"""客户 C 级与产品 R 级的公共适当性校验。"""
from __future__ import annotations

from dataclasses import dataclass
import re


@dataclass(frozen=True)
class SuitabilityResult:
    ok: bool
    reason: str


_RISK_PATTERN = re.compile(r"^[CR]([1-5])$")


def check_suitability(customer_risk: str, product_risk: str) -> SuitabilityResult:
    customer_match = _RISK_PATTERN.fullmatch(customer_risk or "")
    product_match = _RISK_PATTERN.fullmatch(product_risk or "")
    if not customer_match or not product_match:
        return SuitabilityResult(False, "客户或产品风险等级无效")
    if customer_risk[0] != "C" or product_risk[0] != "R":
        return SuitabilityResult(False, "客户或产品风险等级类型无效")

    customer_level = int(customer_match.group(1))
    product_level = int(product_match.group(1))
    if product_level > customer_level:
        return SuitabilityResult(False, "产品风险等级高于客户风险等级")
    return SuitabilityResult(True, "适当性校验通过")