1 files changed, 133 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.Web/Clients/OAuth2/OAuth2Client.cs b/src/DotNetOpenAuth.Web/Clients/OAuth2/OAuth2Client.cs
new file mode 100644
index 0000000..9920065
--- /dev/null
+++ b/src/DotNetOpenAuth.Web/Clients/OAuth2/OAuth2Client.cs
@@ -0,0 +1,133 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Web;
+
+namespace DotNetOpenAuth.Web.Clients
+{
+    /// <summary>
+    /// Represents the base class for OAuth 2.0 clients
+    /// </summary>
+    public abstract class OAuth2Client : IAuthenticationClient
+    {
+        private readonly string _providerName;
+        private Uri _returnUrl;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OAuth2Client"/> class with the specified provider name.
+        /// </summary>
+        /// <param name="providerName">Name of the provider.</param>
+        protected OAuth2Client(string providerName)
+        {
+            if (providerName == null)
+            {
+                throw new ArgumentNullException("providerName");
+            }
+
+            _providerName = providerName;
+        }
+
+        /// <summary>
+        /// Gets the name of the provider which provides authentication service.
+        /// </summary>
+        public string ProviderName
+        {
+            get { return _providerName; }
+        }
+
+        /// <summary>
+        /// Attempts to authenticate users by forwarding them to an external website, and
+        /// upon succcess or failure, redirect users back to the specified url.
+        /// </summary>
+        /// <param name="returnUrl">The return url after users have completed authenticating against external website.</param>
+        public virtual void RequestAuthentication(HttpContextBase context, Uri returnUrl)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException("context");
+            }
+
+            if (returnUrl == null)
+            {
+                throw new ArgumentNullException("returnUrl");
+            }
+
+            _returnUrl = returnUrl;
+
+            string redirectUrl = GetServiceLoginUrl(returnUrl).ToString();
+            context.Response.Redirect(redirectUrl, endResponse: true);
+        }
+
+        /// <summary>
+        /// Check if authentication succeeded after user is redirected back from the service provider.
+        /// </summary>
+        /// <returns>
+        /// An instance of <see cref="AuthenticationResult"/> containing authentication result.
+        /// </returns>
+        public virtual AuthenticationResult VerifyAuthentication(HttpContextBase context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException("context");
+            }
+
+            string code = context.Request.QueryString["code"];
+            if (String.IsNullOrEmpty(code))
+            {
+                return AuthenticationResult.Failed;
+            }
+
+            string accessToken = QueryAccessToken(_returnUrl, code);
+            if (accessToken == null)
+            {
+                return AuthenticationResult.Failed;
+            }
+
+            IDictionary<string, string> userData = GetUserData(accessToken);
+            if (userData == null)
+            {
+                return AuthenticationResult.Failed;
+            }
+            string id = userData["id"];
+            string name;
+            // Some oAuth providers do not return value for the 'username' attribute. 
+            // In that case, try the 'name' attribute. If it's still unavailable, fall back to 'id'
+            if (!userData.TryGetValue("username", out name) && !userData.TryGetValue("name", out name))
+            {
+                name = id;
+            }
+
+            return new AuthenticationResult(
+                isSuccessful: true,
+                provider: ProviderName,
+                providerUserId: id,
+                userName: name,
+                extraData: userData);
+        }
+
+        /// <summary>
+        /// Gets the full url pointing to the login page for this client. The url should include the 
+        /// specified return url so that when the login completes, user is redirected back to that url.
+        /// </summary>
+        /// <param name="returnUrl">The return URL.</param>
+        /// <returns></returns>
+        [SuppressMessage("Microsoft.Naming", "CA1726:UsePreferredTerms", MessageId = "Login", Justification = "Login is used more consistently in ASP.Net")]
+        protected abstract Uri GetServiceLoginUrl(Uri returnUrl);
+
+        /// <summary>
+        /// Queries the access token from the specified authorization code.
+        /// </summary>
+        /// <param name="returnUrl">The return URL.</param>
+        /// <param name="authorizationCode">The authorization code.</param>
+        /// <returns></returns>
+        protected abstract string QueryAccessToken(Uri returnUrl, string authorizationCode);
+
+        /// <summary>
+        /// Given the access token, gets the logged-in user's data. The returned dictionary must include
+        /// two keys 'id', and 'username'.
+        /// </summary>
+        /// <param name="accessToken">The access token of the current user.</param>
+        /// <returns>A dictionary contains key-value pairs of user data</returns>
+        protected abstract IDictionary<string, string> GetUserData(string accessToken);
+    }
+}
+\ No newline at end of file