"""
Vitalwerte: Zeitreihen + einfache Fitness-/Recovery-Einordnung (Layer 1, Issue 53).

Keine Diagnose — deskriptive Trends, Korrelationen und Varianz-Hinweise.
"""

from __future__ import annotations

import statistics
from datetime import datetime, timedelta
from typing import Any, Dict, List, Optional, Sequence

from db import get_db, get_cursor
from data_layer.utils import safe_float, serialize_dates

SERIES_CONFIG = (
    ("resting_hr", "Ruhepuls", "bpm", "#3B82F6"),
    ("hrv", "HRV", "ms", "#1D9E75"),
    ("vo2_max", "VO2max", "ml/kg/min", "#8B5CF6"),
    ("spo2", "SpO2", "%", "#0EA5E9"),
    ("respiratory_rate", "Atemfrequenz", "/min", "#F59E0B"),
)


def _date_to_ord(d: Any) -> float:
    if hasattr(d, "toordinal"):
        return float(d.toordinal())
    if isinstance(d, str):
        return float(datetime.fromisoformat(d[:10]).date().toordinal())
    return 0.0


def _linear_slope(dates: Sequence[Any], values: Sequence[float]) -> float:
    if len(values) < 3 or len(dates) != len(values):
        return 0.0
    xs = [_date_to_ord(d) for d in dates]
    ys = list(values)
    n = len(xs)
    mx = sum(xs) / n
    my = sum(ys) / n
    den = sum((x - mx) ** 2 for x in xs)
    if den < 1e-9:
        return 0.0
    return sum((x - mx) * (y - my) for x, y in zip(xs, ys)) / den


def _pearson(xs: Sequence[float], ys: Sequence[float]) -> Optional[float]:
    n = len(xs)
    if n < 5 or len(ys) != n:
        return None
    mx = statistics.mean(xs)
    my = statistics.mean(ys)
    sx = statistics.pstdev(xs) if n > 1 else 0.0
    sy = statistics.pstdev(ys) if n > 1 else 0.0
    if sx < 1e-9 or sy < 1e-9:
        return None
    cov = sum((x - mx) * (y - my) for x, y in zip(xs, ys)) / n
    return cov / (sx * sy)


def _daily_training_load(cur: Any, profile_id: str, cutoff: str) -> Dict[str, float]:
    """Summe Trainingsminuten pro Kalendertag als Belastungs-Proxy."""
    cur.execute(
        """
        SELECT date::text AS d, COALESCE(SUM(duration_min), 0)::float AS minutes
        FROM activity_log
        WHERE profile_id = %s AND date >= %s::date AND duration_min IS NOT NULL AND duration_min > 0
        GROUP BY date
        ORDER BY date
        """,
        (profile_id, cutoff),
    )
    rows = cur.fetchall()
    return {r["d"]: float(r["minutes"]) for r in rows}


def _trailing_window_means(vals: List[float], window: int = 7) -> List[float]:
    """Gleitender Mittelwert über die letzten bis zu `window` aufeinanderfolgenden Messungen (nicht Kalendertage)."""
    out: List[float] = []
    for i in range(len(vals)):
        chunk = vals[max(0, i - window + 1) : i + 1]
        out.append(round(statistics.mean(chunk), 2))
    return out


def _build_consolidated_paragraphs(
    series: Dict[str, Any],
    hrv_vs_baseline_pct: Optional[float],
    rhr_vs_baseline_pct: Optional[float],
    r_pearson: Optional[float],
    pairs_n: int,
) -> List[str]:
    """Eine zusammenhängende Einordnung statt vieler einzelner Karten zu Puls/HRV/Basis."""
    paras: List[str] = []

    basis_bits: List[str] = []
    if hrv_vs_baseline_pct is not None:
        basis_bits.append(
            f"HRV liegt gegenüber der älteren Referenz bei {hrv_vs_baseline_pct:+.1f} %".replace(".", ",")
        )
    if rhr_vs_baseline_pct is not None:
        basis_bits.append(
            f"Ruhepuls relativ zur Referenz bei {rhr_vs_baseline_pct:+.1f} %".replace(".", ",")
        )
    if basis_bits:
        paras.append(
            " ".join(basis_bits)
            + " (Vergleich kurzfristiges Mittel vs. ältere Basis — individuell interpretieren)."
        )

    rhr = series.get("resting_hr")
    hrv_s = series.get("hrv")
    var_bits: List[str] = []
    if rhr and rhr.get("stdev") is not None and rhr.get("n", 0) >= 3:
        var_bits.append(f"Ruhepuls Schwankungsbreite im Fenster etwa σ = {rhr['stdev']} bpm")
    if hrv_s and hrv_s.get("stdev") is not None and hrv_s.get("n", 0) >= 3:
        var_bits.append(f"HRV etwa σ = {hrv_s['stdev']} ms")
    if var_bits:
        paras.append(
            "Einzelwerte können stark springen; die gestrichelte Linie zeigt einen gleitenden Mittelwert (max. 7 Messungen). "
            + "Im Fenster: " + "; ".join(var_bits) + "."
        )

    if rhr and rhr.get("points") and len(rhr["points"]) >= 10:
        pts = rhr["points"]
        last7 = [p["value"] for p in pts[-7:]]
        before = [p["value"] for p in pts[:-7][-14:]] if len(pts) > 7 else []
        if before:
            m7 = statistics.mean(last7)
            mb = statistics.mean(before)
            diff = m7 - mb
            if abs(diff) > 3:
                paras.append(
                    f"Kurzfristig liegt der Ruhepuls im Mittel der letzten 7 Messungen "
                    f"{'über' if diff > 0 else 'unter'} dem vorherigen Fenster (Δ ca. {abs(diff):.1f} bpm) — Kontext: Belastung, Schlaf, Stress."
                )

    vo2 = series.get("vo2_max")
    if vo2 and vo2.get("n", 0) >= 4 and vo2.get("slope_per_day") is not None:
        s = vo2["slope_per_day"]
        if s > 0.002:
            paras.append(
                "VO2max steigt im gewählten Fenster tendenziell — oft mit Trainingsreiz oder stabilen Messungen vereinbar."
            )
        elif s < -0.002:
            paras.append(
                "VO2max fällt im Fenster leicht — kann Pause, Krankheit oder Messrauschen widerspiegeln."
            )

    if r_pearson is not None and pairs_n >= 8:
        if r_pearson > 0.35:
            paras.append(
                f"Korrelation Trainingsminuten (Tag) → Ruhepuls (Folgetag): r ≈ {r_pearson:.2f} (n = {pairs_n} Paare). "
                "Höhere Belastung und etwas höherer Ruhepuls am nächsten Morgen kommen in den Daten häufig zusammen — kein Kausalbeweis."
            )
        elif r_pearson < -0.25:
            paras.append(
                f"Zwischen Tages-Belastung und Folge-Ruhepuls zeigt sich ein leicht negatives Zusammenspiel (r ≈ {r_pearson:.2f}, n = {pairs_n}). "
                "Stark von Ausreißern und Datenlücken abhängig."
            )

    return [p for p in paras if p]


def _rhr_by_date(cur: Any, profile_id: str, cutoff: str) -> Dict[str, float]:
    cur.execute(
        """
        SELECT date::text AS d, resting_hr::float AS rhr
        FROM vitals_baseline
        WHERE profile_id = %s AND date >= %s::date AND resting_hr IS NOT NULL
        ORDER BY date
        """,
        (profile_id, cutoff),
    )
    return {r["d"]: float(r["rhr"]) for r in cur.fetchall()}


def build_vitals_history_and_analytics(
    profile_id: str,
    days: int,
    hrv_vs_baseline_pct: Optional[float] = None,
    rhr_vs_baseline_pct: Optional[float] = None,
) -> Dict[str, Any]:
    """
    Zeitreihen pro Kennzahl (eigene Einheit / eigene Skala im Frontend) + zusammengefasste Einordnung.

    Optional: Abweichung HRV/Ruhepuls zur älteren Basis — für einen Absatz statt doppelter KPI-Texte.
    """
    if days < 7:
        days = 7
    if days > 365:
        days = 365
    cutoff = (datetime.now() - timedelta(days=days)).strftime("%Y-%m-%d")

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            """
            SELECT date, resting_hr, hrv, vo2_max, spo2, respiratory_rate
            FROM vitals_baseline
            WHERE profile_id = %s AND date >= %s
            ORDER BY date ASC
            """,
            (profile_id, cutoff),
        )
        rows = cur.fetchall()

    series: Dict[str, Any] = {}
    for key, label_de, unit, color in SERIES_CONFIG:
        pts: List[Dict[str, Any]] = []
        dates: List[Any] = []
        vals: List[float] = []
        for r in rows:
            v = r.get(key)
            if v is None:
                continue
            fv = safe_float(v)
            d = r["date"]
            d_iso = d.isoformat() if hasattr(d, "isoformat") else str(d)[:10]
            pts.append({"date": d_iso, "value": round(fv, 2)})
            dates.append(d)
            vals.append(fv)
        if pts:
            ma_vals = _trailing_window_means(vals, window=7)
            points_ma7 = [
                {"date": pts[i]["date"], "value": ma_vals[i]} for i in range(len(pts))
            ]
            series[key] = {
                "key": key,
                "label_de": label_de,
                "unit": unit,
                "color": color,
                "points": pts,
                "points_ma7": points_ma7,
                "n": len(pts),
                "last": vals[-1] if vals else None,
                "mean": round(statistics.mean(vals), 2) if len(vals) >= 1 else None,
                "stdev": round(statistics.pstdev(vals), 2) if len(vals) >= 2 else None,
                "slope_per_day": round(_linear_slope(dates, vals), 6) if len(vals) >= 3 else None,
            }

    # Belastung (Activity) vs Ruhepuls am Folgetag
    with get_db() as conn:
        cur = get_cursor(conn)
        load_by_d = _daily_training_load(cur, profile_id, cutoff)
        rhr_by_d = _rhr_by_date(cur, profile_id, cutoff)

    pairs_load: List[float] = []
    pairs_rhr: List[float] = []
    for d_str, load_min in load_by_d.items():
        try:
            d0 = datetime.fromisoformat(d_str[:10]).date()
        except ValueError:
            continue
        d1 = (d0 + timedelta(days=1)).isoformat()
        if d1 in rhr_by_d and load_min > 0:
            pairs_load.append(load_min)
            pairs_rhr.append(rhr_by_d[d1])

    r_pearson = _pearson(pairs_load, pairs_rhr) if len(pairs_load) >= 8 else None
    pairs_n = len(pairs_load)

    consolidated = _build_consolidated_paragraphs(
        series,
        hrv_vs_baseline_pct,
        rhr_vs_baseline_pct,
        r_pearson,
        pairs_n,
    )

    if not series:
        return {
            "chart_type": "vitals_dashboard",
            "window_days": days,
            "series": {},
            "analytics": {"bullets": [], "consolidated_paragraphs": consolidated},
            "metadata": {
                "confidence": "insufficient",
                "message": "Keine Vital-Zeitreihen im Fenster",
                "load_rhr_pairs_n": pairs_n,
                "load_rhr_correlation": round(r_pearson, 3) if r_pearson is not None else None,
            },
        }

    return {
        "chart_type": "vitals_dashboard",
        "window_days": days,
        "series": serialize_dates(series),
        "analytics": {
            "bullets": [],
            "consolidated_paragraphs": consolidated,
        },
        "metadata": {
            "confidence": "medium",
            "note": "Deskriptive Auswertung; keine medizinische Diagnose.",
            "load_rhr_pairs_n": pairs_n,
            "load_rhr_correlation": round(r_pearson, 3) if r_pearson is not None else None,
        },
    }