from __future__ import annotations

import asyncio
from datetime import UTC, datetime, timedelta
from typing import Any

import pytest

from arbitrade.risk.loss_limits import LossLimitGuard


class _FakeAlertNotifier:
    def __init__(self) -> None:
        self.events: list[dict[str, Any]] = []

    async def notify(
        self,
        *,
        category: str,
        severity: str,
        title: str,
        message: str,
        details: dict[str, str] | None = None,
    ) -> bool:
        self.events.append(
            {
                "category": category,
                "severity": severity,
                "title": title,
                "message": message,
                "details": details or {},
            }
        )
        return True


def test_loss_limit_guard_tracks_daily_and_cumulative_pnl() -> None:
    guard = LossLimitGuard(daily_loss_limit=100.0, cumulative_loss_limit=200.0)
    t0 = datetime.now(UTC)

    guard.register_realized_pnl(-40.0, at=t0)
    guard.register_realized_pnl(10.0, at=t0)

    assert guard.cumulative_pnl == -30.0
    assert guard.daily_pnl(t0.date()) == -30.0
    assert not guard.is_halted


def test_loss_limit_guard_halts_on_daily_limit() -> None:
    guard = LossLimitGuard(daily_loss_limit=50.0)
    t0 = datetime.now(UTC)

    guard.register_realized_pnl(-30.0, at=t0)
    guard.register_realized_pnl(-25.0, at=t0)

    assert guard.is_halted
    assert guard.halted_reason == "daily_loss_limit_breached"


def test_loss_limit_guard_halts_on_cumulative_limit_across_days() -> None:
    guard = LossLimitGuard(cumulative_loss_limit=60.0)
    t0 = datetime.now(UTC)

    guard.register_realized_pnl(-40.0, at=t0)
    guard.register_realized_pnl(-25.0, at=t0 + timedelta(days=1))

    assert guard.is_halted
    assert guard.halted_reason == "cumulative_loss_limit_breached"


def test_loss_limit_guard_rejects_invalid_limits() -> None:
    with pytest.raises(ValueError, match="daily_loss_limit"):
        LossLimitGuard(daily_loss_limit=0.0)

    with pytest.raises(ValueError, match="cumulative_loss_limit"):
        LossLimitGuard(cumulative_loss_limit=-1.0)


@pytest.mark.asyncio
async def test_loss_limit_guard_emits_alert_on_breach() -> None:
    notifier = _FakeAlertNotifier()
    guard = LossLimitGuard(daily_loss_limit=50.0, alert_notifier=notifier)

    guard.register_realized_pnl(-60.0, at=datetime.now(UTC))
    await asyncio.sleep(0)

    assert guard.is_halted
    assert len(notifier.events) == 1
    assert notifier.events[0]["category"] == "threshold"
    assert notifier.events[0]["title"] == "Daily loss limit breached"