"""
Circuit Breaker 測試
====================
ADR-038: OpenClaw 雙層保護機制

測試項目：
- Circuit Breaker 狀態轉換
- Semaphore 並發控制
- Graceful Degradation
"""

import asyncio

import pytest

from src.core.circuit_breaker import (
    CircuitBreakerConfig,
    CircuitState,
    OpenClawGuard,
    get_openclaw_guard,
    reset_openclaw_guard,
)


class TestCircuitBreaker:
    """Circuit Breaker 核心功能測試"""

    def setup_method(self):
        """每個測試前重置全域 Guard"""
        reset_openclaw_guard()

    def test_initial_state_is_closed(self):
        """初始狀態應該是 CLOSED"""
        guard = OpenClawGuard()
        assert guard.state == CircuitState.CLOSED
        assert guard.failure_count == 0
        assert not guard.is_circuit_open()

    def test_record_success_resets_failure_count(self):
        """成功應該重置失敗計數"""
        guard = OpenClawGuard()
        guard.failure_count = 3
        guard.record_success()
        assert guard.failure_count == 0

    def test_record_failure_increments_count(self):
        """失敗應該增加計數"""
        guard = OpenClawGuard()
        guard.record_failure()
        assert guard.failure_count == 1
        guard.record_failure()
        assert guard.failure_count == 2

    def test_circuit_opens_after_threshold(self):
        """連續失敗達到閾值後應該觸發斷路"""
        config = CircuitBreakerConfig(failure_threshold=3)
        guard = OpenClawGuard(config)

        guard.record_failure()
        guard.record_failure()
        assert guard.state == CircuitState.CLOSED

        guard.record_failure()
        assert guard.state == CircuitState.OPEN
        assert guard.is_circuit_open()

    def test_circuit_half_open_after_timeout(self):
        """冷卻期後應該切換到 HALF_OPEN"""
        config = CircuitBreakerConfig(failure_threshold=2, timeout_s=0.1)
        guard = OpenClawGuard(config)

        # 觸發斷路
        guard.record_failure()
        guard.record_failure()
        assert guard.state == CircuitState.OPEN
        assert guard.is_circuit_open()

        # 等待冷卻
        import time

        time.sleep(0.15)

        # 應該切換到 HALF_OPEN
        assert not guard.is_circuit_open()
        assert guard.state == CircuitState.HALF_OPEN

    def test_circuit_closes_after_success_in_half_open(self):
        """HALF_OPEN 狀態下成功應該恢復 CLOSED"""
        guard = OpenClawGuard()
        guard.state = CircuitState.HALF_OPEN

        guard.record_success()
        assert guard.state == CircuitState.CLOSED
        assert guard.failure_count == 0

    def test_get_metrics(self):
        """應該正確返回指標"""
        guard = OpenClawGuard()
        guard.record_failure()
        guard.record_failure()

        metrics = guard.get_metrics()
        assert metrics["state"] == "closed"
        assert metrics["failure_count"] == 2
        assert metrics["max_concurrent"] == 3

    def test_singleton_pattern(self):
        """全域 Guard 應該是單例"""
        guard1 = get_openclaw_guard()
        guard2 = get_openclaw_guard()
        assert guard1 is guard2

    def test_reset_clears_singleton(self):
        """reset 應該清除單例"""
        guard1 = get_openclaw_guard()
        reset_openclaw_guard()
        guard2 = get_openclaw_guard()
        assert guard1 is not guard2


class TestSemaphore:
    """Semaphore 並發控制測試"""

    def setup_method(self):
        reset_openclaw_guard()

    @pytest.mark.asyncio
    async def test_semaphore_limits_concurrency(self):
        """Semaphore 應該限制並發數"""
        config = CircuitBreakerConfig(max_concurrent=2)
        guard = OpenClawGuard(config)

        concurrent_count = 0
        max_concurrent_seen = 0
        results = []

        async def worker(worker_id: int):
            nonlocal concurrent_count, max_concurrent_seen

            async with guard.semaphore:
                concurrent_count += 1
                max_concurrent_seen = max(max_concurrent_seen, concurrent_count)
                await asyncio.sleep(0.05)
                results.append(worker_id)
                concurrent_count -= 1

        # 啟動 5 個並發任務
        tasks = [asyncio.create_task(worker(i)) for i in range(5)]
        await asyncio.gather(*tasks)

        # 確認最大並發數不超過限制
        assert max_concurrent_seen <= 2
        assert len(results) == 5

    @pytest.mark.asyncio
    async def test_semaphore_created_lazily(self):
        """Semaphore 應該延遲建立"""
        guard = OpenClawGuard()
        assert guard._semaphore is None

        # 存取 semaphore 屬性會觸發建立
        sem = guard.semaphore
        assert guard._semaphore is not None
        assert sem is guard._semaphore