chore: add gitutils package to inspect local git repo

internal/gitutil/state.go

@@ -0,0 +1,91 @@
+package gitutil
+
+import (
+	"fmt"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// GitState contains raw information about the Git repository state.
+type GitState struct {
+	// IsDirty indicates whether there are uncommitted changes.
+	IsDirty bool
+	// IsRepo indicates whether the directory is a Git repository.
+	IsRepo bool
+	// SHA is the full SHA-1 (40 characters) of the current commit.
+	SHA string
+	// Time is the current commit datetime.
+	Time time.Time
+}
+
+// InspectGitState inspects the Git repo state from the specified directory.
+// If the directory is not a Git repository, returns GitState with IsRepo=false.
+func InspectGitState(dir string) (GitState, error) {
+	state := GitState{
+		IsRepo: isGitRepo(dir),
+	}
+
+	if !state.IsRepo {
+		return state, nil
+	}
+
+	// Get the current commit SHA.
+	sha, err := gitCommand(dir, "rev-parse", "HEAD")
+	if err != nil {
+		return state, fmt.Errorf("get current commit SHA: %w", err)
+	}
+	state.SHA = strings.TrimSpace(sha)
+
+	// Get the current commit timestamp.
+	timestamp, err := gitCommand(dir, "log", "-1", "--format=%ct")
+	if err != nil {
+		return state, fmt.Errorf("get current commit timestamp: %w", err)
+	}
+	seconds, err := strconv.ParseInt(strings.TrimSpace(timestamp), 10, 64)
+	if err != nil {
+		return state, fmt.Errorf("parse current commit timestamp: %w", err)
+	}
+	state.Time = time.Unix(seconds, 0)
+
+	// Check for uncommitted changes.
+	status, err := gitCommand(dir, "status", "--porcelain")
+	if err != nil {
+		return state, fmt.Errorf("check git status: %w", err)
+	}
+	state.IsDirty = strings.TrimSpace(status) != ""
+
+	return state, nil
+}
+
+// isGitRepo checks if the directory is a Git repository.
+func isGitRepo(dir string) bool {
+	_, err := gitCommand(dir, "rev-parse", "--git-dir")
+	return err == nil
+}
+
+// gitCommand runs a git command in the specified directory.
+func gitCommand(dir string, args ...string) (string, error) {
+	cmd := exec.Command("git", args...)
+	cmd.Dir = dir
+	output, err := cmd.Output()
+	if err != nil {
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			return "", fmt.Errorf("git command failed: %s", exitErr.Stderr)
+		}
+		return "", err
+	}
+
+	return string(output), nil
+}
+
+// ShortSHA returns a truncated SHA with the specified length.
+// If length is negative, zero, or greater than the SHA length, it returns the full SHA.
+// Returns empty string if SHA is empty.
+func (s *GitState) ShortSHA(length int) string {
+	if length <= 0 || length > len(s.SHA) {
+		length = len(s.SHA)
+	}
+	return s.SHA[:length]
+}