<?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();

require_once($CFG->dirroot . '/enrol/locallib.php');


/**
 * 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 {
    /**
     * Event processor - cohort member added
     * @param stdClass $ca
     * @return bool
     */
    public function member_added($ca) {
        global $DB;

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

        // does any enabled cohort instance want to sync with this cohort?
        $sql = "SELECT e.*, r.id as roleexists
                  FROM {enrol} e
             LEFT JOIN {role} r ON (r.id = e.roleid)
                 WHERE customint1 = :cohortid AND enrol = 'cohort'
              ORDER BY id ASC";
        if (!$instances = $DB->get_records_sql($sql, array('cohortid'=>$ca->cohortid))) {
            return true;
        }

        $plugin = enrol_get_plugin('cohort');
        foreach ($instances as $instance) {
            if ($instance->status != ENROL_INSTANCE_ENABLED ) {
                // no roles for disabled instances
                $instance->roleid = 0;
            } else if ($instance->roleid and !$instance->roleexists) {
                // invalid role - let's just enrol, they will have to create new sync and delete this one
                $instance->roleid = 0;
            }
            unset($instance->roleexists);
            // no problem if already enrolled
            $plugin->enrol_user($instance, $ca->userid, $instance->roleid, 0, 0, ENROL_USER_ACTIVE);
        }

        return true;
    }

    /**
     * Event processor - cohort member removed
     * @param stdClass $ca
     * @return bool
     */
    public function member_removed($ca) {
        global $DB;

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

        $plugin = enrol_get_plugin('cohort');
        $unenrolaction = $plugin->get_config('unenrolaction', ENROL_EXT_REMOVED_UNENROL);

        foreach ($instances as $instance) {
            if (!$ue = $DB->get_record('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$ca->userid))) {
                continue;
            }
            if ($unenrolaction == ENROL_EXT_REMOVED_UNENROL) {
                $plugin->unenrol_user($instance, $ca->userid);

            } else {
                if ($ue->status != ENROL_USER_SUSPENDED) {
                    $plugin->update_user_enrol($instance, $ue->userid, ENROL_USER_SUSPENDED);
                    $context = context_course::instance($instance->courseid);
                    role_unassign_all(array('userid'=>$ue->userid, 'contextid'=>$context->id, 'component'=>'enrol_cohort', 'itemid'=>$instance->id));
                }
            }
        }

        return true;
    }

    /**
     * Event processor - cohort deleted
     * @param stdClass $cohort
     * @return bool
     */
    public function deleted($cohort) {
        global $DB;

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

        $plugin = enrol_get_plugin('cohort');
        $unenrolaction = $plugin->get_config('unenrolaction', ENROL_EXT_REMOVED_UNENROL);

        foreach ($instances as $instance) {
            if ($unenrolaction == ENROL_EXT_REMOVED_SUSPENDNOROLES) {
                $context = context_course::instance($instance->courseid);
                role_unassign_all(array('contextid'=>$context->id, 'component'=>'enrol_cohort', 'itemid'=>$instance->id));
                $plugin->update_status($instance, ENROL_INSTANCE_DISABLED);
            } else {
                $plugin->delete_instance($instance);
            }
        }

        return true;
    }
}


/**
 * Sync all cohort course links.
 * @param int $courseid one course, empty mean all
 * @param bool $verbose verbose CLI output
 * @return int 0 means ok, 1 means error, 2 means plugin disabled
 */
function enrol_cohort_sync($courseid = NULL, $verbose = false) {
    global $CFG, $DB;

    // purge all roles if cohort sync disabled, those can be recreated later here by cron or CLI
    if (!enrol_is_enabled('cohort')) {
        if ($verbose) {
            mtrace('Cohort sync plugin is disabled, unassigning all plugin roles and stopping.');
        }
        role_unassign_all(array('component'=>'enrol_cohort'));
        return 2;
    }

    // unfortunately this may take a long time, this script can be interrupted without problems
    @set_time_limit(0);
    raise_memory_limit(MEMORY_HUGE);

    if ($verbose) {
        mtrace('Starting user enrolment synchronisation...');
    }

    $allroles = get_all_roles();
    $instances = array(); //cache

    $plugin = enrol_get_plugin('cohort');
    $unenrolaction = $plugin->get_config('unenrolaction', ENROL_EXT_REMOVED_UNENROL);


    // iterate through all not enrolled yet users
    $onecourse = $courseid ? "AND e.courseid = :courseid" : "";
    $sql = "SELECT cm.userid, e.id AS enrolid, ue.status
              FROM {cohort_members} cm
              JOIN {enrol} e ON (e.customint1 = cm.cohortid 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 OR ue.status = :suspended";
    $params = array();
    $params['courseid'] = $courseid;
    $params['suspended'] = ENROL_USER_SUSPENDED;
    $rs = $DB->get_recordset_sql($sql, $params);
    foreach($rs as $ue) {
        if (!isset($instances[$ue->enrolid])) {
            $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
        }
        $instance = $instances[$ue->enrolid];
        if ($ue->status == ENROL_USER_SUSPENDED) {
            $plugin->update_user_enrol($instance, $ue->userid, ENROL_USER_ACTIVE);
            if ($verbose) {
                mtrace("  unsuspending: $ue->userid ==> $instance->courseid via cohort $instance->customint1");
            }
        } else {
            $plugin->enrol_user($instance, $ue->userid);
            if ($verbose) {
                mtrace("  enrolling: $ue->userid ==> $instance->courseid via cohort $instance->customint1");
            }
        }
    }
    $rs->close();


    // unenrol as necessary
    $sql = "SELECT ue.*, e.courseid
              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";
    $rs = $DB->get_recordset_sql($sql, array('courseid'=>$courseid));
    foreach($rs as $ue) {
        if (!isset($instances[$ue->enrolid])) {
            $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
        }
        $instance = $instances[$ue->enrolid];
        if ($unenrolaction == ENROL_EXT_REMOVED_UNENROL) {
            // remove enrolment together with group membership, grades, preferences, etc.
            $plugin->unenrol_user($instance, $ue->userid);
            if ($verbose) {
                mtrace("  unenrolling: $ue->userid ==> $instance->courseid via cohort $instance->customint1");
            }

        } else { // ENROL_EXT_REMOVED_SUSPENDNOROLES
            // just disable and ignore any changes
            if ($ue->status != ENROL_USER_SUSPENDED) {
                $plugin->update_user_enrol($instance, $ue->userid, ENROL_USER_SUSPENDED);
                $context = context_course::instance($instance->courseid);
                role_unassign_all(array('userid'=>$ue->userid, 'contextid'=>$context->id, 'component'=>'enrol_cohort', 'itemid'=>$instance->id));
                if ($verbose) {
                    mtrace("  suspending and unsassigning all roles: $ue->userid ==> $instance->courseid");
                }
            }
        }
    }
    $rs->close();
    unset($instances);


    // now assign all necessary roles to enrolled users - skip suspended instances and users
    $onecourse = $courseid ? "AND e.courseid = :courseid" : "";
    $sql = "SELECT e.roleid, ue.userid, c.id AS contextid, e.id AS itemid, e.courseid
              FROM {user_enrolments} ue
              JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'cohort' AND e.status = :statusenabled $onecourse)
              JOIN {role} r ON (r.id = e.roleid)
              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 ue.status = :useractive AND ra.id IS NULL";
    $params = array();
    $params['statusenabled'] = ENROL_INSTANCE_ENABLED;
    $params['useractive'] = ENROL_USER_ACTIVE;
    $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', $ra->itemid);
        if ($verbose) {
            mtrace("  assigning role: $ra->userid ==> $ra->courseid as ".$allroles[$ra->roleid]->shortname);
        }
    }
    $rs->close();


    // remove unwanted roles - sync role can not be changed, we only remove role when unenrolled
    $onecourse = $courseid ? "AND e.courseid = :courseid" : "";
    $sql = "SELECT ra.roleid, ra.userid, ra.contextid, ra.itemid, e.courseid
              FROM {role_assignments} ra
              JOIN {context} c ON (c.id = ra.contextid AND c.contextlevel = :coursecontext)
              JOIN {enrol} e ON (e.id = ra.itemid AND e.enrol = 'cohort' $onecourse)
         LEFT JOIN {user_enrolments} ue ON (ue.enrolid = e.id AND ue.userid = ra.userid AND ue.status = :useractive)
             WHERE ra.component = 'enrol_cohort' AND (ue.id IS NULL OR e.status <> :statusenabled)";
    $params = array();
    $params['statusenabled'] = ENROL_INSTANCE_ENABLED;
    $params['useractive'] = ENROL_USER_ACTIVE;
    $params['coursecontext'] = CONTEXT_COURSE;
    $params['courseid'] = $courseid;

    $rs = $DB->get_recordset_sql($sql, $params);
    foreach($rs as $ra) {
        role_unassign($ra->roleid, $ra->userid, $ra->contextid, 'enrol_cohort', $ra->itemid);
        if ($verbose) {
            mtrace("  unassigning role: $ra->userid ==> $ra->courseid as ".$allroles[$ra->roleid]->shortname);
        }
    }
    $rs->close();


    if ($verbose) {
        mtrace('...user enrolment synchronisation finished.');
    }

    return 0;
}

/**
 * Enrols all of the users in a cohort through a manual plugin instance.
 *
 * In order for this to succeed the course must contain a valid manual
 * enrolment plugin instance that the user has permission to enrol users through.
 *
 * @global moodle_database $DB
 * @param course_enrolment_manager $manager
 * @param int $cohortid
 * @param int $roleid
 * @return int
 */
function enrol_cohort_enrol_all_users(course_enrolment_manager $manager, $cohortid, $roleid) {
    global $DB;
    $context = $manager->get_context();
    require_capability('moodle/course:enrolconfig', $context);

    $instance = false;
    $instances = $manager->get_enrolment_instances();
    foreach ($instances as $i) {
        if ($i->enrol == 'manual') {
            $instance = $i;
            break;
        }
    }
    $plugin = enrol_get_plugin('manual');
    if (!$instance || !$plugin || !$plugin->allow_enrol($instance) || !has_capability('enrol/'.$plugin->get_name().':enrol', $context)) {
        return false;
    }
    $sql = "SELECT com.userid
              FROM {cohort_members} com
         LEFT JOIN (
                SELECT *
                FROM {user_enrolments} ue
                WHERE ue.enrolid = :enrolid
                 ) ue ON ue.userid=com.userid
             WHERE com.cohortid = :cohortid AND ue.id IS NULL";
    $params = array('cohortid' => $cohortid, 'enrolid' => $instance->id);
    $rs = $DB->get_recordset_sql($sql, $params);
    $count = 0;
    foreach ($rs as $user) {
        $count++;
        $plugin->enrol_user($instance, $user->userid, $roleid);
    }
    $rs->close();
    return $count;
}

/**
 * Gets all the cohorts the user is able to view.
 *
 * @global moodle_database $DB
 * @param course_enrolment_manager $manager
 * @return array
 */
function enrol_cohort_get_cohorts(course_enrolment_manager $manager) {
    global $DB;
    $context = $manager->get_context();
    $cohorts = array();
    $instances = $manager->get_enrolment_instances();
    $enrolled = array();
    foreach ($instances as $instance) {
        if ($instance->enrol == 'cohort') {
            $enrolled[] = $instance->customint1;
        }
    }
    list($sqlparents, $params) = $DB->get_in_or_equal(get_parent_contexts($context));
    $sql = "SELECT id, name, contextid
              FROM {cohort}
             WHERE contextid $sqlparents
          ORDER BY name ASC";
    $rs = $DB->get_recordset_sql($sql, $params);
    foreach ($rs as $c) {
        $context = get_context_instance_by_id($c->contextid);
        if (!has_capability('moodle/cohort:view', $context)) {
            continue;
        }
        $cohorts[$c->id] = array(
            'cohortid'=>$c->id,
            'name'=>format_string($c->name),
            'users'=>$DB->count_records('cohort_members', array('cohortid'=>$c->id)),
            'enrolled'=>in_array($c->id, $enrolled)
        );
    }
    $rs->close();
    return $cohorts;
}

/**
 * Check if cohort exists and user is allowed to enrol it
 *
 * @global moodle_database $DB
 * @param int $cohortid Cohort ID
 * @return boolean
 */
function enrol_cohort_can_view_cohort($cohortid) {
    global $DB;
    $cohort = $DB->get_record('cohort', array('id' => $cohortid), 'id, contextid');
    if ($cohort) {
        $context = get_context_instance_by_id($cohort->contextid);
        if (has_capability('moodle/cohort:view', $context)) {
            return true;
        }
    }
    return false;
}

/**
 * Gets cohorts the user is able to view.
 *
 * @global moodle_database $DB
 * @param course_enrolment_manager $manager
 * @param int $offset limit output from
 * @param int $limit items to output per load
 * @param string $search search string
 * @return array    Array(more => bool, offset => int, cohorts => array)
 */
function enrol_cohort_search_cohorts(course_enrolment_manager $manager, $offset = 0, $limit = 25, $search = '') {
    global $DB;
    $context = $manager->get_context();
    $cohorts = array();
    $instances = $manager->get_enrolment_instances();
    $enrolled = array();
    foreach ($instances as $instance) {
        if ($instance->enrol == 'cohort') {
            $enrolled[] = $instance->customint1;
        }
    }

    list($sqlparents, $params) = $DB->get_in_or_equal(get_parent_contexts($context));

    // Add some additional sensible conditions
    $tests = array('contextid ' . $sqlparents);

    // Modify the query to perform the search if required
    if (!empty($search)) {
        $conditions = array(
            'name',
            'idnumber',
            'description'
        );
        $searchparam = '%' . $search . '%';
        foreach ($conditions as $key=>$condition) {
            $conditions[$key] = $DB->sql_like($condition,"?", false);
            $params[] = $searchparam;
        }
        $tests[] = '(' . implode(' OR ', $conditions) . ')';
    }
    $wherecondition = implode(' AND ', $tests);

    $fields = 'SELECT id, name, contextid, description';
    $countfields = 'SELECT COUNT(1)';
    $sql = " FROM {cohort}
             WHERE $wherecondition";
    $order = ' ORDER BY name ASC';
    $rs = $DB->get_recordset_sql($fields . $sql . $order, $params, $offset);

    // Produce the output respecting parameters
    foreach ($rs as $c) {
        // Track offset
        $offset++;
        // Check capabilities
        $context = get_context_instance_by_id($c->contextid);
        if (!has_capability('moodle/cohort:view', $context)) {
            continue;
        }
        if ($limit === 0) {
            // we have reached the required number of items and know that there are more, exit now
            $offset--;
            break;
        }
        $cohorts[$c->id] = array(
            'cohortid'=>$c->id,
            'name'=>  shorten_text(format_string($c->name), 35),
            'users'=>$DB->count_records('cohort_members', array('cohortid'=>$c->id)),
            'enrolled'=>in_array($c->id, $enrolled)
        );
        // Count items
        $limit--;
    }
    $rs->close();
    return array('more' => !(bool)$limit, 'offset' => $offset, 'cohorts' => $cohorts);
}