import asyncio
from datetime import UTC, datetime
from typing import Self

import pytest

from app import probes
from app.models import HealthStatus, ProbeResult, Service, ServiceKind


def _service() -> Service:
    now = datetime.now(UTC)
    return Service(
        id="service-1",
        name="API",
        kind=ServiceKind.HTTP,
        url="https://api.local",
        created_at=now,
        updated_at=now,
    )


def _tcp_service() -> Service:
    now = datetime.now(UTC)
    return Service(
        id="tcp-service-1",
        name="TCP service",
        kind=ServiceKind.TCP,
        host="tcp.local",
        port=5432,
        created_at=now,
        updated_at=now,
    )


@pytest.mark.parametrize(
    ("status_code", "expected"),
    [
        (200, HealthStatus.HEALTHY),
        (302, HealthStatus.HEALTHY),
        (404, HealthStatus.DEGRADED),
        (503, HealthStatus.DOWN),
    ],
)
def test_http_status_classification(
    monkeypatch: pytest.MonkeyPatch,
    status_code: int,
    expected: HealthStatus,
) -> None:
    class FakeResponse:
        def __init__(self, code: int) -> None:
            self.status_code = code

    class FakeClient:
        async def __aenter__(self) -> Self:
            return self

        async def __aexit__(self, *args: object) -> None:
            return None

        async def get(self, url: str) -> FakeResponse:
            assert url == "https://api.local"
            return FakeResponse(status_code)

    monkeypatch.setattr(probes.httpx, "AsyncClient", lambda **kwargs: FakeClient())

    status, detail = asyncio.run(probes._probe_once(_service(), 1.0))

    assert status == expected
    assert detail == f"HTTP {status_code}"


def test_retry_latency_reports_final_attempt_not_backoff(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    calls = 0

    async def fake_probe_once(service: Service, timeout_seconds: float) -> tuple[HealthStatus, str]:
        nonlocal calls
        calls += 1
        if calls == 1:
            raise OSError("temporary failure")
        return HealthStatus.HEALTHY, "HTTP 200"

    timings = iter([10.0, 10.05, 20.0, 20.02])
    monkeypatch.setattr(probes, "_probe_once", fake_probe_once)
    monkeypatch.setattr(probes, "perf_counter", lambda: next(timings))

    result = asyncio.run(probes.probe_service(_service(), timeout_seconds=1.0, retries=1))

    assert calls == 2
    assert result.status == HealthStatus.HEALTHY
    assert result.latency_ms == pytest.approx(20.0)
    assert result.detail == "HTTP 200 after 2 attempts"


def test_tcp_probe_success_and_failure(monkeypatch: pytest.MonkeyPatch) -> None:
    class FakeWriter:
        def close(self) -> None:
            return None

        async def wait_closed(self) -> None:
            return None

    async def fake_open_connection(host: str | None, port: int | None) -> tuple[object, FakeWriter]:
        assert (host, port) == ("tcp.local", 5432)
        return object(), FakeWriter()

    monkeypatch.setattr(probes.asyncio, "open_connection", fake_open_connection)
    status, detail = asyncio.run(probes._probe_once(_tcp_service(), 1.0))
    assert status == HealthStatus.HEALTHY
    assert detail == "TCP tcp.local:5432 reachable"

    async def failing_open_connection(host: str | None, port: int | None) -> tuple[object, FakeWriter]:
        raise ConnectionRefusedError("refused")

    monkeypatch.setattr(probes.asyncio, "open_connection", failing_open_connection)
    result = asyncio.run(probes.probe_service(_tcp_service(), timeout_seconds=1.0, retries=0))
    assert result.status == HealthStatus.DOWN
    assert "ConnectionRefusedError" in result.detail


def test_probe_many_respects_concurrency_boundary(monkeypatch: pytest.MonkeyPatch) -> None:
    services = [
        _service().model_copy(update={"id": f"service-{index}", "name": f"API-{index}"})
        for index in range(5)
    ]
    active = 0
    maximum = 0

    async def fake_probe_service(
        service: Service,
        *,
        timeout_seconds: float,
        retries: int,
    ) -> ProbeResult:
        nonlocal active, maximum
        active += 1
        maximum = max(maximum, active)
        await asyncio.sleep(0)
        active -= 1
        return ProbeResult(
            id=f"probe-{service.id}",
            service_id=service.id,
            status=HealthStatus.HEALTHY,
            latency_ms=1.0,
            detail="ok",
            checked_at=datetime.now(UTC),
        )

    monkeypatch.setattr(probes, "probe_service", fake_probe_service)

    results = asyncio.run(probes.probe_many(services, concurrency=2))

    assert len(results) == len(services)
    assert maximum <= 2