"""Tests for detailed backtest metrics."""

import math
from datetime import datetime, timedelta, timezone
from decimal import Decimal

import pytest

from backtester.metrics import TradeRecord, compute_detailed_metrics


def _make_trade(side: str, price: str, minutes_offset: int = 0) -> TradeRecord:
    return TradeRecord(
        time=datetime(2025, 1, 1, tzinfo=timezone.utc) + timedelta(minutes=minutes_offset),
        symbol="BTCUSDT",
        side=side,
        price=Decimal(price),
        quantity=Decimal("1"),
    )


def test_compute_metrics_basic():
    """Two round-trip trades: 1 win, 1 loss. Verify counts and win_rate."""
    trades = [
        _make_trade("BUY", "100", 0),
        _make_trade("SELL", "120", 10),  # win: +20
        _make_trade("BUY", "130", 20),
        _make_trade("SELL", "110", 30),  # loss: -20
    ]
    metrics = compute_detailed_metrics(trades, Decimal("10000"), Decimal("10000"))

    assert metrics.total_trades == 4
    assert metrics.winning_trades == 1
    assert metrics.losing_trades == 1
    assert metrics.win_rate == pytest.approx(50.0)


def test_compute_metrics_profit_factor():
    """Verify profit_factor = gross_profit / gross_loss."""
    trades = [
        _make_trade("BUY", "100", 0),
        _make_trade("SELL", "150", 10),  # win: +50
        _make_trade("BUY", "150", 20),
        _make_trade("SELL", "130", 30),  # loss: -20
    ]
    metrics = compute_detailed_metrics(trades, Decimal("10000"), Decimal("10030"))

    # gross_profit=50, gross_loss=20 → profit_factor=2.5
    assert metrics.profit_factor == pytest.approx(2.5)


def test_compute_metrics_max_drawdown():
    """Max drawdown should be > 0 when there is a losing trade after a peak."""
    trades = [
        _make_trade("BUY", "100", 0),
        _make_trade("SELL", "150", 10),  # win: equity goes up
        _make_trade("BUY", "150", 20),
        _make_trade("SELL", "120", 30),  # loss: equity drops
    ]
    metrics = compute_detailed_metrics(trades, Decimal("10000"), Decimal("10020"))

    assert metrics.max_drawdown > 0


def test_compute_metrics_sharpe_ratio():
    """Sharpe ratio should be a finite number with multiple trades."""
    trades = [
        _make_trade("BUY", "100", 0),
        _make_trade("SELL", "110", 60),
        _make_trade("BUY", "105", 120),
        _make_trade("SELL", "115", 180),
        _make_trade("BUY", "110", 240),
        _make_trade("SELL", "108", 300),
    ]
    metrics = compute_detailed_metrics(trades, Decimal("10000"), Decimal("10018"))

    assert math.isfinite(metrics.sharpe_ratio)
    assert math.isfinite(metrics.sortino_ratio)


def test_compute_metrics_empty_trades():
    """Empty trades should return all zeros."""
    metrics = compute_detailed_metrics([], Decimal("10000"), Decimal("10000"))

    assert metrics.total_return == 0.0
    assert metrics.total_trades == 0
    assert metrics.winning_trades == 0
    assert metrics.losing_trades == 0
    assert metrics.win_rate == 0.0
    assert metrics.profit_factor == 0.0
    assert metrics.sharpe_ratio == 0.0
    assert metrics.sortino_ratio == 0.0
    assert metrics.calmar_ratio == 0.0
    assert metrics.max_drawdown == 0.0
    assert metrics.monthly_returns == {}