"""模拟盘行情统一接口（raw 真实价 / qfq 前复权 双源，spec §3.3 / §5）。

双源（分红除权准确方案）：
- raw：撮合/涨跌停/成交价用真实价（adjustflag=3 / akshare adjust=""），cfg.data_paths['raw_dir']
- qfq：策略信号用前复权（无除权缺口，MA 信号准），cfg.data_paths['qfq_dir']
- daily_dir 是历史 mixed（hfq+raw），仅 backtest 兼容，模拟盘不用

_read_fn 内 lazy import datareader，避免模块级依赖 vnpy 链（tzlocal 等），
本机无 vnpy 完整依赖时仍可 import + 单测（mock _read_fn）。
"""
import logging
from collections.abc import Iterator

logger = logging.getLogger(__name__)


def _read_fn(interval: str):
    """按 interval 返回读取函数（lazy import）。"""
    if interval == "d":
        from sanguo_data.datareader import read_parquet_daily
        return read_parquet_daily
    if interval == "15m":
        from sanguo_data.datareader import read_parquet_15min
        return read_parquet_15min
    raise ValueError(f"不支持的 interval: {interval}（首版仅 d / 15m）")


def _resolve_dir_key(adjust: str, interval: str) -> str:
    """adjust+interval → cfg.data_paths 目录 key。日线/15min 均支持 raw/qfq 双源。"""
    if interval == "d":
        if adjust == "raw":
            return "raw_dir"
        if adjust == "qfq":
            return "qfq_dir"   # 干净 qfq（daily_dir 是 mixed，仅 backtest 兼容）
        return "daily_dir"
    if interval in ("15m", "15min"):
        if adjust == "raw":
            return "minute_15_raw_dir"
        if adjust == "qfq":
            return "minute_15_qfq_dir"
        return "minute_15_dir"
    raise ValueError(f"不支持的 interval: {interval}（仅 d / 15m）")


def _check_adjust_cfg(adjust: str, cfg, interval: str = "d") -> None:
    """raw/qfq 需对应 dir 配置，缺失明确报错（不静默 fallback，避免混源）。"""
    need = {
        ("raw", "d"): "raw_dir", ("qfq", "d"): "qfq_dir",
        ("raw", "15m"): "minute_15_raw_dir", ("qfq", "15m"): "minute_15_qfq_dir",
    }.get((adjust, interval))
    if need and cfg and need not in getattr(cfg, "data_paths", {}):
        raise ValueError(
            f"{adjust} 模式需 cfg.data_paths['{need}']（未配置；"
            f"先用对应下载脚本生成 parquet）"
        )


def iter_bars(
    symbols: list[str],
    start: str,
    end: str,
    interval: str,
    adjust: str = "qfq",
    cfg=None,
) -> Iterator[tuple]:
    """按日期 cross-section yield (date, {symbol: BarData})。"""
    dir_key = _resolve_dir_key(adjust, interval)
    _check_adjust_cfg(adjust, cfg, interval)
    read_fn = _read_fn(interval)
    by_date: dict = {}
    for sym in symbols:
        for bar in read_fn(sym, start, end, cfg, dir_key):
            dt = bar.datetime
            key = dt.date() if hasattr(dt, "date") else dt
            by_date.setdefault(key, {})[sym] = bar
    for date in sorted(by_date.keys()):
        yield date, by_date[date]


def fetch_day(symbol: str, date: str, interval: str,
              adjust: str = "qfq", cfg=None):
    """实走模式拉当日 bar（C-S3 用）。"""
    dir_key = _resolve_dir_key(adjust, interval)
    _check_adjust_cfg(adjust, cfg, interval)
    read_fn = _read_fn(interval)
    bars = read_fn(symbol, date, date, cfg, dir_key)
    return bars[-1] if bars else None