Proyectos de Subversion Moodle

<?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/>.

/**

 * Group visibility methods

 *

 * @package   core_group

 * @copyright 2022 onwards Catalyst IT EU {@link https://catalyst-eu.net}

 * @author    Mark Johnson <mark.johnson@catalyst-eu.net>

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

namespace core_group;

/**

 * Group visibility methods.

 */

class visibility {

    /**

     * Store the number groups with visibility other than ALL on the course.

     *

     * @param int $courseid Course ID to update the cache for.

     * @param \cache|null $cache Existing cache instance. If null, once will be created.

     * @return void

     * @throws \dml_exception

     */

    public static function update_hiddengroups_cache(int $courseid, ?\cache $cache = null): void {

        global $DB;

        if (!$cache) {

            $cache = \cache::make('core', 'coursehiddengroups');

        }

        $hiddengroups = $DB->count_records_select('groups', 'courseid = ? AND visibility != ?',

                [$courseid, GROUPS_VISIBILITY_ALL]);

        $cache->set($courseid, $hiddengroups);

    }

    /**

     * Return whether a course currently had hidden groups.

     *

     * This can be used as a shortcut to decide whether visibility restrictions need to be applied. If this returns false,

     * we may be able to use cached data, or do a much simpler query.

     *

     * @param int $courseid

     * @return bool

     * @throws \coding_exception

     * @throws \dml_exception

     */

    public static function course_has_hidden_groups(int $courseid): bool {

        $cache = \cache::make('core', 'coursehiddengroups');

        $hiddengroups = $cache->get($courseid);

        if ($hiddengroups === false) {

            self::update_hiddengroups_cache($courseid, $cache);

            $cache->get($courseid);

        }

        return $hiddengroups > 0;

    }

    /**

     * Can the current user view all the groups on the course?

     *

     * Returns true if there are no groups on the course with visibility != ALL,

     * or if the user has viewhiddengroups.

     *

     * This is useful for deciding whether we need to perform additional visibility checkes

     * such as the sql_* methods of this class.

     *

     * @param int $courseid

     * @return bool

     */

    public static function can_view_all_groups(int $courseid): bool {

        $viewhidden = has_capability('moodle/course:viewhiddengroups', \context_course::instance($courseid));

        $hashidden = self::course_has_hidden_groups($courseid);

        return $viewhidden || !$hashidden;

    }

    /**

     * Return SQL conditions for determining whether a user can see a group and its memberships.

     *

     * @param int $userid

     * @param string $groupsalias The SQL alias being used for the groups table.

     * @param string $groupsmembersalias The SQL alias being used for the groups_members table.

     * @return array [$where, $params]

     */

    public static function sql_group_visibility_where(int $userid,

            string $groupsalias = 'g', string $groupsmembersalias = 'gm'): array {

        global $USER;

        // Apply visibility restrictions.

        // Everyone can see who is in groups with ALL visibility.

        $where = "({$groupsalias}.visibility = :all";

        $params['all'] = GROUPS_VISIBILITY_ALL;

        if ($userid == $USER->id) {

            // If the user is looking at their own groups, they can see those with MEMBERS or OWN visibility.

            $where .= " OR {$groupsalias}.visibility IN (:members, :own)";

            $params['members'] = GROUPS_VISIBILITY_MEMBERS;

            $params['own'] = GROUPS_VISIBILITY_OWN;

        } else {

            list($memberssql, $membersparams) = self::sql_members_visibility_condition($groupsalias, $groupsmembersalias);

            // If someone else's groups, they can see those with MEMBERS visibilty, only if they are a member too.

            $where .= " OR ($memberssql)";

            $params = array_merge($params, $membersparams);

        }

        $where .= ")";

        return [$where, $params];

    }

    /**

     * Return SQL conditions for determining whether a user can see a group's members.

     *

     * @param string $groupsalias The SQL alias being used for the groups table.

     * @param string $groupsmembersalias The SQL alias being used for the groups_members table.

     * @param string $useralias The SQL alias being used for the user table.

     * @param string $paramprefix Prefix for the parameter names.

     * @return array [$where, $params]

     */

    public static function sql_member_visibility_where(

        string $groupsalias = 'g',

        string $groupsmembersalias = 'gm',

        string $useralias = 'u',

        string $paramprefix = '',

    ): array {

        global $USER;

        list($memberssql, $membersparams) = self::sql_members_visibility_condition($groupsalias, $groupsmembersalias, $paramprefix);

        $where = "(

            {$groupsalias}.visibility = :{$paramprefix}all

            OR ($memberssql)

            OR ({$groupsalias}.visibility = :{$paramprefix}own AND {$useralias}.id = :{$paramprefix}currentuser2)

        )";

        $params = [

            "{$paramprefix}all" => GROUPS_VISIBILITY_ALL,

            "{$paramprefix}own" => GROUPS_VISIBILITY_OWN,

            "{$paramprefix}currentuser2" => $USER->id,

        ];

        $params = array_merge($params, $membersparams);

        return [$where, $params];

    }

    /**

     * Return a condition to check if a user can view a group because it has MEMBERS visibility and they are a member.

     *

     * @param string $groupsalias The SQL alias being used for the groups table.

     * @param string $groupsmembersalias The SQL alias being used for the groups_members table.

     * @param string $paramprefix Prefix for the parameter names.

     * @return array [$sql, $params]

     */

    protected static function sql_members_visibility_condition(

        string $groupsalias = 'g',

        string $groupsmembersalias = 'gm',

        string $paramprefix = '',

    ): array {

        global $USER;

        $sql = "{$groupsalias}.visibility = :{$paramprefix}members

                    AND (

                        SELECT gm2.id

                          FROM {groups_members} gm2

                         WHERE gm2.groupid = {$groupsmembersalias}.groupid

                               AND gm2.userid = :{$paramprefix}currentuser

                    ) IS NOT NULL";

        $params = [

            "{$paramprefix}members" => GROUPS_VISIBILITY_MEMBERS,

            "{$paramprefix}currentuser" => $USER->id

        ];

        return [$sql, $params];

    }

}