"""回测参数校验（2026-08-15：此前结束时间选 2029 也能提交，零校验跑垃圾结果）。

L1 静态规则零 IO 秒判（格式/先后/未来/区间长度/资金/费率）；
L2 数据可用性查 dbbardata 锚定标的（600000 日线）最新日期，
模块级缓存 24h——只在提交时服务端调用一次，页面加载零开销；
查库失败返回 None 自动退化为仅 L1，数据层抖动不挡正常提交。
"""
from __future__ import annotations

import sqlite3
import time
from datetime import date, datetime

from fastapi import HTTPException

# 锚定标的:600000 浦发银行,上市以来从未长期停牌,是「数据灌到哪天」的可靠探针
_ANCHOR_SYMBOL = "600000"
_ANCHOR_EXCHANGE = "SSE"
_CACHE_TTL_SEC = 24 * 3600
_MIN_SPAN_DAYS = 30
_RATE_MAX = 0.01  # 费率上限 1%:填 3 这种是百分数/万分位口径错

_latest_cache: tuple[float, str] | None = None  # (查询时刻, 最新日期)


def _parse(name: str, value: str) -> date:
    try:
        return datetime.strptime(value, "%Y-%m-%d").date()
    except (ValueError, TypeError):
        raise HTTPException(400, f"{name}格式应为 YYYY-MM-DD: {value!r}")


def validate_backtest_range(start: str, end: str, min_days: int = _MIN_SPAN_DAYS) -> None:
    """L1+L2 区间校验,非法即抛 400(中文业务提示)。合法返回 None。"""
    s = _parse("开始日期", start)
    e = _parse("结束日期", end)
    if s >= e:
        raise HTTPException(400, f"开始日期({start})必须早于结束日期({end})")
    if (e - s).days < min_days:
        raise HTTPException(400, f"区间过短(不足 {min_days} 天),统计无参考意义,请至少选 {min_days} 天")
    today = date.today().isoformat()
    if end > today:
        raise HTTPException(400, f"结束日期 {end} 在未来,请选择历史日期(今天: {today})")
    latest = get_latest_daily_date()
    if latest and end > latest:
        raise HTTPException(400, f"结束日期 {end} 超出数据范围:日线数据最新到 {latest}")


def validate_capital(name: str, value: float) -> None:
    if value <= 0:
        raise HTTPException(400, f"{name}需大于 0,当前: {value}")


def validate_rate(name: str, value: float) -> None:
    if not (0 <= value <= _RATE_MAX):
        raise HTTPException(400, f"{name}应在 0~{_RATE_MAX:g} 之间(小数,万3=0.0003),当前: {value}")


def validate_cta_request(req) -> None:
    """CTA 回测(个股/优化共用):区间 + 资金 + 费率。"""
    validate_backtest_range(req.start, req.end)
    validate_capital("初始资金", req.capital)
    validate_rate("佣金率", req.commission_rate)
    validate_rate("印花税率", req.stamp_duty_rate)
    validate_rate("过户费率", req.transfer_fee_rate)
    validate_rate("滑点", req.slippage)


def validate_portfolio_request(req) -> None:
    """组合回测:区间 + 资金 + 费率(字段名与 CTA 不同:initial_cash/start_date)。"""
    validate_backtest_range(req.start_date, req.end_date)
    validate_capital("初始资金", req.initial_cash)
    validate_rate("佣金率", req.commission_rate)
    validate_rate("印花税率", req.stamp_duty_rate)
    validate_rate("滑点", req.slippage)


def _query_latest_daily_date() -> str | None:
    """直查 dbbardata 锚定标的日线最大日期;任何异常返回 None(退化为仅 L1)。"""
    try:
        from sanguo_data.config import load_config, find_config_path

        db_path = load_config(find_config_path()).data_paths.get("vnpy_db")
        if not db_path:
            return None
        conn = sqlite3.connect(db_path, timeout=5)
        try:
            row = conn.execute(
                "SELECT MAX(substr(datetime,1,10)) FROM dbbardata "
                "WHERE symbol=? AND exchange=? AND interval='d'",
                (_ANCHOR_SYMBOL, _ANCHOR_EXCHANGE),
            ).fetchone()
        finally:
            conn.close()
        return row[0] if row and row[0] else None
    except Exception:
        return None


def get_latest_daily_date() -> str | None:
    """数据最新交易日(带 24h 缓存)。日线 18 点后更新,无需每次提交都查。"""
    global _latest_cache
    now = time.time()
    if _latest_cache and now - _latest_cache[0] < _CACHE_TTL_SEC:
        return _latest_cache[1]
    latest = _query_latest_daily_date()
    if latest:
        _latest_cache = (now, latest)
    return latest