"""中文大写金额与阿拉伯金额互转（发票大小写金额一致性校验用）。

支持 "壹仟陆佰伍拾元整"、"壹佰贰拾叁元肆角伍分"、"拾元整" 等常见发票大写写法；
同时兼容 "¥1,234.50" / "1234.50元" 等阿拉伯写法的清洗。
解析失败返回 None，由调用方降级为"待确认"，不做硬性驳回。
"""

from __future__ import annotations

import re
from typing import Optional

_DIGITS = {
    "零": 0,
    "壹": 1,
    "贰": 2,
    "叁": 3,
    "肆": 4,
    "伍": 5,
    "陆": 6,
    "柒": 7,
    "捌": 8,
    "玖": 9,
}
_SMALL_UNITS = {"拾": 10, "佰": 100, "仟": 1000}
_GROUP_UNITS = {"万": 10**4, "亿": 10**8}
_ALL_KEYS = r"零壹贰叁肆伍陆柒捌玖拾佰仟万亿元圆角分整"

_TRAILING_CHARS = re.compile(r"[人民币¥￥\s,，元圆整]|人民币$")


def clean_amount_text(text: str) -> str:
    """清洗阿拉伯金额文本，返回可 float() 的字符串（失败返回原文本去掉常见缀符）。"""
    cleaned = _TRAILING_CHARS.sub("", (text or "").strip())
    return cleaned


def parse_cny_upper(text: str) -> Optional[float]:
    """解析中文大写金额为数值；无法解析时返回 None。"""
    if not text:
        return None
    raw = (text or "").strip()
    raw = raw.replace("人民币", "").replace("￥", "").replace("¥", "").strip()
    raw = re.sub(r"[\s,，]", "", raw)
    if not raw:
        return None
    if re.search(r"[0-9]", raw):
        return None  # 纯阿拉伯数字写法不属于大写金额

    if not re.fullmatch(rf"[{_ALL_KEYS}]+", raw):
        return None

    int_part, frac_part = raw, ""
    for sep in ("元", "圆"):
        if sep in raw:
            int_part, frac_part = raw.split(sep, 1)
            break

    try:
        yuan = _parse_integer_section(int_part) if int_part else 0.0
    except ValueError:
        return None

    jiao = fen = 0
    m_jiao = re.search(r"([零壹贰叁肆伍陆柒捌玖])角", frac_part)
    if m_jiao:
        jiao = _DIGITS[m_jiao.group(1)]
    m_fen = re.search(r"([零壹贰叁肆伍陆柒捌玖])分", frac_part)
    if m_fen:
        fen = _DIGITS[m_fen.group(1)]
    return round(yuan + jiao / 10 + fen / 100, 2)


def _parse_integer_section(section: str) -> float:
    """解析整数段（元之前的部分），如 壹仟陆佰伍拾 / 拾贰万零壹佰。"""
    if not section:
        return 0.0
    if section == "零":
        return 0.0

    total = 0.0
    group_value = 0
    number = 0
    for ch in section:
        if ch in _DIGITS:
            number = _DIGITS[ch]
        elif ch in _SMALL_UNITS:
            unit = _SMALL_UNITS[ch]
            group_value += (number if number else 1) * unit
            number = 0
        elif ch in _GROUP_UNITS:
            unit = _GROUP_UNITS[ch]
            group_value = (group_value + number) * unit
            total += group_value
            group_value = 0
            number = 0
        else:
            raise ValueError(f"非法大写字符: {ch}")
    total += group_value + number
    if total <= 0:
        raise ValueError("大写金额解析为 0")
    return total