"""顺丰月结抬头与结算规则。不访问数据库。"""
from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime
from decimal import Decimal, InvalidOperation, ROUND_HALF_UP
from typing import Any, Optional

SF_TRANSPORT_MODE = "sfkd"
SETTLE_UNSETTLED = "wjs"
SETTLE_SETTLED = "yjs"
_AMOUNT_QUANT = Decimal("0.01")
_MAX_AMOUNT = Decimal("9999999999999999.99")


@dataclass(frozen=True)
class FreightHeaderPlan:
    transport_mode: str
    waybill_no: Optional[str]
    freight_amount: Optional[Decimal]
    settle_status: Optional[str]
    clear_settle_time: bool


def normalize_waybill(value: Any) -> str:
    return str(value or "").strip()


def _is_blank(value: Any) -> bool:
    return value is None or (isinstance(value, str) and value.strip() == "")


def parse_optional_amount(value: Any) -> Optional[Decimal]:
    if _is_blank(value):
        return None
    try:
        amount = Decimal(str(value))
    except (InvalidOperation, ValueError):
        raise ValueError("运费金额格式不正确")
    if not amount.is_finite():
        raise ValueError("运费金额格式不正确")
    if amount < 0:
        raise ValueError("运费不能为负数")
    if amount > _MAX_AMOUNT:
        raise ValueError("运费金额超出范围")
    return amount.quantize(_AMOUNT_QUANT, rounding=ROUND_HALF_UP)


def freight_amount_label(transport_mode: Optional[str], amount: Optional[Decimal]) -> str:
    if (transport_mode or "") == SF_TRANSPORT_MODE and amount is None:
        return "月结"
    if amount is None:
        return ""
    return format(Decimal(amount).quantize(_AMOUNT_QUANT, rounding=ROUND_HALF_UP), "f")


def plan_freight_header(
    *,
    transport_mode: str,
    waybill_no: Any = None,
    freight_amount: Any = None,
) -> FreightHeaderPlan:
    mode = str(transport_mode or "").strip()
    if not mode:
        raise ValueError("请选择运输方式")
    if mode == SF_TRANSPORT_MODE:
        waybill = normalize_waybill(waybill_no)
        if not waybill:
            raise ValueError("请填写顺丰单号")
        if len(waybill) > 64:
            raise ValueError("顺丰单号不能超过 64 个字符")
        return FreightHeaderPlan(mode, waybill, None, SETTLE_UNSETTLED, True)
    if normalize_waybill(waybill_no):
        raise ValueError("该运输方式不能填写顺丰单号")
    amount = parse_optional_amount(freight_amount)
    if amount is None:
        raise ValueError("请填写运费")
    return FreightHeaderPlan(mode, None, amount, None, True)


def resolve_header_for_save(
    *,
    transport_mode: str,
    existing_waybill: Any,
    existing_amount: Any,
    existing_settle_status: Any,
    waybill_supplied: bool,
    waybill_no: Any,
    amount_supplied: bool,
    freight_amount: Any,
) -> FreightHeaderPlan:
    if (existing_settle_status or "") == SETTLE_SETTLED:
        raise ValueError("已结算的运费不能修改运输方式或顺丰单号")
    if transport_mode == SF_TRANSPORT_MODE:
        waybill = waybill_no if waybill_supplied else existing_waybill
        return plan_freight_header(
            transport_mode=transport_mode, waybill_no=waybill, freight_amount=None
        )
    amount = freight_amount if amount_supplied else existing_amount
    return plan_freight_header(
        transport_mode=transport_mode, waybill_no="", freight_amount=amount
    )


def plan_settle(*, current_amount: Optional[Decimal], submitted_amount: Any, now: datetime):
    amount = current_amount if _is_blank(submitted_amount) else parse_optional_amount(submitted_amount)
    return amount, SETTLE_SETTLED, now


def assert_settle_request(ids: list, submitted_amount: Any) -> None:
    if not ids:
        raise ValueError("请选择运费批次")
    if len(ids) != 1 and not _is_blank(submitted_amount):
        raise ValueError("批量结算不能填写运费")


def plan_fill_amount(*, current_amount: Optional[Decimal], settle_status: Optional[str], submitted_amount: Any) -> Decimal:
    if settle_status != SETTLE_SETTLED or current_amount is not None:
        raise ValueError("只有已结算且仍为月结的运费可以补填金额")
    amount = parse_optional_amount(submitted_amount)
    if amount is None:
        raise ValueError("请填写运费")
    return amount


def assert_freight_mutable(settle_status: Optional[str], action: str) -> None:
    if (settle_status or "") != SETTLE_SETTLED:
        return
    if action == "delete":
        raise ValueError("已结算的运费不能删除")
    if action == "items":
        raise ValueError("已结算的运费不能调整样本")
    raise ValueError("已结算的运费不能修改运输方式或顺丰单号")