/**
  * Observer for role_assigned event.
  *
  * @param \core\event\role_assigned $event
  * @return void
  */
 public static function role_assigned(\core\event\role_assigned $event)
 {
     global $CFG, $DB;
     $context = context::instance_by_id($event->contextid, MUST_EXIST);
     // If contextlevel is course then only subscribe user. Role assignment
     // at course level means user is enroled in course and can subscribe to forum.
     if ($context->contextlevel != CONTEXT_COURSE) {
         return;
     }
     // Forum lib required for the constant used below.
     require_once $CFG->dirroot . '/mod/forum/lib.php';
     $userid = $event->relateduserid;
     $sql = "SELECT f.id, cm.id AS cmid\n                  FROM {forum} f\n                  JOIN {course_modules} cm ON (cm.instance = f.id)\n                  JOIN {modules} m ON (m.id = cm.module)\n             LEFT JOIN {forum_subscriptions} fs ON (fs.forum = f.id AND fs.userid = :userid)\n                 WHERE f.course = :courseid\n                   AND f.forcesubscribe = :initial\n                   AND m.name = 'forum'\n                   AND fs.id IS NULL";
     $params = array('courseid' => $context->instanceid, 'userid' => $userid, 'initial' => FORUM_INITIALSUBSCRIBE);
     $forums = $DB->get_records_sql($sql, $params);
     foreach ($forums as $forum) {
         // If user doesn't have allowforcesubscribe capability then don't subscribe.
         if (has_capability('mod/forum:allowforcesubscribe', context_module::instance($forum->cmid), $userid)) {
             forum_subscribe($userid, $forum->id);
         }
     }
 }

/**
 * This function gets run whenever user is assigned role in course
 *
 * @param stdClass $cp
 * @return void
 */
function forum_user_role_assigned($cp) {
    global $DB;

    $context = context::instance_by_id($cp->contextid, MUST_EXIST);

    // If contextlevel is course then only subscribe user. Role assignment
    // at course level means user is enroled in course and can subscribe to forum.
    if ($context->contextlevel != CONTEXT_COURSE) {
        return;
    }

    $sql = "SELECT f.id, cm.id AS cmid
              FROM {forum} f
              JOIN {course_modules} cm ON (cm.instance = f.id)
              JOIN {modules} m ON (m.id = cm.module)
         LEFT JOIN {forum_subscriptions} fs ON (fs.forum = f.id AND fs.userid = :userid)
             WHERE f.course = :courseid
               AND f.forcesubscribe = :initial
               AND m.name = 'forum'
               AND fs.id IS NULL";
    $params = array('courseid'=>$context->instanceid, 'userid'=>$cp->userid, 'initial'=>FORUM_INITIALSUBSCRIBE);

    $forums = $DB->get_records_sql($sql, $params);
    foreach ($forums as $forum) {
        // If user doesn't have allowforcesubscribe capability then don't subscribe.
        if (has_capability('mod/forum:allowforcesubscribe', context_module::instance($forum->cmid), $cp->userid)) {
            forum_subscribe($cp->userid, $forum->id);
        }
    }
}

    }
    // Can proceed now, the user is not guest and is enrolled
    foreach ($modinfo->get_instances_of('forum') as $forumid => $cm) {
        $forum = $forums[$forumid];
        $modcontext = context_module::instance($cm->id);
        $cansub = false;
        if (has_capability('mod/forum:viewdiscussion', $modcontext)) {
            $cansub = true;
        }
        if ($cansub && $cm->visible == 0 && !has_capability('mod/forum:managesubscriptions', $modcontext)) {
            $cansub = false;
        }
        if (!forum_is_forcesubscribed($forum)) {
            $subscribed = forum_is_subscribed($USER->id, $forum);
            if ((has_capability('moodle/course:manageactivities', $coursecontext, $USER->id) || $forum->forcesubscribe != FORUM_DISALLOWSUBSCRIBE) && $subscribe && !$subscribed && $cansub) {
                forum_subscribe($USER->id, $forumid, $modcontext);
            } else {
                if (!$subscribe && $subscribed) {
                    forum_unsubscribe($USER->id, $forumid, $modcontext);
                }
            }
        }
    }
    $returnto = forum_go_back_to("index.php?id={$course->id}");
    $shortname = format_string($course->shortname, true, array('context' => context_course::instance($course->id)));
    if ($subscribe) {
        redirect($returnto, get_string('nowallsubscribed', 'forum', $shortname), 1);
    } else {
        redirect($returnto, get_string('nowallunsubscribed', 'forum', $shortname), 1);
    }
}

/**
 * Add subscriptions for new users
 *
 * @global object
 * @uses CONTEXT_SYSTEM
 * @uses CONTEXT_COURSE
 * @uses CONTEXT_COURSECAT
 * @uses FORUM_INITIALSUBSCRIBE
 * @param int $userid
 * @param object $context
 * @return bool
 */
function forum_add_user_default_subscriptions($userid, $context) {
    global $DB;
    if (empty($context->contextlevel)) {
        return false;
    }

    switch ($context->contextlevel) {

        case CONTEXT_SYSTEM:   // For the whole site
             $rs = $DB->get_recordset('course',null,'','id');
             foreach ($rs as $course) {
                 $subcontext = get_context_instance(CONTEXT_COURSE, $course->id);
                 forum_add_user_default_subscriptions($userid, $subcontext);
             }
             $rs->close();
             break;

        case CONTEXT_COURSECAT:   // For a whole category
             $rs = $DB->get_recordset('course', array('category' => $context->instanceid),'','id');
             foreach ($rs as $course) {
                 $subcontext = get_context_instance(CONTEXT_COURSE, $course->id);
                 forum_add_user_default_subscriptions($userid, $subcontext);
             }
             $rs->close();
             if ($categories = $DB->get_records('course_categories', array('parent' => $context->instanceid))) {
                 foreach ($categories as $category) {
                     $subcontext = get_context_instance(CONTEXT_COURSECAT, $category->id);
                     forum_add_user_default_subscriptions($userid, $subcontext);
                 }
             }
             break;


        case CONTEXT_COURSE:   // For a whole course
             if (is_enrolled($context, $userid)) {
                if ($course = $DB->get_record('course', array('id' => $context->instanceid))) {
                     if ($forums = get_all_instances_in_course('forum', $course, $userid, false)) {
                         foreach ($forums as $forum) {
                             if ($forum->forcesubscribe != FORUM_INITIALSUBSCRIBE) {
                                 continue;
                             }
                             if ($modcontext = get_context_instance(CONTEXT_MODULE, $forum->coursemodule)) {
                                 if (has_capability('mod/forum:viewdiscussion', $modcontext, $userid)) {
                                     forum_subscribe($userid, $forum->id);
                                 }
                             }
                         }
                     }
                 }
             }
             break;

        case CONTEXT_MODULE:   // Just one forum
            if (has_capability('mod/forum:initialsubscriptions', $context, $userid)) {
                 if ($cm = get_coursemodule_from_id('forum', $context->instanceid)) {
                     if ($forum = $DB->get_record('forum', array('id' => $cm->instance))) {
                         if ($forum->forcesubscribe != FORUM_INITIALSUBSCRIBE) {
                             continue;
                         }
                         if (has_capability('mod/forum:viewdiscussion', $context, $userid)) {
                             forum_subscribe($userid, $forum->id);
                         }
                     }
                 }
            }
            break;
    }

    return true;
}

                        unset($learningforums[$forum->keyreference]);
                    }
                }
                break;
        }
    }
}
/// Do course wide subscribe/unsubscribe
if (!is_null($subscribe) && !isguest()) {
    $allforums = array_merge($generalforums, $learningforums);
    if ($allforums) {
        foreach ($allforums as $forum) {
            if (!forum_is_forcesubscribed($forum->id)) {
                $subscribed = forum_is_subscribed($USER->id, $forum->id);
                if ($subscribe && !$subscribed) {
                    forum_subscribe($USER->id, $forum->id);
                } elseif (!$subscribe && $subscribed) {
                    forum_unsubscribe($USER->id, $forum->id);
                }
            }
        }
    }
    $returnto = forum_go_back_to("index.php?id={$course->id}");
    if ($subscribe) {
        add_to_log($course->id, "forum", "subscribeall", "index.php?id={$course->id}", $course->id);
        redirect($returnto, get_string("nowallsubscribed", "forum", format_string($course->shortname)), 1);
    } else {
        add_to_log($course->id, "forum", "unsubscribeall", "index.php?id={$course->id}", $course->id);
        redirect($returnto, get_string("nowallunsubscribed", "forum", format_string($course->shortname)), 1);
    }
}

/**
 * This function gets run whenever user is enrolled into course
 *
 * @param stdClass $cp
 * @return void
 */
function forum_user_enrolled($cp) {
    global $DB;

    // NOTE: this has to be as fast as possible - we do not want to slow down enrolments!
    //       Originally there used to be 'mod/forum:initialsubscriptions' which was
    //       introduced because we did not have enrolment information in earlier versions...

    $sql = "SELECT f.id
              FROM {forum} f
         LEFT JOIN {forum_subscriptions} fs ON (fs.forum = f.id AND fs.userid = :userid)
             WHERE f.course = :courseid AND f.forcesubscribe = :initial AND fs.id IS NULL";
    $params = array('courseid'=>$cp->courseid, 'userid'=>$cp->userid, 'initial'=>FORUM_INITIALSUBSCRIBE);

    $forums = $DB->get_records_sql($sql, $params);
    foreach ($forums as $forum) {
        forum_subscribe($cp->userid, $forum->id);
    }
}

/// We are in editing mode.
$strexistingsubscribers = get_string("existingsubscribers", 'forum');
$strpotentialsubscribers = get_string("potentialsubscribers", 'forum');
$straddsubscriber = get_string("addsubscriber", 'forum');
$strremovesubscriber = get_string("removesubscriber", 'forum');
$strsearch = get_string("search");
$strsearchresults = get_string("searchresults");
$strshowall = get_string("showall");
$strsubscribers = get_string("subscribers", "forum");
$strforums = get_string("forums", "forum");
$searchtext = optional_param('searchtext', '', PARAM_RAW);
if ($frm = data_submitted()) {
    /// A form was submitted so process the input
    if (!empty($frm->add) and !empty($frm->addselect)) {
        foreach ($frm->addselect as $addsubscriber) {
            if (!forum_subscribe($addsubscriber, $id)) {
                print_error('cannotaddsubscriber', 'forum', '', $addsubscriber);
            }
        }
    } else {
        if (!empty($frm->remove) and !empty($frm->removeselect)) {
            foreach ($frm->removeselect as $removesubscriber) {
                if (!forum_unsubscribe($removesubscriber, $id)) {
                    print_error('cannotremovesubscriber', 'forum', '', $removesubscriber);
                }
            }
        } else {
            if (!empty($frm->showall)) {
                $searchtext = '';
            }
        }

        forum_forcesubscribe($forum->id, 1);
        redirect($returnto, get_string("everyoneisnowsubscribed", "forum"), 1);
    }
}
if (forum_is_forcesubscribed($forum)) {
    redirect($returnto, get_string("everyoneisnowsubscribed", "forum"), 1);
}
$info->name = fullname($user);
$info->forum = format_string($forum->name);
if (forum_is_subscribed($user->id, $forum->id)) {
    if (forum_unsubscribe($user->id, $forum->id)) {
        add_to_log($course->id, "forum", "unsubscribe", "view.php?f={$forum->id}", $forum->id, $cm->id);
        redirect($returnto, get_string("nownotsubscribed", "forum", $info), 1);
    } else {
        print_error('cannotunsubscribe', 'forum', $_SERVER["HTTP_REFERER"]);
    }
} else {
    // subscribe
    if ($forum->forcesubscribe == FORUM_DISALLOWSUBSCRIBE && !has_capability('mod/forum:managesubscriptions', $context)) {
        print_error('disallowsubscribe', 'forum', $_SERVER["HTTP_REFERER"]);
    }
    if (!has_capability('mod/forum:viewdiscussion', $context)) {
        print_error('cannotsubscribe', 'forum', $_SERVER["HTTP_REFERER"]);
    }
    if (forum_subscribe($user->id, $forum->id)) {
        add_to_log($course->id, "forum", "subscribe", "view.php?f={$forum->id}", $forum->id, $cm->id);
        redirect($returnto, get_string("nowsubscribed", "forum", $info), 1);
    } else {
        print_error('cannotsubscribe', 'forum', $_SERVER["HTTP_REFERER"]);
    }
}

 /**
  * Test that toggling the forum-level subscription for a different user does not affect their discussion-level
  * subscriptions.
  */
 public function test_forum_subscribe_toggle_as_other()
 {
     global $DB;
     $this->resetAfterTest(true);
     // Create a course, with a forum.
     $course = $this->getDataGenerator()->create_course();
     $options = array('course' => $course->id, 'forcesubscribe' => FORUM_CHOOSESUBSCRIBE);
     $forum = $this->getDataGenerator()->create_module('forum', $options);
     // Create a user enrolled in the course as a student.
     list($author) = $this->helper_create_users($course, 1);
     // Post a discussion to the forum.
     list($discussion, $post) = $this->helper_post_to_forum($forum, $author);
     // Check that the user is currently not subscribed to the forum.
     $this->assertFalse(\mod_forum\subscriptions::is_subscribed($author->id, $forum));
     // Check the deprecated function too.
     $this->assertFalse(forum_is_subscribed($author->id, $forum));
     $this->assertEquals(1, count(phpunit_util::get_debugging_messages()));
     phpunit_util::reset_debugging();
     // Check that the user is unsubscribed from the discussion too.
     $this->assertFalse(\mod_forum\subscriptions::is_subscribed($author->id, $forum, $discussion->id));
     // Check that we have no records in either of the subscription tables.
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Subscribing to the forum should create a record in the subscriptions table, but not the forum discussion
     // subscriptions table.
     \mod_forum\subscriptions::subscribe_user($author->id, $forum);
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing should remove the record from the forum subscriptions table, and not modify the forum
     // discussion subscriptions table.
     \mod_forum\subscriptions::unsubscribe_user($author->id, $forum);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // The same thing should happen calling the deprecated versions of
     // these functions.
     // Subscribing to the forum should create a record in the subscriptions table, but not the forum discussion
     // subscriptions table.
     forum_subscribe($author->id, $forum->id);
     $this->assertEquals(1, count(phpunit_util::get_debugging_messages()));
     phpunit_util::reset_debugging();
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing should remove the record from the forum subscriptions table, and not modify the forum
     // discussion subscriptions table.
     forum_unsubscribe($author->id, $forum->id);
     $this->assertEquals(1, count(phpunit_util::get_debugging_messages()));
     phpunit_util::reset_debugging();
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Enroling the user in the discussion should add one record to the forum discussion table without modifying the
     // form subscriptions.
     \mod_forum\subscriptions::subscribe_user_to_discussion($author->id, $discussion);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing should remove the record from the forum subscriptions table, and not modify the forum
     // discussion subscriptions table.
     \mod_forum\subscriptions::unsubscribe_user_from_discussion($author->id, $discussion);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Re-subscribe to the discussion so that we can check the effect of forum-level subscriptions.
     \mod_forum\subscriptions::subscribe_user_to_discussion($author->id, $discussion);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Subscribing to the forum should have no effect on the forum discussion subscriptions table if the user did
     // not request the change themself.
     \mod_forum\subscriptions::subscribe_user($author->id, $forum);
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing from the forum should have no effect on the forum discussion subscriptions table if the user
     // did not request the change themself.
     \mod_forum\subscriptions::unsubscribe_user($author->id, $forum);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Subscribing to the forum should remove the per-discussion subscription preference if the user requested the
     // change themself.
     \mod_forum\subscriptions::subscribe_user($author->id, $forum, null, true);
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Now unsubscribe from the current discussion whilst being subscribed to the forum as a whole.
     \mod_forum\subscriptions::unsubscribe_user_from_discussion($author->id, $discussion);
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing from the forum should remove the per-discussion subscription preference if the user requested the
     // change themself.
     \mod_forum\subscriptions::unsubscribe_user($author->id, $forum, null, true);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(0, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Subscribe to the discussion.
     \mod_forum\subscriptions::subscribe_user_to_discussion($author->id, $discussion);
     $this->assertEquals(0, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Subscribe to the forum without removing the discussion preferences.
     \mod_forum\subscriptions::subscribe_user($author->id, $forum);
     $this->assertEquals(1, $DB->count_records('forum_subscriptions', array('userid' => $author->id, 'forum' => $forum->id)));
     $this->assertEquals(1, $DB->count_records('forum_discussion_subs', array('userid' => $author->id, 'discussion' => $discussion->id)));
     // Unsubscribing from the discussion should result in a change.
//.........这里部分代码省略.........

$options = array('forumid' => $forum->id, 'currentgroup' => $currentgroup, 'context' => $context);
$existingselector = new forum_existing_subscriber_selector('existingsubscribers', $options);
$subscriberselector = new forum_potential_subscriber_selector('potentialsubscribers', $options);
$subscriberselector->set_existing_subscribers($existingselector->find_users(''));
if (data_submitted()) {
    require_sesskey();
    $subscribe = (bool) optional_param('subscribe', false, PARAM_RAW);
    $unsubscribe = (bool) optional_param('unsubscribe', false, PARAM_RAW);
    /** It has to be one or the other, not both or neither */
    if (!($subscribe xor $unsubscribe)) {
        print_error('invalidaction');
    }
    if ($subscribe) {
        $users = $subscriberselector->get_selected_users();
        foreach ($users as $user) {
            if (!forum_subscribe($user->id, $id)) {
                print_error('cannotaddsubscriber', 'forum', '', $user->id);
            }
        }
    } else {
        if ($unsubscribe) {
            $users = $existingselector->get_selected_users();
            foreach ($users as $user) {
                if (!forum_unsubscribe($user->id, $id)) {
                    print_error('cannotremovesubscriber', 'forum', '', $user->id);
                }
            }
        }
    }
    $subscriberselector->invalidate_selected_users();
    $existingselector->invalidate_selected_users();