Structure because structure

Tools/WebTools.cs

@@ -0,0 +1,78 @@
+namespace Xorog.UniversalExtensions;
+
+public static class WebTools
+{
+    /// <summary>
+    /// Get the URL a redirect leads to (limited to StatusCodes 301, 303, 307, 308)
+    /// </summary>
+    /// <param name="url">The shortened URL</param>
+    /// <returns>The URL the redirect leads to</returns>
+    public static async Task<string> UnshortenUrl(string url, bool UseHeadMethod = true)
+    {
+        _logger?.LogDebug("Unshortening Url '{Url}', using head method: {UseHeadMethod}", url, UseHeadMethod);
+
+        HttpClient client = new(new HttpClientHandler()
+        {
+            AllowAutoRedirect = false,
+            AutomaticDecompression = DecompressionMethods.GZip,
+
+        });
+        client.Timeout = TimeSpan.FromSeconds(60);
+        client.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.82 Safari/537.36");
+        client.DefaultRequestHeaders.Add("upgrade-insecure-requests", "1");
+        client.DefaultRequestHeaders.Add("accept-encoding", "gzip, deflate, br");
+        client.DefaultRequestHeaders.Add("accept-language", "en-US,en;q=0.9");
+        client.MaxResponseContentBufferSize = 4096;
+
+        HttpRequestMessage requestMessage = new HttpRequestMessage((UseHeadMethod ? HttpMethod.Head : HttpMethod.Get), url);
+
+        CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
+        var request_task = client.SendAsync(requestMessage, cancellationTokenSource.Token);
+
+        try
+        {
+            await request_task.WaitAsync(TimeSpan.FromSeconds(3));
+        }
+        catch (Exception)
+        {
+            if (UseHeadMethod)
+                return await UnshortenUrl(url, false);
+
+            throw;
+        }
+
+        if (!request_task.IsCompleted)
+            cancellationTokenSource.Cancel();
+
+        if (UseHeadMethod && request_task.IsFaulted && request_task.Exception.InnerException.GetType() == typeof(HttpRequestException))
+        {
+            _logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
+            return await UnshortenUrl(url, false);
+        }
+
+        var statuscode = request_task.Result.StatusCode;
+        var header = request_task.Result.Headers;
+
+        if (UseHeadMethod && statuscode is HttpStatusCode.NotFound or HttpStatusCode.InternalServerError)
+        {
+            _logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
+            return await UnshortenUrl(url, false);
+        }
+
+        if (statuscode is HttpStatusCode.Found
+            or HttpStatusCode.Redirect
+            or HttpStatusCode.SeeOther
+            or HttpStatusCode.RedirectKeepVerb
+            or HttpStatusCode.RedirectMethod
+            or HttpStatusCode.PermanentRedirect
+            or HttpStatusCode.TemporaryRedirect)
+        {
+            if (header is not null && header.Location is not null)
+                return await UnshortenUrl(header.Location.AbsoluteUri);
+            else
+                return url;
+        }
+        else
+            return url;
+    }
+}