"""
trend_detector.py — Trend strength and maturity helpers.

Utility functions for computing trend alignment, acceleration, persistence.
Used by regime_detector and price_structure scorer.
"""

import numpy as np
import pandas as pd


def ema_alignment_score(close: float, ema20: float, ema60: float, ema120: float) -> float:
    """Score EMA alignment: 0=bearish, 50=neutral, 100=bullish."""
    if any(pd.isna(x) for x in [ema20, ema60, ema120]):
        return 50.0

    alignments = 0
    if ema20 > ema60:
        alignments += 1
    if ema60 > ema120:
        alignments += 1
    if ema20 > ema120:
        alignments += 1

    if alignments == 3:
        return 85.0
    elif alignments == 2:
        return 65.0
    elif alignments == 1:
        return 35.0
    else:
        return 15.0


def adx_trend_score(adx: float) -> float:
    """Convert ADX value to trend score: 0-100."""
    if pd.isna(adx):
        return 50.0
    if adx > 40:
        return 90.0
    elif adx > 25:
        return 60.0 + (adx - 25) / 15 * 30
    elif adx > 15:
        return 40.0 + (adx - 15) / 10 * 20
    else:
        return max(10.0, adx / 15 * 40)


def breadth_persistence(breadth_scores: list[float], window: int = 5) -> float:
    """How consistently has breadth stayed at its current level? 0-100."""
    if len(breadth_scores) < window:
        return 50.0
    recent = breadth_scores[-window:]
    mean_val = np.mean(recent)
    std_val = np.std(recent) if len(recent) > 1 else 0
    # Low std = high persistence
    persistence = 100 - min(std_val * 5, 100)
    # Bias: higher breadth = higher persistence score
    return persistence * 0.5 + mean_val * 0.5


def trend_strength_composite(ema_score: float, adx_score: float,
                              breadth_score: float) -> float:
    """Composite trend strength 0-100."""
    return ema_score * 0.25 + adx_score * 0.25 + breadth_score * 0.50


def compute_maturity(trend_strength: float, breadth_persistence: float,
                     vol_expansion: float) -> float:
    """
    Compute regime maturity score 0-100.

    EMERGING (0-30): trend accelerating, breadth expanding
    CONFIRMED (30-70): trend stable, breadth stable
    EXHAUSTING (70-100): trend decelerating, breadth contracting, vol abnormal
    """
    return (
        trend_strength * 0.50 +
        breadth_persistence * 0.30 +
        (100 - vol_expansion) * 0.20  # inverted: low vol = early stage
    )