"""Unit tests for background loader service optimization (no full rescans)."""

import asyncio
from pathlib import Path
from unittest.mock import AsyncMock, Mock, patch

import pytest

from src.server.services.background_loader_service import (
    BackgroundLoaderService,
    LoadingStatus,
    SeriesLoadingTask,
)


@pytest.fixture
def mock_websocket_service():
    """Mock WebSocket service."""
    service = Mock()
    service.broadcast = AsyncMock()
    return service


@pytest.fixture
def mock_anime_service():
    """Mock anime service."""
    service = Mock()
    service.rescan = AsyncMock()
    return service


@pytest.fixture
def mock_series_app(tmp_path):
    """Mock SeriesApp."""
    app = Mock()
    app.directory_to_search = str(tmp_path)
    app.nfo_service = Mock()
    app.nfo_service.has_nfo = Mock(return_value=False)
    app.nfo_service.create_tvshow_nfo = AsyncMock()
    return app


@pytest.fixture
async def background_loader(mock_websocket_service, mock_anime_service, mock_series_app):
    """Create BackgroundLoaderService instance."""
    service = BackgroundLoaderService(
        websocket_service=mock_websocket_service,
        anime_service=mock_anime_service,
        series_app=mock_series_app
    )
    yield service
    await service.stop()


class TestFindSeriesDirectory:
    """Test finding series directory without full rescan."""

    @pytest.mark.asyncio
    async def test_find_existing_directory(self, background_loader, tmp_path):
        """Test finding a series directory that exists."""
        # Create series directory
        series_dir = tmp_path / "Test Series"
        series_dir.mkdir()
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Find directory
        result = await background_loader._find_series_directory(task)
        
        # Verify
        assert result is not None
        assert result == series_dir
        assert result.exists()

    @pytest.mark.asyncio
    async def test_find_nonexistent_directory(self, background_loader, tmp_path):
        """Test finding a series directory that doesn't exist."""
        task = SeriesLoadingTask(
            key="nonexistent",
            folder="Nonexistent Series",
            name="Nonexistent Series"
        )
        
        # Find directory
        result = await background_loader._find_series_directory(task)
        
        # Verify
        assert result is None

    @pytest.mark.asyncio
    async def test_find_directory_with_special_characters(self, background_loader, tmp_path):
        """Test finding directory with special characters in name."""
        # Create series directory with special characters
        series_dir = tmp_path / "Series (2023) - Special!"
        series_dir.mkdir()
        
        task = SeriesLoadingTask(
            key="special-series",
            folder="Series (2023) - Special!",
            name="Series (2023) - Special!"
        )
        
        # Find directory
        result = await background_loader._find_series_directory(task)
        
        # Verify
        assert result is not None
        assert result == series_dir


class TestScanSeriesEpisodes:
    """Test scanning episodes for a specific series."""

    @pytest.mark.asyncio
    async def test_scan_single_season(self, background_loader, tmp_path):
        """Test scanning a series with one season."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        season_dir = series_dir / "Season 1"
        season_dir.mkdir(parents=True)
        (season_dir / "episode1.mp4").touch()
        (season_dir / "episode2.mp4").touch()
        (season_dir / "episode3.mp4").touch()
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Scan episodes
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        
        # Verify
        assert "Season 1" in episodes
        assert len(episodes["Season 1"]) == 3
        assert "episode1.mp4" in episodes["Season 1"]
        assert "episode2.mp4" in episodes["Season 1"]
        assert "episode3.mp4" in episodes["Season 1"]

    @pytest.mark.asyncio
    async def test_scan_multiple_seasons(self, background_loader, tmp_path):
        """Test scanning a series with multiple seasons."""
        # Create series structure
        series_dir = tmp_path / "Multi Season Series"
        
        for season_num in range(1, 4):
            season_dir = series_dir / f"Season {season_num}"
            season_dir.mkdir(parents=True)
            
            for episode_num in range(1, 6):
                (season_dir / f"episode{episode_num}.mp4").touch()
        
        task = SeriesLoadingTask(
            key="multi-season",
            folder="Multi Season Series",
            name="Multi Season Series"
        )
        
        # Scan episodes
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        
        # Verify
        assert len(episodes) == 3
        assert "Season 1" in episodes
        assert "Season 2" in episodes
        assert "Season 3" in episodes
        assert all(len(eps) == 5 for eps in episodes.values())

    @pytest.mark.asyncio
    async def test_scan_ignores_non_mp4_files(self, background_loader, tmp_path):
        """Test that only .mp4 files are counted as episodes."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        season_dir = series_dir / "Season 1"
        season_dir.mkdir(parents=True)
        
        (season_dir / "episode1.mp4").touch()
        (season_dir / "episode2.mkv").touch()  # Should be ignored
        (season_dir / "subtitle.srt").touch()  # Should be ignored
        (season_dir / "readme.txt").touch()  # Should be ignored
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Scan episodes
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        
        # Verify - only .mp4 file should be counted
        assert "Season 1" in episodes
        assert len(episodes["Season 1"]) == 1
        assert episodes["Season 1"][0] == "episode1.mp4"

    @pytest.mark.asyncio
    async def test_scan_empty_seasons_ignored(self, background_loader, tmp_path):
        """Test that seasons with no episodes are ignored."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        season1_dir = series_dir / "Season 1"
        season2_dir = series_dir / "Season 2"
        season1_dir.mkdir(parents=True)
        season2_dir.mkdir(parents=True)
        
        # Only add episodes to Season 1
        (season1_dir / "episode1.mp4").touch()
        # Season 2 is empty
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Scan episodes
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        
        # Verify - Season 2 should not be included
        assert len(episodes) == 1
        assert "Season 1" in episodes
        assert "Season 2" not in episodes

    @pytest.mark.asyncio
    async def test_scan_ignores_files_in_series_root(self, background_loader, tmp_path):
        """Test that files directly in series root are ignored."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        series_dir.mkdir()
        season_dir = series_dir / "Season 1"
        season_dir.mkdir()
        
        # Add episode in season folder
        (season_dir / "episode1.mp4").touch()
        
        # Add file in series root (should be ignored)
        (series_dir / "random.mp4").touch()
        (series_dir / "info.txt").touch()
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Scan episodes
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        
        # Verify - only episode in season folder should be counted
        assert len(episodes) == 1
        assert "Season 1" in episodes
        assert len(episodes["Season 1"]) == 1


class TestLoadEpisodesOptimization:
    """Test that loading episodes doesn't trigger full rescans."""

    @pytest.mark.asyncio
    async def test_load_episodes_no_full_rescan(
        self, background_loader, mock_anime_service, tmp_path
    ):
        """Test that loading episodes doesn't call anime_service.rescan()."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        season_dir = series_dir / "Season 1"
        season_dir.mkdir(parents=True)
        (season_dir / "episode1.mp4").touch()
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Mock database
        mock_db = AsyncMock()
        mock_series_db = Mock()
        
        with patch('src.server.database.service.AnimeSeriesService.get_by_key') as mock_get:
            mock_get.return_value = mock_series_db
            
            # Load episodes
            await background_loader._load_episodes(task, mock_db)
            
            # Verify rescan was NOT called
            mock_anime_service.rescan.assert_not_called()
            
            # Verify progress was updated
            assert task.progress["episodes"] is True
            
            # Verify database was updated
            assert mock_series_db.episodes_loaded is True
            mock_db.commit.assert_called_once()

    @pytest.mark.asyncio
    async def test_load_episodes_handles_missing_directory(
        self, background_loader, tmp_path
    ):
        """Test that loading episodes handles missing directory gracefully."""
        task = SeriesLoadingTask(
            key="nonexistent",
            folder="Nonexistent Series",
            name="Nonexistent Series"
        )
        
        mock_db = AsyncMock()
        
        # Load episodes
        await background_loader._load_episodes(task, mock_db)
        
        # Verify progress was marked as failed
        assert task.progress["episodes"] is False

    @pytest.mark.asyncio
    async def test_load_episodes_handles_empty_directory(
        self, background_loader, tmp_path
    ):
        """Test that loading episodes handles directory with no episodes."""
        # Create empty series directory
        series_dir = tmp_path / "Empty Series"
        series_dir.mkdir()
        
        task = SeriesLoadingTask(
            key="empty-series",
            folder="Empty Series",
            name="Empty Series"
        )
        
        mock_db = AsyncMock()
        
        # Load episodes
        await background_loader._load_episodes(task, mock_db)
        
        # Verify progress was marked as failed
        assert task.progress["episodes"] is False

    @pytest.mark.asyncio
    async def test_load_episodes_updates_database_correctly(
        self, background_loader, tmp_path
    ):
        """Test that loading episodes updates database with correct information."""
        # Create series structure
        series_dir = tmp_path / "Test Series"
        season_dir = series_dir / "Season 1"
        season_dir.mkdir(parents=True)
        (season_dir / "episode1.mp4").touch()
        (season_dir / "episode2.mp4").touch()
        
        task = SeriesLoadingTask(
            key="test-series",
            folder="Test Series",
            name="Test Series"
        )
        
        # Mock database
        mock_db = AsyncMock()
        mock_series_db = Mock()
        mock_series_db.episodes_loaded = False
        mock_series_db.loading_status = None
        
        with patch('src.server.database.service.AnimeSeriesService.get_by_key') as mock_get:
            mock_get.return_value = mock_series_db
            
            # Load episodes
            await background_loader._load_episodes(task, mock_db)
            
            # Verify database fields were updated
            assert mock_series_db.episodes_loaded is True
            assert mock_series_db.loading_status == "loading_episodes"
            mock_db.commit.assert_called_once()


class TestIntegrationNoFullRescan:
    """Integration tests verifying no full rescans occur."""

    @pytest.mark.asyncio
    async def test_full_loading_workflow_no_rescan(
        self, background_loader, mock_anime_service, tmp_path
    ):
        """Test complete loading workflow doesn't trigger rescan."""
        # Create series structure
        series_dir = tmp_path / "Complete Series"
        season_dir = series_dir / "Season 1"
        season_dir.mkdir(parents=True)
        (season_dir / "episode1.mp4").touch()
        (season_dir / "episode2.mp4").touch()
        
        task = SeriesLoadingTask(
            key="complete-series",
            folder="Complete Series",
            name="Complete Series"
        )
        
        # Mock database
        mock_db = AsyncMock()
        mock_series_db = Mock()
        mock_series_db.episodes_loaded = False
        mock_series_db.has_nfo = False
        mock_series_db.logo_loaded = False
        mock_series_db.images_loaded = False
        
        with patch('src.server.database.service.AnimeSeriesService.get_by_key') as mock_get:
            with patch('src.server.database.connection.get_db_session') as mock_get_db:
                mock_get.return_value = mock_series_db
                mock_get_db.return_value.__aenter__.return_value = mock_db
                
                # Check missing data and load
                missing = await background_loader.check_missing_data(
                    task.key,
                    task.folder,
                    str(tmp_path),
                    mock_db
                )
                
                if missing["episodes"]:
                    await background_loader._load_episodes(task, mock_db)
                
                # Verify NO full rescan was triggered
                mock_anime_service.rescan.assert_not_called()
                
                # Verify task completed successfully
                assert task.progress["episodes"] is True

    @pytest.mark.asyncio
    async def test_multiple_series_no_cross_contamination(
        self, background_loader, tmp_path
    ):
        """Test loading multiple series doesn't cause cross-contamination."""
        # Create multiple series
        for series_name in ["Series A", "Series B", "Series C"]:
            series_dir = tmp_path / series_name
            season_dir = series_dir / "Season 1"
            season_dir.mkdir(parents=True)
            (season_dir / "episode1.mp4").touch()
        
        tasks = [
            SeriesLoadingTask(key=f"series-{i}", folder=f"Series {chr(65+i)}", name=f"Series {chr(65+i)}")
            for i in range(3)
        ]
        
        mock_db = AsyncMock()
        
        # Load all series
        for task in tasks:
            series_dir = await background_loader._find_series_directory(task)
            assert series_dir is not None
            
            episodes = await background_loader._scan_series_episodes(series_dir, task)
            assert len(episodes) == 1
            assert "Season 1" in episodes


class TestPerformanceComparison:
    """Tests to demonstrate performance improvement."""

    @pytest.mark.asyncio
    async def test_scan_single_series_is_fast(self, background_loader, tmp_path):
        """Test that scanning a single series is fast."""
        import time

        # Create series structure
        series_dir = tmp_path / "Performance Test"
        for season_num in range(1, 6):
            season_dir = series_dir / f"Season {season_num}"
            season_dir.mkdir(parents=True)
            
            for episode_num in range(1, 26):
                (season_dir / f"episode{episode_num}.mp4").touch()
        
        task = SeriesLoadingTask(
            key="performance-test",
            folder="Performance Test",
            name="Performance Test"
        )
        
        # Measure time
        start_time = time.time()
        episodes = await background_loader._scan_series_episodes(series_dir, task)
        elapsed_time = time.time() - start_time
        
        # Verify it's fast (should be under 1 second even for 125 episodes)
        assert elapsed_time < 1.0
        assert len(episodes) == 5
        assert all(len(eps) == 25 for eps in episodes.values())