"""Qlib 数据读取（dataset）：qlib.init 幂等 + 从 provider_uri 读行情面板。"""

from __future__ import annotations

from datetime import date
from pathlib import Path

import pandas as pd

_init_state: dict = {"uri": None}


def ensure_qlib_init(provider_uri: Path) -> None:
    """初始化 qlib（进程内同 uri 幂等；不同 uri 会重新 init）。"""
    if _init_state["uri"] == str(provider_uri):
        return
    import qlib
    from qlib.config import REG_CN

    qlib.init(provider_uri={"day": str(provider_uri)}, region=REG_CN)
    _init_state["uri"] = str(provider_uri)


def load_close_panel(
    provider_uri: Path,
    symbols: list[str],
    start: date,
    end: date,
) -> pd.DataFrame:
    """经 qlib D.features 读取 $close，返回 date×symbol 面板（index datetime）。"""
    ensure_qlib_init(provider_uri)
    from qlib.data import D

    lower = [s.lower() for s in symbols]
    df = D.features(
        lower,
        ["$close"],
        start_time=start.strftime("%Y-%m-%d"),
        end_time=end.strftime("%Y-%m-%d"),
        freq="day",
    )
    if df.empty:
        return pd.DataFrame()
    close = df["$close"].unstack(level="instrument")
    close.index = pd.to_datetime(close.index)
    close.columns = [c.upper() for c in close.columns]
    return close.sort_index()