group_xinghuo_jinrong/scripts/dev/calc_convert_demo.py

# -*- coding: utf-8 -*-
"""基金转换主示例实算（T-2b · PRD §5.3 数值来源 · 禁止手算）。

**为什么必须调用生产 `app.service.convert.calc` 而不是脚本内再写一套公式**

v0.7 曾两次因「手算与口径不符」被外部审查质疑；而"脚本自己实现一份公式"
是同一类问题的变体——**两处公式必然漂移**（生产 `calc.py` 改了、脚本没改，
PRD 里的数字就变成假证据）。这与 D18（批次补建规则只留一个副本）是同一条纪律。

故本脚本：
1. **只做输入准备与输出打印**，全部计算走 `calc` / `fee` 的生产函数；
2. 打印后与 PRD §5.3 的**期望值逐项比对**，不一致即 `exit 1`
   —— 这样它同时是一道「PRD 数字 ↔ 生产口径」一致性门禁。

运行：<托管 Python> scripts/dev/calc_convert_demo.py
"""

from __future__ import annotations

import sys
from datetime import date, datetime, time, timedelta
from decimal import Decimal
from pathlib import Path

# ① sys.path 引导项目根（直跑脚本时 sys.path[0] 为脚本目录；同 verify_convert_seed 先例）
ROOT = Path(__file__).resolve().parents[2]
sys.path.insert(0, str(ROOT))

from app.service.convert import calc, fee  # noqa: E402
from app.service.convert.types import FeeRule, Lot  # noqa: E402

#: 与 PRD §5.3 同一交易日（也是 06-seed-nav.sql 的净值日期）。
TRADE_DATE = date(2026, 9, 4)

#: 07-seed-fee-rule.sql 的赎回费五档（22 号文 §10 下限）。
RULES = [
    FeeRule(0, 7, Decimal("0.0150")),
    FeeRule(7, 30, Decimal("0.0100")),
    FeeRule(30, 180, Decimal("0.0050")),
    FeeRule(180, 365, Decimal("0.0025")),
    FeeRule(365, None, Decimal("0.0000")),
]

# 两端同属**华夏模拟基金 / TA-CN-001**（满足转换前置硬约束：同管理人 + 同 TA）。
NAV_OUT = Decimal("1.0300")  # PROD-110022 稳健债基 A（bond）
NAV_IN = Decimal("0.9500")  # PROD-003095 医药健康精选（stock / 主动偏股型）
SUB_RATE_OUT = Decimal("0.0030")  # 转出端申购费率（债基，22 号文 §8 上限 0.3%）
SUB_RATE_IN = Decimal("0.0080")  # 转入端申购费率（主动偏股型，上限 0.8%）

REQUESTED_QTY = Decimal("50000.0000")

#: PRD §5.3 期望值 —— 实算结果必须逐项命中。
EXPECTED = {
    "批次 1 amount": "30900.00",
    "批次 1 fee": "154.50",
    "批次 2 amount": "20600.00",
    "批次 2 fee": "309.00",
    "out_amount": "51500.00",
    "redeem_fee": "463.50",
    "convert_amount": "51036.50",
    "diff_fee(B)": "252.40",
    "in_amount": "50784.10",
    "in_qty(B)": "53456.95",
    "rounding_diff": "-0.0026",
    "diff_fee(A)": "253.91",
    "in_qty(A)": "53455.36",
    "同费率 diff_fee": "0.00",
    "同费率 in_qty": "53722.63",
}


def _lot(lot_id: str, hold_days: int, qty: str, nav: Decimal) -> Lot:
    """构造 `hold_days` 天前确认的批次（交易日固定为 TRADE_DATE）。"""
    confirmed = datetime.combine(TRADE_DATE - timedelta(days=hold_days), time(10, 0, 0))
    return Lot(
        lot_id=lot_id,
        confirmed_at=confirmed,
        remain_qty=Decimal(qty),
        nav=nav,
        qty=Decimal(qty),
    )


def compute() -> dict[str, str]:
    """跑一遍主示例全链，返回**结果字典**（键与 EXPECTED 对齐）。"""
    # —— 输入：跨 2 个批次、持有期不同 → 费率不同（30000 份满 30 日 / 20000 份不足 7 日）
    lots = [
        _lot("LOT-DEMO-01", 100, "30000.0000", NAV_OUT),
        _lot("LOT-DEMO-02", 3, "20000.0000", NAV_OUT),
    ]

    plan = calc.plan_lots(lots, REQUESTED_QTY)
    result: dict[str, str] = {}

    # —— 逐批：先各自 2 位舍入、再求和（PRD §12「舍入顺序」）——
    out_amount = Decimal("0")
    redeem_fee = Decimal("0")
    for idx, alloc in enumerate(plan.allocations, start=1):
        hold_days = calc.hold_days(TRADE_DATE, alloc.confirmed_at)
        rate = fee.pick_fee_rate(RULES, hold_days)
        amount = calc.lot_amount(alloc.qty, alloc.nav)
        fee_amount = calc.lot_fee(amount, rate)
        out_amount += amount
        redeem_fee += fee_amount
        result[f"批次 {idx} amount"] = str(amount)
        result[f"批次 {idx} fee"] = str(fee_amount)
        print(
            f"批次 {idx}（{alloc.lot_id}）{alloc.qty} 份 / 持有 {hold_days} 天 / "
            f"费率 {rate}（{rate * 100}%）→ amount={amount}  fee={fee_amount}"
        )

    convert_amount = calc.convert_amount(out_amount, redeem_fee)
    result["out_amount"] = str(out_amount)
    result["redeem_fee"] = str(redeem_fee)
    result["convert_amount"] = str(convert_amount)

    # —— 口径 B：价外法两端差（本期默认，PRD §2.1.1）——
    diff_b = calc.diff_fee(convert_amount, SUB_RATE_OUT, SUB_RATE_IN, "amount_diff")
    in_amount = calc.convert_amount(convert_amount, diff_b)
    in_qty_b = calc.in_qty(in_amount, NAV_IN)
    result["diff_fee(B)"] = str(diff_b)
    result["in_amount"] = str(in_amount)
    result["in_qty(B)"] = str(in_qty_b)
    result["rounding_diff"] = str(calc.rounding_diff(in_amount, NAV_IN, in_qty_b))

    # —— 口径 A：费率差法（配置 convert_diff_fee_mode='rate_diff' 时启用）——
    diff_a = calc.diff_fee(convert_amount, SUB_RATE_OUT, SUB_RATE_IN, "rate_diff")
    in_qty_a = calc.in_qty(calc.convert_amount(convert_amount, diff_a), NAV_IN)
    result["diff_fee(A)"] = str(diff_a)
    result["in_qty(A)"] = str(in_qty_a)

    # —— 同费率对照（两端均为 0.0030）→ 补差 0，用于 PRD §9 第 19 条 ——
    diff_same = calc.diff_fee(convert_amount, SUB_RATE_OUT, SUB_RATE_OUT, "amount_diff")
    in_amount_same = calc.convert_amount(convert_amount, diff_same)
    result["同费率 diff_fee"] = str(diff_same)
    result["同费率 in_qty"] = str(calc.in_qty(in_amount_same, NAV_IN))

    return result


def main() -> int:
    print("=== 主示例实算（与生产 calc.py 同一套公式）===")
    actual = compute()

    print()
    print("=== 与 PRD §5.3 期望值逐项比对 ===")
    mismatches = []
    for key, expected in EXPECTED.items():
        got = actual.get(key, "<缺失>")
        ok = got == expected
        if not ok:
            mismatches.append((key, expected, got))
        print(f"  [{'OK ' if ok else 'FAIL'}] {key:<18} 期望 {expected:<12} 实算 {got}")

    if mismatches:
        print()
        print(f"❌ {len(mismatches)} 项不一致 —— PRD 数字或生产口径已被改动，停下查清：")
        for key, expected, got in mismatches:
            print(f"   · {key}：期望 {expected} / 实算 {got}")
        return 1

    print()
    print(f"✅ 全部 {len(EXPECTED)} 项与 PRD §5.3 一致（口径 B in_qty=53456.95）")
    return 0


if __name__ == "__main__":
    try:  # Windows 控制台默认 cp936，避免打印中文报错
        sys.stdout.reconfigure(encoding="utf-8")
    except Exception:  # noqa: BLE001 - 环境不支持时忽略，不影响计算
        pass
    raise SystemExit(main())