"""Utility functions for shell history automation."""

import os
import re
from datetime import datetime
from typing import Optional


def normalize_command(command: str) -> str:
    """Normalize a shell command for comparison."""
    return command.strip()


def extract_command_keywords(command: str) -> list[str]:
    """Extract keywords from a command."""
    parts = command.split()
    keywords = [p for p in parts if not p.startswith("-")]
    return keywords


def format_timestamp(dt: Optional[datetime]) -> str:
    """Format a datetime object to a readable string."""
    if dt is None:
        return "Unknown"
    return dt.strftime("%Y-%m-%d %H:%M:%S")


def parse_timestamp(ts: str) -> Optional[datetime]:
    """Parse a timestamp string to datetime."""
    try:
        return datetime.strptime(ts, "%Y-%m-%d %H:%M:%S")
    except ValueError:
        return None


def escape_shell_string(s: str) -> str:
    """Escape special characters in a string for shell use."""
    return re.sub(r"([\\'"])", r"\\\1", s)