"""数据编排：拉取（Tushare 主 -> AKShare 兜底）+ 本地缓存。

真实行情落库到 candles 表（timeframe='1d'），回测统一从库读。
"""
from __future__ import annotations

import asyncio

from sqlalchemy import delete, func, select
from sqlalchemy.ext.asyncio import AsyncSession

from ..config import settings
from ..domain import Bar
from ..models import Candle
from . import akshare_provider, tushare_provider

DEFAULT_START = settings.data_default_start or "20200101"


def _providers(source: str):
    """按优先级返回 (名称, 同步拉取函数) 列表。"""
    seq = []
    if source in ("auto", "tushare") and settings.tushare_token:
        seq.append(("tushare", tushare_provider.fetch_daily))
    if source in ("auto", "akshare"):
        seq.append(("akshare", akshare_provider.fetch_daily))
    return seq


async def count_cached(session: AsyncSession, symbol: str) -> int:
    res = await session.execute(
        select(func.count()).select_from(Candle).where(
            Candle.symbol == symbol, Candle.timeframe == "1d"
        )
    )
    return int(res.scalar() or 0)


async def is_cached(session: AsyncSession, symbol: str) -> bool:
    return await count_cached(session, symbol) > 0


async def sync_symbol(
    session: AsyncSession,
    code: str,
    start: str | None = None,
    end: str | None = None,
    source: str = "auto",
    force: bool = False,
) -> dict:
    """拉取并缓存某标的日线。已缓存且非 force 时直接返回缓存计数。"""
    if not force and await is_cached(session, code):
        return {"symbol": code, "bars": await count_cached(session, code), "source": "cache"}

    start = start or DEFAULT_START
    adjust = settings.data_adjust
    errors: list[str] = []
    bars: list[Bar] = []
    used = None

    for name, fn in _providers(source):
        try:
            # tushare/akshare 是同步网络 IO，丢到线程池避免阻塞事件循环
            bars = await asyncio.to_thread(fn, code, start, end, adjust)
            used = name
            break
        except Exception as e:  # noqa: BLE001
            errors.append(f"{name}: {e}")

    if not bars:
        raise RuntimeError("所有数据源均失败 -> " + " | ".join(errors) if errors else "无可用数据源")

    # 全量替换该标的日线（避免重复主键）
    await session.execute(delete(Candle).where(Candle.symbol == code, Candle.timeframe == "1d"))
    for b in bars:
        session.add(
            Candle(symbol=code, timeframe="1d", ts=b.ts, open=b.open, high=b.high,
                   low=b.low, close=b.close, volume=b.volume)
        )
    await session.commit()
    return {"symbol": code, "bars": len(bars), "source": used}