refstore: Add ref shortening

2 files changed, 61 insertions, 0 deletions

diff --git a/refstore/loose/loose_test.go b/refstore/loose/loose_test.go
index b56e40ac..63898721 100644
--- a/refstore/loose/loose_test.go
+++ b/refstore/loose/loose_test.go
@@ -147,3 +147,35 @@ func TestLooseMalformedDetachedRef(t *testing.T) {
 		}
 	})
 }
+
+func TestLooseShorten(t *testing.T) {
+	testgit.ForEachAlgorithm(t, func(t *testing.T, algo objectid.Algorithm) {
+		testRepo := testgit.NewBareRepo(t, algo)
+		_, _, commitID := testRepo.MakeCommit(t, "shorten refs commit")
+		testRepo.UpdateRef(t, "refs/heads/main", commitID)
+		testRepo.UpdateRef(t, "refs/tags/main", commitID)
+		testRepo.UpdateRef(t, "refs/remotes/origin/main", commitID)
+
+		store := openLooseStore(t, testRepo.Dir(), algo)
+
+		shortHead, err := store.Shorten("refs/heads/main")
+		if err != nil {
+			t.Fatalf("Shorten(head): %v", err)
+		}
+		if shortHead != "heads/main" {
+			t.Fatalf("Shorten(refs/heads/main) = %q, want %q", shortHead, "heads/main")
+		}
+
+		shortRemote, err := store.Shorten("refs/remotes/origin/main")
+		if err != nil {
+			t.Fatalf("Shorten(remote): %v", err)
+		}
+		if shortRemote != "origin/main" {
+			t.Fatalf("Shorten(remote) = %q, want %q", shortRemote, "origin/main")
+		}
+
+		if _, err := store.Shorten("refs/heads/does-not-exist"); !errors.Is(err, refstore.ErrReferenceNotFound) {
+			t.Fatalf("Shorten(not-found) error = %v", err)
+		}
+	})
+}
diff --git a/refstore/loose/shorten.go b/refstore/loose/shorten.go
new file mode 100644
index 00000000..17a60def
--- /dev/null
+++ b/refstore/loose/shorten.go
@@ -0,0 +1,29 @@
+package loose
+
+import (
+	"codeberg.org/lindenii/furgit/refstore"
+)
+
+// Shorten returns the shortest unambiguous shorthand for a loose ref name.
+func (store *Store) Shorten(name string) (string, error) {
+	refs, err := store.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
+}