Support refreshtokens in OAuth flow (#2749)

* Support refreshtokens in OAuth flow
Fixes #2731

* Added summary to OauthToken.cs constructors

* Mark deprecation of non-refreshToken constructor for OauthToken

* Remove unnecessary comment

---------

Co-authored-by: Keegan Campbell <me@kfcampbell.com>

Octokit/Models/Request/OauthTokenRenewalRequest.cs

@@ -0,0 +1,67 @@
+using System.Diagnostics;
+using System.Globalization;
+using Octokit.Internal;
+
+namespace Octokit
+{
+    /// <summary>
+    /// Used to create an Oauth login request.
+    /// </summary>
+    [DebuggerDisplay("{DebuggerDisplay,nq}")]
+    public class OauthTokenRenewalRequest : RequestParameters
+    {
+        /// <summary>
+        /// Creates an instance of the OAuth token refresh request.
+        /// </summary>
+        /// <param name="clientId">The client Id you received from GitHub when you registered the application.</param>
+        /// <param name="clientSecret">The client secret you received from GitHub when you registered.</param>
+        /// <param name="refreshToken">The refresh token you received when making the original oauth token request.</param>
+        public OauthTokenRenewalRequest(string clientId, string clientSecret, string refreshToken)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(clientId, nameof(clientId));
+            Ensure.ArgumentNotNullOrEmptyString(clientSecret, nameof(clientSecret));
+            Ensure.ArgumentNotNullOrEmptyString(refreshToken, nameof(refreshToken));
+
+            ClientId = clientId;
+            ClientSecret = clientSecret;
+            RefreshToken = refreshToken;
+        }
+
+        /// <summary>
+        /// The client Id you received from GitHub when you registered the application.
+        /// </summary>
+        [Parameter(Key = "client_id")]
+        public string ClientId { get; private set; }
+
+        /// <summary>
+        /// The client secret you received from GitHub when you registered.
+        /// </summary>
+        [Parameter(Key = "client_secret")]
+        public string ClientSecret { get; private set; }
+
+        /// <summary>
+        /// The type of grant. Should be ommited, unless renewing an access token.
+        /// </summary>
+        [Parameter(Key = "grant_type")]
+        public string GrantType { get; private set; } = "refresh_token";
+
+        /// <summary>
+        /// The refresh token you received as a response to making the <see cref="IOauthClient.CreateAccessToken">OAuth login
+        /// request</see>.
+        /// </summary>
+        [Parameter(Key = "refresh_token")]
+        public string RefreshToken { get; private set; }
+
+        internal string DebuggerDisplay
+        {
+            get
+            {
+                return string.Format(CultureInfo.InvariantCulture, "ClientId: {0}, ClientSecret: {1}, GrantType: {2}, RefreshToken: {3}",
+                    ClientId,
+                    ClientSecret,
+                    GrantType,
+                    RefreshToken);
+            }
+        }
+    }
+}

Octokit/Models/Response/OauthToken.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
 using Octokit.Internal;
@@ -10,6 +11,17 @@ namespace Octokit
     {
         public OauthToken() { }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OauthToken"/> class.
+        /// Use this constructor when you don't have a refreshToken.
+        /// </summary>
+        /// <param name="tokenType">The type of token returned by GitHub.</param>
+        /// <param name="accessToken">The access token returned by GitHub.</param>
+        /// <param name="scope">The auhtorization scope of the returned token.</param>
+        /// <param name="error">The error code returned by the GitHub API.</param>
+        /// <param name="errorDescription">The error message, if any, returned by the GitHub API.</param>
+        /// <param name="errorUri">The GitHub documentation link, detailing the error message.</param>
+        [Obsolete("This constructor is being deprecated and will be removed in the future. Use OauthToken.OauthToken (with refreshToken paramters) instead.")]
         public OauthToken(string tokenType, string accessToken, IReadOnlyList<string> scope, string error, string errorDescription, string errorUri)
         {
             this.TokenType = tokenType;
@@ -20,6 +32,32 @@ namespace Octokit
             this.ErrorUri = errorUri;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OauthToken"/> class.
+        /// Use this constructor by default.
+        /// </summary>
+        /// <param name="tokenType">The type of token returned by GitHub.</param>
+        /// <param name="accessToken">The access token returned by GitHub.</param>
+        /// <param name="expiresIn">The amount of seconds, before the access token expires.</param>
+        /// <param name="refreshToken">The refresh token returned by GitHub. Use this, to get a new access token if it expires.</param>
+        /// <param name="refreshTokenExpiresIn">The amount of seconds, before the refresh token expires.</param>
+        /// <param name="scope">The auhtorization scope of the returned token.</param>
+        /// <param name="error">The error code returned by the GitHub API.</param>
+        /// <param name="errorDescription">The error message, if any, returned by the GitHub API.</param>
+        /// <param name="errorUri">The GitHub documentation link, detailing the error message.</param>
+        public OauthToken(string tokenType, string accessToken, int expiresIn, string refreshToken, int refreshTokenExpiresIn, IReadOnlyList<string> scope, string error, string errorDescription, string errorUri)
+        {
+            this.TokenType = tokenType;
+            this.AccessToken = accessToken;
+            this.ExpiresIn = expiresIn;
+            this.RefreshToken = refreshToken;
+            this.RefreshTokenExpiresIn = refreshTokenExpiresIn;
+            this.Scope = scope;
+            this.Error = error;
+            this.ErrorDescription = errorDescription;
+            this.ErrorUri = errorUri;
+        }
+
         /// <summary>
         /// The type of OAuth token
         /// </summary>
@@ -30,6 +68,25 @@ namespace Octokit
         /// </summary>
         public string AccessToken { get; private set; }
 
+        /// <summary>
+        /// The amount of seconds, until the acces token expires.
+        /// </summary>
+        [Parameter(Key = "expires_in")]
+        public int ExpiresIn { get; private set; }
+
+        /// <summary>
+        /// The secret refresh token.
+        /// Use this to get a new access token, without going through the OAuth flow again.
+        /// </summary>
+        [Parameter(Key = "refresh_token")]
+        public string RefreshToken { get; private set; }
+
+        /// <summary>
+        /// The amount of seconds, until the refresh token expires.
+        /// </summary>
+        [Parameter(Key = "refresh_token_expires_in")]
+        public int RefreshTokenExpiresIn { get; private set; }
+
         /// <summary>
         /// The list of scopes the token includes.
         /// </summary>