# Quake PAK was implemented as SEA ARC

Compression.Tests/Pak/PakDescriptorTests.cs

@@ -1,16 +1,72 @@
+using System.Buffers.Binary;
+using System.Text;
+using Compression.Registry;
+using FileFormat.Pak;
+
 namespace Compression.Tests.Pak;
 
 [TestFixture]
 public class PakDescriptorTests {
 
   [Test, Category("HappyPath")]
   public void Descriptor_Properties() {
-    var desc = new FileFormat.Pak.PakFormatDescriptor();
+    var desc = new PakFormatDescriptor();
+
+    Assert.Multiple(() => {
+      Assert.That(desc.Id, Is.EqualTo("Pak"));
+      Assert.That(desc.DefaultExtension, Is.EqualTo(".pak"));
+      Assert.That(desc.Category, Is.EqualTo(FormatCategory.Archive));
+      Assert.That(desc.Description, Does.Contain("Quake"));
+      Assert.That(desc.MagicSignatures.Single().Bytes, Is.EqualTo("PACK"u8.ToArray()));
+    });
+  }
+
+  [Test, Category("KnownAnswer")]
+  public void Reader_ParsesCanonicalPackVector_NotArc() {
+    // Independent minimal PACK image:
+    // header: "PACK", directory @ 15, one 64-byte record
+    // payload @ 12: "abc"
+    var image = new byte[12 + 3 + 64];
+    "PACK"u8.CopyTo(image);
+    BinaryPrimitives.WriteInt32LittleEndian(image.AsSpan(4, 4), 15);
+    BinaryPrimitives.WriteInt32LittleEndian(image.AsSpan(8, 4), 64);
+    "abc"u8.CopyTo(image.AsSpan(12, 3));
+    Encoding.ASCII.GetBytes("maps/test.bsp").CopyTo(image, 15);
+    BinaryPrimitives.WriteInt32LittleEndian(image.AsSpan(15 + 56, 4), 12);
+    BinaryPrimitives.WriteInt32LittleEndian(image.AsSpan(15 + 60, 4), 3);
+
+    using var stream = new MemoryStream(image, writable: false);
+    using var reader = new PakReader(stream);
+    var entry = reader.GetNextEntry();
+
+    Assert.Multiple(() => {
+      Assert.That(entry, Is.Not.Null);
+      Assert.That(entry!.FileName, Is.EqualTo("maps/test.bsp"));
+      Assert.That(entry.FileOffset, Is.EqualTo(12));
+      Assert.That(entry.Size, Is.EqualTo(3));
+      Assert.That(reader.ReadEntryData(), Is.EqualTo("abc"u8.ToArray()));
+      Assert.That(reader.GetNextEntry(), Is.Null);
+    });
+  }
 
-    Assert.That(desc.Id, Is.EqualTo("Pak"));
-    Assert.That(desc.DefaultExtension, Is.EqualTo(".pak"));
-    Assert.That(desc.Category, Is.EqualTo(Compression.Registry.FormatCategory.Archive));
-    Assert.That(desc.Description, Does.Contain("Quake"));
+  [Test, Category("KnownAnswer")]
+  public void Writer_EmitsPackHeaderPayloadThenTrailingDirectory() {
+    using var stream = new MemoryStream();
+    using (var writer = new PakWriter(stream)) {
+      writer.AddEntry("test.txt", "xyz"u8.ToArray());
+      writer.Finish();
+    }
+    var bytes = stream.ToArray();
+
+    Assert.Multiple(() => {
+      Assert.That(bytes.AsSpan(0, 4).ToArray(), Is.EqualTo("PACK"u8.ToArray()));
+      Assert.That(BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(4, 4)), Is.EqualTo(15));
+      Assert.That(BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(8, 4)), Is.EqualTo(64));
+      Assert.That(bytes.AsSpan(12, 3).ToArray(), Is.EqualTo("xyz"u8.ToArray()));
+      Assert.That(Encoding.ASCII.GetString(bytes, 15, 8), Is.EqualTo("test.txt"));
+      Assert.That(BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(15 + 56, 4)), Is.EqualTo(12));
+      Assert.That(BinaryPrimitives.ReadInt32LittleEndian(bytes.AsSpan(15 + 60, 4)), Is.EqualTo(3));
+    });
   }
 
   [Test, Category("HappyPath")]
@@ -22,25 +78,18 @@ public void RoundTrip_ViaInterface() {
       var data = "Hello PAK archive!"u8.ToArray();
       File.WriteAllBytes(tmpFile, data);
 
-      var desc = new FileFormat.Pak.PakFormatDescriptor();
-      var ops = desc;
-
-      // Create
+      var desc = new PakFormatDescriptor();
       using var ms = new MemoryStream();
-      ops.Create(ms, [new Compression.Registry.ArchiveInputInfo(tmpFile, "test.txt", false)],
-        new Compression.Registry.FormatCreateOptions());
+      desc.Create(ms, [new ArchiveInputInfo(tmpFile, "test.txt", false)], new FormatCreateOptions());
 
-      // List
       ms.Position = 0;
-      var entries = ops.List(ms, null);
+      var entries = desc.List(ms, null);
       Assert.That(entries, Has.Count.EqualTo(1));
       Assert.That(entries[0].Name, Is.EqualTo("test.txt"));
 
-      // Extract
       ms.Position = 0;
-      ops.Extract(ms, tmpDir, null, null);
-      var extracted = File.ReadAllBytes(Path.Combine(tmpDir, "test.txt"));
-      Assert.That(extracted, Is.EqualTo(data));
+      desc.Extract(ms, tmpDir, null, null);
+      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "test.txt")), Is.EqualTo(data));
     } finally {
       File.Delete(tmpFile);
       if (Directory.Exists(tmpDir)) Directory.Delete(tmpDir, true);
@@ -49,89 +98,50 @@ public void RoundTrip_ViaInterface() {
 
   [Test, Category("HappyPath")]
   public void RoundTrip_MultipleFiles() {
-    var tmpFiles = new string[3];
-    var tmpDir = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
-    Directory.CreateDirectory(tmpDir);
-    try {
-      var data1 = "First file content"u8.ToArray();
-      var data2 = "Second file content"u8.ToArray();
-      var data3 = "Third file content"u8.ToArray();
-
-      tmpFiles[0] = Path.GetTempFileName();
-      tmpFiles[1] = Path.GetTempFileName();
-      tmpFiles[2] = Path.GetTempFileName();
-      File.WriteAllBytes(tmpFiles[0], data1);
-      File.WriteAllBytes(tmpFiles[1], data2);
-      File.WriteAllBytes(tmpFiles[2], data3);
-
-      var desc = new FileFormat.Pak.PakFormatDescriptor();
-      var ops = desc;
-
-      using var ms = new MemoryStream();
-      ops.Create(ms, [
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[0], "a.txt", false),
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[1], "b.txt", false),
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[2], "c.txt", false),
-      ], new Compression.Registry.FormatCreateOptions());
-
-      // List
-      ms.Position = 0;
-      var entries = ops.List(ms, null);
-      Assert.That(entries, Has.Count.EqualTo(3));
-      Assert.That(entries[0].Name, Is.EqualTo("a.txt"));
-      Assert.That(entries[1].Name, Is.EqualTo("b.txt"));
-      Assert.That(entries[2].Name, Is.EqualTo("c.txt"));
-
-      // Extract all and verify
-      ms.Position = 0;
-      ops.Extract(ms, tmpDir, null, null);
-      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "a.txt")), Is.EqualTo(data1));
-      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "b.txt")), Is.EqualTo(data2));
-      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "c.txt")), Is.EqualTo(data3));
-    } finally {
-      foreach (var f in tmpFiles) if (f != null) File.Delete(f);
-      if (Directory.Exists(tmpDir)) Directory.Delete(tmpDir, true);
-    }
+    var data1 = "First file content"u8.ToArray();
+    var data2 = "Second file content"u8.ToArray();
+    var data3 = "Third file content"u8.ToArray();
+    var desc = new PakFormatDescriptor();
+    using var ms = new MemoryStream();
+    desc.Create(ms, [
+      ArchiveInputInfo.InMemory("a.txt", data1),
+      ArchiveInputInfo.InMemory("b.txt", data2),
+      ArchiveInputInfo.InMemory("c.txt", data3),
+    ], new FormatCreateOptions());
+
+    ms.Position = 0;
+    var entries = desc.List(ms, null);
+    Assert.That(entries.Select(entry => entry.Name), Is.EqualTo(new[] { "a.txt", "b.txt", "c.txt" }));
+
+    ms.Position = 0;
+    Assert.That(desc.ExtractEntryToMemory(ms, "a.txt", null), Is.EqualTo(data1));
+    ms.Position = 0;
+    Assert.That(desc.ExtractEntryToMemory(ms, "b.txt", null), Is.EqualTo(data2));
+    ms.Position = 0;
+    Assert.That(desc.ExtractEntryToMemory(ms, "c.txt", null), Is.EqualTo(data3));
   }
 
   [Test, Category("HappyPath")]
   public void Extract_WithFilter() {
-    var tmpFiles = new string[3];
+    var desc = new PakFormatDescriptor();
+    using var archive = new MemoryStream();
+    desc.Create(archive, [
+      ArchiveInputInfo.InMemory("alpha.txt", "Alpha"u8.ToArray()),
+      ArchiveInputInfo.InMemory("bravo.txt", "Bravo"u8.ToArray()),
+      ArchiveInputInfo.InMemory("charlie.txt", "Charlie"u8.ToArray()),
+    ], new FormatCreateOptions());
+
     var tmpDir = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
     Directory.CreateDirectory(tmpDir);
     try {
-      var data1 = "Alpha"u8.ToArray();
-      var data2 = "Bravo"u8.ToArray();
-      var data3 = "Charlie"u8.ToArray();
-
-      tmpFiles[0] = Path.GetTempFileName();
-      tmpFiles[1] = Path.GetTempFileName();
-      tmpFiles[2] = Path.GetTempFileName();
-      File.WriteAllBytes(tmpFiles[0], data1);
-      File.WriteAllBytes(tmpFiles[1], data2);
-      File.WriteAllBytes(tmpFiles[2], data3);
-
-      var desc = new FileFormat.Pak.PakFormatDescriptor();
-      var ops = desc;
-
-      using var ms = new MemoryStream();
-      ops.Create(ms, [
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[0], "alpha.txt", false),
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[1], "bravo.txt", false),
-        new Compression.Registry.ArchiveInputInfo(tmpFiles[2], "charlie.txt", false),
-      ], new Compression.Registry.FormatCreateOptions());
-
-      // Extract only bravo.txt
-      ms.Position = 0;
-      ops.Extract(ms, tmpDir, null, ["bravo.txt"]);
-
+      archive.Position = 0;
+      desc.Extract(archive, tmpDir, null, ["bravo.txt"]);
       Assert.That(File.Exists(Path.Combine(tmpDir, "bravo.txt")), Is.True);
-      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "bravo.txt")), Is.EqualTo(data2));
+      Assert.That(File.ReadAllBytes(Path.Combine(tmpDir, "bravo.txt")), Is.EqualTo("Bravo"u8.ToArray()));
       Assert.That(File.Exists(Path.Combine(tmpDir, "alpha.txt")), Is.False);
       Assert.That(File.Exists(Path.Combine(tmpDir, "charlie.txt")), Is.False);
     } finally {
-      foreach (var f in tmpFiles) if (f != null) File.Delete(f);
-      if (Directory.Exists(tmpDir)) Directory.Delete(tmpDir, true);
+      Directory.Delete(tmpDir, true);
     }
   }
 }