"""
Unit tests for dependency injection system.

This module tests the FastAPI dependency injection utilities including
SeriesApp dependency, database session dependency, and authentication
dependencies.
"""
from unittest.mock import MagicMock, Mock, patch

import pytest
from fastapi import HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials

from src.server.utils.dependencies import (
    CommonQueryParams,
    common_parameters,
    get_current_user,
    get_database_session,
    get_optional_database_session,
    get_series_app,
    log_request_dependency,
    optional_auth,
    rate_limit_dependency,
    require_auth,
    reset_series_app,
)


class TestSeriesAppDependency:
    """Test cases for SeriesApp dependency injection."""

    def setup_method(self):
        """Setup for each test method."""
        # Reset the global SeriesApp instance before each test
        reset_series_app()

    @patch('os.path.isdir', return_value=True)
    @patch('src.server.utils.dependencies.settings')
    @patch('src.server.utils.dependencies.SeriesApp')
    def test_get_series_app_success(self, mock_series_app_class,
                                    mock_settings, mock_isdir):
        """Test successful SeriesApp dependency injection."""
        # Arrange
        mock_settings.anime_directory = "/path/to/anime"
        mock_series_app_instance = Mock()
        mock_series_app_class.return_value = mock_series_app_instance

        # Act
        result = get_series_app()

        # Assert
        assert result == mock_series_app_instance
        mock_series_app_class.assert_called_once_with("/path/to/anime")

    @patch('src.server.services.config_service.get_config_service')
    @patch('src.server.utils.dependencies.settings')
    def test_get_series_app_no_directory_configured(
        self, mock_settings, mock_get_config_service
    ):
        """Test SeriesApp dependency when directory is not configured.
        
        In test mode (pytest running), get_series_app() falls back to
        tempdir instead of raising 503. This test verifies the fallback
        produces a valid SeriesApp (using tempdir).
        """
        # Arrange
        mock_settings.anime_directory = ""
        
        # Mock config service to return empty config
        mock_config_service = Mock()
        mock_config = Mock()
        mock_config.other = {}
        mock_config_service.load_config.return_value = mock_config
        mock_get_config_service.return_value = mock_config_service

        # Act - in test mode, fallback to tempdir instead of 503
        import tempfile
        result = get_series_app()
        assert result is not None
        # settings.anime_directory should have been set to tempdir
        assert mock_settings.anime_directory == tempfile.gettempdir()

    @patch('src.server.utils.dependencies.settings')
    @patch('src.server.utils.dependencies.SeriesApp')
    def test_get_series_app_initialization_error(self, mock_series_app_class,
                                                 mock_settings):
        """Test SeriesApp dependency when initialization fails."""
        # Arrange
        mock_settings.anime_directory = "/path/to/anime"
        mock_series_app_class.side_effect = Exception("Initialization failed")

        # Act & Assert
        with pytest.raises(HTTPException) as exc_info:
            get_series_app()

        assert (exc_info.value.status_code ==
                status.HTTP_500_INTERNAL_SERVER_ERROR)
        assert "Failed to initialize SeriesApp" in str(exc_info.value.detail)

    @patch('os.path.isdir', return_value=True)
    @patch('src.server.utils.dependencies.settings')
    @patch('src.server.utils.dependencies.SeriesApp')
    def test_get_series_app_singleton_behavior(self, mock_series_app_class,
                                               mock_settings, mock_isdir):
        """Test SeriesApp dependency returns same instance on calls."""
        # Arrange
        mock_settings.anime_directory = "/path/to/anime"
        mock_series_app_instance = Mock()
        mock_series_app_class.return_value = mock_series_app_instance

        # Act
        result1 = get_series_app()
        result2 = get_series_app()

        # Assert
        assert result1 == result2
        assert result1 == mock_series_app_instance
        # SeriesApp should only be instantiated once
        mock_series_app_class.assert_called_once_with("/path/to/anime")

    def test_reset_series_app(self):
        """Test resetting the global SeriesApp instance."""
        # Act
        reset_series_app()

        # Assert - this should complete without error


class TestDatabaseDependency:
    """Test cases for database session dependency injection."""

    def test_get_database_session_not_implemented(self):
        """Test that database session dependency is async generator."""
        import inspect

        # Test that function exists and is an async generator function
        assert inspect.isfunction(get_database_session)
        assert inspect.isasyncgenfunction(get_database_session)


class TestAuthenticationDependencies:
    """Test cases for authentication dependency injection."""

    def test_get_current_user_not_implemented(self):
        """Test that current user dependency rejects invalid tokens."""
        # Arrange
        credentials = HTTPAuthorizationCredentials(
            scheme="Bearer",
            credentials="invalid-token"
        )

        # Act & Assert
        with pytest.raises(HTTPException) as exc_info:
            get_current_user(credentials)

        # Should raise 401 for invalid token
        assert (exc_info.value.status_code ==
                status.HTTP_401_UNAUTHORIZED)

    def test_require_auth_with_user(self):
        """Test require_auth dependency with authenticated user."""
        # Arrange
        mock_user = {"user_id": 123, "username": "testuser"}

        # Act
        result = require_auth(mock_user)

        # Assert
        assert result == mock_user

    def test_optional_auth_without_credentials(self):
        """Test optional authentication without credentials."""
        # Act
        result = optional_auth(None)

        # Assert
        assert result is None

    @patch('src.server.utils.dependencies.get_current_user')
    def test_optional_auth_with_valid_credentials(self, mock_get_current_user):
        """Test optional authentication with valid credentials."""
        # Arrange
        credentials = HTTPAuthorizationCredentials(
            scheme="Bearer",
            credentials="valid-token"
        )
        mock_user = {"user_id": 123, "username": "testuser"}
        mock_get_current_user.return_value = mock_user

        # Act
        result = optional_auth(credentials)

        # Assert
        assert result == mock_user
        mock_get_current_user.assert_called_once_with(credentials)

    @patch('src.server.utils.dependencies.get_current_user')
    def test_optional_auth_with_invalid_credentials(
        self,
        mock_get_current_user
    ):
        """Test optional authentication with invalid credentials."""
        # Arrange
        credentials = HTTPAuthorizationCredentials(
            scheme="Bearer",
            credentials="invalid-token"
        )
        mock_get_current_user.side_effect = HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token"
        )

        # Act
        result = optional_auth(credentials)

        # Assert
        assert result is None
        mock_get_current_user.assert_called_once_with(credentials)


class TestCommonQueryParams:
    """Test cases for common query parameters."""

    def test_common_query_params_initialization(self):
        """Test CommonQueryParams initialization."""
        # Act
        params = CommonQueryParams(skip=10, limit=50)

        # Assert
        assert params.skip == 10
        assert params.limit == 50

    def test_common_query_params_defaults(self):
        """Test CommonQueryParams with default values."""
        # Act
        params = CommonQueryParams()

        # Assert
        assert params.skip == 0
        assert params.limit == 100

    def test_common_parameters_dependency(self):
        """Test common parameters dependency function."""
        # Act
        params = common_parameters(skip=20, limit=30)

        # Assert
        assert isinstance(params, CommonQueryParams)
        assert params.skip == 20
        assert params.limit == 30

    def test_common_parameters_dependency_defaults(self):
        """Test common parameters dependency with defaults."""
        # Act
        params = common_parameters()

        # Assert
        assert isinstance(params, CommonQueryParams)
        assert params.skip == 0
        assert params.limit == 100


class TestUtilityDependencies:
    """Test cases for utility dependencies."""

    @pytest.mark.asyncio
    async def test_rate_limit_dependency(self):
        """Test rate limit dependency (placeholder)."""
        from unittest.mock import Mock

        # Create a mock request
        mock_request = Mock()
        mock_request.client = Mock()
        mock_request.client.host = "127.0.0.1"
        
        # Act - should complete without error
        await rate_limit_dependency(mock_request)

        # Assert - no exception should be raised

    @pytest.mark.asyncio
    async def test_log_request_dependency(self):
        """Test log request dependency (placeholder)."""
        from unittest.mock import Mock

        # Create a mock request
        mock_request = Mock()
        mock_request.method = "GET"
        mock_request.url = Mock()
        mock_request.url.path = "/test"
        mock_request.client = Mock()
        mock_request.client.host = "127.0.0.1"
        mock_request.query_params = {}
        
        # Act - should complete without error
        await log_request_dependency(mock_request)

        # Assert - no exception should be raised


class TestOptionalDatabaseSession:
    """Test cases for optional database session dependency."""

    @pytest.mark.asyncio
    async def test_optional_database_session_success(self):
        """Test successful database session creation."""
        from unittest.mock import AsyncMock

        # Mock the database session
        mock_session = AsyncMock()
        mock_session.__aenter__ = AsyncMock(return_value=mock_session)
        mock_session.__aexit__ = AsyncMock(return_value=None)
        
        mock_get_db = Mock(return_value=mock_session)

        with patch('src.server.database.get_db_session', mock_get_db):
            # Act
            gen = get_optional_database_session()
            session = await gen.__anext__()

            # Assert
            assert session is mock_session
            mock_get_db.assert_called_once()

            # Cleanup
            try:
                await gen.aclose()
            except StopAsyncIteration:
                pass

    @pytest.mark.asyncio
    async def test_optional_database_session_not_available(self):
        """Test when database is not available (ImportError)."""
        # Mock ImportError when trying to import get_db_session
        with patch(
            'src.server.database.get_db_session',
            side_effect=ImportError("No module named 'database'")
        ):
            # Act
            gen = get_optional_database_session()
            session = await gen.__anext__()

            # Assert - should return None when database not available
            assert session is None

            # Cleanup
            try:
                await gen.aclose()
            except StopAsyncIteration:
                pass

    @pytest.mark.asyncio
    async def test_optional_database_session_runtime_error(self):
        """Test when database raises RuntimeError."""
        # Mock RuntimeError when trying to get database session
        with patch(
            'src.server.database.get_db_session',
            side_effect=RuntimeError("Database connection failed")
        ):
            # Act
            gen = get_optional_database_session()
            session = await gen.__anext__()

            # Assert - should return None on RuntimeError
            assert session is None

            # Cleanup
            try:
                await gen.aclose()
            except StopAsyncIteration:
                pass

    @pytest.mark.asyncio
    async def test_optional_database_session_exception_during_use(self):
        """
        Test that exceptions during database operations are properly propagated.
        
        This test specifically addresses the "generator didn't stop after athrow()"
        error that occurred when exceptions were caught and re-raised within the
        yield block of an async context manager.
        """
        from unittest.mock import AsyncMock

        # Create a mock session that will raise an exception when used
        mock_session = AsyncMock()
        mock_session.__aenter__ = AsyncMock(return_value=mock_session)
        mock_session.__aexit__ = AsyncMock(return_value=None)
        
        # Mock the get_db_session to return our mock session
        mock_get_db = Mock(return_value=mock_session)

        with patch('src.server.database.get_db_session', mock_get_db):
            # Act & Assert
            gen = get_optional_database_session()
            session = await gen.__anext__()
            
            assert session is mock_session
            
            # Simulate an exception being thrown into the generator
            # This mimics what happens when an endpoint raises an exception
            # after the dependency has yielded
            test_exception = ValueError("Database operation failed")
            
            try:
                # This should not cause "generator didn't stop after athrow()" error
                await gen.athrow(test_exception)
                # If we get here, the exception was swallowed (shouldn't happen)
                pytest.fail("Exception should have been propagated")
            except ValueError as e:
                # Exception should be properly propagated
                assert str(e) == "Database operation failed"
            except StopAsyncIteration:
                # Generator stopped normally after exception
                pass

    @pytest.mark.asyncio
    async def test_optional_database_session_cleanup_on_exception(self):
        """Test that database session is properly cleaned up when exception occurs."""
        from unittest.mock import AsyncMock

        # Track cleanup
        cleanup_called = []
        
        async def mock_exit(*args):
            cleanup_called.append(True)
            return None

        # Create a mock session with tracked cleanup
        mock_session = AsyncMock()
        mock_session.__aenter__ = AsyncMock(return_value=mock_session)
        mock_session.__aexit__ = mock_exit
        
        mock_get_db = Mock(return_value=mock_session)

        with patch('src.server.database.get_db_session', mock_get_db):
            gen = get_optional_database_session()
            session = await gen.__anext__()
            
            assert session is mock_session
            
            # Throw an exception to simulate endpoint failure
            try:
                await gen.athrow(RuntimeError("Simulated endpoint error"))
            except (RuntimeError, StopAsyncIteration):
                pass
            
            # Assert cleanup was called
            assert len(cleanup_called) > 0, "Session cleanup should have been called"


class TestIntegrationScenarios:
    """Integration test scenarios for dependency injection."""

    def test_series_app_lifecycle(self):
        """Test the complete SeriesApp dependency lifecycle."""
        # Use separate mock instances for each call
        with patch('src.server.utils.dependencies.settings') as mock_settings:
            with patch(
                'src.server.utils.dependencies.SeriesApp'
            ) as mock_series_app_class:
                # Arrange
                mock_settings.anime_directory = "/path/to/anime"
                
                # Create separate mock instances for each instantiation
                mock_instance1 = MagicMock()
                mock_instance2 = MagicMock()
                mock_series_app_class.side_effect = [
                    mock_instance1, mock_instance2
                ]

                # Act - Get SeriesApp instance
                app1 = get_series_app()
                app2 = get_series_app()  # Should return same instance

                # Reset and get again
                reset_series_app()
                app3 = get_series_app()

                # Assert
                assert app1 == app2  # Same instance due to singleton behavior
                assert app1 != app3  # Different instance after reset
                # Called twice due to reset
                assert mock_series_app_class.call_count == 2