_plugin('cohort');
        foreach ($enrols as $enrol) {
            $plugin->delete_instance($enrol);
        }

        return true;
    }
}

/**
 * Sync all cohort course links.
 * @param int $courseid one course, empty mean all
 * @return void
 */
function enrol_cohort_sync($courseid = NULL) {
    global $CFG, $DB;

    // unfortunately this may take a long time
    @set_time_limit(0); //if this fails during upgrade we can continue from cron, no big deal

    $cohort = enrol_get_plugin('cohort');

    $onecourse = $courseid ? "AND e.courseid = :courseid" : "";

    // iterate through all not enrolled yet users
    if (enrol_is_enabled('cohort')) {
        $params = array();
        $onecourse = "";
        if ($courseid) {
            $params['courseid'] = $courseid;
            $onecourse = "AND e.courseid = :courseid";
        }
        $sql = "SELECT cm.userid, e.id AS enrolid
                  FROM {cohort_members} cm
                  JOIN {enrol} e ON (e.customint1 = cm.cohortid AND e.status = :statusenabled AND e.enrol = 'cohort' $onecourse)
             LEFT JOIN {user_enrolments} ue ON (ue.enrolid = e.id AND ue.userid = cm.userid)
                 WHERE ue.id IS NULL";
        $params['statusenabled'] = ENROL_INSTANCE_ENABLED;
        $params['courseid'] = $courseid;
        $rs = $DB->get_recordset_sql($sql, $params);
        $instances = array(); //cache
        foreach($rs as $ue) {
            if (!isset($instances[$ue->enrolid])) {
                $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
            }
            $cohort->enrol_user($instances[$ue->enrolid], $ue->userid);
        }
        $rs->close();
        unset($instances);
    }

    // unenrol as necessary - ignore enabled flag, we want to get rid of all
    $sql = "SELECT ue.userid, e.id AS enrolid
              FROM {user_enrolments} ue
              JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'cohort' $onecourse)
         LEFT JOIN {cohort_members} cm ON (cm.cohortid  = e.customint1 AND cm.userid = ue.userid)
             WHERE cm.id IS NULL";
    //TODO: this may use a bit of SQL optimisation
    $rs = $DB->get_recordset_sql($sql, array('courseid'=>$courseid));
    $instances = array(); //cache
    foreach($rs as $ue) {
        if (!isset($instances[$ue->enrolid])) {
            $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
        }
        $cohort->unenrol_user($instances[$ue->enrolid], $ue->userid);
    }
    $rs->close();
    unset($instances);

    // now assign all necessary roles
    if (enrol_is_enabled('cohort')) {
        $sql = "SELECT e.roleid, ue.userid, c.id AS contextid, e.id AS itemid
                  FROM {user_enrolments} ue
                  JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'cohort' AND e.status = :statusenabled $onecourse)
                  JOIN {context} c ON (c.instanceid = e.courseid AND c.contextlevel = :coursecontext)
             LEFT JOIN {role_assignments} ra ON (ra.contextid = c.id AND ra.userid = ue.userid AND ra.itemid = e.id AND ra.component = 'enrol_cohort' AND e.roleid = ra.roleid)
                 WHERE ra.id IS NULL";
        $params = array();
        $params['statusenabled'] = ENROL_INSTANCE_ENABLED;
        $params['coursecontext'] = CONTEXT_COURSE;
        $params['courseid'] = $courseid;

        $rs = $DB->get_recordset_sql($sql, $params);
        foreach($rs as $ra) {
            role_assign($ra->roleid, $ra->userid, $ra->contextid, 'enrol_cohort', $ra->itemid);
        }
        $rs->close();
    }

    // remove unwanted roles - include ignored roles and disabled plugins too
    $onecourse = $courseid ? "AND c.instanceid = :courseid" : "";
    $sql = "SELECT ra.roleid, ra.userid, ra.contextid, ra.itemid
              FROM {role_assignments} ra
              JOIN {context} c ON (c.id = ra.contextid AND c.contextlevel = :coursecontext $onecourse)
         LEFT JOIN (SELECT e.id AS enrolid, e.roleid, ue.userid
                      FROM {user_enrolments} ue
                      JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'cohort')
                   ) x ON (x.enrolid = ra.itemid AND ra.component = 'enrol_cohort' AND x.roleid = ra.roleid AND x.userid = ra.userid)
             WHERE x.userid IS NULL AND ra.component = 'enrol_cohort'";
    $params = array('coursecontext' => CONTEXT_COURSE, 'courseid' => $courseid);

    $rs = $DB->get_recordset_sql($sql, $params);
    foreach($rs as $ra) {
        role_unassign($ra->roleid, $ra->userid, $ra->contextid, 'enrol_cohort', $ra->itemid);
    }
    $rs->close();

}