Using IFormCollection for VerifyIncomingSignatureFromForm

LiteCharms.Features.MidrandBooks/Payments/PayfastService.cs

@@ -48,21 +48,24 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
         }
     }
 
-    public static bool VerifyIncomingSignature(IDictionary<string, string> formFields, string passphrase)
+    public static bool VerifyIncomingSignatureFromForm(IFormCollection formCollection, string passphrase)
     {
-        if (!formFields.TryGetValue("signature", out string? incomingSignature))
-            return false;
+        var sortedFields = new Dictionary<string, string>(StringComparer.Ordinal);
+
+        foreach (var field in formCollection)
+        {
+            sortedFields.Add(field.Key, field.Value.ToString());
+        }
+
+        if (!sortedFields.TryGetValue("signature", out var incomingSignature)) return false;
 
         var stringBuilder = new StringBuilder();
 
-        foreach (var key in formFields.Keys)
+        foreach (var key in sortedFields.Keys)
         {
-            if (key.Equals("signature", StringComparison.OrdinalIgnoreCase))
-                continue;
+            if (key.Equals("signature", StringComparison.OrdinalIgnoreCase)) continue;
 
-            string rawValue = formFields[key] ?? string.Empty;
-
-            string encodedVal = HttpUtility.UrlEncode(rawValue.Trim());
+            string encodedVal = HttpUtility.UrlEncode(sortedFields[key].Trim());
             string cleanVal = PercentEncodingRegex.Replace(encodedVal, m => m.Value.ToUpperInvariant());
 
             stringBuilder.Append($"{key}={cleanVal}&");