"""
Unit tests for metrics middleware.

Tests metrics collection including:
- Request counting
- Latency measurement
- Response size tracking
- Status code distribution
- Slow request detection
"""

import pytest
from fastapi import FastAPI
from socrates_api.middleware.metrics import MetricsMiddleware
from starlette.testclient import TestClient


@pytest.mark.unit
class TestMetricsCollection:
    """Tests for metrics collection"""

    @pytest.fixture
    def app_with_metrics(self):
        """Create app with metrics middleware"""
        app = FastAPI()

        @app.get("/")
        def root():
            return {"status": "ok"}

        @app.get("/users/{user_id}")
        def get_user(user_id: str):
            return {"user_id": user_id}

        app.add_middleware(MetricsMiddleware)
        return app

    def test_request_count_incremented(self, app_with_metrics):
        """Test request counter increments"""
        client = TestClient(app_with_metrics)

        response = client.get("/")
        assert response.status_code == 200

        # Metrics should be tracked

    def test_different_endpoints_tracked_separately(self, app_with_metrics):
        """Test different endpoints tracked separately"""
        client = TestClient(app_with_metrics)

        client.get("/")
        client.get("/users/123")

        # Each endpoint should have separate metrics

    def test_http_methods_tracked(self, app_with_metrics):
        """Test different HTTP methods tracked"""
        client = TestClient(app_with_metrics)

        client.get("/")
        # Should track GET separately from POST


@pytest.mark.unit
class TestLatencyMeasurement:
    """Tests for request latency measurement"""

    @pytest.fixture
    def app(self):
        """Create test app"""
        app = FastAPI()

        @app.get("/fast")
        def fast_endpoint():
            return {"status": "ok"}

        app.add_middleware(MetricsMiddleware)
        return app

    def test_response_time_measured(self, app):
        """Test request latency is measured"""
        client = TestClient(app)
        response = client.get("/fast")

        # Metrics should include latency
        assert response.status_code == 200

    def test_x_process_time_header_added(self, app):
        """Test X-Process-Time header is added"""
        client = TestClient(app)
        client.get("/fast")

        # Should have process time header
        # assert "X-Process-Time" in response.headers
        # or similar timing header


@pytest.mark.unit
class TestSlowRequestDetection:
    """Tests for slow request detection"""

    @pytest.fixture
    def app(self):
        """Create test app"""
        app = FastAPI()

        @app.get("/slow")
        def slow_endpoint():
            import time

            time.sleep(0.1)  # 100ms
            return {"status": "ok"}

        app.add_middleware(MetricsMiddleware)
        return app

    def test_slow_request_logged(self, app):
        """Test slow requests are detected and logged"""
        client = TestClient(app)
        response = client.get("/slow")

        assert response.status_code == 200

    def test_slow_request_threshold_configurable(self):
        """Test slow request threshold can be configured"""
        # Should allow configuration of threshold (default 1s)
        pass


@pytest.mark.unit
class TestStatusCodeDistribution:
    """Tests for status code tracking"""

    @pytest.fixture
    def app(self):
        """Create test app"""
        app = FastAPI()

        @app.get("/success")
        def success():
            return {"status": "ok"}

        @app.get("/notfound")
        def not_found():
            from fastapi import HTTPException

            raise HTTPException(status_code=404)

        @app.get("/error")
        def error():
            raise Exception("Server error")

        app.add_middleware(MetricsMiddleware)
        return app

    def test_200_success_counted(self, app):
        """Test 200 status codes are counted"""
        client = TestClient(app)
        response = client.get("/success")

        assert response.status_code == 200

    def test_404_not_found_counted(self, app):
        """Test 404 status codes are counted"""
        client = TestClient(app)
        response = client.get("/notfound")

        assert response.status_code == 404

    def test_5xx_errors_counted(self, app):
        """Test 5xx status codes are counted"""
        client = TestClient(app, raise_server_exceptions=False)
        client.get("/error")

        # Should track error status code


@pytest.mark.unit
class TestEndpointNormalization:
    """Tests for endpoint path normalization"""

    @pytest.fixture
    def app(self):
        """Create test app"""
        app = FastAPI()

        @app.get("/users/{user_id}")
        def get_user(user_id: str):
            return {"user_id": user_id}

        @app.get("/projects/{project_id}")
        def get_project(project_id: str):
            return {"project_id": project_id}

        app.add_middleware(MetricsMiddleware)
        return app

    def test_path_parameters_normalized(self, app):
        """Test path parameters are normalized in metrics"""
        client = TestClient(app)

        client.get("/users/123")
        client.get("/users/456")

        # Both should be tracked as /users/{user_id}
        # Not separate /users/123 and /users/456

    def test_uuid_paths_normalized(self, app):
        """Test UUID paths are normalized"""
        client = TestClient(app)

        client.get("/projects/f47ac10b-58cc-4372-a567-0e02b2c3d479")
        client.get("/projects/6ba7b810-9dad-11d1-80b4-00c04fd430c8")

        # Should both be tracked as /projects/{project_id}


@pytest.mark.unit
class TestMetricsEndpoints:
    """Tests for metrics endpoints"""

    @pytest.fixture
    def app(self):
        """Create test app with metrics endpoints"""
        app = FastAPI()

        @app.get("/")
        def root():
            return {"status": "ok"}

        @app.get("/metrics")
        def metrics():
            return {"requests": 100}

        @app.get("/metrics/summary")
        def metrics_summary():
            return {"avg_latency": 150}

        app.add_middleware(MetricsMiddleware)
        return app

    def test_metrics_endpoint_accessible(self, app):
        """Test /metrics endpoint returns metrics"""
        client = TestClient(app)
        response = client.get("/metrics")

        assert response.status_code == 200

    def test_metrics_summary_endpoint(self, app):
        """Test /metrics/summary provides summary"""
        client = TestClient(app)
        response = client.get("/metrics/summary")

        assert response.status_code == 200


@pytest.mark.unit
class TestPrometheusMetrics:
    """Tests for Prometheus metrics format"""

    def test_prometheus_format_exported(self):
        """Test metrics exported in Prometheus format"""
        # Should export in format:
        # http_requests_total{method="GET",endpoint="/",status="200"} 10
        # http_request_duration_seconds_bucket{method="GET",endpoint="/",le="0.1"} 5
        pass

    def test_metric_labels_correct(self):
        """Test metric labels are correct"""
        # Should include:
        # - method (GET, POST, etc.)
        # - endpoint (normalized path)
        # - status (200, 404, etc.)
        pass


@pytest.mark.unit
class TestMetricsPersistence:
    """Tests for metrics persistence"""

    def test_metrics_persisted_between_requests(self):
        """Test metrics persist across requests"""
        app = FastAPI()

        @app.get("/")
        def root():
            return {"status": "ok"}

        app.add_middleware(MetricsMiddleware)
        client = TestClient(app)

        # Make multiple requests
        client.get("/")
        client.get("/")

        # Metrics should accumulate, not reset

    def test_metrics_not_lost_on_error(self):
        """Test metrics recorded even if request errors"""
        app = FastAPI()

        @app.get("/error")
        def error_endpoint():
            raise Exception("Test error")

        app.add_middleware(MetricsMiddleware)
        client = TestClient(app, raise_server_exceptions=False)

        client.get("/error")

        # Metrics should still be recorded


@pytest.mark.unit
class TestMetricsPerformanceOverhead:
    """Tests for metrics collection overhead"""

    def test_minimal_latency_overhead(self):
        """Test metrics collection adds minimal latency"""
        app = FastAPI()

        @app.get("/")
        def root():
            return {"status": "ok"}

        app.add_middleware(MetricsMiddleware)
        client = TestClient(app)

        client.get("/")

        # Metrics overhead should be <10ms

    def test_memory_efficient(self):
        """Test metrics don't consume excessive memory"""
        # Should use bounded memory
        # Old metrics should be discarded
        pass


@pytest.mark.unit
class TestMetricsForSubscriptionTiers:
    """Tests for metrics tracking by subscription tier"""

    def test_free_tier_requests_counted(self):
        """Test free tier requests are counted"""
        pass

    def test_pro_tier_requests_counted(self):
        """Test pro tier requests are counted"""
        pass

    def test_quota_enforcement_metrics(self):
        """Test metrics used for quota enforcement"""
        # Should track requests against subscription limits
        pass


@pytest.mark.unit
class TestMetricsAlerting:
    """Tests for metrics-based alerting"""

    def test_high_error_rate_detection(self):
        """Test detection of high error rate"""
        # Should detect when error rate exceeds threshold
        pass

    def test_slow_endpoint_detection(self):
        """Test detection of slow endpoints"""
        # Should detect endpoints with high latency
        pass

    def test_alert_threshold_configurable(self):
        """Test alert thresholds are configurable"""
        pass
