<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.

/**
 * Library of functions and constants for module wiki
 *
 * It contains the great majority of functions defined by Moodle
 * that are mandatory to develop a module.
 *
 * @package mod_wiki
 * @copyright 2009 Marc Alier, Jordi Piguillem marc.alier@upc.edu
 * @copyright 2009 Universitat Politecnica de Catalunya http://www.upc.edu
 *
 * @author Jordi Piguillem
 * @author Marc Alier
 * @author David Jimenez
 * @author Josep Arus
 * @author Kenneth Riba
 *
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod.html) this function
 * will create a new instance and return the id number
 * of the new instance.
 *
 * @param object $instance An object from the form in mod.html
 * @return int The id of the newly inserted wiki record
 **/
function wiki_add_instance($wiki) {
    global $DB;

    $wiki->timemodified = time();
    # May have to add extra stuff in here #
    if (empty($wiki->forceformat)) {
        $wiki->forceformat = 0;
    }

    $id = $DB->insert_record('wiki', $wiki);

    $completiontimeexpected = !empty($wiki->completionexpected) ? $wiki->completionexpected : null;
    \core_completion\api::update_completion_date_event($wiki->coursemodule, 'wiki', $id, $completiontimeexpected);

    return $id;
}

/**
 * Given an object containing all the necessary data,
 * (defined by the form in mod.html) this function
 * will update an existing instance with new data.
 *
 * @param object $instance An object from the form in mod.html
 * @return boolean Success/Fail
 **/
function wiki_update_instance($wiki) {
    global $DB;

    $wiki->timemodified = time();
    $wiki->id = $wiki->instance;
    if (empty($wiki->forceformat)) {
        $wiki->forceformat = 0;
    }

    $completiontimeexpected = !empty($wiki->completionexpected) ? $wiki->completionexpected : null;
    \core_completion\api::update_completion_date_event($wiki->coursemodule, 'wiki', $wiki->id, $completiontimeexpected);

    # May have to add extra stuff in here #

    return $DB->update_record('wiki', $wiki);
}

/**
 * Given an ID of an instance of this module,
 * this function will permanently delete the instance
 * and any data that depends on it.
 *
 * @param int $id Id of the module instance
 * @return boolean Success/Failure
 **/
function wiki_delete_instance($id) {
    global $DB;

    if (!$wiki = $DB->get_record('wiki', array('id' => $id))) {
        return false;
    }

    $result = true;

    # Get subwiki information #
    $subwikis = $DB->get_records('wiki_subwikis', array('wikiid' => $wiki->id));

    foreach ($subwikis as $subwiki) {
        # Get existing links, and delete them #
        if (!$DB->delete_records('wiki_links', array('subwikiid' => $subwiki->id), IGNORE_MISSING)) {
            $result = false;
        }

        # Get existing pages #
        if ($pages = $DB->get_records('wiki_pages', array('subwikiid' => $subwiki->id))) {
            foreach ($pages as $page) {
                # Get locks, and delete them #
                if (!$DB->delete_records('wiki_locks', array('pageid' => $page->id), IGNORE_MISSING)) {
                    $result = false;
                }

                # Get versions, and delete them #
                if (!$DB->delete_records('wiki_versions', array('pageid' => $page->id), IGNORE_MISSING)) {
                    $result = false;
                }
            }

            # Delete pages #
            if (!$DB->delete_records('wiki_pages', array('subwikiid' => $subwiki->id), IGNORE_MISSING)) {
                $result = false;
            }
        }

        # Get existing synonyms, and delete them #
        if (!$DB->delete_records('wiki_synonyms', array('subwikiid' => $subwiki->id), IGNORE_MISSING)) {
            $result = false;
        }

        # Delete any subwikis #
        if (!$DB->delete_records('wiki_subwikis', array('id' => $subwiki->id), IGNORE_MISSING)) {
            $result = false;
        }
    }

    $cm = get_coursemodule_from_instance('wiki', $id);
    \core_completion\api::update_completion_date_event($cm->id, 'wiki', $wiki->id, null);

    # Delete any dependent records here #
    if (!$DB->delete_records('wiki', array('id' => $wiki->id))) {
        $result = false;
    }

    return $result;
}

/**
 * Implements callback to reset course
 *
 * @param stdClass $data
 * @return boolean|array
 */
function wiki_reset_userdata($data) {
    global $CFG, $DB;
    require_once($CFG->dirroot . '/mod/wiki/pagelib.php');
    require_once($CFG->dirroot . "/mod/wiki/locallib.php");

    $componentstr = get_string('modulenameplural', 'wiki');
    $status = [];

    // Get the wiki(s) in this course.
    if (!$wikis = $DB->get_records('wiki', ['course' => $data->courseid])) {
        return false;
    }
    if (empty($data->reset_wiki_comments) && empty($data->reset_wiki_tags) && empty($data->reset_wiki_pages)) {
        return $status;
    }

    foreach ($wikis as $wiki) {
        if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id, $data->courseid)) {
            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) {
                            core_tag_tag::remove_all_item_tags('mod_wiki', 'wiki_pages', $page->id);
                        }
                    } else {
                        // Otherwise we are removing pages and tags.
                        wiki_delete_pages($context, $pages, $subwiki->id);
                    }
                }
                if (!empty($data->reset_wiki_pages)) {
                    // Delete any subwikis.
                    $DB->delete_records('wiki_subwikis', ['id' => $subwiki->id]);

                    // Delete any attached files.
                    $fs = get_file_storage();
                    $fs->delete_area_files($context->id, 'mod_wiki', 'attachments');
                }
            }

            if (!empty($data->reset_wiki_pages)) {
                $status[] = [
                    'component' => $componentstr,
                    'item' => get_string('deleteallpages', 'wiki'),
                    'error' => false,
                ];
            }
            if (!empty($data->reset_wiki_tags)) {
                $status[] = [
                    'component' => $componentstr,
                    'item' => get_string('removeallwikitags', 'wiki'),
                    'error' => false,
                ];
            }
        }

        // Remove all comments.
        if (!empty($data->reset_wiki_comments) || !empty($data->reset_wiki_pages)) {
            $DB->delete_records_select('comments', "contextid = ? AND commentarea='wiki_page'", [$context->id]);
            if (!empty($data->reset_wiki_comments)) {
                $status[] = [
                    'component' => $componentstr,
                    'item' => get_string('deleteallcomments'),
                    'error' => false,
                ];
            }
        }
    }

    // Any changes to the list of dates that needs to be rolled should be same during course restore and course reset.
    // See MDL-9367.
    shift_course_mod_dates('wiki', ['editbegin', 'editend'], $data->timeshift, $data->courseid);
    $status[] = [
        'component' => $componentstr,
        'item' => get_string('date'),
        'error' => false,
    ];

    return $status;
}


function wiki_reset_course_form_definition(&$mform) {
    $mform->addElement('header', 'wikiheader', get_string('modulenameplural', 'wiki'));
    $mform->addElement('static', 'wikidelete', get_string('delete'));
    $mform->addElement('advcheckbox', 'reset_wiki_pages', get_string('deleteallpages', 'wiki'));
    $mform->addElement('advcheckbox', 'reset_wiki_tags', get_string('removeallwikitags', 'wiki'));
    $mform->addElement('advcheckbox', 'reset_wiki_comments', get_string('deleteallcomments'));
}

/**
 * Indicates API features that the wiki supports.
 *
 * @uses FEATURE_GROUPS
 * @uses FEATURE_GROUPINGS
 * @uses FEATURE_MOD_INTRO
 * @uses FEATURE_COMPLETION_TRACKS_VIEWS
 * @uses FEATURE_COMPLETION_HAS_RULES
 * @uses FEATURE_GRADE_HAS_GRADE
 * @uses FEATURE_GRADE_OUTCOMES
 * @param string $feature
 * @return mixed True if module supports feature, false if not, null if doesn't know or string for the module purpose.
 */
function wiki_supports($feature) {
    switch ($feature) {
    case FEATURE_GROUPS:
        return true;
    case FEATURE_GROUPINGS:
        return true;
    case FEATURE_MOD_INTRO:
        return true;
    case FEATURE_COMPLETION_TRACKS_VIEWS:
        return true;
    case FEATURE_GRADE_HAS_GRADE:
        return false;
    case FEATURE_GRADE_OUTCOMES:
        return false;
    case FEATURE_RATE:
        return false;
    case FEATURE_BACKUP_MOODLE2:
        return true;
    case FEATURE_SHOW_DESCRIPTION:
        return true;
    case FEATURE_COMMENT:
        return true;
    case FEATURE_MOD_PURPOSE:
        return MOD_PURPOSE_COLLABORATION;

    default:
        return null;
    }
}

/**
 * Given a course and a time, this module should find recent activity
 * that has occurred in wiki activities and print it out.
 * Return true if there was output, or false is there was none.
 *
 * @global $CFG
 * @global $DB
 * @uses CONTEXT_MODULE
 * @uses VISIBLEGROUPS
 * @param object $course
 * @param bool $viewfullnames capability
 * @param int $timestart
 * @return boolean
 **/
function wiki_print_recent_activity($course, $viewfullnames, $timestart) {
    global $CFG, $DB, $OUTPUT;

    $sql = "SELECT p.id, p.timemodified, p.subwikiid, sw.wikiid, w.wikimode, sw.userid, sw.groupid
            FROM {wiki_pages} p
                JOIN {wiki_subwikis} sw ON sw.id = p.subwikiid
                JOIN {wiki} w ON w.id = sw.wikiid
            WHERE p.timemodified > ? AND w.course = ?
            ORDER BY p.timemodified ASC";
    if (!$pages = $DB->get_records_sql($sql, array($timestart, $course->id))) {
        return false;
    }
    require_once($CFG->dirroot . "/mod/wiki/locallib.php");

    $wikis = array();

    $modinfo = get_fast_modinfo($course);

    $subwikivisible = array();
    foreach ($pages as $page) {
        if (!isset($subwikivisible[$page->subwikiid])) {
            $subwiki = (object)array('id' => $page->subwikiid, 'wikiid' => $page->wikiid,
                'groupid' => $page->groupid, 'userid' => $page->userid);
            $wiki = (object)array('id' => $page->wikiid, 'course' => $course->id, 'wikimode' => $page->wikimode);
            $subwikivisible[$page->subwikiid] = wiki_user_can_view($subwiki, $wiki);
        }
        if ($subwikivisible[$page->subwikiid]) {
            $wikis[] = $page;
        }
    }
    unset($subwikivisible);
    unset($pages);

    if (!$wikis) {
        return false;
    }
    echo $OUTPUT->heading(get_string("updatedwikipages", 'wiki') . ':', 6);
    foreach ($wikis as $wiki) {
        $cm = $modinfo->instances['wiki'][$wiki->wikiid];
        $link = $CFG->wwwroot . '/mod/wiki/view.php?pageid=' . $wiki->id;
        print_recent_activity_note($wiki->timemodified, $wiki, $cm->name, $link, false, $viewfullnames);
    }

    return true; //  True if anything was printed, otherwise false
}

/**
 * Must return an array of grades for a given instance of this module,
 * indexed by user.  It also returns a maximum allowed grade.
 *
 * Example:
 *    $return->grades = array of grades;
 *    $return->maxgrade = maximum allowed grade;
 *
 *    return $return;
 *
 * @param int $wikiid ID of an instance of this module
 * @return mixed Null or object with an array of grades and with the maximum grade
 **/
function wiki_grades($wikiid) {
    return null;
}

/**
 * @deprecated since Moodle 3.8
 */
function wiki_scale_used() {
    throw new coding_exception('wiki_scale_used() can not be used anymore. Plugins can implement ' .
        '<modname>_scale_used_anywhere, all implementations of <modname>_scale_used are now ignored');
}

/**
 * Checks if scale is being used by any instance of wiki.
 * This function was added in 1.9
 *
 * This is used to find out if scale used anywhere
 * @param $scaleid int
 * @return boolean True if the scale is used by any wiki
 */
function wiki_scale_used_anywhere($scaleid) {
    global $DB;

    //if ($scaleid and $DB->record_exists('wiki', array('grade' => -$scaleid))) {
    //    return true;
    //} else {
    //    return false;
    //}

    return false;
}

/**
 * file serving callback
 *
 * @copyright Josep Arus
 * @package  mod_wiki
 * @category files
 * @param stdClass $course course object
 * @param stdClass $cm course module object
 * @param stdClass $context context object
 * @param string $filearea file area
 * @param array $args extra arguments
 * @param bool $forcedownload whether or not force download
 * @param array $options additional options affecting the file serving
 * @return bool false if the file was not found, just send the file otherwise and do not return anything
 */
function wiki_pluginfile($course, $cm, $context, $filearea, $args, $forcedownload, array $options=array()) {
    global $CFG;

    if ($context->contextlevel != CONTEXT_MODULE) {
        return false;
    }

    require_login($course, true, $cm);

    require_once($CFG->dirroot . "/mod/wiki/locallib.php");

    if ($filearea == 'attachments') {
        $swid = (int) array_shift($args);

        if (!$subwiki = wiki_get_subwiki($swid)) {
            return false;
        }

        require_capability('mod/wiki:viewpage', $context);

        $relativepath = implode('/', $args);

        $fullpath = "/$context->id/mod_wiki/attachments/$swid/$relativepath";

        $fs = get_file_storage();
        if (!$file = $fs->get_file_by_hash(sha1($fullpath)) or $file->is_directory()) {
            return false;
        }

        send_stored_file($file, null, 0, $options);
    }
}

/**
 * Search for wiki
 *
 * @param stdClass $cm course module object
 * @param string $search searchword.
 * @param stdClass $subwiki Optional Subwiki.
 * @return Search wiki input form
 */
function wiki_search_form($cm, $search = '', $subwiki = null) {
    global $OUTPUT;

    $hiddenfields = [
        (object) ['type' => 'hidden', 'name' => 'courseid', 'value' => $cm->course],
        (object) ['type' => 'hidden', 'name' => 'cmid', 'value' => $cm->id],
        (object) ['type' => 'hidden', 'name' => 'searchwikicontent', 'value' => 1],
    ];
    if (!empty($subwiki->id)) {
        $hiddenfields[] = (object) ['type' => 'hidden', 'name' => 'subwikiid', 'value' => $subwiki->id];
    }
    $data = [
        'action' => new moodle_url('/mod/wiki/search.php'),
        'hiddenfields' => $hiddenfields,
        'inputname' => 'searchstring',
        'query' => s($search, true),
        'searchstring' => get_string('searchwikis', 'wiki'),
        'extraclasses' => 'mt-2'
    ];
    return $OUTPUT->render_from_template('core/search_input', $data);
}

/**
 * Extends the global navigation tree by adding wiki nodes if there is a relevant content
 *
 * This can be called by an AJAX request so do not rely on $PAGE as it might not be set up properly.
 *
 * @param navigation_node $navref An object representing the navigation tree node of the workshop module instance
 * @param stdClass $course the course object
 * @param stdClass $instance the activity record object
 * @param cm_info $cm the course module object
 */
function wiki_extend_navigation(navigation_node $navref, stdClass $course, stdClass $instance, cm_info $cm) {
    global $CFG, $USER;

    require_once($CFG->dirroot . '/mod/wiki/locallib.php');

    $context = context_module::instance($cm->id);
    $userid = ($instance->wikimode == 'individual') ? $USER->id : 0;
    $gid = groups_get_activity_group($cm) ?: 0;

    if (!$subwiki = wiki_get_subwiki_by_group($cm->instance, $gid, $userid)) {
        return;
    }

    $pageid = optional_param('pageid', null, PARAM_INT);
    if (empty($pageid)) {
        // wiki main page
        $page = wiki_get_page_by_title($subwiki->id, $instance->firstpagetitle);
        $pageid = $page->id;
    }

    if (wiki_can_create_pages($context)) {
        $link = new moodle_url('/mod/wiki/create.php', ['action' => 'new', 'swid' => $subwiki->id]);
        $navref->add(get_string('newpage', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }

    if (empty($pageid)) {
        return;
    }

    $canviewpage = has_capability('mod/wiki:viewpage', $context);

    if ($canviewpage) {
        $link = new moodle_url('/mod/wiki/view.php', ['pageid' => $pageid]);
        $navref->add(get_string('view', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }

    if (wiki_user_can_edit($subwiki)) {
        $link = new moodle_url('/mod/wiki/edit.php', ['pageid' => $pageid]);
        $navref->add(get_string('edit', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }

    if (has_capability('mod/wiki:viewcomment', $context)) {
        $link = new moodle_url('/mod/wiki/comments.php', ['pageid' => $pageid]);
        $navref->add(get_string('comments', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }

    if ($canviewpage) {
        $link = new moodle_url('/mod/wiki/history.php', ['pageid' => $pageid]);
        $navref->add(get_string('history', 'wiki'), $link, navigation_node::TYPE_SETTING);

        $link = new moodle_url('/mod/wiki/map.php', ['pageid' => $pageid]);
        $navref->add(get_string('map', 'wiki'), $link, navigation_node::TYPE_SETTING);

        $link = new moodle_url('/mod/wiki/files.php', ['pageid' => $pageid]);
        $navref->add(get_string('files', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }

    if (has_capability('mod/wiki:managewiki', $context)) {
        $link = new moodle_url('/mod/wiki/admin.php', ['pageid' => $pageid]);
        $navref->add(get_string('admin', 'wiki'), $link, navigation_node::TYPE_SETTING);
    }
}
/**
 * Returns all other caps used in wiki module
 *
 * @return array
 */
function wiki_get_extra_capabilities() {
    return array('moodle/comment:view', 'moodle/comment:post', 'moodle/comment:delete');
}

/**
 * Running addtional permission check on plugin, for example, plugins
 * may have switch to turn on/off comments option, this callback will
 * affect UI display, not like pluginname_comment_validate only throw
 * exceptions.
 * Capability check has been done in comment->check_permissions(), we
 * don't need to do it again here.
 *
 * @package  mod_wiki
 * @category comment
 *
 * @param stdClass $comment_param {
 *              context  => context the context object
 *              courseid => int course id
 *              cm       => stdClass course module object
 *              commentarea => string comment area
 *              itemid      => int itemid
 * }
 * @return array
 */
function wiki_comment_permissions($comment_param) {
    return array('post'=>true, 'view'=>true);
}

/**
 * Validate comment parameter before perform other comments actions
 *
 * @param stdClass $comment_param {
 *              context  => context the context object
 *              courseid => int course id
 *              cm       => stdClass course module object
 *              commentarea => string comment area
 *              itemid      => int itemid
 * }
 *
 * @package  mod_wiki
 * @category comment
 *
 * @return boolean
 */
function wiki_comment_validate($comment_param) {
    global $DB, $CFG;
    require_once($CFG->dirroot . '/mod/wiki/locallib.php');
    // validate comment area
    if ($comment_param->commentarea != 'wiki_page') {
        throw new comment_exception('invalidcommentarea');
    }
    // validate itemid
    if (!$record = $DB->get_record('wiki_pages', array('id'=>$comment_param->itemid))) {
        throw new comment_exception('invalidcommentitemid');
    }
    if (!$subwiki = wiki_get_subwiki($record->subwikiid)) {
        throw new comment_exception('invalidsubwikiid');
    }
    if (!$wiki = wiki_get_wiki_from_pageid($comment_param->itemid)) {
        throw new comment_exception('invalidid', 'data');
    }
    if (!$course = $DB->get_record('course', array('id'=>$wiki->course))) {
        throw new comment_exception('coursemisconf');
    }
    if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id, $course->id)) {
        throw new comment_exception('invalidcoursemodule');
    }
    $context = context_module::instance($cm->id);
    // group access
    if ($subwiki->groupid) {
        $groupmode = groups_get_activity_groupmode($cm, $course);
        if ($groupmode == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {
            if (!groups_is_member($subwiki->groupid)) {
                throw new comment_exception('notmemberofgroup');
            }
        }
    }
    // validate context id
    if ($context->id != $comment_param->context->id) {
        throw new comment_exception('invalidcontext');
    }
    // validation for comment deletion
    if (!empty($comment_param->commentid)) {
        if ($comment = $DB->get_record('comments', array('id'=>$comment_param->commentid))) {
            if ($comment->commentarea != 'wiki_page') {
                throw new comment_exception('invalidcommentarea');
            }
            if ($comment->contextid != $context->id) {
                throw new comment_exception('invalidcontext');
            }
            if ($comment->itemid != $comment_param->itemid) {
                throw new comment_exception('invalidcommentitemid');
            }
        } else {
            throw new comment_exception('invalidcommentid');
        }
    }
    return true;
}

/**
 * Return a list of page types
 * @param string $pagetype current page type
 * @param stdClass $parentcontext Block's parent context
 * @param stdClass $currentcontext Current context of block
 */
function wiki_page_type_list($pagetype, $parentcontext, $currentcontext) {
    $module_pagetype = array(
        'mod-wiki-*'=>get_string('page-mod-wiki-x', 'wiki'),
        'mod-wiki-view'=>get_string('page-mod-wiki-view', 'wiki'),
        'mod-wiki-comments'=>get_string('page-mod-wiki-comments', 'wiki'),
        'mod-wiki-history'=>get_string('page-mod-wiki-history', 'wiki'),
        'mod-wiki-map'=>get_string('page-mod-wiki-map', 'wiki')
    );
    return $module_pagetype;
}

/**
 * Mark the activity completed (if required) and trigger the course_module_viewed event.
 *
 * @param  stdClass $wiki       Wiki object.
 * @param  stdClass $course     Course object.
 * @param  stdClass $cm         Course module object.
 * @param  stdClass $context    Context object.
 * @since Moodle 3.1
 */
function wiki_view($wiki, $course, $cm, $context) {
    // Trigger course_module_viewed event.
    $params = array(
        'context' => $context,
        'objectid' => $wiki->id
    );
    $event = \mod_wiki\event\course_module_viewed::create($params);
    $event->add_record_snapshot('course_modules', $cm);
    $event->add_record_snapshot('course', $course);
    $event->add_record_snapshot('wiki', $wiki);
    $event->trigger();

    // Completion.
    $completion = new completion_info($course);
    $completion->set_module_viewed($cm);
}

/**
 * Mark the activity completed (if required) and trigger the page_viewed event.
 *
 * @param  stdClass $wiki       Wiki object.
 * @param  stdClass $page       Page object.
 * @param  stdClass $course     Course object.
 * @param  stdClass $cm         Course module object.
 * @param  stdClass $context    Context object.
 * @param  int $uid             Optional User ID.
 * @param  array $other         Optional Other params: title, wiki ID, group ID, groupanduser, prettyview.
 * @param  stdClass $subwiki    Optional Subwiki.
 * @since Moodle 3.1
 */
function wiki_page_view($wiki, $page, $course, $cm, $context, $uid = null, $other = null, $subwiki = null) {

    // Trigger course_module_viewed event.
    $params = array(
        'context' => $context,
        'objectid' => $page->id
    );
    if ($uid != null) {
        $params['relateduserid'] = $uid;
    }
    if ($other != null) {
        $params['other'] = $other;
    }

    $event = \mod_wiki\event\page_viewed::create($params);

    $event->add_record_snapshot('wiki_pages', $page);
    $event->add_record_snapshot('course_modules', $cm);
    $event->add_record_snapshot('course', $course);
    $event->add_record_snapshot('wiki', $wiki);
    if ($subwiki != null) {
        $event->add_record_snapshot('wiki_subwikis', $subwiki);
    }
    $event->trigger();

    // Completion.
    $completion = new completion_info($course);
    $completion->set_module_viewed($cm);
}

/**
 * Check if the module has any update that affects the current user since a given time.
 *
 * @param  cm_info $cm course module data
 * @param  int $from the time to check updates from
 * @param  array $filter  if we need to check only specific updates
 * @return stdClass an object with the different type of areas indicating if they were updated or not
 * @since Moodle 3.2
 */
function wiki_check_updates_since(cm_info $cm, $from, $filter = array()) {
    global $DB, $CFG;
    require_once($CFG->dirroot . '/mod/wiki/locallib.php');

    $updates = new stdClass();
    if (!has_capability('mod/wiki:viewpage', $cm->context)) {
        return $updates;
    }
    $updates = course_check_module_updates_since($cm, $from, array('attachments'), $filter);

    // Check only pages updated in subwikis the user can access.
    $updates->pages = (object) array('updated' => false);
    $wiki = $DB->get_record($cm->modname, array('id' => $cm->instance), '*', MUST_EXIST);
    if ($subwikis = wiki_get_visible_subwikis($wiki, $cm, $cm->context)) {
        $subwikisids = array();
        foreach ($subwikis as $subwiki) {
            $subwikisids[] = $subwiki->id;
        }
        list($subwikissql, $params) = $DB->get_in_or_equal($subwikisids, SQL_PARAMS_NAMED);
        $select = 'subwikiid ' . $subwikissql . ' AND (timemodified > :since1 OR timecreated > :since2)';
        $params['since1'] = $from;
        $params['since2'] = $from;
        $pages = $DB->get_records_select('wiki_pages', $select, $params, '', 'id');
        if (!empty($pages)) {
            $updates->pages->updated = true;
            $updates->pages->itemids = array_keys($pages);
        }
    }
    return $updates;
}

/**
 * Get icon mapping for font-awesome.
 */
function mod_wiki_get_fontawesome_icon_map() {
    return [
        'mod_wiki:attachment' => 'fa-paperclip',
    ];
}

/**
 * This function receives a calendar event and returns the action associated with it, or null if there is none.
 *
 * This is used by block_myoverview in order to display the event appropriately. If null is returned then the event
 * is not displayed on the block.
 *
 * @param calendar_event $event
 * @param \core_calendar\action_factory $factory
 * @param int $userid User id to use for all capability checks, etc. Set to 0 for current user (default).
 * @return \core_calendar\local\event\entities\action_interface|null
 */
function mod_wiki_core_calendar_provide_event_action(calendar_event $event,
                                                    \core_calendar\action_factory $factory,
                                                    int $userid = 0) {
    global $USER;

    if (!$userid) {
        $userid = $USER->id;
    }

    $cm = get_fast_modinfo($event->courseid, $userid)->instances['wiki'][$event->instance];

    if (!$cm->uservisible) {
        // The module is not visible to the user for any reason.
        return null;
    }

    $completion = new \completion_info($cm->get_course());

    $completiondata = $completion->get_data($cm, false, $userid);

    if ($completiondata->completionstate != COMPLETION_INCOMPLETE) {
        return null;
    }

    return $factory->create_instance(
        get_string('view'),
        new \moodle_url('/mod/wiki/view.php', ['id' => $cm->id]),
        1,
        true
    );
}

/**
 * Sets dynamic information about a course module
 *
 * This callback is called from cm_info when checking module availability (incl. $cm->uservisible)
 *
 * Main viewing capability in mod_wiki is 'mod/wiki:viewpage' instead of the expected standardised 'mod/wiki:view'.
 * The method cm_info::is_user_access_restricted_by_capability() does not work for wiki, we need to implement
 * this callback.
 *
 * @param cm_info $cm
 */
function wiki_cm_info_dynamic(cm_info $cm) {
    if (!has_capability('mod/wiki:viewpage', $cm->context, $cm->get_modinfo()->get_user_id())) {
        $cm->set_available(false);
    }
}