Added checksum and version checking

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_data/lib/src/wl_parser.dart

@@ -1,6 +1,8 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
+import 'package:crypto/crypto.dart' show md5;
+import 'package:wolf_3d_data/src/data_version.dart';
 import 'package:wolf_3d_data_types/wolf_3d_data_types.dart';
 
 abstract class WLParser {
@@ -21,42 +23,72 @@ abstract class WLParser {
   /// Asynchronously discovers the game version and loads all necessary files.
   /// Provide a [fileFetcher] callback (e.g., Flutter's rootBundle.load) that
   /// takes a filename and returns its ByteData.
+  /// Asynchronously discovers the game version and loads all necessary files.
+  /// Asynchronously discovers the game version and loads all necessary files.
   static Future<WolfensteinData> loadAsync(
     Future<ByteData> Function(String filename) fileFetcher,
   ) async {
     GameVersion? detectedVersion;
     ByteData? vswap;
 
-    // 1. Probe the data source to figure out which version we have
+    // 1. Probe the data source for VSWAP to determine the GameVersion
     for (final version in GameVersion.values) {
       try {
         vswap = await fileFetcher('VSWAP.${version.fileExtension}');
         detectedVersion = version;
-        break; // We found the version!
-      } catch (_) {
-        // File wasn't found, try the next version extension
-      }
+        break;
+      } catch (_) {}
     }
 
     if (detectedVersion == null || vswap == null) {
-      throw Exception(
-        'Could not locate a valid VSWAP file for any game version.',
-      );
+      throw Exception('Could not locate a valid VSWAP file.');
     }
 
     final ext = detectedVersion.fileExtension;
 
-    // 2. Now that we know the version, confidently load the rest of the files
+    // 2. Determine DataIdentity (Checksum) immediately
+    final vswapBytes = vswap.buffer.asUint8List(
+      vswap.offsetInBytes,
+      vswap.lengthInBytes,
+    );
+    final vswapHash = md5.convert(vswapBytes).toString();
+    final dataIdentity = DataVersion.fromChecksum(vswapHash);
+
+    // 3. Load other required files
+    // Special Case: v1.0 Retail uses MAPTEMP instead of GAMEMAPS
+    ByteData gameMapsData;
+    if (dataIdentity == DataVersion.version10Retail) {
+      try {
+        gameMapsData = await fileFetcher('MAPTEMP.$ext');
+      } catch (_) {
+        // Fallback in case v1.0 files were renamed to standard convention
+        gameMapsData = await fileFetcher('GAMEMAPS.$ext');
+      }
+    } else {
+      gameMapsData = await fileFetcher('GAMEMAPS.$ext');
+    }
+
+    final rawFiles = {
+      'MAPHEAD.$ext': await fileFetcher('MAPHEAD.$ext'),
+      'VGADICT.$ext': await fileFetcher('VGADICT.$ext'),
+      'VGAHEAD.$ext': await fileFetcher('VGAHEAD.$ext'),
+      'VGAGRAPH.$ext': await fileFetcher('VGAGRAPH.$ext'),
+      'AUDIOHED.$ext': await fileFetcher('AUDIOHED.$ext'),
+      'AUDIOT.$ext': await fileFetcher('AUDIOT.$ext'),
+    };
+
+    // 4. Final call to load with the required dataIdentity
     return load(
       version: detectedVersion,
+      dataIdentity: dataIdentity, // Now correctly passed
       vswap: vswap,
-      mapHead: await fileFetcher('MAPHEAD.$ext'),
-      gameMaps: await fileFetcher('GAMEMAPS.$ext'),
-      vgaDict: await fileFetcher('VGADICT.$ext'),
-      vgaHead: await fileFetcher('VGAHEAD.$ext'),
-      vgaGraph: await fileFetcher('VGAGRAPH.$ext'),
-      audioHed: await fileFetcher('AUDIOHED.$ext'),
-      audioT: await fileFetcher('AUDIOT.$ext'),
+      mapHead: rawFiles['MAPHEAD.$ext']!,
+      gameMaps: gameMapsData,
+      vgaDict: rawFiles['VGADICT.$ext']!,
+      vgaHead: rawFiles['VGAHEAD.$ext']!,
+      vgaGraph: rawFiles['VGAGRAPH.$ext']!,
+      audioHed: rawFiles['AUDIOHED.$ext']!,
+      audioT: rawFiles['AUDIOT.$ext']!,
     );
   }
 
@@ -73,9 +105,15 @@ abstract class WLParser {
     required ByteData vgaGraph,
     required ByteData audioHed,
     required ByteData audioT,
+    required DataVersion dataIdentity,
   }) {
     final isShareware = version == GameVersion.shareware;
 
+    // v1.0/1.1 used different HUD strings and had different secret wall bugs
+    final isLegacy =
+        dataIdentity == DataVersion.version10Retail ||
+        dataIdentity == DataVersion.version11Retail;
+
     final audio = parseAudio(audioHed, audioT, version);
 
     return WolfensteinData(