"""
Funding and basis behavior analytics.

Analyses funding rate regimes, basis dynamics (spot vs perp),
and carry trade profitability.
"""

from __future__ import annotations

import math

import numpy as np


# ── Funding rate analytics ──────────────────────────────────

def funding_regime(
    funding_rates: list[float],
    window_hours: int = 24,
    n_samples_per_hour: int = 60,  # e.g., 1 sample/min → 60/hr
) -> dict:
    """Classify current funding regime.

    Returns regime classification and rolling stats.
    """
    window = window_hours * n_samples_per_hour
    if len(funding_rates) < window:
        return {"regime": "insufficient_data", "mean_annual": 0, "volatility": 0}

    recent = funding_rates[-window:]
    mean_rate = float(np.mean(recent))
    std_rate = float(np.std(recent))

    # Funding is per-hour rate. Annualize: compounded 3x daily.
    # Hyperliquid funding: 8h rate * 3 = daily, * 365 = annual (approx)
    ann_rate = mean_rate * 3 * 365 * 100  # *100 to convert from fraction to %

    if ann_rate > 15:
        regime = "high_positive"
    elif ann_rate > 5:
        regime = "positive"
    elif ann_rate < -15:
        regime = "high_negative"
    elif ann_rate < -5:
        regime = "negative"
    else:
        regime = "neutral"

    return {
        "regime": regime,
        "mean_hourly": round(float(mean_rate), 8),
        "mean_annual_pct": round(ann_rate, 2),
        "volatility": round(float(std_rate), 8),
        "window_hours": window_hours,
    }


def funding_predictability(
    funding_history: list[float],
    n_lags: int = 3,
) -> dict:
    """Measure funding rate autocorrelation — is funding momentum persistent?"""
    if len(funding_history) < n_lags + 2:
        return {"autocorr": [], "momentum_strength": 0}

    autocorr = []
    for lag in range(1, n_lags + 1):
        x = funding_history[:-lag]
        y = funding_history[lag:]
        if len(x) < 2:
            autocorr.append(0)
            continue
        corr = np.corrcoef(x, y)[0, 1]
        autocorr.append(round(float(corr) if not np.isnan(corr) else 0, 4))

    momentum = float(np.mean([abs(a) for a in autocorr]))

    return {
        "autocorr": autocorr,
        "momentum_strength": round(momentum, 4),
        "is_momentum": momentum > 0.3,
    }


def funding_carry_pnl(
    funding_rates: list[float],
    position_size: float = 1.0,
    mark_prices: list[float] | None = None,
    n_samples_per_hour: int = 60,
) -> dict:
    """Estimate carry PnL from holding a position given funding rates.

    For positive funding → shorts earn, longs pay.
    """
    if not funding_rates:
        return {"cumulative_pnl": 0, "hourly_pnl": []}

    hourly = []
    cum = 0.0
    for i, rate in enumerate(funding_rates):
        if i % n_samples_per_hour == 0:
            notional = position_size * (mark_prices[i] if mark_prices and i < len(mark_prices) else 1.0)
            pnl = rate * notional  # funding rate * position notional
            cum += pnl
            hourly.append(round(pnl, 8))

    return {
        "cumulative_pnl": round(cum, 6),
        "hourly_pnl": hourly[-72:],  # last 72 hours
        "n_hours": len(hourly),
    }


# ── Basis analytics ──────────────────────────────────────────

def basis_spread(
    perp_prices: list[float],
    spot_prices: list[float],
) -> dict:
    """Compute basis (perp premium over spot) and its statistics.

    basis_bps = (perp - spot) / spot * 10000
    """
    min_len = min(len(perp_prices), len(spot_prices))
    if min_len < 2:
        return {"current_basis_bps": 0, "mean_basis_bps": 0, "max_basis_bps": 0}

    perp = perp_prices[-min_len:]
    spot = spot_prices[-min_len:]
    basis_arr = []

    for p, s in zip(perp, spot):
        if s > 0:
            basis_arr.append((p - s) / s * 10000)

    a = np.array(basis_arr) if basis_arr else np.array([0.0])

    return {
        "current_basis_bps": round(float(a[-1]), 2) if len(a) > 0 else 0,
        "mean_basis_bps": round(float(np.mean(a)), 2),
        "std_basis_bps": round(float(np.std(a)), 2),
        "max_basis_bps": round(float(np.max(a)), 2),
        "min_basis_bps": round(float(np.min(a)), 2),
        "n_samples": len(a),
    }


def basis_convergence_speed(
    basis_history: list[float],
    half_life_lookback: int = 1440,  # 24h at 1min samples
) -> dict:
    """Estimate basis mean-reversion half-life via AR(1).

    Half-life = -log(2) / log(|rho|)
    """
    if len(basis_history) < 10:
        return {"half_life_minutes": 0, "ar1_coef": 0, "mean_reverting": False}

    x = basis_history[-half_life_lookback:]
    if len(x) < 10:
        return {"half_life_minutes": 0, "ar1_coef": 0, "mean_reverting": False}

    x_t = x[:-1]
    x_t1 = x[1:]

    rho = np.corrcoef(x_t, x_t1)[0, 1]
    rho = max(min(rho, 0.999), -0.999)

    if abs(rho) < 0.01:
        half_life = 0
    else:
        half_life = -math.log(2) / math.log(abs(rho))

    return {
        "half_life_minutes": round(half_life, 1),
        "ar1_coef": round(float(rho), 4),
        "mean_reverting": abs(rho) > 0.1 and rho < 0.95,
    }