refstore: Add ref shortening

1 files changed, 24 insertions, 0 deletions

diff --git a/refstore/chain/chain.go b/refstore/chain/chain.go
index b84aac55..0a78dc94 100644
--- a/refstore/chain/chain.go
+++ b/refstore/chain/chain.go
@@ -102,6 +102,30 @@ func (chain *Chain) List(pattern string) ([]ref.Ref, error) {
 	return refs, nil
 }
 
+// Shorten shortens a full reference name using the chain-visible namespace.
+func (chain *Chain) Shorten(name string) (string, error) {
+	refs, err := chain.List("")
+	if err != nil {
+		return "", err
+	}
+	names := make([]string, 0, len(refs))
+	found := false
+	for _, entry := range refs {
+		if entry == nil {
+			continue
+		}
+		full := entry.Name()
+		names = append(names, full)
+		if full == name {
+			found = true
+		}
+	}
+	if !found {
+		return "", refstore.ErrReferenceNotFound
+	}
+	return refstore.ShortenName(name, names), nil
+}
+
 // Close closes all backends and joins close errors.
 func (chain *Chain) Close() error {
 	var errs []error