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