"""分期缴费：应缴日计算（整数月按日历递增，小数月按 30 天/月换算）""" from __future__ import annotations import calendar import json from decimal import Decimal, ROUND_DOWN, ROUND_HALF_UP from typing import List, Optional, Sequence, Union Number = Union[int, float, Decimal, str] DAYS_PER_MONTH = 30 DEFAULT_INSTALLMENT_ADVANCE_DAYS = 30 def add_days_yyyymmdd(date_str: str, days: int) -> str: raw = (date_str or "").strip().replace("-", "") if len(raw) != 8: return "" from datetime import date, timedelta y = int(raw[0:4]) m = int(raw[4:6]) d = int(raw[6:8]) dt = date(y, m, d) + timedelta(days=days) return f"{dt.year:04d}{dt.month:02d}{dt.day:02d}" def add_months_yyyymmdd(date_str: str, months: int) -> str: raw = (date_str or "").strip().replace("-", "") if len(raw) != 8: return "" y = int(raw[0:4]) m = int(raw[4:6]) d = int(raw[6:8]) month_index = m - 1 + months ny = y + month_index // 12 nm = month_index % 12 + 1 last_day = calendar.monthrange(ny, nm)[1] nd = min(d, last_day) return f"{ny:04d}{nm:02d}{nd:02d}" def add_interval_months_yyyymmdd(date_str: str, total_months: Number) -> str: """整数部分按日历加月，小数部分按 30 天/月换算为天数。""" raw = (date_str or "").strip().replace("-", "") if len(raw) != 8: return "" total = Decimal(str(total_months)) if total == 0: return raw whole = int(total.to_integral_value(rounding=ROUND_DOWN)) frac = total - Decimal(whole) result = raw if whole: result = add_months_yyyymmdd(result, whole) if frac: days = int( (frac * Decimal(DAYS_PER_MONTH)).to_integral_value( rounding=ROUND_HALF_UP ) ) if days: result = add_days_yyyymmdd(result, days) return result def calc_fq_installment_due_date( start_date: str, index: int, interval_months: Number, advance_days: int = DEFAULT_INSTALLMENT_ADVANCE_DAYS, ) -> str: """第 1 期=开始时间；第 2 期起在间隔递增基础上提前 advance_days 天。""" total_months = Decimal(str(index)) * Decimal(str(interval_months)) base = add_interval_months_yyyymmdd(start_date, total_months) if index >= 1: return add_days_yyyymmdd(base, -int(advance_days or 0)) return base def parse_installment_ratios(raw: Optional[str]) -> List[Decimal]: if not raw: return [] try: data = json.loads(raw) return [Decimal(str(x)) for x in data] if isinstance(data, list) else [] except (json.JSONDecodeError, TypeError, ValueError): return [] def is_legacy_installment_ratios( values: Sequence[Number], contract_amount: Optional[Decimal] = None, ) -> bool: if not values: return False nums = [Decimal(str(v)) for v in values] total = sum(nums) mx = max(nums) if contract_amount is not None and abs(total - contract_amount) < Decimal('0.02'): return False return mx <= Decimal('100') and abs(total - Decimal('100')) < Decimal('0.05') def _money_to_cents(value: Decimal) -> int: return int( (Decimal(str(value)) * Decimal('100')).to_integral_value( rounding=ROUND_HALF_UP ) ) def resolve_installment_due_amounts( contract_amount: Optional[Decimal], stored: Sequence[Number], count: int, ) -> List[Decimal]: if stored and len(stored) == count: if is_legacy_installment_ratios(stored, contract_amount): return calc_installment_due_amounts_by_ratios(contract_amount, stored) return [Decimal(str(x)) for x in stored] return _calc_installment_due_amounts_inline(contract_amount, count) def _calc_installment_due_amounts_inline( contract_amount: Optional[Decimal], count: int, ) -> List[Decimal]: if contract_amount is None or count < 1: return [] total_cents = _money_to_cents(contract_amount) base_cents = total_cents // count amounts: List[Decimal] = [] sum_cents = 0 for i in range(count): if i == count - 1: cents = total_cents - sum_cents else: cents = base_cents sum_cents += base_cents amounts.append(Decimal(cents) / Decimal(100)) return amounts def calc_installment_due_amounts_by_ratios( contract_amount: Optional[Decimal], ratios: Sequence[Number], ) -> List[Decimal]: """全额分配：前 n-1 期 floor 到分，末位补尾差。""" if contract_amount is None or not ratios: return [] count = len(ratios) total_cents = _money_to_cents(contract_amount) amounts: List[Decimal] = [] sum_cents = 0 for i in range(count): if i == count - 1: cents = total_cents - sum_cents else: ratio = Decimal(str(ratios[i])) cents = int( (Decimal(total_cents) * ratio / Decimal('100')).to_integral_value( rounding=ROUND_DOWN ) ) sum_cents += cents amounts.append(Decimal(cents) / Decimal(100)) return amounts def calc_unpaid_amounts_by_ratios( remaining: Decimal, ratios: Sequence[Number], unpaid_indices: Sequence[int], ) -> List[Decimal]: """部分已缴：按未缴期次比例归一化分配 remaining。""" if remaining <= 0 or not unpaid_indices: return [] subset = [Decimal(str(ratios[i])) for i in unpaid_indices] ratio_sum = sum(subset) if ratio_sum <= 0: return [] total_cents = _money_to_cents(remaining) amounts: List[Decimal] = [] sum_cents = 0 for j, _idx in enumerate(unpaid_indices): if j == len(unpaid_indices) - 1: cents = total_cents - sum_cents else: cents = int( (Decimal(total_cents) * subset[j] / ratio_sum).to_integral_value( rounding=ROUND_DOWN ) ) sum_cents += cents amounts.append(Decimal(cents) / Decimal(100)) return amounts def resolve_locked_remaining_due_amounts( contract_amount: Decimal, locked_due_amount: Decimal, stored: Sequence[Number], unpaid_indices: Sequence[int], ) -> List[Decimal]: """按剩余合同金额分配未缴期次；有期次权重时按权重，无则均摊。""" contract = Decimal(str(contract_amount)) locked = Decimal(str(locked_due_amount)) remaining = contract - locked if remaining < 0: raise ValueError("合同金额不能小于已缴或锁定明细金额") indices = [int(index) for index in unpaid_indices] if not indices: return [] values = [Decimal(str(value)) for value in stored] if ( values and max(indices) < len(values) and all(values[index] > 0 for index in indices) ): weighted = calc_unpaid_amounts_by_ratios(remaining, values, indices) if weighted: return weighted return _calc_installment_due_amounts_inline(remaining, len(indices))