/**
 * Clear a course out completely, deleting all content
 * but don't delete the course itself.
 * This function does not verify any permissions.
 *
 * Please note this function also deletes all user enrolments,
 * enrolment instances and role assignments by default.
 *
 * $options:
 *  - 'keep_roles_and_enrolments' - false by default
 *  - 'keep_groups_and_groupings' - false by default
 *
 * @param int $courseid The id of the course that is being deleted
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @param array $options extra options
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function remove_course_contents($courseid, $showfeedback = true, array $options = null)
{
    global $CFG, $DB, $OUTPUT;
    require_once $CFG->libdir . '/badgeslib.php';
    require_once $CFG->libdir . '/completionlib.php';
    require_once $CFG->libdir . '/questionlib.php';
    require_once $CFG->libdir . '/gradelib.php';
    require_once $CFG->dirroot . '/group/lib.php';
    require_once $CFG->dirroot . '/tag/coursetagslib.php';
    require_once $CFG->dirroot . '/comment/lib.php';
    require_once $CFG->dirroot . '/rating/lib.php';
    require_once $CFG->dirroot . '/notes/lib.php';
    // Handle course badges.
    badges_handle_course_deletion($courseid);
    // NOTE: these concatenated strings are suboptimal, but it is just extra info...
    $strdeleted = get_string('deleted') . ' - ';
    // Some crazy wishlist of stuff we should skip during purging of course content
    $options = (array) $options;
    $course = $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
    $coursecontext = context_course::instance($courseid);
    $fs = get_file_storage();
    // Delete course completion information, this has to be done before grades and enrols
    $cc = new completion_info($course);
    $cc->clear_criteria();
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('completion', 'completion'), 'notifysuccess');
    }
    // Remove all data from gradebook - this needs to be done before course modules
    // because while deleting this information, the system may need to reference
    // the course modules that own the grades.
    remove_course_grades($courseid, $showfeedback);
    remove_grade_letters($coursecontext, $showfeedback);
    // Delete course blocks in any all child contexts,
    // they may depend on modules so delete them first
    $childcontexts = $coursecontext->get_child_contexts();
    // returns all subcontexts since 2.2
    foreach ($childcontexts as $childcontext) {
        blocks_delete_all_for_context($childcontext->id);
    }
    unset($childcontexts);
    blocks_delete_all_for_context($coursecontext->id);
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('type_block_plural', 'plugin'), 'notifysuccess');
    }
    // Delete every instance of every module,
    // this has to be done before deleting of course level stuff
    $locations = get_plugin_list('mod');
    foreach ($locations as $modname => $moddir) {
        if ($modname === 'NEWMODULE') {
            continue;
        }
        if ($module = $DB->get_record('modules', array('name' => $modname))) {
            include_once "{$moddir}/lib.php";
            // Shows php warning only if plugin defective
            $moddelete = $modname . '_delete_instance';
            // Delete everything connected to an instance
            $moddeletecourse = $modname . '_delete_course';
            // Delete other stray stuff (uncommon)
            if ($instances = $DB->get_records($modname, array('course' => $course->id))) {
                foreach ($instances as $instance) {
                    if ($cm = get_coursemodule_from_instance($modname, $instance->id, $course->id)) {
                        /// Delete activity context questions and question categories
                        question_delete_activity($cm, $showfeedback);
                    }
                    if (function_exists($moddelete)) {
                        // This purges all module data in related tables, extra user prefs, settings, etc.
                        $moddelete($instance->id);
                    } else {
                        // NOTE: we should not allow installation of modules with missing delete support!
                        debugging("Defective module '{$modname}' detected when deleting course contents: missing function {$moddelete}()!");
                        $DB->delete_records($modname, array('id' => $instance->id));
                    }
                    if ($cm) {
                        // Delete cm and its context - orphaned contexts are purged in cron in case of any race condition
                        context_helper::delete_instance(CONTEXT_MODULE, $cm->id);
                        $DB->delete_records('course_modules', array('id' => $cm->id));
                    }
                }
            }
            if (function_exists($moddeletecourse)) {
                // Execute ptional course cleanup callback
//.........这里部分代码省略.........

/**
 * Clear a course out completely, deleting all content but don't delete the course itself.
 *
 * This function does not verify any permissions.
 *
 * Please note this function also deletes all user enrolments,
 * enrolment instances and role assignments by default.
 *
 * $options:
 *  - 'keep_roles_and_enrolments' - false by default
 *  - 'keep_groups_and_groupings' - false by default
 *
 * @param int $courseid The id of the course that is being deleted
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @param array $options extra options
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function remove_course_contents($courseid, $showfeedback = true, array $options = null)
{
    global $CFG, $DB, $OUTPUT;
    require_once $CFG->libdir . '/badgeslib.php';
    require_once $CFG->libdir . '/completionlib.php';
    require_once $CFG->libdir . '/questionlib.php';
    require_once $CFG->libdir . '/gradelib.php';
    require_once $CFG->dirroot . '/group/lib.php';
    require_once $CFG->dirroot . '/comment/lib.php';
    require_once $CFG->dirroot . '/rating/lib.php';
    require_once $CFG->dirroot . '/notes/lib.php';
    // Handle course badges.
    badges_handle_course_deletion($courseid);
    // NOTE: these concatenated strings are suboptimal, but it is just extra info...
    $strdeleted = get_string('deleted') . ' - ';
    // Some crazy wishlist of stuff we should skip during purging of course content.
    $options = (array) $options;
    $course = $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
    $coursecontext = context_course::instance($courseid);
    $fs = get_file_storage();
    // Delete course completion information, this has to be done before grades and enrols.
    $cc = new completion_info($course);
    $cc->clear_criteria();
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('completion', 'completion'), 'notifysuccess');
    }
    // Remove all data from gradebook - this needs to be done before course modules
    // because while deleting this information, the system may need to reference
    // the course modules that own the grades.
    remove_course_grades($courseid, $showfeedback);
    remove_grade_letters($coursecontext, $showfeedback);
    // Delete course blocks in any all child contexts,
    // they may depend on modules so delete them first.
    $childcontexts = $coursecontext->get_child_contexts();
    // Returns all subcontexts since 2.2.
    foreach ($childcontexts as $childcontext) {
        blocks_delete_all_for_context($childcontext->id);
    }
    unset($childcontexts);
    blocks_delete_all_for_context($coursecontext->id);
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('type_block_plural', 'plugin'), 'notifysuccess');
    }
    // Get the list of all modules that are properly installed.
    $allmodules = $DB->get_records_menu('modules', array(), '', 'name, id');
    // Delete every instance of every module,
    // this has to be done before deleting of course level stuff.
    $locations = core_component::get_plugin_list('mod');
    foreach ($locations as $modname => $moddir) {
        if ($modname === 'NEWMODULE') {
            continue;
        }
        if (array_key_exists($modname, $allmodules)) {
            $sql = "SELECT cm.*, m.id AS modinstance, m.name, '{$modname}' AS modname\n              FROM {" . $modname . "} m\n                   LEFT JOIN {course_modules} cm ON cm.instance = m.id AND cm.module = :moduleid\n             WHERE m.course = :courseid";
            $instances = $DB->get_records_sql($sql, array('courseid' => $course->id, 'modulename' => $modname, 'moduleid' => $allmodules[$modname]));
            include_once "{$moddir}/lib.php";
            // Shows php warning only if plugin defective.
            $moddelete = $modname . '_delete_instance';
            // Delete everything connected to an instance.
            $moddeletecourse = $modname . '_delete_course';
            // Delete other stray stuff (uncommon).
            if ($instances) {
                foreach ($instances as $cm) {
                    if ($cm->id) {
                        // Delete activity context questions and question categories.
                        question_delete_activity($cm, $showfeedback);
                        // Notify the competency subsystem.
                        \core_competency\api::hook_course_module_deleted($cm);
                    }
                    if (function_exists($moddelete)) {
                        // This purges all module data in related tables, extra user prefs, settings, etc.
                        $moddelete($cm->modinstance);
                    } else {
                        // NOTE: we should not allow installation of modules with missing delete support!
                        debugging("Defective module '{$modname}' detected when deleting course contents: missing function {$moddelete}()!");
                        $DB->delete_records($modname, array('id' => $cm->modinstance));
                    }
                    if ($cm->id) {
                        // Delete cm and its context - orphaned contexts are purged in cron in case of any race condition.
                        context_helper::delete_instance(CONTEXT_MODULE, $cm->id);
                        $DB->delete_records('course_modules', array('id' => $cm->id));
//.........这里部分代码省略.........

/**
 * Delete a course, including all related data from the database,
 * and any associated files.
 *
 * @global object
 * @global object
 * @param mixed $courseorid The id of the course or course object to delete.
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function delete_course($courseorid, $showfeedback = true)
{
    global $DB;
    if (is_object($courseorid)) {
        $courseid = $courseorid->id;
        $course = $courseorid;
    } else {
        $courseid = $courseorid;
        if (!($course = $DB->get_record('course', array('id' => $courseid)))) {
            return false;
        }
    }
    $context = context_course::instance($courseid);
    // frontpage course can not be deleted!!
    if ($courseid == SITEID) {
        return false;
    }
    // Handle course badges.
    badges_handle_course_deletion($courseid);
    // make the course completely empty
    remove_course_contents($courseid, $showfeedback);
    // delete the course and related context instance
    delete_context(CONTEXT_COURSE, $courseid);
    // We will update the course's timemodified, as it will be passed to the course_deleted event,
    // which should know about this updated property, as this event is meant to pass the full course record
    $course->timemodified = time();
    $DB->delete_records("course", array("id" => $courseid));
    $DB->delete_records("course_format_options", array("courseid" => $courseid));
    //trigger events
    $course->context = $context;
    // you can not fetch context in the event because it was already deleted
    events_trigger('course_deleted', $course);
    return true;
}