1 files changed, 123 insertions, 0 deletions
diff --git a/internal/vcs/repository.go b/internal/vcs/repository.go
new file mode 100644
index 0000000..5950e53
--- /dev/null
+++ b/internal/vcs/repository.go
@@ -0,0 +1,123 @@
+package vcs
+
+import (
+	"os"
+
+	"go.alanpearce.eu/website/internal/config"
+	"go.alanpearce.eu/x/log"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"gitlab.com/tozd/go/errors"
+)
+
+type Config struct {
+	LocalPath string
+	RemoteURL config.URL
+	Branch    string `conf:"default:main"`
+}
+
+type Repository struct {
+	repo *git.Repository
+	log  *log.Logger
+}
+
+func CloneOrUpdate(cfg *Config, log *log.Logger) (*Repository, error) {
+	gr, err := git.PlainClone(cfg.LocalPath, false, &git.CloneOptions{
+		URL:      cfg.RemoteURL.String(),
+		Progress: os.Stdout,
+	})
+	if err != nil {
+		if !errors.Is(err, git.ErrRepositoryAlreadyExists) {
+			return nil, err
+		}
+		gr, err = git.PlainOpen(cfg.LocalPath)
+		if err != nil {
+			return nil, err
+		}
+		repo := &Repository{
+			repo: gr,
+			log:  log,
+		}
+		_, err := repo.Update()
+		if err != nil {
+			return nil, err
+		}
+
+		return repo, nil
+	}
+
+	return &Repository{
+		repo: gr,
+		log:  log,
+	}, nil
+}
+
+func (r *Repository) Update() (bool, error) {
+	r.log.Info("updating repository")
+
+	head, err := r.repo.Head()
+	if err != nil {
+		return false, err
+	}
+
+	r.log.Info("updating from", "rev", head.Hash().String())
+	err = r.repo.Fetch(&git.FetchOptions{
+		Prune: true,
+	})
+	if err != nil {
+		if errors.Is(err, git.NoErrAlreadyUpToDate) {
+			r.log.Info("already up-to-date")
+
+			return true, nil
+		}
+
+		return false, err
+	}
+
+	rem, err := r.repo.Remote("origin")
+	if err != nil {
+		return false, err
+	}
+	refs, err := rem.List(&git.ListOptions{
+		Timeout: 5,
+	})
+
+	var hash plumbing.Hash
+	for _, ref := range refs {
+		if ref.Name() == plumbing.Main {
+			hash = ref.Hash()
+		}
+	}
+
+	wt, err := r.repo.Worktree()
+	if err != nil {
+		return false, err
+	}
+	wt.Checkout(&git.CheckoutOptions{
+		Hash:  hash,
+		Force: true,
+	})
+
+	r.log.Info("updated to", "rev", hash)
+
+	return true, r.Clean(wt)
+}
+
+func (r *Repository) Clean(wt *git.Worktree) error {
+	st, err := wt.Status()
+	if err != nil {
+		return err
+	}
+
+	if !st.IsClean() {
+		err = wt.Clean(&git.CleanOptions{
+			Dir: true,
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}