Src/Support/Google.Apis.Auth/OAuth2/RequestExtensions.cs

/*
Copyright 2019 Google Inc

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.
*/

using Google.Apis.Http;
using Google.Apis.Requests;
using Google.Apis.Util;
using System;

namespace Google.Apis.Auth.OAuth2
{
    /// <summary>
    /// Extension methods for requests.
    /// </summary>
    public static class RequestExtensions
    {
        /// <summary>
        /// Add a credential that is used for this request only.
        /// This will override a service-level credential (if there is one).
        /// Do not call more than once per request instance, as each call incrementally adds the provided credential.
        /// To perform identical requests but with distinct credentials, create a separate request instance for each credential.
        /// </summary>
        /// <typeparam name="T">The request type.</typeparam>
        /// <param name="request">The request which requires a credential. Must not be null.</param>
        /// <param name="credential">The credential to use for this request only. Must not be null.</param>
        /// <returns></returns>
        public static T AddCredential<T>(this T request, ICredential credential) where T : ClientServiceRequest
        {
            request.ThrowIfNull(nameof(request));
            credential.ThrowIfNull(nameof(credential));
            // Get underlying credential if passed credential is a GoogleCredential.
            if (credential is GoogleCredential googleCredential)
            {
                credential = googleCredential.UnderlyingCredential;
            }
            // Add the required execute interceptor to this request.
            var httpExecuteInterceptor = credential as IHttpExecuteInterceptor;
            if (httpExecuteInterceptor == null)
            {
                throw new ArgumentException("Credential must implement IHttpExecuteInterceptor.", nameof(credential));
            }
            request.Credential = httpExecuteInterceptor;

            return request;
        }
    }
}