feat: twitch api look up twitch users

Author: ProgrammingByPermutation

src/Nullinside.Api.Common/Twitch/ITwitchApiProxy.cs

@@ -48,9 +48,17 @@ public interface ITwitchApiProxy {
   ///   Gets the twitch id and username of the owner of the <see cref="OAuth" />.
   /// </summary>
   /// <param name="token">The cancellation token.</param>
-  /// <returns>The twitch username if successful, null otherwise.</returns>
+  /// <returns>The twitch user information if successful, null otherwise.</returns>
   Task<(string? id, string? username)> GetUser(CancellationToken token = new());
 
+  /// <summary>
+  ///   Gets the twitch id and username of the username provided.
+  /// </summary>
+  /// <param name="username">The username to look up.</param>
+  /// <param name="token">The cancellation token.</param>
+  /// <returns>The twitch information if successful, null otherwise.</returns>
+  Task<(string? id, string? username)> GetUser(string username, CancellationToken token = new());
+
   /// <summary>
   ///   Gets the email address of the owner of the <see cref="OAuth" />.
   /// </summary>

src/Nullinside.Api.Common/Twitch/TwitchApiProxy.cs

@@ -150,6 +150,20 @@ public TwitchApiProxy(string token, string refreshToken, DateTime tokenExpires,
     }, Retries, token);
   }
 
+  /// <inheritdoc />
+  public virtual async Task<(string? id, string? username)> GetUser(string username, CancellationToken token = new()) {
+    return await Retry.Execute(async () => {
+      ITwitchAPI api = GetApi();
+      GetUsersResponse? response = await api.Helix.Users.GetUsersAsync(logins: [username]);
+      if (null == response) {
+        return (null, null);
+      }
+
+      User? user = response.Users.FirstOrDefault();
+      return (user?.Id, user?.Login);
+    }, Retries, token);
+  }
+
   /// <inheritdoc />
   public virtual async Task<string?> GetUserEmail(CancellationToken token = new()) {
     return await Retry.Execute(async () => {