// OpenFileInEditor opens filename in a text editor, and blocks until the editor terminates.
func OpenFileInEditor(filename string) error {
	editor := os.Getenv("VISUAL")
	if editor == "" {
		editor = os.Getenv("EDITOR")
		if editor == "" {
			fmt.Println("No $VISUAL or $EDITOR env is set, defaulting to vim")
			editor = "vi"
		}
	}

	// Get the full executable path for the editor.
	executable, err := exec.LookPath(editor)
	if err != nil {
		return err
	}

	cmd := exec.Command(executable, filename)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	return cmd.Run()
}