function wiki_reset_userdata($data)
{
    global $CFG, $DB;
    require_once $CFG->dirroot . '/mod/wiki/pagelib.php';
    require_once $CFG->dirroot . '/tag/lib.php';
    $componentstr = get_string('modulenameplural', 'wiki');
    $status = array();
    //get the wiki(s) in this course.
    if (!($wikis = $DB->get_records('wiki', array('course' => $data->courseid)))) {
        return false;
    }
    $errors = false;
    foreach ($wikis as $wiki) {
        // remove all comments
        if (!empty($data->reset_wiki_comments)) {
            if (!($cm = get_coursemodule_from_instance('wiki', $wiki->id))) {
                continue;
            }
            $context = context_module::instance($cm->id);
            $DB->delete_records_select('comments', "contextid = ? AND commentarea='wiki_page'", array($context->id));
            $status[] = array('component' => $componentstr, 'item' => get_string('deleteallcomments'), 'error' => false);
        }
        if (!empty($data->reset_wiki_tags)) {
            # Get subwiki information #
            $subwikis = $DB->get_records('wiki_subwikis', array('wikiid' => $wiki->id));
            foreach ($subwikis as $subwiki) {
                if ($pages = $DB->get_records('wiki_pages', array('subwikiid' => $subwiki->id))) {
                    foreach ($pages as $page) {
                        $tags = tag_get_tags_array('wiki_pages', $page->id);
                        foreach ($tags as $tagid => $tagname) {
                            // Delete the related tag_instances related to the wiki page.
                            $errors = tag_delete_instance('wiki_pages', $page->id, $tagid);
                            $status[] = array('component' => $componentstr, 'item' => get_string('tagsdeleted', 'wiki'), 'error' => $errors);
                        }
                    }
                }
            }
        }
    }
    return $status;
}

/**
 * Delete pages and all related data
 *
 * @param mixed $context context in which page needs to be deleted.
 * @param mixed $pageids id's of pages to be deleted
 * @param int $subwikiid id of the subwiki for which all pages should be deleted
 */
function wiki_delete_pages($context, $pageids = null, $subwikiid = null)
{
    global $DB;
    if (!empty($pageids) && is_int($pageids)) {
        $pageids = array($pageids);
    } else {
        if (!empty($subwikiid)) {
            $pageids = wiki_get_page_list($subwikiid);
        }
    }
    //If there is no pageid then return as we can't delete anything.
    if (empty($pageids)) {
        return;
    }
    /// Delete page and all it's relevent data
    foreach ($pageids as $pageid) {
        if (is_object($pageid)) {
            $pageid = $pageid->id;
        }
        //Delete page comments
        $comments = wiki_get_comments($context->id, $pageid);
        foreach ($comments as $commentid => $commentvalue) {
            wiki_delete_comment($commentid, $context, $pageid);
        }
        //Delete page tags
        $tags = tag_get_tags_array('wiki_pages', $pageid);
        foreach ($tags as $tagid => $tagvalue) {
            tag_delete_instance('wiki_pages', $pageid, $tagid);
        }
        //Delete Synonym
        wiki_delete_synonym($subwikiid, $pageid);
        //Delete all page versions
        wiki_delete_page_versions(array($pageid => array(0)));
        //Delete all page locks
        wiki_delete_locks($pageid);
        //Delete all page links
        wiki_delete_links(null, $pageid);
        //Delete page
        $params = array('id' => $pageid);
        $DB->delete_records('wiki_pages', $params);
    }
}

 /**
  * Test the tag removed event.
  */
 public function test_tag_removed()
 {
     global $DB;
     $this->setAdminUser();
     // Create a course to tag.
     $course = $this->getDataGenerator()->create_course();
     // Create a wiki page to tag.
     $wikigenerator = $this->getDataGenerator()->get_plugin_generator('mod_wiki');
     $wiki = $wikigenerator->create_instance(array('course' => $course->id));
     $subwikiid = wiki_add_subwiki($wiki->id, 0);
     $wikipageid = wiki_create_page($subwikiid, 'Title', FORMAT_HTML, '2');
     // Create the tag.
     $tag = $this->getDataGenerator()->create_tag();
     // Assign a tag to a course.
     tag_assign('course', $course->id, $tag->id, 1, 2, 'core', context_course::instance($course->id)->id);
     // Trigger and capture the event for untagging a course.
     $sink = $this->redirectEvents();
     coursetag_delete_keyword($tag->id, 2, $course->id);
     $events = $sink->get_events();
     $event = reset($events);
     // Check that the tag was removed from the course and the event data is valid.
     $this->assertEquals(0, $DB->count_records('tag_instance'));
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event);
     $this->assertEquals(context_course::instance($course->id), $event->get_context());
     // Create the tag.
     $tag = $this->getDataGenerator()->create_tag();
     // Assign a tag to a wiki this time.
     tag_assign('wiki_pages', $wikipageid, $tag->id, 1, 2, 'mod_wiki', context_module::instance($wiki->cmid)->id);
     // Trigger and capture the event for deleting this tag instance.
     $sink = $this->redirectEvents();
     tag_delete_instance('wiki_pages', $wikipageid, $tag->id);
     $events = $sink->get_events();
     $event = reset($events);
     // Check that tag was removed from the wiki page and the event data is valid.
     $this->assertEquals(0, $DB->count_records('tag_instance'));
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event);
     $this->assertEquals(context_module::instance($wiki->cmid), $event->get_context());
     // Create a tag again - the other would have been deleted since there were no more instances associated with it.
     $tag = $this->getDataGenerator()->create_tag();
     // Assign a tag to the wiki again.
     tag_assign('wiki_pages', $wikipageid, $tag->id, 1, 2, 'mod_wiki', context_module::instance($wiki->cmid)->id);
     // Now we want to delete this tag, and because there is only one tag instance
     // associated with it, it should get deleted as well.
     $sink = $this->redirectEvents();
     tag_delete($tag->id);
     $events = $sink->get_events();
     $event = reset($events);
     // Check that tag was removed from the wiki page and the event data is valid.
     $this->assertEquals(0, $DB->count_records('tag_instance'));
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event);
     $this->assertEquals(context_module::instance($wiki->cmid), $event->get_context());
     // Create a tag again - the other would have been deleted since there were no more instances associated with it.
     $tag = $this->getDataGenerator()->create_tag();
     // Assign a tag to the wiki again.
     tag_assign('wiki_pages', $wikipageid, $tag->id, 1, 2, 'mod_wiki', context_module::instance($wiki->cmid)->id);
     // Delete all tag instances for this wiki instance.
     $sink = $this->redirectEvents();
     tag_delete_instances('mod_wiki', context_module::instance($wiki->cmid)->id);
     $events = $sink->get_events();
     $event = reset($events);
     // Check that tag was removed from the wiki page and the event data is valid.
     $this->assertEquals(0, $DB->count_records('tag_instance'));
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event);
     $this->assertEquals(context_module::instance($wiki->cmid), $event->get_context());
     // Create another wiki.
     $wiki2 = $wikigenerator->create_instance(array('course' => $course->id));
     $subwikiid2 = wiki_add_subwiki($wiki2->id, 0);
     $wikipageid2 = wiki_create_page($subwikiid2, 'Title', FORMAT_HTML, '2');
     // Assign a tag to both wiki pages.
     tag_assign('wiki_pages', $wikipageid, $tag->id, 1, 2, 'mod_wiki', context_module::instance($wiki->cmid)->id);
     tag_assign('wiki_pages', $wikipageid2, $tag->id, 1, 2, 'mod_wiki', context_module::instance($wiki2->cmid)->id);
     // Now remove all tag_instances associated with all wikis.
     $sink = $this->redirectEvents();
     tag_delete_instances('mod_wiki');
     $events = $sink->get_events();
     // There will be two events - one for each wiki instance removed.
     $event1 = reset($events);
     $event2 = $events[1];
     // Check that the tags were removed from the wiki pages.
     $this->assertEquals(0, $DB->count_records('tag_instance'));
     // Check the first event data is valid.
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event1);
     $this->assertEquals(context_module::instance($wiki->cmid), $event1->get_context());
     // Check that the second event data is valid.
     $this->assertInstanceOf('\\core\\event\\tag_removed', $event2);
     $this->assertEquals(context_module::instance($wiki2->cmid), $event2->get_context());
 }

/** 
 * Clean up the tag tables, making sure all tagged object still exists.
 *
 * This should normally not be necessary, but in case related tags are not deleted
 * when the tagged record is removed, this should be done once in a while, perhaps on
 * an occasional cron run.  On a site with lots of tags, this could become an expensive 
 * function to call: don't run at peak time.
 */
function tag_cleanup()
{
    global $CFG;
    $instances = get_recordset('tag_instance');
    // cleanup tag instances
    while ($instance = rs_fetch_next_record($instances)) {
        $delete = false;
        if (!record_exists('tag', 'id', $instance->tagid)) {
            // if the tag has been removed, instance should be deleted.
            $delete = true;
        } else {
            switch ($instance->itemtype) {
                case 'user':
                    // users are marked as deleted, but not actually deleted
                    if (record_exists('user', 'id', $instance->itemid, 'deleted', 1)) {
                        $delete = true;
                    }
                    break;
                default:
                    // anything else, if the instance is not there, delete.
                    if (!record_exists($instance->itemtype, 'id', $instance->itemid)) {
                        $delete = true;
                    }
                    break;
            }
        }
        if ($delete) {
            tag_delete_instance($instance->itemtype, $instance->itemid, $instance->tagid);
            //debugging('deleting tag_instance #'. $instance->id .', linked to tag id #'. $instance->tagid, DEBUG_DEVELOPER);
        }
    }
    rs_close($instances);
    // TODO: this will only clean tags of type 'default'.  This is good as
    // it won't delete 'official' tags, but the day we get more than two
    // types, we need to fix this.
    $unused_tags = get_recordset_sql("SELECT tg.id FROM {$CFG->prefix}tag tg WHERE tg.tagtype = 'default' AND NOT EXISTS (" . "SELECT 'x' FROM {$CFG->prefix}tag_instance ti WHERE ti.tagid = tg.id)");
    // cleanup tags
    while ($unused_tag = rs_fetch_next_record($unused_tags)) {
        tag_delete($unused_tag->id);
        //debugging('deleting unused tag #'. $unused_tag->id,  DEBUG_DEVELOPER);
    }
    rs_close($unused_tags);
}

/**
 * Deletes a personal tag for a user for a course.
 *
 * @package  core_tag
 * @category tag
 * @param    int      $tagid    the tag we wish to delete
 * @param    int      $userid   the user that the tag is associated with
 * @param    int      $courseid the course that the tag is associated with
 */
function coursetag_delete_keyword($tagid, $userid, $courseid)
{
    tag_delete_instance('course', $courseid, $tagid, $userid);
}

/**
 * Clean up the tag tables, making sure all tagged object still exists.
 *
 * This should normally not be necessary, but in case related tags are not deleted
 * when the tagged record is removed, this should be done once in a while, perhaps on
 * an occasional cron run.  On a site with lots of tags, this could become an expensive
 * function to call: don't run at peak time.
 */
function tag_cleanup()
{
    global $DB;
    $instances = $DB->get_recordset('tag_instance');
    // cleanup tag instances
    foreach ($instances as $instance) {
        $delete = false;
        if (!$DB->record_exists('tag', array('id' => $instance->tagid))) {
            // if the tag has been removed, instance should be deleted.
            $delete = true;
        } else {
            switch ($instance->itemtype) {
                case 'user':
                    // users are marked as deleted, but not actually deleted
                    if ($DB->record_exists('user', array('id' => $instance->itemid, 'deleted' => 1))) {
                        $delete = true;
                    }
                    break;
                default:
                    // anything else, if the instance is not there, delete.
                    if (!$DB->record_exists($instance->itemtype, array('id' => $instance->itemid))) {
                        $delete = true;
                    }
                    break;
            }
        }
        if ($delete) {
            tag_delete_instance($instance->itemtype, $instance->itemid, $instance->tagid);
            //debugging('deleting tag_instance #'. $instance->id .', linked to tag id #'. $instance->tagid, DEBUG_DEVELOPER);
        }
    }
    $instances->close();
    // TODO: this will only clean tags of type 'default'.  This is good as
    // it won't delete 'official' tags, but the day we get more than two
    // types, we need to fix this.
    $unused_tags = $DB->get_recordset_sql("SELECT tg.id\n                                             FROM {tag} tg\n                                            WHERE tg.tagtype = 'default'\n                                                  AND NOT EXISTS (\n                                                      SELECT 'x'\n                                                        FROM {tag_instance} ti\n                                                       WHERE ti.tagid = tg.id\n                                                  )");
    // cleanup tags
    foreach ($unused_tags as $unused_tag) {
        tag_delete($unused_tag->id);
        //debugging('deleting unused tag #'. $unused_tag->id,  DEBUG_DEVELOPER);
    }
    $unused_tags->close();
}

/**
 * Course tagging function used only during the deletion of a course (called by lib/moodlelib.php) to clean up associated tags
 *
 * @package core_tag
 * @param   int      $courseid     the course we wish to delete tag instances from
 * @param   bool     $showfeedback if we should output a notification of the delete to the end user
 */
function coursetag_delete_course_tags($courseid, $showfeedback = false)
{
    global $DB, $OUTPUT;
    if ($taginstances = $DB->get_recordset_select('tag_instance', "itemtype = 'course' AND itemid = :courseid", array('courseid' => $courseid), '', 'tagid, tiuserid')) {
        foreach ($taginstances as $record) {
            tag_delete_instance('course', $courseid, $record->tagid, $record->tiuserid);
        }
        $taginstances->close();
    }
    if ($showfeedback) {
        echo $OUTPUT->notification(get_string('deletedcoursetags', 'tag'), 'notifysuccess');
    }
}

/**
 * Set the tags assigned to a record.  This overwrites the current tags.
 *
 * This function is meant to be fed the string coming up from the user interface, which contains all tags assigned to a record.
 *
 * @package core_tag
 * @category tag
 * @access public
 * @param string $record_type the type of record to tag ('post' for blogs, 'user' for users, 'tag' for tags, etc.)
 * @param int $record_id the id of the record to tag
 * @param array $tags the array of tags to set on the record. If given an empty array, all tags will be removed.
 * @param string|null $component the component that was tagged
 * @param int|null $contextid the context id of where this tag was assigned
 * @return bool|null
 */
function tag_set($record_type, $record_id, $tags, $component = null, $contextid = null)
{
    static $in_recursion_semaphore = false;
    // this is to prevent loops when tagging a tag
    if ($record_type == 'tag' && !$in_recursion_semaphore) {
        $current_tagged_tag_name = tag_get_name($record_id);
    }
    $tags_ids = tag_get_id($tags, TAG_RETURN_ARRAY);
    // force an array, even if we only have one tag.
    $cleaned_tags = tag_normalize($tags);
    //echo 'tags-in-tag_set'; var_dump($tags); var_dump($tags_ids); var_dump($cleaned_tags);
    $current_ids = tag_get_tags_ids($record_type, $record_id);
    //var_dump($current_ids);
    // for data coherence reasons, it's better to remove deleted tags
    // before adding new data: ordering could be duplicated.
    foreach ($current_ids as $current_id) {
        if (!in_array($current_id, $tags_ids)) {
            tag_delete_instance($record_type, $record_id, $current_id);
            if ($record_type == 'tag' && !$in_recursion_semaphore) {
                // if we are removing a tag-on-a-tag (manually related tag),
                // we need to remove the opposite relationship as well.
                tag_delete_instance('tag', $current_id, $record_id);
            }
        }
    }
    if (empty($tags)) {
        return true;
    }
    foreach ($tags as $ordering => $tag) {
        $tag = trim($tag);
        if (!$tag) {
            continue;
        }
        $clean_tag = $cleaned_tags[$tag];
        $tag_current_id = $tags_ids[$clean_tag];
        if (is_null($tag_current_id)) {
            // create new tags
            //echo "call to add tag $tag\n";
            $new_tag = tag_add($tag);
            $tag_current_id = $new_tag[$clean_tag];
        }
        tag_assign($record_type, $record_id, $tag_current_id, $ordering, 0, $component, $contextid);
        // if we are tagging a tag (adding a manually-assigned related tag), we
        // need to create the opposite relationship as well.
        if ($record_type == 'tag' && !$in_recursion_semaphore) {
            $in_recursion_semaphore = true;
            tag_set_add('tag', $tag_current_id, $current_tagged_tag_name, $component, $contextid);
            $in_recursion_semaphore = false;
        }
    }
}

/**
 * 
 * 
 */
function bookmarks_untag($itemid, $tagname)
{
    $tag = tag_get('name', $tagname);
    return tag_delete_instance('bookmark', $itemid, $tag->id);
}

function wiki_reset_userdata($data)
{
    global $CFG, $DB;
    require_once $CFG->dirroot . '/mod/wiki/pagelib.php';
    require_once $CFG->dirroot . '/tag/lib.php';
    require_once $CFG->dirroot . "/mod/wiki/locallib.php";
    $componentstr = get_string('modulenameplural', 'wiki');
    $status = array();
    //get the wiki(s) in this course.
    if (!($wikis = $DB->get_records('wiki', array('course' => $data->courseid)))) {
        return false;
    }
    $errors = false;
    foreach ($wikis as $wiki) {
        if (!($cm = get_coursemodule_from_instance('wiki', $wiki->id))) {
            continue;
        }
        $context = context_module::instance($cm->id);
        // Remove tags or all pages.
        if (!empty($data->reset_wiki_pages) || !empty($data->reset_wiki_tags)) {
            // Get subwiki information.
            $subwikis = wiki_get_subwikis($wiki->id);
            foreach ($subwikis as $subwiki) {
                // Get existing pages.
                if ($pages = wiki_get_page_list($subwiki->id)) {
                    // If the wiki page isn't selected then we are only removing tags.
                    if (empty($data->reset_wiki_pages)) {
                        // Go through each page and delete the tags.
                        foreach ($pages as $page) {
                            $tags = tag_get_tags_array('wiki_pages', $page->id);
                            foreach ($tags as $tagid => $tagname) {
                                // Delete the related tag_instances related to the wiki page.
                                $errors = tag_delete_instance('wiki_pages', $page->id, $tagid);
                                $status[] = array('component' => $componentstr, 'item' => get_string('tagsdeleted', 'wiki'), 'error' => $errors);
                            }
                        }
                    } else {
                        // Otherwise we are removing pages and tags.
                        wiki_delete_pages($context, $pages, $subwiki->id);
                    }
                }
                if (!empty($data->reset_wiki_pages)) {
                    // Delete any subwikis.
                    $DB->delete_records('wiki_subwikis', array('id' => $subwiki->id), IGNORE_MISSING);
                    // Delete any attached files.
                    $fs = get_file_storage();
                    $fs->delete_area_files($context->id, 'mod_wiki', 'attachments');
                    $status[] = array('component' => $componentstr, 'item' => get_string('deleteallpages', 'wiki'), 'error' => $errors);
                }
            }
        }
        // Remove all comments.
        if (!empty($data->reset_wiki_comments) || !empty($data->reset_wiki_pages)) {
            $DB->delete_records_select('comments', "contextid = ? AND commentarea='wiki_page'", array($context->id));
            $status[] = array('component' => $componentstr, 'item' => get_string('deleteallcomments'), 'error' => false);
        }
    }
    return $status;
}

/**
 * Delete pages and all related data
 *
 * @param mixed $context context in which page needs to be deleted.
 * @param mixed $pageids id's of pages to be deleted
 * @param int $subwikiid id of the subwiki for which all pages should be deleted
 */
function wiki_delete_pages($context, $pageids = null, $subwikiid = null)
{
    global $DB, $CFG;
    if (!empty($pageids) && is_int($pageids)) {
        $pageids = array($pageids);
    } else {
        if (!empty($subwikiid)) {
            $pageids = wiki_get_page_list($subwikiid);
        }
    }
    //If there is no pageid then return as we can't delete anything.
    if (empty($pageids)) {
        return;
    }
    require_once $CFG->dirroot . '/tag/lib.php';
    /// Delete page and all it's relevent data
    foreach ($pageids as $pageid) {
        if (is_object($pageid)) {
            $pageid = $pageid->id;
        }
        //Delete page comments
        $comments = wiki_get_comments($context->id, $pageid);
        foreach ($comments as $commentid => $commentvalue) {
            wiki_delete_comment($commentid, $context, $pageid);
        }
        //Delete page tags
        $tags = tag_get_tags_array('wiki_pages', $pageid);
        foreach ($tags as $tagid => $tagvalue) {
            tag_delete_instance('wiki_pages', $pageid, $tagid);
        }
        //Delete Synonym
        wiki_delete_synonym($subwikiid, $pageid);
        //Delete all page versions
        wiki_delete_page_versions(array($pageid => array(0)), $context);
        //Delete all page locks
        wiki_delete_locks($pageid);
        //Delete all page links
        wiki_delete_links(null, $pageid);
        $params = array('id' => $pageid);
        // Get page before deleting.
        $page = $DB->get_record('wiki_pages', $params);
        //Delete page
        $DB->delete_records('wiki_pages', $params);
        // Trigger page_deleted event.
        $event = \mod_wiki\event\page_deleted::create(array('context' => $context, 'objectid' => $pageid, 'other' => array('subwikiid' => $subwikiid)));
        $event->add_record_snapshot('wiki_pages', $page);
        $event->trigger();
    }
}