Mods as feature + Patches implementation

WheelWizard/Features/Archives/ArchivesExtensions.cs

@@ -0,0 +1,10 @@
+namespace WheelWizard.Features.Archives;
+
+public static class ArchivesExtensions
+{
+    public static IServiceCollection AddArchives(this IServiceCollection services)
+    {
+        services.AddSingleton<ISzsArchiveDecoder, SzsArchiveDecoder>();
+        return services;
+    }
+}

WheelWizard/Features/Archives/Domain/DecodedArchive.cs

@@ -0,0 +1,3 @@
+namespace WheelWizard.Features.Archives;
+
+public sealed record DecodedArchive(IReadOnlyDictionary<string, byte[]> Files);

WheelWizard/Features/Archives/Domain/U8Node.cs

@@ -0,0 +1,3 @@
+namespace WheelWizard.Features.Archives;
+
+public sealed record U8Node(int Type, int NameOffset, int DataOffset, int Size);

WheelWizard/Features/Archives/ISzsArchiveDecoder.cs

@@ -0,0 +1,8 @@
+namespace WheelWizard.Features.Archives;
+
+public interface ISzsArchiveDecoder
+{
+    OperationResult<DecodedArchive> TryDecodeU8Archive(byte[] bytes);
+
+    OperationResult<byte[]> DecompressYaz0IfNeeded(byte[] bytes);
+}

WheelWizard/Features/Archives/SzsArchiveDecoder.cs

@@ -0,0 +1,176 @@
+using WheelWizard.Helpers;
+
+namespace WheelWizard.Features.Archives;
+
+public sealed class SzsArchiveDecoder : ISzsArchiveDecoder
+{
+    private const uint U8Magic = 0x55aa382d;
+
+    public OperationResult<DecodedArchive> TryDecodeU8Archive(byte[] bytes)
+    {
+        try
+        {
+            var decompressResult = DecompressYaz0IfNeeded(bytes);
+            if (decompressResult.IsFailure)
+                return decompressResult.Error;
+
+            var raw = decompressResult.Value;
+
+            if (raw.Length < 8)
+                return new OperationError { Message = "The provided file is too small to contain a valid U8 archive header." };
+            if (BigEndianBinaryHelper.BufferToUint32(raw, 0) != U8Magic)
+                return new OperationError { Message = "The provided file is not a valid Yaz0/U8 archive." };
+
+            return ParseU8Archive(raw);
+        }
+        catch (Exception ex)
+        {
+            return new OperationError { Message = $"Failed to decode U8 archive: {ex.Message}", Exception = ex };
+        }
+    }
+
+    public OperationResult<byte[]> DecompressYaz0IfNeeded(byte[] bytes)
+    {
+        try
+        {
+            if (bytes.Length < 4)
+                return bytes;
+
+            if (BinaryStringHelper.ReadAscii(bytes, 0, 4) != "Yaz0")
+                return bytes;
+
+            if (bytes.Length < 8)
+                return new OperationError { Message = "Yaz0 header is truncated." };
+
+            var outputSize = checked((int)BigEndianBinaryHelper.BufferToUint32(bytes, 4));
+            var output = new byte[outputSize];
+            var src = 0x10;
+            var dst = 0;
+            var groupHeader = 0;
+            var bitsRemaining = 0;
+
+            while (dst < output.Length)
+            {
+                if (bitsRemaining == 0)
+                {
+                    if (src >= bytes.Length)
+                        return new OperationError { Message = "Yaz0 group header is truncated." };
+                    groupHeader = bytes[src++];
+                    bitsRemaining = 8;
+                }
+
+                if ((groupHeader & 0x80) != 0)
+                {
+                    if (src >= bytes.Length)
+                        return new OperationError { Message = "Yaz0 literal chunk is truncated." };
+                    output[dst++] = bytes[src++];
+                }
+                else
+                {
+                    if (src + 1 >= bytes.Length)
+                        return new OperationError { Message = "Yaz0 backreference is truncated." };
+
+                    var b1 = bytes[src++];
+                    var b2 = bytes[src++];
+                    var backOffset = (((b1 & 0x0f) << 8) | b2) + 1;
+                    var length = b1 >> 4;
+                    if (length == 0)
+                    {
+                        if (src >= bytes.Length)
+                            return new OperationError { Message = "Yaz0 extended length byte is truncated." };
+                        length = bytes[src++] + 0x12;
+                    }
+                    else
+                    {
+                        length += 2;
+                    }
+
+                    if (backOffset > dst)
+                        return new OperationError { Message = "Yaz0 backreference offset is out of bounds." };
+
+                    var copySrc = dst - backOffset;
+                    for (var index = 0; index < length && dst < output.Length; index++)
+                        output[dst++] = output[copySrc++];
+                }
+
+                groupHeader <<= 1;
+                bitsRemaining--;
+            }
+
+            return output;
+        }
+        catch (Exception ex)
+        {
+            return new OperationError { Message = $"Failed to decompress Yaz0 data: {ex.Message}", Exception = ex };
+        }
+    }
+
+    private static DecodedArchive ParseU8Archive(byte[] bytes)
+    {
+        var rootOffset = (int)BigEndianBinaryHelper.BufferToUint32(bytes, 4);
+        var rootNode = ReadU8Node(bytes, rootOffset);
+        var nodeCount = rootNode.Size;
+        var stringTableOffset = rootOffset + nodeCount * 12;
+        var files = new Dictionary<string, byte[]>(StringComparer.Ordinal);
+
+        if (rootNode.Type != 1)
+            throw new InvalidDataException("U8 root node is not a directory.");
+        if (nodeCount == 0 || stringTableOffset > bytes.Length)
+            throw new InvalidDataException("U8 node table is invalid or truncated.");
+
+        void Walk(int dirIndex, string prefix, int parentEndIndex)
+        {
+            var nodeIndex = dirIndex + 1;
+            var directoryNode = ReadU8Node(bytes, rootOffset + dirIndex * 12);
+            var endIndex = Math.Min(directoryNode.Size, parentEndIndex);
+
+            if (endIndex <= dirIndex)
+                return;
+
+            while (nodeIndex < endIndex)
+            {
+                var nodeOffset = rootOffset + nodeIndex * 12;
+                var node = ReadU8Node(bytes, nodeOffset);
+                var nameOffset = stringTableOffset + node.NameOffset;
+
+                if (nameOffset < stringTableOffset || nameOffset >= bytes.Length)
+                {
+                    nodeIndex++;
+                    continue;
+                }
+
+                var name = BinaryStringHelper.ReadNullTerminatedAscii(bytes, nameOffset);
+                var logicalPath = string.IsNullOrEmpty(prefix) ? name : $"{prefix}/{name}";
+
+                if (node.Type == 1)
+                {
+                    Walk(nodeIndex, logicalPath, endIndex);
+                    nodeIndex = Math.Min(Math.Max(node.Size, nodeIndex + 1), endIndex);
+                }
+                else
+                {
+                    var endOffset = node.DataOffset + node.Size;
+                    if (endOffset <= bytes.Length && endOffset >= node.DataOffset)
+                        files[logicalPath] = bytes[node.DataOffset..endOffset];
+                    nodeIndex++;
+                }
+            }
+        }
+
+        Walk(0, string.Empty, nodeCount);
+        return new(files);
+    }
+
+    private static U8Node ReadU8Node(byte[] bytes, int offset)
+    {
+        if (offset + 12 > bytes.Length)
+            throw new InvalidDataException("U8 node table is truncated.");
+
+        return new(
+            bytes[offset] == 0 ? 0 : 1,
+            (bytes[offset + 1] << 16) | (bytes[offset + 2] << 8) | bytes[offset + 3],
+            (int)BigEndianBinaryHelper.BufferToUint32(bytes, offset + 4),
+            (int)BigEndianBinaryHelper.BufferToUint32(bytes, offset + 8)
+        );
+    }
+}

WheelWizard/Features/GameBanana/Domain/GameBananaModPreview.cs

@@ -1,5 +1,4 @@
 using System.Text.Json.Serialization;
-using WheelWizard.Services;
 
 namespace WheelWizard.GameBanana.Domain;
 
@@ -56,5 +55,16 @@ public class GameBananaModPreview
     public required string ModelName { get; set; }
 
     [JsonIgnore]
-    public bool UsesPatches => ModStorageSystemHelper.UsesPatches(Tags);
+    public bool UsesPatches => Tags.Any(tag => IsPatchesTag(tag.Title));
+
+    private static bool IsPatchesTag(string? tagTitle)
+    {
+        var normalizedTitle = tagTitle?.Trim();
+        if (string.IsNullOrWhiteSpace(normalizedTitle))
+            return false;
+
+        var titleOnly = normalizedTitle.Split(':', 2)[0].Trim();
+        return titleOnly.Equals("patch", StringComparison.OrdinalIgnoreCase)
+            || titleOnly.Equals("patches", StringComparison.OrdinalIgnoreCase);
+    }
 }