1 files changed, 35 insertions, 0 deletions
diff --git a/reachability/peel.go b/reachability/peel.go
new file mode 100644
index 00000000..9df9bb4d
--- /dev/null
+++ b/reachability/peel.go
@@ -0,0 +1,35 @@
+package reachability
+
+import (
+	"codeberg.org/lindenii/furgit/object"
+	"codeberg.org/lindenii/furgit/objectid"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+func (r *Reachability) peelRootToDomain(id objectid.ObjectID, domain Domain) (objectid.ObjectID, error) {
+	if err := validateDomain(domain); err != nil {
+		return objectid.ObjectID{}, err
+	}
+	for {
+		ty, err := r.readHeaderType(id)
+		if err != nil {
+			return objectid.ObjectID{}, err
+		}
+		if ty != objecttype.TypeTag {
+			if domain == DomainCommits && ty != objecttype.TypeCommit {
+				return objectid.ObjectID{}, &ErrObjectType{OID: id, Got: ty, Want: objecttype.TypeCommit}
+			}
+			return id, nil
+		}
+
+		content, err := r.readBytesContent(id)
+		if err != nil {
+			return objectid.ObjectID{}, err
+		}
+		tag, err := object.ParseTag(content, id.Algorithm())
+		if err != nil {
+			return objectid.ObjectID{}, err
+		}
+		id = tag.Target
+	}
+}