"""Historical backtest (Phase 1): replay the price-derived engine over stored
OHLCV and measure how the CURRENT config would have performed.

For each ticker we step through history (weekly), and at each as-of date D we
rebuild the setup using only bars ≤ D (no lookahead), then walk the actual bars
after D to record the realized outcome. Two reports come out:

  - realized hit-rate / expectancy of qualified setups (and of all setups)
  - a probability calibration curve: do "60% likely" targets hit ~60% of the time?

Limitation: sentiment and fundamentals have no point-in-time history, so they're
held neutral here — this calibrates the price/S-R/probability machinery only.
"""

from __future__ import annotations

import json
import logging
from collections.abc import Callable
from datetime import datetime, timezone
from types import SimpleNamespace
from typing import Any

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.settings import SystemSetting
from app.models.ticker import Ticker
from app.services.admin_service import get_activation_config, update_setting
from app.services.indicator_service import _extract_ohlcv, compute_atr
from app.services.outcome_service import (
    OUTCOME_AMBIGUOUS,
    OUTCOME_STOP_HIT,
    OUTCOME_TARGET_HIT,
    Bar,
    evaluate_setup_against_bars,
)
from app.services.price_service import query_ohlcv
from app.services.qualification import best_target_probability, setup_qualifies
from app.services.recommendation_service import (
    _choose_recommended_action,
    _classify_by_probability,
    _risk_level_from_conflicts,
    _select_primary_target,
    _zone_representative_levels,
    direction_analyzer,
    get_recommendation_config,
    probability_estimator,
    signal_conflict_detector,
    target_generator,
)
from app.services.scoring_service import (
    compute_momentum_from_closes,
    compute_technical_from_arrays,
)
from app.services.sr_service import detect_sr_levels

logger = logging.getLogger(__name__)

KEY_REPORT = "backtest_report"

STEP_DAYS = 5          # weekly cadence (≈ 5 trading days)
MIN_LOOKBACK = 60      # bars needed before D for indicators (EMA cross needs 51)
HORIZON = 30           # trading days to resolve an outcome (matches the evaluator)
ATR_MULTIPLIER = 1.5

_CAL_BUCKETS = [(0, 20), (20, 40), (40, 60), (60, 80), (80, 100.01)]


def _wrap_levels(level_dicts: list[dict]) -> list[Any]:
    return [
        SimpleNamespace(
            id=i,
            price_level=float(d["price_level"]),
            type=d["type"],
            strength=int(d["strength"]),
        )
        for i, d in enumerate(level_dicts)
    ]


def _window_setups(
    window_records: list,
    config: dict,
    activation: dict,
) -> list[dict]:
    """Rebuild the setup(s) at the last bar of ``window_records`` (the as-of date),
    using only those bars. Returns one dict per tradeable direction."""
    if len(window_records) < MIN_LOOKBACK:
        return []

    _, highs, lows, closes, volumes = _extract_ohlcv(window_records)
    entry = closes[-1]
    if entry <= 0:
        return []

    try:
        atr = compute_atr(highs, lows, closes)["atr"]
    except Exception:
        return []
    if atr <= 0:
        return []

    sr_levels = _wrap_levels(detect_sr_levels(highs, lows, closes, volumes))
    if not sr_levels:
        return []

    technical = (compute_technical_from_arrays(highs, lows, closes, volumes)[0]) or 50.0
    momentum = (compute_momentum_from_closes(closes)[0]) or 50.0
    dim_scores = {"technical": technical, "momentum": momentum}

    conflicts = signal_conflict_detector.detect_conflicts(dim_scores, None, config)
    confidences = {
        "long": direction_analyzer.calculate_confidence("long", dim_scores, None, conflicts),
        "short": direction_analyzer.calculate_confidence("short", dim_scores, None, conflicts),
    }

    # First pass: build targets per direction
    per_dir: dict[str, dict] = {}
    for direction in ("long", "short"):
        stop = entry - atr * ATR_MULTIPLIER if direction == "long" else entry + atr * ATR_MULTIPLIER
        zone_levels = _zone_representative_levels(sr_levels, entry)
        targets = target_generator.generate_targets(direction, entry, stop, zone_levels, atr)
        if not targets:
            continue
        for t in targets:
            t["probability"] = probability_estimator.estimate_probability(
                t, dim_scores, None, direction, config
            )
            t["classification"] = _classify_by_probability(t["probability"])
        primary = _select_primary_target(targets)
        if primary is None:
            continue
        per_dir[direction] = {"stop": stop, "targets": targets, "primary": primary}

    available = set(per_dir.keys())
    if not available:
        return []

    action = _choose_recommended_action(confidences["long"], confidences["short"], config, available)

    out: list[dict] = []
    for direction, data in per_dir.items():
        targets, primary, stop = data["targets"], data["primary"], data["stop"]
        setup_conflicts = list(conflicts)
        if len(targets) < 3:
            setup_conflicts.append("target-availability: Fewer than 3 valid S/R targets available")
        risk_level = _risk_level_from_conflicts(setup_conflicts)
        rr = float(primary["rr_ratio"])
        target_price = float(primary["price"])

        setup_ns = SimpleNamespace(
            rr_ratio=rr,
            confidence_score=confidences[direction],
            recommended_action=action,
            risk_level=risk_level,
            targets=targets,
            direction=direction,
            target=target_price,
            stop_loss=stop,
            entry_price=entry,
        )
        out.append({
            "direction": direction,
            "entry": entry,
            "stop": stop,
            "target": target_price,
            "rr": rr,
            "confidence": confidences[direction],
            "primary_prob": float(primary["probability"]),
            "best_prob": best_target_probability(setup_ns),
            "action": action,
            "risk_level": risk_level,
            "qualified": setup_qualifies(setup_ns, activation),
        })
    return out


def _replay_ticker(symbol: str, records: list, config: dict, activation: dict) -> list[dict]:
    """Walk one ticker's history weekly, building setups and their realized outcomes."""
    candidates: list[dict] = []
    n = len(records)
    if n < MIN_LOOKBACK + HORIZON:
        return candidates

    for i in range(MIN_LOOKBACK - 1, n - HORIZON, STEP_DAYS):
        window = records[: i + 1]
        forward = records[i + 1 :]
        forward_bars = [Bar(date=r.date, high=r.high, low=r.low) for r in forward]

        for s in _window_setups(window, config, activation):
            outcome, _ = evaluate_setup_against_bars(
                s["direction"], s["stop"], s["target"], forward_bars, HORIZON
            )
            if outcome is None:
                continue
            target_hit = outcome == OUTCOME_TARGET_HIT
            if outcome == OUTCOME_TARGET_HIT:
                realized_r = s["rr"]
            elif outcome in (OUTCOME_STOP_HIT, OUTCOME_AMBIGUOUS):
                realized_r = -1.0
            else:  # expired
                realized_r = 0.0
            candidates.append({
                "symbol": symbol,
                "date": records[i].date.isoformat(),
                "direction": s["direction"],
                "rr": s["rr"],
                "confidence": s["confidence"],
                "primary_prob": s["primary_prob"],
                "qualified": s["qualified"],
                "outcome": outcome,
                "target_hit": target_hit,
                "realized_r": realized_r,
            })
    return candidates


def _bucket_stats(cands: list[dict]) -> dict:
    wins = sum(1 for c in cands if c["target_hit"])
    losses = sum(1 for c in cands if c["outcome"] in (OUTCOME_STOP_HIT, OUTCOME_AMBIGUOUS))
    expired = sum(1 for c in cands if c["outcome"] not in (OUTCOME_TARGET_HIT, OUTCOME_STOP_HIT, OUTCOME_AMBIGUOUS))
    decided = wins + losses
    rs = [c["realized_r"] for c in cands]
    return {
        "total": len(cands),
        "wins": wins,
        "losses": losses,
        "expired": expired,
        "hit_rate": round(wins / decided * 100, 1) if decided else None,
        "avg_r": round(sum(rs) / len(rs), 3) if rs else None,
        "total_r": round(sum(rs), 2) if rs else None,
    }


def _calibration(cands: list[dict]) -> list[dict]:
    """Predicted target probability vs realized hit rate, per probability bucket."""
    rows: list[dict] = []
    for lo, hi in _CAL_BUCKETS:
        bucket = [c for c in cands if lo <= c["primary_prob"] < hi]
        if not bucket:
            continue
        hits = sum(1 for c in bucket if c["target_hit"])
        rows.append({
            "bucket": f"{int(lo)}-{int(min(hi, 100))}%",
            "n": len(bucket),
            "predicted_avg": round(sum(c["primary_prob"] for c in bucket) / len(bucket), 1),
            "realized_hit_rate": round(hits / len(bucket) * 100, 1),
        })
    return rows


async def run_backtest(
    db: AsyncSession,
    progress_cb: Callable[[int, int, str], None] | None = None,
) -> dict:
    """Replay every ticker and aggregate the Phase-1 reports for the current config."""
    config = await get_recommendation_config(db)
    activation = await get_activation_config(db)

    result = await db.execute(select(Ticker).order_by(Ticker.symbol))
    tickers = list(result.scalars().all())
    total = len(tickers)

    candidates: list[dict] = []
    for index, ticker in enumerate(tickers):
        if progress_cb is not None:
            progress_cb(index, total, ticker.symbol)
        try:
            records = await query_ohlcv(db, ticker.symbol)
            candidates.extend(_replay_ticker(ticker.symbol, records, config, activation))
        except Exception:
            logger.exception("Backtest replay failed for %s", ticker.symbol)

    if progress_cb is not None and total:
        progress_cb(total, total, "")

    qualified = [c for c in candidates if c["qualified"]]
    longs = [c for c in qualified if c["direction"] == "long"]
    shorts = [c for c in qualified if c["direction"] == "short"]

    return {
        "generated_at": datetime.now(timezone.utc).isoformat(),
        "tickers": total,
        "candidates": len(candidates),
        "qualified": len(qualified),
        "params": {"step_days": STEP_DAYS, "horizon_days": HORIZON, "min_lookback": MIN_LOOKBACK},
        "activation": activation,
        "overall_qualified": _bucket_stats(qualified),
        "overall_all": _bucket_stats(candidates),
        "by_direction": {
            "long": _bucket_stats(longs),
            "short": _bucket_stats(shorts),
        },
        "calibration": _calibration(candidates),
        "note": (
            "Sentiment & fundamentals held neutral (no point-in-time history). "
            "~6 months ≈ one market regime — treat as directional, not gospel."
        ),
    }


async def run_and_store(
    db: AsyncSession,
    progress_cb: Callable[[int, int, str], None] | None = None,
) -> dict:
    """Run the backtest and cache the report in a SystemSetting. Job entrypoint."""
    report = await run_backtest(db, progress_cb)
    await update_setting(db, KEY_REPORT, json.dumps(report))
    return report


async def get_backtest_report(db: AsyncSession) -> dict | None:
    """Return the last cached backtest report, or None if never run."""
    result = await db.execute(select(SystemSetting).where(SystemSetting.key == KEY_REPORT))
    setting = result.scalar_one_or_none()
    if setting is None:
        return None
    try:
        return json.loads(setting.value)
    except (TypeError, ValueError):
        return None