"""Historical K-line loader for the backtest result chart.

Reads daily bars from the A-share DB via sanguo_data.datareader.read_db_daily
and returns plain dicts for the frontend candlestick chart. Task S1.5.
"""
from __future__ import annotations


def load_kline(symbol: str, start: str, end: str, cfg=None) -> list[dict]:
    """Return [{datetime, open, high, low, close, volume, vt_symbol}, ...].

    Args:
        symbol: Bare symbol e.g. "600000" (DB stores without exchange suffix).
        start: Start date YYYY-MM-DD.
        end: End date YYYY-MM-DD.
        cfg: Optional data config; None uses default data_platform.yaml.
    """
    from sanguo_data.datareader import read_db_daily
    from sanguo_data.config import load_config, find_config_path

    if cfg is None:
        cfg = load_config(find_config_path())
    bars = read_db_daily(symbol, start, end, cfg)
    return [
        {
            "datetime": str(b.datetime),
            "open": b.open_price,
            "high": b.high_price,
            "low": b.low_price,
            "close": b.close_price,
            "volume": getattr(b, "volume", 0),
            "vt_symbol": getattr(b, "vt_symbol", symbol),
        }
        for b in bars
    ]