feat: Add ref support

Now log and tree can be loaded using a given reference.

1 files changed, 52 insertions, 30 deletions

diff --git a/pkg/git/git.go b/pkg/git/git.go
index 7ef23f7..ce72465 100644
--- a/pkg/git/git.go
+++ b/pkg/git/git.go
@@ -13,19 +13,50 @@ import (
 var ()
 
 var (
-	MissingHeadErr = errors.New("Head not found")
+	MissingRefErr = errors.New("Reference not found")
 )
 
 type (
 	GitRepository struct {
-		path string
+		path       string
+		repository *git.Repository
+
+		ref plumbing.Hash
+		// this is setRef when ref is setRef
+		setRef bool
 	}
 )
 
-func NewGitRepository(dir string) *GitRepository {
-	return &GitRepository{
+func OpenRepository(dir string) (*GitRepository, error) {
+	g := &GitRepository{
 		path: dir,
 	}
+
+	repo, err := git.PlainOpen(dir)
+	if err != nil {
+		return nil, err
+	}
+	g.repository = repo
+
+	return g, nil
+}
+
+func (g *GitRepository) SetRef(ref string) error {
+	if ref == "" {
+		head, err := g.repository.Head()
+		if err != nil {
+			return errors.Join(MissingRefErr, err)
+		}
+		g.ref = head.Hash()
+	} else {
+		hash, err := g.repository.ResolveRevision(plumbing.Revision(ref))
+		if err != nil {
+			return errors.Join(MissingRefErr, err)
+		}
+		g.ref = *hash
+	}
+	g.setRef = true
+	return nil
 }
 
 func (g *GitRepository) Path() string {
@@ -33,17 +64,12 @@ func (g *GitRepository) Path() string {
 }
 
 func (g *GitRepository) LastCommit() (*object.Commit, error) {
-	repo, err := git.PlainOpen(g.path)
+	err := g.validateRef()
 	if err != nil {
 		return nil, err
 	}
 
-	ref, err := repo.Head()
-	if err != nil {
-		return nil, errors.Join(MissingHeadErr, err)
-	}
-
-	c, err := repo.CommitObject(ref.Hash())
+	c, err := g.repository.CommitObject(g.ref)
 	if err != nil {
 		return nil, err
 	}
@@ -51,17 +77,12 @@ func (g *GitRepository) LastCommit() (*object.Commit, error) {
 }
 
 func (g *GitRepository) Commits() ([]*object.Commit, error) {
-	repo, err := git.PlainOpen(g.path)
+	err := g.validateRef()
 	if err != nil {
 		return nil, err
 	}
 
-	ref, err := repo.Head()
-	if err != nil {
-		return nil, errors.Join(MissingHeadErr, err)
-	}
-
-	ci, err := repo.Log(&git.LogOptions{From: ref.Hash()})
+	ci, err := g.repository.Log(&git.LogOptions{From: g.ref})
 	if err != nil {
 		return nil, fmt.Errorf("commits from ref: %w", err)
 	}
@@ -84,13 +105,12 @@ func (g *GitRepository) Commits() ([]*object.Commit, error) {
 	return commits, nil
 }
 
-func (g *GitRepository) Tags() ([]*object.Tag, error) {
-	repo, err := git.PlainOpen(g.path)
-	if err != nil {
-		return nil, err
-	}
+func (g *GitRepository) Head() (*plumbing.Reference, error) {
+	return g.repository.Head()
+}
 
-	ti, err := repo.TagObjects()
+func (g *GitRepository) Tags() ([]*object.Tag, error) {
+	ti, err := g.repository.TagObjects()
 	if err != nil {
 		return nil, err
 	}
@@ -108,12 +128,7 @@ func (g *GitRepository) Tags() ([]*object.Tag, error) {
 }
 
 func (g *GitRepository) Branches() ([]*plumbing.Reference, error) {
-	repo, err := git.PlainOpen(g.path)
-	if err != nil {
-		return nil, err
-	}
-
-	bs, err := repo.Branches()
+	bs, err := g.repository.Branches()
 	if err != nil {
 		return nil, err
 	}
@@ -129,3 +144,10 @@ func (g *GitRepository) Branches() ([]*plumbing.Reference, error) {
 
 	return branches, nil
 }
+
+func (g *GitRepository) validateRef() error {
+	if !g.setRef {
+		return g.SetRef("")
+	}
+	return nil
+}