Fix ndc encoding

Author: RoboNET

src/FlexRender.Content.Ndc/NdcEncodings.cs

@@ -11,7 +11,8 @@ internal static class NdcEncodings
     // QWERTY->JCUKEN mapping table (lowercase ASCII -> lowercase Cyrillic).
     // Source: Bfs.Integration.Ndc/Utils/NdcDisplayControls.RussianUppercaseLettersDict
     // Verified in production for years across multiple banks.
-    // Uppercase is derived via char.ToUpper() on the mapped result.
+    // Only lowercase Latin letters are mapped; uppercase Latin letters are preserved as-is
+    // (they represent actual Latin characters in NDC data, not Cyrillic).
     private static readonly Dictionary<char, char> QwertyToJcukenMap = new()
     {
         ['q'] = 'й', ['w'] = 'ц', ['e'] = 'у', ['r'] = 'к', ['t'] = 'е',
@@ -50,8 +51,7 @@ private static string DecodeQwertyJcuken(string text, bool uppercase)
         var needsMapping = false;
         foreach (var ch in text)
         {
-            if (QwertyToJcukenMap.ContainsKey(ch) ||
-                (char.IsAsciiLetterUpper(ch) && QwertyToJcukenMap.ContainsKey(char.ToLower(ch, CultureInfo.InvariantCulture))))
+            if (QwertyToJcukenMap.ContainsKey(ch))
             {
                 needsMapping = true;
                 break;
@@ -70,18 +70,13 @@ private static string DecodeQwertyJcuken(string text, bool uppercase)
         var sb = new StringBuilder(text.Length);
         foreach (var ch in text)
         {
-            // Try lowercase key first
             if (QwertyToJcukenMap.TryGetValue(ch, out var mapped))
             {
                 sb.Append(uppercase ? char.ToUpper(mapped, CultureInfo.InvariantCulture) : mapped);
             }
-            // Try converting uppercase ASCII to lowercase for lookup
-            else if (char.IsAsciiLetterUpper(ch) && QwertyToJcukenMap.TryGetValue(char.ToLower(ch, CultureInfo.InvariantCulture), out var mappedFromUpper))
-            {
-                sb.Append(uppercase ? char.ToUpper(mappedFromUpper, CultureInfo.InvariantCulture) : mappedFromUpper);
-            }
             else
             {
+                // Uppercase Latin letters and all non-mapped chars preserved as-is
                 sb.Append(uppercase ? char.ToUpper(ch, CultureInfo.InvariantCulture) : ch);
             }
         }

tests/FlexRender.Tests/Content/Ndc/NdcEncodingsTests.cs

@@ -44,10 +44,25 @@ public void QwertyJcuken_UppercaseFlag_ConvertsToUppercase()
     [Fact]
     public void QwertyJcuken_WithoutUppercase_AllLowercase()
     {
-        // Without uppercase flag, uppercase ASCII keys still map to lowercase Cyrillic
         Assert.Equal("банк", NdcEncodings.Decode("~fyr", "qwerty-jcuken"));
     }
 
+    [Fact]
+    public void QwertyJcuken_UppercaseLatinPreserved()
+    {
+        // Uppercase Latin letters are NOT converted — they represent actual Latin chars in NDC data
+        Assert.Equal("A", NdcEncodings.Decode("A", "qwerty-jcuken"));
+        Assert.Equal("TEST", NdcEncodings.Decode("TEST", "qwerty-jcuken"));
+        Assert.Equal("Aбанк", NdcEncodings.Decode("A~fyr", "qwerty-jcuken"));
+    }
+
+    [Fact]
+    public void QwertyJcuken_UppercaseFlag_PreservesUppercaseLatin()
+    {
+        // With uppercase=true, uppercase Latin stays as-is, mapped chars become uppercase Cyrillic
+        Assert.Equal("AБАНК", NdcEncodings.Decode("A~fyr", "qwerty-jcuken", uppercase: true));
+    }
+
     [Fact]
     public void QwertyJcuken_PreservesNonMappedChars()
     {