refactor: return err instead of panic and use errgroup

1 files changed, 30 insertions, 59 deletions

diff --git a/internal/git/git.go b/internal/git/git.go
index 96856c3..41031e4 100644
--- a/internal/git/git.go
+++ b/internal/git/git.go
@@ -11,14 +11,25 @@ import (
 	"time"
 )
 
-func Branches(repoDir string) ([]Ref, error) {
-	cmd := exec.Command("git", "for-each-ref", "--format=%(refname:short)", "refs/heads/")
+func gitCmd(repoDir string, args ...string) ([]byte, error) {
+	cmd := exec.Command("git", args...)
 	if repoDir != "" {
 		cmd.Dir = repoDir
 	}
 	out, err := cmd.Output()
 	if err != nil {
-		return nil, fmt.Errorf("failed to list branches: %w", err)
+		if ee, ok := err.(*exec.ExitError); ok {
+			return nil, fmt.Errorf("git %s: %w: %s", args[0], err, ee.Stderr)
+		}
+		return nil, err
+	}
+	return out, nil
+}
+
+func Branches(repoDir string) ([]Ref, error) {
+	out, err := gitCmd(repoDir, "for-each-ref", "--format=%(refname:short)", "refs/heads/")
+	if err != nil {
+		return nil, err
 	}
 	lines := strings.Split(string(out), "\n")
 	branches := make([]Ref, 0, len(lines))
@@ -33,24 +44,19 @@ func Branches(repoDir string) ([]Ref, error) {
 
 func Tags(repoDir string) ([]Tag, error) {
 	format := []string{
-		"%(refname:short)",    // tag name
-		"%(creatordate:unix)", // creation date
-		"%(objectname)",       // commit hash for lightweight tags
-		"%(*objectname)",      // peeled object => commit hash
+		"%(refname:short)",
+		"%(creatordate:unix)",
+		"%(objectname)",
+		"%(*objectname)",
 	}
-	args := []string{
+	out, err := gitCmd(repoDir,
 		"for-each-ref",
 		"--sort=-creatordate",
-		"--format=" + strings.Join(format, "%00"),
+		"--format="+strings.Join(format, "%00"),
 		"refs/tags",
-	}
-	cmd := exec.Command("git", args...)
-	if repoDir != "" {
-		cmd.Dir = repoDir
-	}
-	out, err := cmd.Output()
+	)
 	if err != nil {
-		return nil, fmt.Errorf("failed to list tags: %w", err)
+		return nil, err
 	}
 
 	lines := strings.Split(strings.TrimSpace(string(out)), "\n")
@@ -194,52 +200,22 @@ func BlobContent(ref Ref, path string, repoDir string) ([]byte, bool, error) {
 	if ref.IsEmpty() {
 		ref = NewRef("HEAD")
 	}
-	// Use `git show ref:path` to get the blob content at that ref
-	cmd := exec.Command("git", "show", ref.String()+":"+path)
-	if repoDir != "" {
-		cmd.Dir = repoDir
-	}
-	out, err := cmd.Output()
+	out, err := gitCmd(repoDir, "show", ref.String()+":"+path)
 	if err != nil {
-		// include stderr if available
-		if ee, ok := err.(*exec.ExitError); ok {
-			return nil, false, fmt.Errorf("git show failed: %v: %s", err, string(ee.Stderr))
-		}
-		return nil, false, fmt.Errorf("git show failed: %w", err)
+		return nil, false, err
 	}
 	return out, IsBinary(out), nil
 }
 
 func Commits(ref Ref, repoDir string) ([]Commit, error) {
-	format := []string{
-		"%H",  // commit hash
-		"%h",  // abbreviated commit hash
-		"%s",  // subject
-		"%b",  // body
-		"%an", // author name
-		"%ae", // author email
-		"%ad", // author date
-		"%cn", // committer name
-		"%ce", // committer email
-		"%cd", // committer date
-		"%P",  // parent hashes
-		"%D",  // ref names without the "(", ")" wrapping.
-	}
-
-	args := []string{
+	format := []string{"%H", "%h", "%s", "%b", "%an", "%ae", "%ad", "%cn", "%ce", "%cd", "%P", "%D"}
+	out, err := gitCmd(repoDir,
 		"log",
 		"--date=unix",
-		"--pretty=format:" + strings.Join(format, "\x1F"),
-		"-z", // Separate the commits with NULs instead of newlines
+		"--pretty=format:"+strings.Join(format, "\x1F"),
+		"-z",
 		ref.String(),
-	}
-
-	cmd := exec.Command("git", args...)
-	if repoDir != "" {
-		cmd.Dir = repoDir
-	}
-
-	out, err := cmd.Output()
+	)
 	if err != nil {
 		return nil, err
 	}
@@ -347,12 +323,7 @@ func parseRefNames(refNames string) []RefName {
 }
 
 func CommitDiff(hash, repoDir string) (string, error) {
-	// unified diff without a commit header
-	cmd := exec.Command("git", "show", "--pretty=format:", "--patch", hash)
-	if repoDir != "" {
-		cmd.Dir = repoDir
-	}
-	out, err := cmd.Output()
+	out, err := gitCmd(repoDir, "show", "--pretty=format:", "--patch", hash)
 	if err != nil {
 		return "", err
 	}