Fix Windows Wrappers and Extensions

internal/erf/erf.go

@@ -114,13 +114,69 @@ var extensionTypes = map[string]uint16{
 	"png": 0x083E,
 }
 
-var typeExtensions map[uint16]string
+var typeExtensions = map[uint16]string{
+	0x0000: "res",
+	0x0001: "bmp",
+	0x0002: "mve",
+	0x0003: "tga",
+	0x0004: "wav",
+	0x0006: "plt",
+	0x0007: "ini",
+	0x000A: "txt",
+	0x07D2: "mdl",
+	0x07D9: "nss",
+	0x07DA: "ncs",
+	0x07DC: "are",
+	0x07DD: "set",
+	0x07DE: "ifo",
+	0x07DF: "bic",
+	0x07E1: "wok",
+	0x07E2: "2da",
+	0x07E3: "tlk",
+	0x07E6: "txi",
+	0x07E7: "git",
+	0x07E9: "uti",
+	0x07EA: "utt",
+	0x07EB: "utc",
+	0x07ED: "dlg",
+	0x07EE: "itp",
+	0x07F0: "uts",
+	0x07F1: "dds",
+	0x07F6: "fac",
+	0x07F7: "gff",
+	0x07F9: "ute",
+	0x07FB: "utd",
+	0x07FC: "utp",
+	0x07FD: "dfa",
+	0x07FE: "gic",
+	0x07FF: "gui",
+	0x0800: "utm",
+	0x0804: "dwk",
+	0x0805: "pwk",
+	0x0808: "jrl",
+	0x080A: "utw",
+	0x080C: "ssf",
+	0x080D: "hak",
+	0x080E: "nwm",
+	0x080F: "bik",
+	0x0810: "ndb",
+	0x0811: "ptm",
+	0x0812: "ptt",
+	0x0813: "ltr",
+	0x0815: "shd",
+	0x0818: "mtr",
+	0x081E: "lod",
+	0x083E: "png",
+}
 
 func init() {
-	typeExtensions = make(map[uint16]string, len(extensionTypes))
 	for ext, resourceType := range extensionTypes {
-		if _, exists := typeExtensions[resourceType]; !exists {
-			typeExtensions[resourceType] = ext
+		canonicalExt, ok := typeExtensions[resourceType]
+		if !ok {
+			panic(fmt.Sprintf("missing canonical extension for resource type 0x%04X", resourceType))
+		}
+		if canonicalExt == ext {
+			continue
 		}
 	}
 }

internal/erf/erf_test.go

@@ -28,3 +28,31 @@ func TestArchiveRoundTrip(t *testing.T) {
 		t.Fatalf("unexpected first resource: %#v", decoded.Resources[0])
 	}
 }
+
+func TestExtensionMappingsKeep2DAAndTLKDistinct(t *testing.T) {
+	resourceType, ok := ResourceTypeForExtension("2da")
+	if !ok {
+		t.Fatal("expected 2da resource type")
+	}
+	if resourceType != 0x07E2 {
+		t.Fatalf("expected 2da type 0x07E2, got 0x%04X", resourceType)
+	}
+	extension, ok := ExtensionForResourceType(resourceType)
+	if !ok {
+		t.Fatal("expected canonical extension for 2da type")
+	}
+	if extension != "2da" {
+		t.Fatalf("expected 2da extension, got %q", extension)
+	}
+
+	tlkType, ok := ResourceTypeForExtension("tlk")
+	if !ok {
+		t.Fatal("expected tlk resource type")
+	}
+	if tlkType != 0x07E3 {
+		t.Fatalf("expected tlk type 0x07E3, got 0x%04X", tlkType)
+	}
+	if tlkType == resourceType {
+		t.Fatal("expected 2da and tlk resource types to stay distinct")
+	}
+}