/**
 * 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.
 *
 * @param int $courseid The id of the course that is being deleted
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function remove_course_contents($courseid, $showfeedback = true)
{
    global $CFG, $DB, $OUTPUT;
    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';
    $course = $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
    $context = get_context_instance(CONTEXT_COURSE, $courseid, MUST_EXIST);
    $strdeleted = get_string('deleted');
    // Delete course completion information,
    // this has to be done before grades and enrols
    $cc = new completion_info($course);
    $cc->clear_criteria();
    // remove roles and enrolments
    role_unassign_all(array('contextid' => $context->id), true);
    enrol_course_delete($course);
    // Clean up course formats (iterate through all formats in the even the course format was ever changed)
    $formats = get_plugin_list('format');
    foreach ($formats as $format => $formatdir) {
        $formatdelete = 'format_' . $format . '_delete_course';
        $formatlib = "{$formatdir}/lib.php";
        if (file_exists($formatlib)) {
            include_once $formatlib;
            if (function_exists($formatdelete)) {
                if ($showfeedback) {
                    echo $OUTPUT->notification($strdeleted . ' ' . $format);
                }
                $formatdelete($course->id);
            }
        }
    }
    // 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, $showfeedback);
    remove_grade_letters($context, $showfeedback);
    // Remove all data from availability and completion tables that is associated
    // with course-modules belonging to this course. Note this is done even if the
    // features are not enabled now, in case they were enabled previously
    $DB->delete_records_select('course_modules_completion', 'coursemoduleid IN (SELECT id from {course_modules} WHERE course=?)', array($courseid));
    $DB->delete_records_select('course_modules_availability', 'coursemoduleid IN (SELECT id from {course_modules} WHERE course=?)', array($courseid));
    // Delete course blocks - they may depend on modules so delete them first
    blocks_delete_all_for_context($context->id);
    // Delete every instance of every module
    if ($allmods = $DB->get_records('modules')) {
        foreach ($allmods as $mod) {
            $modname = $mod->name;
            $modfile = $CFG->dirroot . '/mod/' . $modname . '/lib.php';
            $moddelete = $modname . '_delete_instance';
            // Delete everything connected to an instance
            $moddeletecourse = $modname . '_delete_course';
            // Delete other stray stuff (uncommon)
            $count = 0;
            if (file_exists($modfile)) {
                include_once $modfile;
                if (function_exists($moddelete)) {
                    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, $showfeedback);
                            }
                            if ($moddelete($instance->id)) {
                                $count++;
                            } else {
                                echo $OUTPUT->notification('Could not delete ' . $modname . ' instance ' . $instance->id . ' (' . format_string($instance->name) . ')');
                            }
                            if ($cm) {
                                // delete cm and its context in correct order
                                delete_context(CONTEXT_MODULE, $cm->id);
                                // some callbacks may try to fetch context, better delete first
                                $DB->delete_records('course_modules', array('id' => $cm->id));
                            }
                        }
                    }
                } else {
                    //note: we should probably delete these anyway
                    echo $OUTPUT->notification('Function ' . $moddelete . '() doesn\'t exist!');
                }
                if (function_exists($moddeletecourse)) {
                    $moddeletecourse($course, $showfeedback);
                }
            }
            if ($showfeedback) {
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('type_mod_plural', 'plugin'), 'notifysuccess');
    }
    // Cleanup the rest of plugins. Deprecated since Moodle 3.2. TODO MDL-53297 remove in 3.6.
    $cleanuplugintypes = array('report', 'coursereport', 'format');
    $callbacks = get_plugins_with_function('delete_course', 'lib.php');
    foreach ($cleanuplugintypes as $type) {
        if (!empty($callbacks[$type])) {
            foreach ($callbacks[$type] as $pluginfunction) {
                debugging("Callback delete_course is deprecated. Function {$pluginfunction} should be converted " . 'to observer of event \\core\\event\\course_content_deleted', DEBUG_DEVELOPER);
                $pluginfunction($course->id, $showfeedback);
            }
            if ($showfeedback) {
                echo $OUTPUT->notification($strdeleted . get_string('type_' . $type . '_plural', 'plugin'), 'notifysuccess');
            }
        }
    }
    // Delete questions and question categories.
    question_delete_course($course, $showfeedback);
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('questions', 'question'), 'notifysuccess');
    }
    // Make sure there are no subcontexts left - all valid blocks and modules should be already gone.
    $childcontexts = $coursecontext->get_child_contexts();
    // Returns all subcontexts since 2.2.
    foreach ($childcontexts as $childcontext) {
        $childcontext->delete();
    }
    unset($childcontexts);
    // Remove all roles and enrolments by default.
    if (empty($options['keep_roles_and_enrolments'])) {
        // This hack is used in restore when deleting contents of existing course.
        role_unassign_all(array('contextid' => $coursecontext->id, 'component' => ''), true);
        enrol_course_delete($course);
        if ($showfeedback) {
            echo $OUTPUT->notification($strdeleted . get_string('type_enrol_plural', 'plugin'), 'notifysuccess');
        }
    }
    // Delete any groups, removing members and grouping/course links first.
    if (empty($options['keep_groups_and_groupings'])) {
        groups_delete_groupings($course->id, $showfeedback);
        groups_delete_groups($course->id, $showfeedback);
    }
    // Filters be gone!
    filter_delete_all_for_context($coursecontext->id);
    // Notes, you shall not pass!
    note_delete_all($course->id);
    // Die comments!
    comment::delete_comments($coursecontext->id);
    // Ratings are history too.
    $delopt = new stdclass();
    $delopt->contextid = $coursecontext->id;
    $rm = new rating_manager();
    $rm->delete_ratings($delopt);
    // Delete course tags.
    core_tag_tag::remove_all_item_tags('core', 'course', $course->id);
    // Notify the competency subsystem.
    \core_competency\api::hook_course_deleted($course);
    // Delete calendar events.
    $DB->delete_records('event', array('courseid' => $course->id));
    $fs->delete_area_files($coursecontext->id, 'calendar');
    // Delete all related records in other core tables that may have a courseid
    // This array stores the tables that need to be cleared, as
    // table_name => column_name that contains the course id.
    $tablestoclear = array('backup_courses' => 'courseid', 'user_lastaccess' => 'courseid');
    foreach ($tablestoclear as $table => $col) {

//.........这里部分代码省略.........
        context_helper::delete_instance(CONTEXT_MODULE, $cm->id);
        $DB->delete_records('course_modules', array('id' => $cm->id));
    }
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('type_mod_plural', 'plugin'), 'notifysuccess');
    }
    // Cleanup the rest of plugins
    $cleanuplugintypes = array('report', 'coursereport', 'format');
    foreach ($cleanuplugintypes as $type) {
        $plugins = get_plugin_list_with_function($type, 'delete_course', 'lib.php');
        foreach ($plugins as $plugin => $pluginfunction) {
            $pluginfunction($course->id, $showfeedback);
        }
        if ($showfeedback) {
            echo $OUTPUT->notification($strdeleted . get_string('type_' . $type . '_plural', 'plugin'), 'notifysuccess');
        }
    }
    // Delete questions and question categories
    question_delete_course($course, $showfeedback);
    if ($showfeedback) {
        echo $OUTPUT->notification($strdeleted . get_string('questions', 'question'), 'notifysuccess');
    }
    // Make sure there are no subcontexts left - all valid blocks and modules should be already gone
    $childcontexts = $coursecontext->get_child_contexts();
    // returns all subcontexts since 2.2
    foreach ($childcontexts as $childcontext) {
        $childcontext->delete();
    }
    unset($childcontexts);
    // Remove all roles and enrolments by default
    if (empty($options['keep_roles_and_enrolments'])) {
        // this hack is used in restore when deleting contents of existing course
        role_unassign_all(array('contextid' => $coursecontext->id, 'component' => ''), true);
        enrol_course_delete($course);
        if ($showfeedback) {
            echo $OUTPUT->notification($strdeleted . get_string('type_enrol_plural', 'plugin'), 'notifysuccess');
        }
    }
    // Delete any groups, removing members and grouping/course links first.
    if (empty($options['keep_groups_and_groupings'])) {
        groups_delete_groupings($course->id, $showfeedback);
        groups_delete_groups($course->id, $showfeedback);
    }
    // filters be gone!
    filter_delete_all_for_context($coursecontext->id);
    // die comments!
    comment::delete_comments($coursecontext->id);
    // ratings are history too
    $delopt = new stdclass();
    $delopt->contextid = $coursecontext->id;
    $rm = new rating_manager();
    $rm->delete_ratings($delopt);
    // Delete course tags
    coursetag_delete_course_tags($course->id, $showfeedback);
    // Delete calendar events
    $DB->delete_records('event', array('courseid' => $course->id));
    $fs->delete_area_files($coursecontext->id, 'calendar');
    // Delete all related records in other core tables that may have a courseid
    // This array stores the tables that need to be cleared, as
    // table_name => column_name that contains the course id.
    $tablestoclear = array('log' => 'course', 'backup_courses' => 'courseid', 'user_lastaccess' => 'courseid');
    foreach ($tablestoclear as $table => $col) {
        $DB->delete_records($table, array($col => $course->id));
    }
    // delete all course backup files
    $fs->delete_area_files($coursecontext->id, 'backup');