"""Market regime classification for strategy risk controls."""

from __future__ import annotations


def _safe_float(value, default: float = 0.0) -> float:
    try:
        if value is None or value == "":
            return default
        return float(value)
    except Exception:
        return default


def _benchmark_change(overview: dict, symbol: str) -> float:
    benchmarks = overview.get("benchmarks") if isinstance(overview, dict) else {}
    item = benchmarks.get(symbol) if isinstance(benchmarks, dict) else {}
    return _safe_float((item or {}).get("change_24h"))


def classify_market_regime(overview: dict | None) -> dict:
    """Return a plain-language market regime from the latest market snapshot.

    The first version intentionally uses broad market facts that already exist
    in `market_overview`: BTC/ETH 24h change, alt breadth, hot/crash counts and
    funding heat. It is meant to be a guardrail, not a prediction model.
    """
    data = overview if isinstance(overview, dict) else {}
    if not data or data.get("snapshot_missing") or _safe_float(data.get("sample_count")) <= 0:
        return {
            "regime": "unknown",
            "label": "数据不足",
            "confidence": 0.2,
            "risk_level": "medium",
            "position_multiplier": 0.75,
            "reasons": ["市场快照不足，保守运行但不直接停止交易"],
            "metrics": {},
        }

    btc_change = _benchmark_change(data, "BTC/USDT")
    eth_change = _benchmark_change(data, "ETH/USDT")
    adv_dec = _safe_float(data.get("advance_decline_ratio"))
    avg_change = _safe_float(data.get("avg_change_24h"))
    hot_count = int(_safe_float(data.get("hot_count_5pct")))
    crash_count = int(_safe_float(data.get("crash_count_5pct")))
    funding = data.get("funding") if isinstance(data.get("funding"), dict) else {}
    extreme_positive = int(_safe_float(funding.get("extreme_positive_count")))
    avg_funding = _safe_float(funding.get("avg_funding_rate"))
    metrics = {
        "btc_change_24h": btc_change,
        "eth_change_24h": eth_change,
        "advance_decline_ratio": adv_dec,
        "avg_change_24h": avg_change,
        "hot_count_5pct": hot_count,
        "crash_count_5pct": crash_count,
        "extreme_positive_funding_count": extreme_positive,
        "avg_funding_rate": avg_funding,
    }

    if btc_change <= -3 or eth_change <= -4 or adv_dec < 0.55 or crash_count >= 30:
        return {
            "regime": "risk_off",
            "label": "风险释放期",
            "confidence": 0.88,
            "risk_level": "critical",
            "position_multiplier": 0.25,
            "reasons": ["主流币或山寨广度明显走弱，新开山寨仓位必须显著降仓并提高质量门槛"],
            "metrics": metrics,
        }

    if crash_count >= 18 or adv_dec < 0.75 or (btc_change <= -1.5 and avg_change < 0):
        return {
            "regime": "risk_off",
            "label": "偏风险释放",
            "confidence": 0.75,
            "risk_level": "high",
            "position_multiplier": 0.35,
            "reasons": ["市场下跌覆盖面较大，只允许特别高质量的机会"],
            "metrics": metrics,
        }

    if hot_count >= 35 and extreme_positive >= 20 and avg_funding >= 0.00045:
        return {
            "regime": "meme_frenzy",
            "label": "情绪过热期",
            "confidence": 0.72,
            "risk_level": "high",
            "position_multiplier": 0.5,
            "reasons": ["强势币和正 funding 同时过热，追高回撤风险升高"],
            "metrics": metrics,
        }

    if avg_change >= 0.8 and adv_dec >= 1.2 and hot_count >= 15 and btc_change > -1:
        return {
            "regime": "altcoin_rotation",
            "label": "山寨轮动期",
            "confidence": 0.78,
            "risk_level": "medium",
            "position_multiplier": 1.0,
            "reasons": ["上涨覆盖面和强势币数量支持继续寻找精选机会"],
            "metrics": metrics,
        }

    if btc_change >= 1.2 and eth_change >= 0.8 and adv_dec >= 0.85:
        return {
            "regime": "btc_main_uptrend",
            "label": "主流带动期",
            "confidence": 0.7,
            "risk_level": "medium",
            "position_multiplier": 0.8,
            "reasons": ["BTC/ETH 提供方向支撑，但山寨仍要精选"],
            "metrics": metrics,
        }

    if abs(avg_change) <= 0.6 and 0.75 <= adv_dec <= 1.25:
        return {
            "regime": "sideways_chop",
            "label": "横盘震荡期",
            "confidence": 0.65,
            "risk_level": "medium",
            "position_multiplier": 0.65,
            "reasons": ["市场没有单边方向，追突破容易来回挨打，偏向等回踩"],
            "metrics": metrics,
        }

    return {
        "regime": "unknown",
        "label": "结构性行情",
        "confidence": 0.45,
        "risk_level": "medium",
        "position_multiplier": 0.75,
        "reasons": ["市场环境不够清晰，保持精选和轻仓"],
        "metrics": metrics,
    }


__all__ = ["classify_market_regime"]