"""Unified data downloader: akshare primary, baostock fallback."""
import logging
from datetime import date, datetime
from typing import Optional
import pandas as pd
import akshare as ak
import baostock as bs

logger = logging.getLogger(__name__)

BAOSTOCK_FREQ_MAP = {"d": "d", "w": "w", "m": "m"}  # baostock only supports daily


def _download_akshare(symbol: str, start: str, end: str, adjust: str = "qfq") -> Optional[pd.DataFrame]:
    """Download daily bars from akshare. Returns DataFrame with OHLCV columns."""
    try:
        # symbol format: 'sh600000' in akshare stock_zh_a_hist expects raw code like '600000'
        # strip exchange prefix for akshare
        raw = symbol.replace("sh", "").replace("sz", "")
        df = ak.stock_zh_a_hist(
            symbol=raw,
            period="daily",
            start_date=start,
            end_date=end,
            adjust=adjust,
        )
        if df is None or df.empty:
            return None
        # Standardize columns
        col_map = {
            "日期": "date",
            "开盘": "open",
            "最高": "high",
            "最低": "low",
            "收盘": "close",
            "成交量": "volume",
            "成交额": "amount",
        }
        df = df.rename(columns=col_map)
        df["symbol"] = symbol
        return df[["symbol", "date", "open", "high", "low", "close", "volume", "amount"]]
    except Exception as e:
        logger.warning(f"akshare download failed for {symbol}: {e}")
        return None


def _download_baostock(symbol: str, start: str, end: str, frequency: str = "d") -> Optional[pd.DataFrame]:
    """Download daily bars from baostock as fallback."""
    try:
        bs.login()
        # baostock format: sh.600000
        code = f"{symbol[:2]}.{symbol[2:]}"
        rs = bs.query_history_k_data_plus(
            code=code,
            fields="date,open,high,low,close,volume,amount",
            start_date=start,
            end_date=end,
            frequency=frequency,
            adjustflag="2",  # qfq
        )
        if rs.error_code != "0":
            logger.warning(f"baostock error for {symbol}: {rs.error_msg}")
            return None
        data_list = []
        while rs.next():
            data_list.append(rs.get_row_data())
        bs.logout()
        if not data_list:
            return None
        df = pd.DataFrame(data_list, columns=["date", "open", "high", "low", "close", "volume", "amount"])
        df[["open", "high", "low", "close", "volume", "amount"]] = df[
            ["open", "high", "low", "close", "volume", "amount"]
        ].astype(float)
        df["symbol"] = symbol
        return df[["symbol", "date", "open", "high", "low", "close", "volume", "amount"]]
    except Exception as e:
        logger.warning(f"baostock download failed for {symbol}: {e}")
        try:
            bs.logout()
        except Exception:
            pass
        return None


def download_daily(
    symbol: str,
    start: str,
    end: str,
    adjust: str = "qfq",
    source: str = "auto",
) -> pd.DataFrame:
    """
    Download daily OHLCV data. Tries akshare first, falls back to baostock.

    Args:
        symbol: Stock symbol like 'sh600000' or 'sz000001'
        start: Start date 'YYYY-MM-DD'
        end: End date 'YYYY-MM-DD'
        adjust: 'qfq' (forward-adjusted), 'hfq' (backward), '' (none)
        source: 'auto' (akshare then baostock fallback), 'akshare' only,
            or 'baostock' only

    Returns:
        DataFrame with columns: symbol, date, open, high, low, close, volume, amount
    """
    df = None
    if source in ("akshare", "auto"):
        df = _download_akshare(symbol, start, end, adjust)
    if df is None and source in ("baostock", "auto"):
        df = _download_baostock(symbol, start, end)

    if df is None or df.empty:
        raise RuntimeError(f"Failed to download data for {symbol} from {start} to {end}")

    df["date"] = pd.to_datetime(df["date"])
    df = df.sort_values("date").reset_index(drop=True)
    return df


def download_batch(
    symbols: list[str],
    start: str,
    end: str,
    adjust: str = "qfq",
) -> dict[str, pd.DataFrame]:
    """Download daily data for multiple symbols. Returns {symbol: DataFrame}."""
    results = {}
    for sym in symbols:
        try:
            results[sym] = download_daily(sym, start, end, adjust)
            logger.info(f"Downloaded {sym}: {len(results[sym])} bars")
        except Exception as e:
            logger.error(f"Failed {sym}: {e}")
    return results