Airship\Engine\Security\Permissions::can PHP Method

    public function can(string $action, string $context_path = '', string $cabin = \CABIN_NAME, int $user_id = 0) : bool
    {
        $state = State::instance();
        if (empty($cabin)) {
            $cabin = \CABIN_NAME;
        }
        // If you don't specify the user ID to check, it will use the current
        // user ID instead, by default.
        if (empty($user_id)) {
            if (!empty($_SESSION['userid'])) {
                $user_id = (int) $_SESSION['userid'];
            }
        }
        // If you're a super-user, the answer is "yes, yes you can".
        if ($this->isSuperUser($user_id)) {
            return true;
        }
        $allowed = false;
        $failed_one = false;
        // Get all applicable contexts
        $contexts = self::getOverlap($context_path, $cabin);
        if (empty($contexts)) {
            // Sane default: In the absence of permissions, return false
            return false;
        }
        if ($user_id > 0) {
            // You need to be allowed in every relevant context.
            foreach ($contexts as $c_id) {
                if (self::checkUser($action, $c_id, $user_id) || self::checkUsersGroups($action, $c_id, $user_id)) {
                    $allowed = true;
                } else {
                    $failed_one = true;
                }
            }
        } else {
            if (!$state->universal['guest_groups']) {
                return false;
            }
            // Guests can be assigned to groups. This fails closed if they aren't given any.
            foreach ($contexts as $c_id) {
                $ctx_res = false;
                foreach ($state->universal['guest_groups'] as $grp) {
                    if (self::checkGroup($action, $c_id, $grp)) {
                        $ctx_res = true;
                    }
                }
                if ($ctx_res) {
                    $allowed = true;
                } else {
                    $failed_one = true;
                }
            }
        }
        // We return true if we were allowed at least once and we did not fail
        // in one of the overlapping contexts
        return $allowed && !$failed_one;
    }