"""国内期货合约乘数与参考保证金比例（用于估算保证金与风险）。"""
import re
from typing import Optional

DEFAULT_SPEC = {"mult": 10, "margin_rate": 0.10}

# 参考交易所常见规格（乘数 + 保证金比例估算）
_SPEC_BY_THS: dict[str, dict] = {
    "ag": {"mult": 15, "margin_rate": 0.14},
    "au": {"mult": 1000, "margin_rate": 0.10},
    "cu": {"mult": 5, "margin_rate": 0.10},
    "al": {"mult": 5, "margin_rate": 0.10},
    "zn": {"mult": 5, "margin_rate": 0.10},
    "pb": {"mult": 5, "margin_rate": 0.10},
    "ni": {"mult": 1, "margin_rate": 0.12},
    "sn": {"mult": 1, "margin_rate": 0.12},
    "rb": {"mult": 10, "margin_rate": 0.09},
    "hc": {"mult": 10, "margin_rate": 0.09},
    "ss": {"mult": 5, "margin_rate": 0.11},
    "sc": {"mult": 1000, "margin_rate": 0.11},
    "fu": {"mult": 10, "margin_rate": 0.11},
    "bu": {"mult": 10, "margin_rate": 0.11},
    "ru": {"mult": 10, "margin_rate": 0.11},
    "sp": {"mult": 10, "margin_rate": 0.10},
    "i": {"mult": 100, "margin_rate": 0.11},
    "j": {"mult": 100, "margin_rate": 0.12},
    "jm": {"mult": 60, "margin_rate": 0.12},
    "m": {"mult": 10, "margin_rate": 0.08},
    "y": {"mult": 10, "margin_rate": 0.08},
    "p": {"mult": 10, "margin_rate": 0.09},
    "c": {"mult": 10, "margin_rate": 0.08},
    "cs": {"mult": 10, "margin_rate": 0.08},
    "jd": {"mult": 10, "margin_rate": 0.09},
    "lh": {"mult": 16, "margin_rate": 0.12},
    "l": {"mult": 5, "margin_rate": 0.09},
    "pp": {"mult": 5, "margin_rate": 0.09},
    "v": {"mult": 5, "margin_rate": 0.09},
    "eg": {"mult": 10, "margin_rate": 0.09},
    "eb": {"mult": 5, "margin_rate": 0.10},
    "pg": {"mult": 20, "margin_rate": 0.10},
    "RM": {"mult": 10, "margin_rate": 0.08},
    "OI": {"mult": 10, "margin_rate": 0.08},
    "SR": {"mult": 10, "margin_rate": 0.08},
    "CF": {"mult": 5, "margin_rate": 0.08},
    "MA": {"mult": 10, "margin_rate": 0.09},
    "TA": {"mult": 5, "margin_rate": 0.09},
    "FG": {"mult": 20, "margin_rate": 0.10},
    "SA": {"mult": 20, "margin_rate": 0.10},
    "UR": {"mult": 20, "margin_rate": 0.10},
    "SF": {"mult": 5, "margin_rate": 0.10},
    "SM": {"mult": 5, "margin_rate": 0.10},
    "AP": {"mult": 10, "margin_rate": 0.10},
    "CJ": {"mult": 5, "margin_rate": 0.10},
    "PK": {"mult": 5, "margin_rate": 0.10},
    "IF": {"mult": 300, "margin_rate": 0.12},
    "IH": {"mult": 300, "margin_rate": 0.12},
    "IC": {"mult": 200, "margin_rate": 0.12},
    "IM": {"mult": 200, "margin_rate": 0.12},
}


def get_contract_spec(ths_code: str) -> dict:
    code = (ths_code or "").strip()
    m = re.match(r"^([A-Za-z]+)", code)
    if not m:
        return dict(DEFAULT_SPEC)
    letters = m.group(1)
    spec = _SPEC_BY_THS.get(letters) or _SPEC_BY_THS.get(letters.upper()) or _SPEC_BY_THS.get(letters.lower())
    if spec:
        return {"mult": spec["mult"], "margin_rate": spec["margin_rate"]}
    return dict(DEFAULT_SPEC)


def calc_position_metrics(
    direction: str,
    entry: float,
    stop_loss: float,
    take_profit: float,
    lots: float,
    mark_price: Optional[float],
    capital: float,
    ths_code: str,
) -> dict:
    spec = get_contract_spec(ths_code)
    mult = spec["mult"]
    margin_rate = spec["margin_rate"]
    lots = lots or 1.0
    margin = entry * mult * lots * margin_rate

    if direction == "long":
        risk_amt = max(0.0, (entry - stop_loss) * mult * lots)
        reward = max(0.0, (take_profit - entry) * mult * lots)
        float_pnl = (mark_price - entry) * mult * lots if mark_price is not None else None
    else:
        risk_amt = max(0.0, (stop_loss - entry) * mult * lots)
        reward = max(0.0, (entry - take_profit) * mult * lots)
        float_pnl = (entry - mark_price) * mult * lots if mark_price is not None else None

    risk_pct = (risk_amt / capital * 100) if capital > 0 else 0.0
    pos_pct = (margin / capital * 100) if capital > 0 else 0.0
    rr = (reward / risk_amt) if risk_amt > 0 else None
    float_pct = (float_pnl / margin * 100) if margin > 0 and float_pnl is not None else None

    return {
        "mult": mult,
        "margin_rate": margin_rate,
        "margin": round(margin, 2),
        "risk_amount": round(risk_amt, 2),
        "risk_pct": round(risk_pct, 2),
        "position_pct": round(pos_pct, 2),
        "float_pnl": round(float_pnl, 2) if float_pnl is not None else None,
        "float_pct": round(float_pct, 2) if float_pct is not None else None,
        "rr_ratio": round(rr, 2) if rr is not None else None,
    }