"""
Global pytest configuration and fixtures for RAG System tests.

This module provides shared test fixtures and configuration that are available
to all test modules across the test suite.
"""

import asyncio
import pytest
from typing import AsyncGenerator, Generator
from pathlib import Path


# ============================================================================
# Event Loop Configuration
# ============================================================================

@pytest.fixture(scope="session")
def event_loop() -> Generator[asyncio.AbstractEventLoop, None, None]:
    """
    Create an event loop for the entire test session.
    
    This fixture ensures that async tests have access to a properly configured
    event loop. The loop is created once per test session and cleaned up after
    all tests complete.
    
    Yields:
        asyncio.AbstractEventLoop: The event loop for async tests
    """
    loop = asyncio.get_event_loop_policy().new_event_loop()
    yield loop
    loop.close()


# ============================================================================
# Singleton Reset
# ============================================================================

@pytest.fixture(autouse=True)
def reset_singletons() -> Generator[None, None, None]:
    """
    Reset singleton instances between tests.
    
    This fixture automatically runs before each test to ensure that singleton
    instances (like configuration objects) are reset, preventing test pollution.
    
    Yields:
        None
    """
    yield
    # Clear any cached configuration instances
    from functools import lru_cache
    # Note: Specific singleton reset logic will be added as needed
    # For example: get_settings.cache_clear() when settings are implemented


# ============================================================================
# Test Data Paths
# ============================================================================

@pytest.fixture(scope="session")
def test_data_dir() -> Path:
    """
    Get the path to the test data directory.
    
    Returns:
        Path: Path to tests/fixtures directory
    """
    return Path(__file__).parent / "fixtures"


@pytest.fixture(scope="session")
def sample_documents_dir(test_data_dir: Path) -> Path:
    """
    Get the path to sample documents for testing.
    
    Args:
        test_data_dir: Path to test data directory
        
    Returns:
        Path: Path to sample documents directory
    """
    return test_data_dir / "documents"


# ============================================================================
# Mock Configuration
# ============================================================================

@pytest.fixture
def mock_settings() -> dict:
    """
    Provide mock settings for testing.
    
    Returns:
        dict: Mock configuration settings
    """
    return {
        "app_name": "RAG System Test",
        "debug": True,
        "vector_db_type": "infinity",
        "database": {
            "host": "localhost",
            "port": 5432,
            "database": "test_rag_system",
            "username": "test_user",
            "password": "test_password",
        },
        "infinity": {
            "host": "localhost",
            "port": 23817,
        },
        "elasticsearch": {
            "host": "localhost",
            "port": 9200,
        },
    }


# ============================================================================
# Test Database Fixtures
# ============================================================================

@pytest.fixture
async def test_db_session() -> AsyncGenerator:
    """
    Provide a test database session.
    
    This fixture will be implemented when the database infrastructure is ready.
    It should provide an isolated database session for each test.
    
    Yields:
        Database session for testing
    """
    # TODO: Implement when database infrastructure is ready
    # Example:
    # async with get_test_session_factory()() as session:
    #     yield session
    #     await session.rollback()
    yield None


# ============================================================================
# Mock External Services
# ============================================================================

@pytest.fixture
def mock_vector_db():
    """
    Provide a mock vector database for testing.
    
    This fixture will be implemented when vector database infrastructure is ready.
    
    Returns:
        Mock vector database instance
    """
    # TODO: Implement when vector database infrastructure is ready
    return None


@pytest.fixture
def mock_embedding_service():
    """
    Provide a mock embedding service for testing.
    
    This fixture generates fake embeddings for testing purposes.
    
    Returns:
        Mock embedding service instance
    """
    # TODO: Implement when embedding service is ready
    return None


# ============================================================================
# Test Markers Configuration
# ============================================================================

def pytest_configure(config):
    """
    Configure custom pytest markers.
    
    Args:
        config: pytest configuration object
    """
    config.addinivalue_line(
        "markers", "unit: Unit tests that test individual components in isolation"
    )
    config.addinivalue_line(
        "markers", "integration: Integration tests that test component interactions"
    )
    config.addinivalue_line(
        "markers", "e2e: End-to-end tests that test complete user workflows"
    )
    config.addinivalue_line(
        "markers", "slow: Tests that take a long time to run (> 1 second)"
    )
    config.addinivalue_line(
        "markers", "requires_db: Tests that require a database connection"
    )
    config.addinivalue_line(
        "markers", "requires_vector_db: Tests that require a vector database connection"
    )
    config.addinivalue_line(
        "markers", "requires_external_service: Tests that require external services"
    )
    config.addinivalue_line(
        "markers", "property: Property-based tests using Hypothesis"
    )
    config.addinivalue_line(
        "markers", "asyncio: Async tests using pytest-asyncio"
    )


# ============================================================================
# Test Collection Configuration
# ============================================================================

def pytest_collection_modifyitems(config, items):
    """
    Modify test collection to add markers based on test location.
    
    Args:
        config: pytest configuration object
        items: List of collected test items
    """
    for item in items:
        # Add markers based on test file location
        if "unit" in str(item.fspath):
            item.add_marker(pytest.mark.unit)
        elif "integration" in str(item.fspath):
            item.add_marker(pytest.mark.integration)
        elif "e2e" in str(item.fspath):
            item.add_marker(pytest.mark.e2e)