feat(git): implement StageFiles and GetFileDiff utility functions

Author: mujib77

internal/git/git.go

@@ -90,4 +90,109 @@ func TruncateDiff(diff string, maxChars int) string {
 		return diff
 	}
 	return diff[:maxChars] + "\n... (diff truncated)"
+}
+
+type FileGroup struct {
+	Files      []string
+	Diff       string
+	Insertions int
+	Deletions  int
+}
+
+func GroupStagedFiles(diff *DiffInfo) []FileGroup {
+	groups := make(map[string][]string)
+
+	for _, file := range diff.StagedFiles {
+		category := categorizeFile(file)
+		groups[category] = append(groups[category], file)
+	}
+
+	if len(groups) <= 1 {
+		return []FileGroup{
+			{
+				Files:      diff.StagedFiles,
+				Diff:       diff.Diff,
+				Insertions: diff.Insertions,
+				Deletions:  diff.Deletions,
+			},
+		}
+	}
+
+	result := []FileGroup{}
+	for _, files := range groups {
+		result = append(result, FileGroup{
+			Files: files,
+		})
+	}
+	return result
+}
+
+func categorizeFile(file string) string {
+	lower := strings.ToLower(file)
+
+	switch {
+	case strings.Contains(lower, "auth") ||
+		strings.Contains(lower, "login") ||
+		strings.Contains(lower, "jwt") ||
+		strings.Contains(lower, "session"):
+		return "auth"
+
+	case strings.Contains(lower, "test") ||
+		strings.Contains(lower, "_test.go") ||
+		strings.Contains(lower, "spec"):
+		return "tests"
+
+	case strings.Contains(lower, "readme") ||
+		strings.Contains(lower, ".md") ||
+		strings.Contains(lower, "doc"):
+		return "docs"
+
+	case strings.Contains(lower, "docker") ||
+		strings.Contains(lower, "ci") ||
+		strings.Contains(lower, "yml") ||
+		strings.Contains(lower, "yaml") ||
+		strings.Contains(lower, "makefile"):
+		return "config"
+
+	case strings.Contains(lower, "ui") ||
+		strings.Contains(lower, "component") ||
+		strings.Contains(lower, "style") ||
+		strings.Contains(lower, "css") ||
+		strings.Contains(lower, "html"):
+		return "ui"
+
+	case strings.Contains(lower, "db") ||
+		strings.Contains(lower, "database") ||
+		strings.Contains(lower, "migration") ||
+		strings.Contains(lower, "schema"):
+		return "database"
+
+	case strings.Contains(lower, "api") ||
+		strings.Contains(lower, "route") ||
+		strings.Contains(lower, "handler") ||
+		strings.Contains(lower, "controller"):
+		return "api"
+
+	default:
+		return "general"
+	}
+}
+
+func GetFileDiff(file string) string {
+	out, err := exec.Command(
+		"git", "diff", "--cached", "--", file,
+	).Output()
+	if err != nil {
+		return ""
+	}
+	return string(out)
+}
+
+func StageFiles(files []string) error {
+	args := append([]string{"add"}, files...)
+	out, err := exec.Command("git", args...).CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("failed to stage files: %s", string(out))
+	}
+	return nil
 }