from __future__ import annotations

import asyncio

import pytest

from yuxi.channels.infra.circuit_breaker import CircuitBreaker, CircuitBreakerOpenError, CircuitState


class TestCircuitBreakerInit:
    def test_default_values(self):
        cb = CircuitBreaker()
        assert cb.failure_threshold == 5
        assert cb.recovery_timeout == 60.0
        assert cb.half_open_max_calls == 3
        assert cb.state == CircuitState.CLOSED
        assert cb._failure_count == 0

    def test_custom_values(self):
        cb = CircuitBreaker(failure_threshold=3, recovery_timeout=10.0, half_open_max_calls=2)
        assert cb.failure_threshold == 3
        assert cb.recovery_timeout == 10.0
        assert cb.half_open_max_calls == 2


class TestCircuitStateTransitions:
    @pytest.mark.asyncio
    async def test_closed_to_open_on_threshold(self):
        cb = CircuitBreaker(failure_threshold=3)
        for _ in range(3):
            await cb.record_failure()
        assert cb.state == CircuitState.OPEN

    @pytest.mark.asyncio
    async def test_not_open_before_threshold(self):
        cb = CircuitBreaker(failure_threshold=5)
        for _ in range(3):
            await cb.record_failure()
        assert cb.state == CircuitState.CLOSED

    @pytest.mark.asyncio
    async def test_half_open_on_recovery_timeout(self):
        cb = CircuitBreaker(failure_threshold=1, recovery_timeout=0.0)
        await cb.record_failure()
        assert cb.state == CircuitState.OPEN

        async def dummy():
            return "ok"

        result = await cb.call(dummy)
        assert result == "ok"
        assert cb.state == CircuitState.CLOSED

    @pytest.mark.asyncio
    async def test_half_open_to_closed_on_success(self):
        cb = CircuitBreaker(failure_threshold=1, recovery_timeout=0.0)
        await cb.record_failure()

        async def ok_func():
            return "ok"

        await cb.call(ok_func)
        assert cb.state == CircuitState.CLOSED

    @pytest.mark.asyncio
    async def test_half_open_to_open_on_failure(self):
        cb = CircuitBreaker(failure_threshold=1, recovery_timeout=0.0)
        await cb.record_failure()

        async def failing():
            raise RuntimeError("boom")

        with pytest.raises(RuntimeError, match="boom"):
            await cb.call(failing)
        assert cb.state == CircuitState.OPEN

    @pytest.mark.asyncio
    async def test_record_success_resets_closed_count(self):
        cb = CircuitBreaker(failure_threshold=5)
        for _ in range(3):
            await cb.record_failure()
        await cb.record_success()
        assert cb._failure_count == 0
        assert cb.state == CircuitState.CLOSED


class TestCircuitBreakerCall:
    @pytest.mark.asyncio
    async def test_call_passes_result(self):
        cb = CircuitBreaker()

        async def func():
            return "hello"

        result = await cb.call(func)
        assert result == "hello"

    @pytest.mark.asyncio
    async def test_call_records_failure_on_exception(self):
        cb = CircuitBreaker()

        async def func():
            raise RuntimeError("fail")

        with pytest.raises(RuntimeError, match="fail"):
            await cb.call(func)
        assert cb._failure_count == 1

    @pytest.mark.asyncio
    async def test_call_blocks_when_open(self):
        cb = CircuitBreaker(failure_threshold=1, recovery_timeout=999.0)
        await cb.record_failure()
        assert cb.state == CircuitState.OPEN

        async def ok_func():
            return "ok"

        with pytest.raises(CircuitBreakerOpenError):
            await cb.call(ok_func)

    @pytest.mark.asyncio
    async def test_call_recovers_after_timeout(self):
        cb = CircuitBreaker(failure_threshold=1, recovery_timeout=0.0)
        await cb.record_failure()

        async def ok_func():
            return "ok"

        await cb.call(ok_func)
        assert cb.state == CircuitState.CLOSED


class TestHalfOpenMaxCalls:
    @pytest.mark.asyncio
    async def test_half_open_max_calls_reached(self):
        cb = CircuitBreaker(half_open_max_calls=2)
        cb.state = CircuitState.HALF_OPEN
        cb._half_open_calls = 2

        async def ok_func():
            return "ok"

        with pytest.raises(CircuitBreakerOpenError):
            await cb.call(ok_func)


class TestConcurrentSafety:
    @pytest.mark.asyncio
    async def test_concurrent_failures(self):
        cb = CircuitBreaker(failure_threshold=3)
        async with cb._lock:
            pass
        results = await asyncio.gather(
            cb.record_failure(),
            cb.record_failure(),
            cb.record_failure(),
        )
        assert cb._failure_count == 3

    @pytest.mark.asyncio
    async def test_concurrent_record_success(self):
        cb = CircuitBreaker(failure_threshold=5)
        for _ in range(3):
            await cb.record_failure()
        assert cb._failure_count == 3

        await asyncio.gather(
            cb.record_success(),
            cb.record_success(),
            cb.record_success(),
        )
        assert cb._failure_count == 0
        assert cb.state == CircuitState.CLOSED