66 lines
2.5 KiB
Python
66 lines
2.5 KiB
Python
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"""持有期 → 赎回费率查表（架构 §7 · D11 数据驱动）。
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规则来自 `core_fee_rule`（`fee_type='redeem'`），**本模块不查库** ——
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调用方（`core_ro.get_redeem_fee_rules(product_id)`）取回规则行后传入。
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**区间口径：左闭右开 `[min_hold_days, max_hold_days)`**，`max_hold_days = NULL` 表示无上限。
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与 `scripts/core/07-seed-fee-rule.sql`、架构 §7 分档表三处一致：
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| 档 | 区间 | 费率（22 号文 §10 下限） |
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| --- | --- | --- |
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| < 7 日 | `[0, 7)` | 0.0150 |
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| 7–30 日 | `[7, 30)` | 0.0100 |
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| 30–180 日 | `[30, 180)` | 0.0050 |
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| 180–365 日 | `[180, 365)` | 0.0025 |
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| ≥ 365 日 | `[365, NULL)` | 0.0000 |
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边界语义举例（PRD §12：**满 7 日归 7–30 档**）：`hold_days = 6` → 1.5%；
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`hold_days = 7` → 1.0%；`hold_days = 365` → 0。
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"""
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from __future__ import annotations
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from decimal import Decimal
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from typing import Iterable, Sequence
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from app.service.convert.errors import FeeRuleMissing
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from app.service.convert.types import FeeRule, to_decimal
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def matches(rule: FeeRule, hold_days: int) -> bool:
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"""单条规则是否命中（左闭右开；`max_hold_days is None` 表示无上限）。"""
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if hold_days < rule.min_hold_days:
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return False
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return rule.max_hold_days is None or hold_days < rule.max_hold_days
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def pick_fee_rate(
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rules: Sequence[FeeRule] | Iterable[FeeRule],
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hold_days: int,
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*,
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product_id: str | None = None,
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) -> Decimal:
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"""按持有天数取赎回费率；**无命中即数据缺失，直接失败**（不降级为 0）。
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多档同时命中时取 `min_hold_days` **最大**的一档（最具体的区间）——
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真实费率表本不应重叠，这条规则是防止种子误配出重叠区间时"取到哪档看运气"。
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⚠️ 为什么无命中不能返回 0：静默按 0 计费会**少收赎回费且不留痕**
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（客户与基金财产双向损失），比直接失败危险得多。费率表必含 `[0, 7)` 档，
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走到这里说明种子漏灌或产品未配档 → `FeeRuleMissing`（500，内部兜底）。
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"""
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candidates = [
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rule
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for rule in rules
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if rule.fee_type == "redeem" and matches(rule, hold_days)
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]
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if not candidates:
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raise FeeRuleMissing(
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f"未匹配到赎回费率档：product_id={product_id!r}，持有 {hold_days} 天"
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)
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best = max(candidates, key=lambda rule: rule.min_hold_days)
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return to_decimal(best.rate)
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__all__ = ["matches", "pick_fee_rate"]
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