/**
 * Removes all grades from gradebook
 *
 * @global stdClass
 * @global object
 * @param int $courseid
 * @param string optional type
 */
function lesson_reset_gradebook($courseid, $type = '')
{
    global $CFG, $DB;
    $sql = "SELECT l.*, cm.idnumber as cmidnumber, l.course as courseid\n              FROM {lesson} l, {course_modules} cm, {modules} m\n             WHERE m.name='lesson' AND m.id=cm.module AND cm.instance=l.id AND l.course=:course";
    $params = array("course" => $courseid);
    if ($lessons = $DB->get_records_sql($sql, $params)) {
        foreach ($lessons as $lesson) {
            lesson_grade_item_update($lesson, 'reset');
        }
    }
}

/**
 * Update grades in central gradebook
 *
 * @param object $lesson null means all lessons
 * @param int $userid specific user only, 0 mean all
 */
function lesson_update_grades($lesson = null, $userid = 0, $nullifnone = true)
{
    global $CFG;
    if (!function_exists('grade_update')) {
        //workaround for buggy PHP versions
        require_once $CFG->libdir . '/gradelib.php';
    }
    if ($lesson != null) {
        if ($grades = lesson_get_user_grades($lesson, $userid)) {
            grade_update('mod/lesson', $lesson->course, 'mod', 'lesson', $lesson->id, 0, $grades);
        } else {
            if ($userid and $nullifnone) {
                $grade = new object();
                $grade->userid = $userid;
                $grade->rawgrade = NULL;
                grade_update('mod/lesson', $lesson->course, 'mod', 'lesson', $lesson->id, 0, $grade);
            }
        }
    } else {
        $sql = "SELECT l.*, cm.idnumber as cmidnumber, l.course as courseid\n                  FROM {$CFG->prefix}lesson l, {$CFG->prefix}course_modules cm, {$CFG->prefix}modules m\n                 WHERE m.name='lesson' AND m.id=cm.module AND cm.instance=l.id";
        if ($rs = get_recordset_sql($sql)) {
            if ($rs->RecordCount() > 0) {
                while ($lesson = rs_fetch_next_record($rs)) {
                    lesson_grade_item_update($lesson);
                    if ($lesson->grade != 0) {
                        lesson_update_grades($lesson, 0, false);
                    }
                }
            }
            rs_close($rs);
        }
    }
}