LiteCharms.Features.MidrandBooks/Payments/PayfastService.cs

@@ -3,7 +3,6 @@ using LiteCharms.Features.Api.Configuration;
 using LiteCharms.Features.Hasher;
 using LiteCharms.Features.MidrandBooks.Payments.Models;
 using LiteCharms.Features.MidrandBooks.Postgres;
-using Microsoft.AspNetCore.Http;
 
 namespace LiteCharms.Features.MidrandBooks.Payments;
 
@@ -51,7 +50,10 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
 
     public static bool VerifyIncomingSignature(HttpRequest request, string passphrase)
     {
-        var formFields = request.Form.ToDictionary(x => x.Key, x => x.Value.ToString());
+        var formFields = new Dictionary<string, string>(StringComparer.Ordinal);
+
+        foreach (var file in request.Form)
+            formFields.Add(file.Key, file.Value.ToString());
 
         if (!formFields.TryGetValue("signature", out string? incomingSignature))
             return false;
@@ -63,7 +65,9 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
             if (key.Equals("signature", StringComparison.OrdinalIgnoreCase))
                 continue;
 
-            string encodedVal = HttpUtility.UrlEncode(formFields[key].Trim());
+            string rawValue = formFields[key] ?? string.Empty;
+
+            string encodedVal = HttpUtility.UrlEncode(rawValue.Trim());
             string cleanVal = PercentEncodingRegex.Replace(encodedVal, m => m.Value.ToUpperInvariant());
 
             stringBuilder.Append($"{key}={cleanVal}&");
@@ -75,6 +79,7 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
         stringBuilder.Append($"passphrase={safePassphrase}");
 
         string generatedSignature = HashService.ToMd5Hash(stringBuilder.ToString()).Value;
+
         return incomingSignature.Equals(generatedSignature, StringComparison.OrdinalIgnoreCase);
     }