"""密码强度校验策略：拒绝常见弱密码，要求字母+数字组合。"""
import re

WEAK_PATTERNS = [
    "123456", "123456789", "password", "111111", "000000", "888888",
    "abc123", "qwerty", "654321", "12345678", "1234567", "admin",
]

CONSECUTIVE = ["0123456789", "9876543210", "abcdef", "qwerty", "asdfgh"]


def validate_password_strength(password: str) -> str | None:
    """返回错误提示；通过则返回 None。要求至少 6 位且含字母与数字。"""
    if not password or len(password) < 6:
        return "密码至少需要 6 个字符"
    low = password.lower()
    if low in WEAK_PATTERNS:
        return "密码过于简单，请使用更复杂的密码"
    if any(seq in low for seq in CONSECUTIVE):
        return "密码包含连续字符，请更换"
    has_letter = bool(re.search(r"[a-zA-Z]", password))
    has_digit = bool(re.search(r"\d", password))
    if not has_letter:
        return "密码必须包含字母"
    if not has_digit:
        return "密码必须包含数字"
    return None