74 lines
2.1 KiB
Python
74 lines
2.1 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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from decimal import Decimal, ROUND_DOWN
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from typing import Union
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Number = Union[int, float, Decimal, str]
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DAYS_PER_MONTH = 30
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FQ_ADVANCE_DAYS = 10
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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(round(float(frac) * DAYS_PER_MONTH))
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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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) -> 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 10 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, -FQ_ADVANCE_DAYS)
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return base
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