fix: ensure catalogue is clean/up-to-date

Closes coop-cloud/organising#367

pkg/git/branch.go

@@ -1,14 +1,16 @@
 package git
 
 import (
+	"fmt"
+
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/sirupsen/logrus"
 )
 
-// Check if a branch exists in a repo.
-// Use this and not repository.Branch(), because the latter does not
-// actually check for existing branches.
-// See https://github.com/go-git/go-git/issues/518
+// Check if a branch exists in a repo. Use this and not repository.Branch(),
+// because the latter does not actually check for existing branches. See
+// https://github.com/go-git/go-git/issues/518 for more.
 func HasBranch(repository *git.Repository, name string) bool {
 	var exist bool
 	if iter, err := repository.Branches(); err == nil {
@@ -24,7 +26,7 @@ func HasBranch(repository *git.Repository, name string) bool {
 	return exist
 }
 
-// GetCurrentBranch retrieves the current branch of a repository
+// GetCurrentBranch retrieves the current branch of a repository.
 func GetCurrentBranch(repository *git.Repository) (string, error) {
 	branchRefs, err := repository.Branches()
 	if err != nil {
@@ -52,3 +54,45 @@ func GetCurrentBranch(repository *git.Repository) (string, error) {
 
 	return currentBranchName, nil
 }
+
+// GetDefaultBranch retrieves the default branch of a repository.
+func GetDefaultBranch(repo *git.Repository, repoPath string) (plumbing.ReferenceName, error) {
+	branch := "master"
+
+	if !HasBranch(repo, "master") {
+		if !HasBranch(repo, "main") {
+			return "", fmt.Errorf("failed to select default branch in %s", repoPath)
+		}
+		branch = "main"
+	}
+
+	return plumbing.ReferenceName(fmt.Sprintf("refs/heads/%s", branch)), nil
+}
+
+// CheckoutDefaultBranch checks out the default branch of a repository.
+func CheckoutDefaultBranch(repo *git.Repository, repoPath string) (plumbing.ReferenceName, error) {
+	branch, err := GetDefaultBranch(repo, repoPath)
+	if err != nil {
+		return plumbing.ReferenceName(""), err
+	}
+
+	worktree, err := repo.Worktree()
+	if err != nil {
+		return plumbing.ReferenceName(""), err
+	}
+
+	checkOutOpts := &git.CheckoutOptions{
+		Create: false,
+		Force:  true,
+		Branch: branch,
+	}
+
+	if err := worktree.Checkout(checkOutOpts); err != nil {
+		logrus.Debugf("failed to check out %s in %s", branch, repoPath)
+		return branch, err
+	}
+
+	logrus.Debugf("successfully checked out %v in %s", branch, repoPath)
+
+	return branch, nil
+}