Factor out sig functions

internal/sig.go

@@ -0,0 +1,39 @@
+package internal
+
+import (
+	"io/fs"
+	"fmt"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/samber/lo"
+)
+
+func DirSig(root fs.FS) string {
+	sigSet := map[string]bool{}
+
+	fs.WalkDir(root, ".", func(path string, entry fs.DirEntry, err error) error {
+		if entry.IsDir() {
+			return nil
+		}
+
+		if strings.HasPrefix(entry.Name(), ".") {
+			return nil
+		}
+
+		sigSet[PathSig(path)] = true
+
+		return nil
+	})
+
+	sigs := lo.Keys(sigSet)
+	sort.Strings(sigs)
+
+	return strings.Join(sigs, ";")
+}
+
+func PathSig(path string) string {
+	parts := strings.Split(filepath.Base(path), ".")
+	return fmt.Sprintf("%s/*.%s", filepath.Dir(path), lo.Must(lo.Last(parts)))
+}