"""Cross-engine parity: manifoldbt vs vectorbt on brackets, shorts, fees.

This suite pins manifoldbt's fill semantics against an independent engine
(vectorbt) on controlled synthetic bars, so a refactor that silently changes a
fill price, a stop level, or PnL booking is caught here rather than in the wild.

Coverage — only what vectorbt can legitimately model apples-to-apples:

* market entry + take-profit          (test_market_take_profit_parity)
* market entry + stop-loss            (test_market_stop_loss_parity)
* combined SL+TP bracket              (test_bracket_sl_tp_parity)
* short entry + take-profit           (test_short_take_profit_parity)
* trailing stop                       (test_trailing_stop_parity)
* fees over multiple round-trips      (test_fees_multi_trade_parity)

Out of scope for vectorbt (validated separately, NOT against vectorbt):

* determined-price / resting limit entry — vectorbt has no resting order, so
  ``test_limit_entry_matches_independent_reference`` pins it against a NumPy
  model instead.
* sizing under fees — with ``FractionOfEquity`` the engines size differently
  once fees exist (manifoldbt charges the fee on top of a full-equity notional;
  vectorbt reserves it out of cash). Both are legitimate; the fee test sizes in
  fixed units to compare the fee arithmetic without that policy difference.

What is compared, and why only this:

* Trade fills (entry price, exit price, exit reason) and final ``total_return``.
  These are computed at full internal resolution and are exact. The *equity
  curve* is deliberately NOT compared: on a Community build the output series is
  capped to daily resolution, so its shape is not apples-to-apples with
  vectorbt. The realised trades and the final equity are unaffected by that cap.

Convention alignment (measured against manifoldbt 0.14.1, not assumed):

* ``signal_delay=0`` + ``AtClose`` → a market entry fills at the *close* of the
  signal bar. vectorbt ``from_signals`` fills the entry bar at close by default,
  so entries line up with no shift.
* ``FractionOfEquity`` sizing is taken at the *signal-bar close*
  (``size_at_fill_price=False``). For a market entry that equals the fill price,
  so vectorbt ``size_type="percent"`` matches. For a resting limit entry the
  signal close and the fill price differ, so vectorbt is fed an explicit unit
  size to reproduce manifoldbt's "size at signal close" rule.
* Take-profit is a passive target: it fills at the level even if the bar gaps
  through it. Stop-loss fills at the level (or worse on a gap). vectorbt's
  ``stop_exit_price=StopMarket`` reproduces the level fill on these
  no-gap-at-open scenarios.

vectorbt has no resting entry order, so the limit-entry scenario also carries an
independent NumPy reference for *where* the order fills; vectorbt only checks the
downstream take-profit off that fill.
"""
import os

import pytest

pd = pytest.importorskip("pandas")
vbt = pytest.importorskip("vectorbt")

import manifoldbt as bt  # noqa: E402
from manifoldbt.expr import col, lit, when  # noqa: E402
from manifoldbt.helpers import Interval, Slippage  # noqa: E402
from vectorbt.portfolio.enums import StopExitPrice, Direction  # noqa: E402

CAPITAL = 10_000.0
REL_TOL = 1e-6

# Exit-reason codes emitted in trades_df (measured):
REASON_NONE, REASON_SL, REASON_TP, REASON_TRAIL = 0, 1, 2, 3


# --------------------------------------------------------------------------- #
# Helpers
# --------------------------------------------------------------------------- #
def _bars(o, h, l, c, start="2023-01-01"):
    ts = pd.date_range(start, periods=len(c), freq="1h", tz="UTC")
    return pd.DataFrame(
        {"timestamp": ts, "open": list(map(float, o)), "high": list(map(float, h)),
         "low": list(map(float, l)), "close": list(map(float, c)),
         "volume": [1000.0] * len(c)}
    )


def _mbt_run(df, strat, tmp_path, name, *, delay=0, allow_short=False,
             sizing="FractionOfEquity", fees=None):
    """Run manifoldbt on an in-memory OHLC frame; return the Result."""
    root = str(tmp_path / name)
    os.makedirs(root, exist_ok=True)
    store = bt.import_dataframe(
        df, symbol="TEST", symbol_id=1, interval="1h",
        data_root=os.path.join(root, "data"),
        metadata_db=os.path.join(root, "meta.sqlite"),
    )
    ts = df["timestamp"]
    cfg = bt.BacktestConfig(
        universe=[1],
        time_range_start=0,
        time_range_end=int(ts.iloc[-1].value) + 30 * 86_400_000_000_000,
        bar_interval=Interval.hours(1),
        initial_capital=CAPITAL,
        execution=bt.ExecutionConfig(
            signal_delay=delay, execution_price="AtClose",
            max_position_pct=1.0, allow_short=allow_short,
            position_sizing_mode=sizing,
        ),
        fees=fees if fees is not None else bt.FeeConfig.zero(),
        slippage=Slippage.none(),
        warmup_bars=0,
    )
    return bt.run(strat, cfg, store)


def _mbt_trades(res):
    """(entry_fill, exit_fill, exit_reason) from a two-row round-trip."""
    tr = res.trades_df()
    assert len(tr) == 2, f"expected one round-trip, got {len(tr)} rows:\n{tr}"
    entry = tr.iloc[0]
    exit_ = tr.iloc[1]
    return float(entry["fill_price"]), float(exit_["fill_price"]), int(exit_["exit_reason"])


def _vbt_from_signals(df, entries, *, exits=None, tp=None, sl=None,
                      sl_trail=False, size=1.0, size_type="percent",
                      direction=None, fees=0.0):
    idx = pd.DatetimeIndex(df["timestamp"])
    close = pd.Series(df["close"].values, index=idx, dtype=float)
    ent = pd.Series(entries, index=idx)
    ex = pd.Series(exits if exits is not None else False, index=idx)
    kwargs = dict(
        open=pd.Series(df["open"].values, index=idx, dtype=float),
        high=pd.Series(df["high"].values, index=idx, dtype=float),
        low=pd.Series(df["low"].values, index=idx, dtype=float),
        init_cash=CAPITAL, size=size, size_type=size_type,
        fees=fees, slippage=0.0, sl_stop=sl, tp_stop=tp, sl_trail=sl_trail,
        stop_exit_price=StopExitPrice.StopMarket,
        freq="1h", accumulate=False,
    )
    if direction is not None:
        kwargs["direction"] = direction
    return vbt.Portfolio.from_signals(close, ent, ex, **kwargs)


def _assert_close(a, b, msg):
    assert abs(a - b) <= REL_TOL * max(1.0, abs(b)), f"{msg}: {a} != {b}"


# --------------------------------------------------------------------------- #
# Scenario A — market entry + take-profit
# --------------------------------------------------------------------------- #
def test_market_take_profit_parity(tmp_path):
    # Enter long at bar 0 close (100). TP +10% (110) is crossed at bar 3
    # (open 108 < 110 < high 115): both engines fill the target at 110.
    df = _bars(
        o=[100, 100, 104, 108, 111, 113],
        h=[101, 102, 106, 115, 112, 114],
        l=[99, 99, 103, 107, 110, 112],
        c=[100, 100, 105, 112, 111, 113],
    )
    # Long only while close in (99.5, 106): true on bars 0-2, false after, so
    # the position is a single clean round-trip closed by the TP.
    entry = when((col("close") > lit(99.5)) & (col("close") < lit(106.0)),
                 lit(1.0), lit(0.0))
    strat = (bt.Strategy.create("mkt_tp")
             .signal("d", col("close")).size(entry).take_profit(pct=10.0))

    res = _mbt_run(df, strat, tmp_path, "A")
    m_entry, m_exit, reason = _mbt_trades(res)
    assert reason == REASON_TP
    _assert_close(m_entry, 100.0, "mbt entry")
    _assert_close(m_exit, 110.0, "mbt tp exit")

    pf = _vbt_from_signals(df, [True, False, False, False, False, False], tp=0.10)
    v_tr = pf.trades.records_readable.iloc[0]
    _assert_close(float(v_tr["Avg Entry Price"]), m_entry, "entry price")
    _assert_close(float(v_tr["Avg Exit Price"]), m_exit, "exit price")
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario B — market entry + stop-loss
# --------------------------------------------------------------------------- #
def test_market_stop_loss_parity(tmp_path):
    # Enter long at bar 0 close (100). SL -5% (95) is hit at bar 3
    # (open 97 > 95, low 94 <= 95): both engines fill the stop at 95.
    df = _bars(
        o=[100, 100, 99, 97, 96, 95],
        h=[101, 101, 100, 98, 97, 96],
        l=[99, 99, 96, 94, 95, 94],
        c=[100, 100, 98, 96, 96, 95],
    )
    entry = when(col("close") >= lit(97.0), lit(1.0), lit(0.0))
    strat = (bt.Strategy.create("mkt_sl")
             .signal("d", col("close")).size(entry).stop_loss(pct=5.0))

    res = _mbt_run(df, strat, tmp_path, "B")
    m_entry, m_exit, reason = _mbt_trades(res)
    assert reason == REASON_SL
    _assert_close(m_entry, 100.0, "mbt entry")
    _assert_close(m_exit, 95.0, "mbt sl exit")

    pf = _vbt_from_signals(df, [True, False, False, False, False, False], sl=0.05)
    v_tr = pf.trades.records_readable.iloc[0]
    _assert_close(float(v_tr["Avg Entry Price"]), m_entry, "entry price")
    _assert_close(float(v_tr["Avg Exit Price"]), m_exit, "exit price")
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario C — resting limit entry at a determined price + take-profit
# --------------------------------------------------------------------------- #
def _resting_limit_reference(df, signal_bar, offset_frac, tp_frac, capital):
    """Independent NumPy model of a resting buy-limit + take-profit.

    Mirrors the measured manifoldbt rule: the limit rests at
    ``signal_close * (1 - offset_frac)``, fills on the first bar AFTER the
    signal bar whose low touches it (fill AT the level), sizes at the signal
    close, then a passive TP at ``fill * (1 + tp_frac)`` closes it on the first
    later bar whose high reaches it.
    """
    close = df["close"].to_numpy(float)
    high = df["high"].to_numpy(float)
    low = df["low"].to_numpy(float)
    signal_close = close[signal_bar]
    limit = signal_close * (1.0 - offset_frac)
    qty = capital / signal_close  # size_at_fill_price=False

    fill_bar = next((i for i in range(signal_bar + 1, len(low)) if low[i] <= limit), None)
    assert fill_bar is not None, "limit never filled in reference"
    tp = limit * (1.0 + tp_frac)
    exit_bar = next((i for i in range(fill_bar, len(high)) if high[i] >= tp), None)
    assert exit_bar is not None, "TP never reached in reference"
    total_return = qty * (tp - limit) / capital
    return dict(limit=limit, qty=qty, fill_bar=fill_bar, tp=tp,
                exit_bar=exit_bar, total_return=total_return)


def test_limit_entry_matches_independent_reference(tmp_path):
    """Determined-price (resting limit) entry — validated WITHOUT vectorbt.

    vectorbt has no resting entry order: it cannot wait across bars for price to
    trade down to a level, so a "vs vectorbt" check would not be apples-to-apples
    and is deliberately not attempted. This manifoldbt-only feature is pinned
    against an independent NumPy model of the resting fill instead. The vectorbt
    suite above covers what both engines share (market entry, SL, TP).

    Signal at bar 0 (close 100). Limit rests 2% below (98). Bar 1 low 97 <= 98
    fills at 98. TP +5% off the fill (102.9) is reached at bar 3 (open 102 < the
    target, so it fills the passive target at the level, not on a gap).
    """
    df = _bars(
        o=[100, 99, 101, 102, 104, 105],
        h=[100.5, 100, 102, 104, 105, 106],
        l=[99.5, 97, 100, 101.5, 103, 104],
        c=[100, 99, 101, 103, 104, 105],
        start="2023-01-02",
    )
    # Signal fires only on bar 0 so exactly one resting order is placed.
    entry = when((col("close") >= lit(99.5)) & (col("close") <= lit(100.5)),
                 lit(1.0), lit(0.0))
    strat = (bt.Strategy.create("lim_tp")
             .signal("d", col("close"))
             .size(entry)
             .limit_entry(offset_bps=200, time_in_force="GTC")  # 200 bps = 2%
             .take_profit(pct=5.0))

    res = _mbt_run(df, strat, tmp_path, "C")
    m_entry, m_exit, reason = _mbt_trades(res)

    ref = _resting_limit_reference(df, signal_bar=0, offset_frac=0.02,
                                   tp_frac=0.05, capital=CAPITAL)
    _assert_close(m_entry, ref["limit"], "limit fill price")   # 98.0
    _assert_close(m_exit, ref["tp"], "tp exit price")          # 102.9
    assert reason == REASON_TP
    _assert_close(res.metrics["total_return"], ref["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario D — combined SL+TP bracket (both armed, the right one fires)
# --------------------------------------------------------------------------- #
def test_bracket_sl_tp_parity(tmp_path):
    # SL -5% (95) AND TP +10% (110) armed together. Price rises, so the TP fires
    # at bar 3 and the stop never triggers — the bracket must not misfire.
    df = _bars(
        o=[100, 100, 104, 108, 111, 113],
        h=[101, 102, 106, 115, 112, 114],
        l=[99, 99, 103, 107, 110, 112],
        c=[100, 100, 105, 112, 111, 113],
    )
    entry = when((col("close") > lit(99.5)) & (col("close") < lit(106.0)),
                 lit(1.0), lit(0.0))
    strat = (bt.Strategy.create("bracket")
             .signal("d", col("close")).size(entry)
             .stop_loss(pct=5.0).take_profit(pct=10.0))

    res = _mbt_run(df, strat, tmp_path, "D")
    m_entry, m_exit, reason = _mbt_trades(res)
    assert reason == REASON_TP
    _assert_close(m_exit, 110.0, "mbt tp exit")

    pf = _vbt_from_signals(df, [True, False, False, False, False, False],
                           sl=0.05, tp=0.10)
    v_tr = pf.trades.records_readable.iloc[0]
    _assert_close(float(v_tr["Avg Exit Price"]), m_exit, "exit price")
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario E — short entry + take-profit
# --------------------------------------------------------------------------- #
def test_short_take_profit_parity(tmp_path):
    # Short at bar 0 close (100). TP -5% (95, profit for a short) is hit at bar 3
    # (open 96 > 95, low 94 <= 95): both engines cover at 95 for a +5% return.
    # Signal is short on bars 0-2 and flat from bar 3, so the TP closes it with
    # no re-entry.
    df = _bars(
        o=[100, 99, 98, 96, 95, 94],
        h=[100.5, 100, 99, 97, 96, 95],
        l=[99.5, 98, 97, 94, 94, 93],
        c=[100, 98, 97, 95, 94, 93],
    )
    entry = when(col("close") >= lit(96.0), lit(-1.0), lit(0.0))
    strat = (bt.Strategy.create("short_tp")
             .signal("d", col("close")).size(entry).take_profit(pct=5.0))

    res = _mbt_run(df, strat, tmp_path, "E", allow_short=True)
    m_entry, m_exit, reason = _mbt_trades(res)
    assert reason == REASON_TP
    _assert_close(m_entry, 100.0, "short entry")
    _assert_close(m_exit, 95.0, "short cover")

    pf = _vbt_from_signals(df, [True, False, False, False, False, False],
                           tp=0.05, direction=Direction.ShortOnly)
    v_tr = pf.trades.records_readable.iloc[0]
    _assert_close(float(v_tr["Avg Entry Price"]), m_entry, "entry price")
    _assert_close(float(v_tr["Avg Exit Price"]), m_exit, "cover price")
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario F — trailing stop
# --------------------------------------------------------------------------- #
def test_trailing_stop_parity(tmp_path):
    # Always long. The high peaks at 112 (bar 3-4), so a 5% trailing stop rests
    # at 112 * 0.95 = 106.4. Bar 5 low (104) trades through it: both engines exit
    # at 106.4. (vectorbt's sl_trail also trails off the high when high is given.)
    df = _bars(
        o=[100, 101, 106, 110, 111, 108],
        h=[100, 102, 108, 112, 112, 109],
        l=[100, 100, 105, 109, 109, 104],
        c=[100, 102, 107, 111, 110, 105],
    )
    strat = (bt.Strategy.create("trail")
             .signal("d", col("close")).size(lit(1.0))
             .trailing_stop(pct=5.0, use_high=True))

    res = _mbt_run(df, strat, tmp_path, "F")
    tr = res.trades_df()
    # Always-long re-enters at the exit bar's close (a mark-flat no-op on the
    # last bar), so the round-trip is the first two rows; assert on those.
    assert float(tr.iloc[1]["fill_price"]) == pytest.approx(106.4)
    assert int(tr.iloc[1]["exit_reason"]) == REASON_TRAIL

    pf = _vbt_from_signals(df, [True, False, False, False, False, False],
                           sl=0.05, sl_trail=True)
    v_tr = pf.trades.records_readable.iloc[0]
    _assert_close(float(v_tr["Avg Exit Price"]), 106.4, "trailing exit")
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")


# --------------------------------------------------------------------------- #
# Scenario G — fees over multiple round-trips (cumulative accounting)
# --------------------------------------------------------------------------- #
def test_fees_multi_trade_parity(tmp_path):
    # Two round-trips with a 20 bps taker fee, sized in FIXED UNITS. Fixed units
    # are deliberate: under FractionOfEquity the engines size differently once
    # fees exist (manifoldbt charges the fee on top of a full-equity notional,
    # vectorbt reserves the fee out of cash), which is a legitimate design choice
    # rather than a parity bug. Fixing the unit count isolates the thing both
    # engines must agree on — the fee arithmetic and its cumulative effect.
    units = 50.0
    close = [100, 101, 102, 99, 98, 103, 99]
    df = _bars(
        o=close, h=[c + 0.5 for c in close], l=[c - 0.5 for c in close], c=close,
        start="2023-06-01",
    )
    # Long while close > 100: enters bar 1, exits bar 3, re-enters bar 5, exits
    # bar 6 → two clean round-trips.
    entry = when(col("close") > lit(100.0), lit(units), lit(0.0))
    strat = bt.Strategy.create("fees").signal("d", col("close")).size(entry)
    fees = bt.FeeConfig(maker_fee_bps=10.0, taker_fee_bps=20.0)

    res = _mbt_run(df, strat, tmp_path, "G", sizing="Units", fees=fees)

    sig = pd.Series(close, dtype=float) > 100
    entries = sig & ~sig.shift(1, fill_value=False)
    exits = ~sig & sig.shift(1, fill_value=False)
    pf = _vbt_from_signals(df, entries.tolist(), exits=exits.tolist(),
                           size=units, size_type="amount", fees=0.002)
    _assert_close(pf.total_return(), res.metrics["total_return"], "total_return")