Show only those with whom you have mutual friends?

Question

PHP

Good afternoon, there is a block to show randomly possible friends, but it would be better to show those with whom there are mutual friends, how can it be implemented?
fields in the table

Function for displaying possible friends

function relationship_suggest($limit, $refId = null, $only_people = true) {
    $ignoredUsers = mostIgnoredUsers();
    $refId = ($refId) ? $refId : get_userid();

    $whereClause = "";

    $ignoredUsers = array_merge($ignoredUsers, get_friends($refId));
    $ignoredUsers = array_merge($ignoredUsers, get_requested_friends($refId));
    $friendsFriends = get_friends_of_friend($refId);
    if ($friendsFriends) {
        $friendsFriends = implode(',', $friendsFriends);
        $whereClause .= "id IN({$friendsFriends}) ";
    }

    //$followersFollowing = get_following_following($refId);
    $ignoredUsers = array_merge($ignoredUsers, get_following($refId));

    $userCountry = get_user_data('country');
    $userCity = get_user_data('city');
    $userState = get_user_data('state');
    $whereClause .= ($whereClause) ? " OR `country`='{$userCountry}' OR `city`='{$userCity}' OR `state`='{$userState}' OR avatar !=''": "`country`='{$userCountry}' OR `city`='{$userCity}' OR `state`='{$userState}' OR avatar !=''";
    $whereClause = fire_hook('users.suggestion.sql', $whereClause);
    $after_whereClause = "";
    $after_whereClause = fire_hook('users.category.filter',$after_whereClause,array($after_whereClause, true));
    $ignoredUsers = implode(',', array_merge(array($refId), $ignoredUsers));
    $mutual = array();
     $loggedInFriends = get_friends();
     $userid = get_userid();
    $thisUserFriends = get_friends($userid);
    if (is_array($thisUserFriends)) {
        foreach($thisUserFriends as $f) {
            if (in_array($f, $loggedInFriends) and $f != get_userid()) $mutual[] = $f;
        }
    }
    $fields = get_users_fields();


    $query = "SELECT {$fields} FROM `users` WHERE `id`NOT IN({$refId}) AND ({$whereClause}) AND id NOT IN ({$ignoredUsers}) AND activated=1 {$after_whereClause} ORDER BY rand()";
    $query = fire_hook("state.city.suggestions",$query,array($fields,$refId,$whereClause,$ignoredUsers));
    if($only_people){

        $query = fire_hook('get.suggest.non.doctors',$query,array($fields,$mutual,$refId,$whereClause,$ignoredUsers));
    }
    //exit($query);
    return paginate($query, $limit);
}

There is also a function that only shows the number of mutual friends

function get_mutual_friends($userid) {
    $loggedInFriends = get_friends();
    $thisUserFriends = get_friends($userid);
    $mutual = array();
    if (is_array($thisUserFriends)) {
        foreach($thisUserFriends as $f) {
            if (in_array($f, $loggedInFriends) and $f != get_userid()) $mutual[] = $f;
        }
    }
    return $mutual;
}

Answer 1

with whom there are mutual friends how to realize

Selection from the table of friends and once again join the same table ("friends of friends"). And then there are all sorts of clarifications on the type of a common city, etc.