"""Unit tests for correlation ID middleware and distributed tracing."""

from typing import Any

import pytest
from httpx import AsyncClient
from starlette.testclient import TestClient

from app.config import Settings
from app.main import create_app
from app.middleware.correlation import CORRELATION_ID_CONTEXT_KEY
from app.models.server import ServerStatus


def test_correlation_middleware_generates_uuid_when_header_absent(
    test_settings: Settings,
) -> None:
    """Correlation middleware generates a UUID4 when X-Correlation-ID header is missing."""
    app = create_app(settings=test_settings)

    # Test with TestClient (synchronous)
    client = TestClient(app)
    response = client.get("/api/v1/health")

    # Should have correlation ID header in response
    assert "X-Correlation-ID" in response.headers
    correlation_id = response.headers["X-Correlation-ID"]
    # UUID4 format: 8-4-4-4-12 hex digits
    assert len(correlation_id) == 36
    assert correlation_id.count("-") == 4


def test_correlation_middleware_preserves_header_from_request(
    test_settings: Settings,
) -> None:
    """Correlation middleware preserves X-Correlation-ID header from client request."""
    app = create_app(settings=test_settings)

    client = TestClient(app)
    test_correlation_id = "550e8400-e29b-41d4-a716-446655440000"
    response = client.get("/api/v1/health", headers={"X-Correlation-ID": test_correlation_id})

    # Should return the same correlation ID in response
    assert response.headers["X-Correlation-ID"] == test_correlation_id


def test_correlation_middleware_stores_in_request_state(
    test_settings: Settings,
) -> None:
    """Correlation middleware stores correlation ID in request.state for handlers."""
    from unittest.mock import MagicMock

    app = create_app(settings=test_settings)
    app.state.server_status = ServerStatus(online=True)
    mock_scheduler = MagicMock()
    mock_scheduler.running = True
    app.state.scheduler = mock_scheduler

    client = TestClient(app)

    # Make a request and verify correlation ID is available to handlers
    test_correlation_id = "550e8400-e29b-41d4-a716-446655440000"
    response = client.get("/api/v1/health", headers={"X-Correlation-ID": test_correlation_id})

    # The health endpoint should return 200, proving the correlation ID was processed
    assert response.status_code == 200
    # Response should have correlation ID header (proves it was stored and added)
    assert response.headers["X-Correlation-ID"] == test_correlation_id


def test_correlation_id_in_response_headers(
    test_settings: Settings,
) -> None:
    """Correlation ID is included in all response headers."""
    app = create_app(settings=test_settings)
    client = TestClient(app)

    # Test without providing header (should generate one)
    response = client.get("/api/v1/health")
    assert "X-Correlation-ID" in response.headers

    # Test with providing header (should preserve it)
    test_id = "test-correlation-id-12345"
    response = client.get("/api/v1/health", headers={"X-Correlation-ID": test_id})
    assert response.headers["X-Correlation-ID"] == test_id