from itertools import count

import fakeredis
import pytest

from app.dsp.stats import InMemoryStatsBackend, RedisStatsBackend


class TestInMemoryStatsBackend:
    @pytest.fixture
    def backend(self) -> InMemoryStatsBackend:
        return InMemoryStatsBackend()

    def test_initial_snapshot_is_zero(self, backend: InMemoryStatsBackend) -> None:
        stats = backend.snapshot()

        assert stats.requests == 0
        assert stats.retries == 0
        assert stats.rate_limited == 0
        assert stats.rps is None

    def test_incr_requests(self, backend: InMemoryStatsBackend) -> None:
        backend.incr_requests()
        backend.incr_requests()

        assert backend.snapshot().requests == 2

    def test_incr_retries(self, backend: InMemoryStatsBackend) -> None:
        backend.incr_retries()
        backend.incr_retries()
        backend.incr_retries()

        assert backend.snapshot().retries == 3

    def test_incr_rate_limited(self, backend: InMemoryStatsBackend) -> None:
        backend.incr_rate_limited()

        assert backend.snapshot().rate_limited == 1

    def test_total_attempts(self, backend: InMemoryStatsBackend) -> None:
        backend.incr_requests()
        backend.incr_requests()
        backend.incr_retries()

        assert backend.snapshot().total_attempts == 3

    def test_rps_is_none_for_single_request(
        self, backend: InMemoryStatsBackend
    ) -> None:
        backend.incr_requests()

        assert backend.snapshot().rps is None

    def test_rps_is_set_after_multiple_requests(
        self, backend: InMemoryStatsBackend, mocker
    ) -> None:
        tick = count(0)
        mocker.patch(
            "app.dsp.stats.time.monotonic", side_effect=lambda: next(tick) * 0.1
        )

        for _ in range(5):
            backend.incr_requests()

        stats = backend.snapshot()

        assert stats.rps is not None
        assert stats.rps > 0


class TestRedisStatsBackend:
    @pytest.fixture
    def backend(self) -> RedisStatsBackend:
        return RedisStatsBackend(fakeredis.FakeRedis(), key_prefix="test")

    def test_initial_snapshot_is_zero(self, backend: RedisStatsBackend) -> None:
        stats = backend.snapshot()

        assert stats.requests == 0
        assert stats.retries == 0
        assert stats.rate_limited == 0
        assert stats.rps is None

    def test_incr_requests(self, backend: RedisStatsBackend) -> None:
        backend.incr_requests()
        backend.incr_requests()

        assert backend.snapshot().requests == 2

    def test_incr_retries(self, backend: RedisStatsBackend) -> None:
        backend.incr_retries()
        backend.incr_retries()
        backend.incr_retries()

        assert backend.snapshot().retries == 3

    def test_incr_rate_limited(self, backend: RedisStatsBackend) -> None:
        backend.incr_rate_limited()

        assert backend.snapshot().rate_limited == 1

    def test_total_attempts(self, backend: RedisStatsBackend) -> None:
        backend.incr_requests()
        backend.incr_requests()
        backend.incr_retries()

        assert backend.snapshot().total_attempts == 3

    def test_rps_is_none_for_single_request(self, backend: RedisStatsBackend) -> None:
        backend.incr_requests()

        assert backend.snapshot().rps is None

    def test_rps_is_set_after_multiple_requests(
        self, backend: RedisStatsBackend, mocker
    ) -> None:
        tick = count(0)
        mocker.patch("app.dsp.stats.time.time", side_effect=lambda: next(tick) * 0.1)

        for _ in range(5):
            backend.incr_requests()

        stats = backend.snapshot()

        assert stats.rps is not None
        assert stats.rps > 0