"""Shared utility functions for crawlers."""

from __future__ import annotations

import re
from datetime import date


def parse_date(text: str) -> str:
    """Return YYYY-MM-DD from common Chinese date formats, or today's date."""
    text = text.strip()
    if not text:
        return date.today().isoformat()
    m = re.search(r"(\d{4})[/-](\d{1,2})[/-](\d{1,2})", text)
    if m:
        try:
            return date(int(m.group(1)), int(m.group(2)), int(m.group(3))).isoformat()
        except ValueError:
            pass
    m2 = re.search(r"(\d{4})年(\d{1,2})月(\d{1,2})日?", text)
    if m2:
        try:
            return date(int(m2.group(1)), int(m2.group(2)), int(m2.group(3))).isoformat()
        except ValueError:
            pass
    return date.today().isoformat()


def extract_tags(standard_code: str, title: str) -> list[str]:
    """Derive simple keyword tags from standard code and title."""
    tags: list[str] = []
    code_upper = standard_code.upper()
    if "GB" in code_upper:
        tags.append("国家标准")
    if "/T" in code_upper:
        tags.append("推荐性")
    else:
        tags.append("强制性")
    keywords = ["电动", "安全", "自动驾驶", "充电", "智能网联", "碰撞", "排放", "网络安全"]
    for kw in keywords:
        if kw in title:
            tags.append(kw)
    return tags[:5]