<?php
/*
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Google\Auth;

/**
 * Describes a Credentials object which supports fetching the project ID.
 */
interface ProjectIdProviderInterface
{
    /**
     * Get the project ID.
     *
     * @param callable|null $httpHandler Callback which delivers psr7 request
     * @return string|null
     */
    public function getProjectId(?callable $httpHandler = null);
}