"""Unit tests for the download queue service.

Tests cover queue management, priority handling, persistence,
concurrent downloads, and error scenarios.
"""
from __future__ import annotations

import asyncio
import json
from datetime import datetime, timezone
from pathlib import Path
from unittest.mock import AsyncMock, MagicMock

import pytest

from src.server.models.download import (
    DownloadItem,
    DownloadPriority,
    DownloadStatus,
    EpisodeIdentifier,
)
from src.server.services.anime_service import AnimeService
from src.server.services.download_service import DownloadService, DownloadServiceError


@pytest.fixture
def mock_anime_service():
    """Create a mock AnimeService."""
    service = MagicMock(spec=AnimeService)
    service.download = AsyncMock(return_value=True)
    return service


@pytest.fixture
def temp_persistence_path(tmp_path):
    """Create a temporary persistence path."""
    return str(tmp_path / "test_queue.json")


@pytest.fixture
def download_service(mock_anime_service, temp_persistence_path):
    """Create a DownloadService instance for testing."""
    return DownloadService(
        anime_service=mock_anime_service,
        max_concurrent_downloads=2,
        max_retries=3,
        persistence_path=temp_persistence_path,
    )


class TestDownloadServiceInitialization:
    """Test download service initialization."""

    def test_initialization_creates_queues(
        self, mock_anime_service, temp_persistence_path
    ):
        """Test that initialization creates empty queues."""
        service = DownloadService(
            anime_service=mock_anime_service,
            persistence_path=temp_persistence_path,
        )

        assert len(service._pending_queue) == 0
        assert len(service._active_downloads) == 0
        assert len(service._completed_items) == 0
        assert len(service._failed_items) == 0
        assert service._is_running is False
        assert service._is_paused is False

    def test_initialization_loads_persisted_queue(
        self, mock_anime_service, temp_persistence_path
    ):
        """Test that initialization loads persisted queue state."""
        # Create a persisted queue file
        persistence_file = Path(temp_persistence_path)
        persistence_file.parent.mkdir(parents=True, exist_ok=True)

        test_data = {
            "pending": [
                {
                    "id": "test-id-1",
                    "serie_id": "series-1",
                    "serie_name": "Test Series",
                    "episode": {"season": 1, "episode": 1, "title": None},
                    "status": "pending",
                    "priority": "normal",
                    "added_at": datetime.now(timezone.utc).isoformat(),
                    "started_at": None,
                    "completed_at": None,
                    "progress": None,
                    "error": None,
                    "retry_count": 0,
                    "source_url": None,
                }
            ],
            "active": [],
            "failed": [],
            "timestamp": datetime.now(timezone.utc).isoformat(),
        }

        with open(persistence_file, "w", encoding="utf-8") as f:
            json.dump(test_data, f)

        service = DownloadService(
            anime_service=mock_anime_service,
            persistence_path=temp_persistence_path,
        )

        assert len(service._pending_queue) == 1
        assert service._pending_queue[0].id == "test-id-1"


class TestQueueManagement:
    """Test queue management operations."""

    @pytest.mark.asyncio
    async def test_add_to_queue_single_episode(self, download_service):
        """Test adding a single episode to queue."""
        episodes = [EpisodeIdentifier(season=1, episode=1)]

        item_ids = await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=episodes,
            priority=DownloadPriority.NORMAL,
        )

        assert len(item_ids) == 1
        assert len(download_service._pending_queue) == 1
        assert download_service._pending_queue[0].serie_id == "series-1"
        assert (
            download_service._pending_queue[0].status
            == DownloadStatus.PENDING
        )

    @pytest.mark.asyncio
    async def test_add_to_queue_multiple_episodes(self, download_service):
        """Test adding multiple episodes to queue."""
        episodes = [
            EpisodeIdentifier(season=1, episode=1),
            EpisodeIdentifier(season=1, episode=2),
            EpisodeIdentifier(season=1, episode=3),
        ]

        item_ids = await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=episodes,
            priority=DownloadPriority.NORMAL,
        )

        assert len(item_ids) == 3
        assert len(download_service._pending_queue) == 3

    @pytest.mark.asyncio
    async def test_add_high_priority_to_front(self, download_service):
        """Test that high priority items are added to front of queue."""
        # Add normal priority item
        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
            priority=DownloadPriority.NORMAL,
        )

        # Add high priority item
        await download_service.add_to_queue(
            serie_id="series-2",
            serie_name="Priority Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
            priority=DownloadPriority.HIGH,
        )

        # High priority should be at front
        assert download_service._pending_queue[0].serie_id == "series-2"
        assert download_service._pending_queue[1].serie_id == "series-1"

    @pytest.mark.asyncio
    async def test_remove_from_pending_queue(self, download_service):
        """Test removing items from pending queue."""
        item_ids = await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )

        removed_ids = await download_service.remove_from_queue(item_ids)

        assert len(removed_ids) == 1
        assert removed_ids[0] == item_ids[0]
        assert len(download_service._pending_queue) == 0

    @pytest.mark.asyncio
    async def test_reorder_queue(self, download_service):
        """Test reordering items in queue."""
        # Add three items
        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Series 1",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )
        await download_service.add_to_queue(
            serie_id="series-2",
            serie_name="Series 2",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )
        await download_service.add_to_queue(
            serie_id="series-3",
            serie_name="Series 3",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )

        # Move last item to position 0
        item_to_move = download_service._pending_queue[2].id
        success = await download_service.reorder_queue(item_to_move, 0)

        assert success is True
        assert download_service._pending_queue[0].id == item_to_move
        assert download_service._pending_queue[0].serie_id == "series-3"


class TestQueueStatus:
    """Test queue status reporting."""

    @pytest.mark.asyncio
    async def test_get_queue_status(self, download_service):
        """Test getting queue status."""
        # Add items to queue
        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[
                EpisodeIdentifier(season=1, episode=1),
                EpisodeIdentifier(season=1, episode=2),
            ],
        )

        status = await download_service.get_queue_status()

        assert status.is_running is False
        assert status.is_paused is False
        assert len(status.pending_queue) == 2
        assert len(status.active_downloads) == 0
        assert len(status.completed_downloads) == 0
        assert len(status.failed_downloads) == 0

    @pytest.mark.asyncio
    async def test_get_queue_stats(self, download_service):
        """Test getting queue statistics."""
        # Add items
        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[
                EpisodeIdentifier(season=1, episode=1),
                EpisodeIdentifier(season=1, episode=2),
            ],
        )

        stats = await download_service.get_queue_stats()

        assert stats.total_items == 2
        assert stats.pending_count == 2
        assert stats.active_count == 0
        assert stats.completed_count == 0
        assert stats.failed_count == 0
        assert stats.total_downloaded_mb == 0.0


class TestQueueControl:
    """Test queue control operations."""

    @pytest.mark.asyncio
    async def test_pause_queue(self, download_service):
        """Test pausing the queue."""
        await download_service.pause_queue()
        assert download_service._is_paused is True

    @pytest.mark.asyncio
    async def test_resume_queue(self, download_service):
        """Test resuming the queue."""
        await download_service.pause_queue()
        await download_service.resume_queue()
        assert download_service._is_paused is False

    @pytest.mark.asyncio
    async def test_clear_completed(self, download_service):
        """Test clearing completed downloads."""
        # Manually add completed item
        completed_item = DownloadItem(
            id="completed-1",
            serie_id="series-1",
            serie_name="Test Series",
            episode=EpisodeIdentifier(season=1, episode=1),
            status=DownloadStatus.COMPLETED,
        )
        download_service._completed_items.append(completed_item)

        count = await download_service.clear_completed()

        assert count == 1
        assert len(download_service._completed_items) == 0


class TestPersistence:
    """Test queue persistence functionality."""

    @pytest.mark.asyncio
    async def test_queue_persistence(self, download_service):
        """Test that queue state is persisted to disk."""
        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )

        # Persistence file should exist
        persistence_path = Path(download_service._persistence_path)
        assert persistence_path.exists()

        # Check file contents
        with open(persistence_path, "r") as f:
            data = json.load(f)

        assert len(data["pending"]) == 1
        assert data["pending"][0]["serie_id"] == "series-1"

    @pytest.mark.asyncio
    async def test_queue_recovery_after_restart(
        self, mock_anime_service, temp_persistence_path
    ):
        """Test that queue is recovered after service restart."""
        # Create and populate first service
        service1 = DownloadService(
            anime_service=mock_anime_service,
            persistence_path=temp_persistence_path,
        )

        await service1.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[
                EpisodeIdentifier(season=1, episode=1),
                EpisodeIdentifier(season=1, episode=2),
            ],
        )

        # Create new service with same persistence path
        service2 = DownloadService(
            anime_service=mock_anime_service,
            persistence_path=temp_persistence_path,
        )

        # Should recover pending items
        assert len(service2._pending_queue) == 2


class TestRetryLogic:
    """Test retry logic for failed downloads."""

    @pytest.mark.asyncio
    async def test_retry_failed_items(self, download_service):
        """Test retrying failed downloads."""
        # Manually add failed item
        failed_item = DownloadItem(
            id="failed-1",
            serie_id="series-1",
            serie_name="Test Series",
            episode=EpisodeIdentifier(season=1, episode=1),
            status=DownloadStatus.FAILED,
            retry_count=0,
            error="Test error",
        )
        download_service._failed_items.append(failed_item)

        retried_ids = await download_service.retry_failed()

        assert len(retried_ids) == 1
        assert len(download_service._failed_items) == 0
        assert len(download_service._pending_queue) == 1
        assert download_service._pending_queue[0].retry_count == 1

    @pytest.mark.asyncio
    async def test_max_retries_not_exceeded(self, download_service):
        """Test that items with max retries are not retried."""
        # Create item with max retries
        failed_item = DownloadItem(
            id="failed-1",
            serie_id="series-1",
            serie_name="Test Series",
            episode=EpisodeIdentifier(season=1, episode=1),
            status=DownloadStatus.FAILED,
            retry_count=3,  # Max retries
            error="Test error",
        )
        download_service._failed_items.append(failed_item)

        retried_ids = await download_service.retry_failed()

        assert len(retried_ids) == 0
        assert len(download_service._failed_items) == 1
        assert len(download_service._pending_queue) == 0


class TestBroadcastCallbacks:
    """Test WebSocket broadcast functionality."""

    @pytest.mark.asyncio
    async def test_set_broadcast_callback(self, download_service):
        """Test setting broadcast callback."""
        mock_callback = AsyncMock()
        download_service.set_broadcast_callback(mock_callback)

        assert download_service._broadcast_callback == mock_callback

    @pytest.mark.asyncio
    async def test_broadcast_on_queue_update(self, download_service):
        """Test that broadcasts are sent on queue updates."""
        mock_callback = AsyncMock()
        download_service.set_broadcast_callback(mock_callback)

        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )

        # Allow async callback to execute
        await asyncio.sleep(0.1)

        # Verify callback was called
        mock_callback.assert_called()


class TestServiceLifecycle:
    """Test service start and stop operations."""

    @pytest.mark.asyncio
    async def test_start_service(self, download_service):
        """Test starting the service."""
        await download_service.start()
        assert download_service._is_running is True

    @pytest.mark.asyncio
    async def test_stop_service(self, download_service):
        """Test stopping the service."""
        await download_service.start()
        await download_service.stop()
        assert download_service._is_running is False

    @pytest.mark.asyncio
    async def test_start_already_running(self, download_service):
        """Test starting service when already running."""
        await download_service.start()
        await download_service.start()  # Should not raise error
        assert download_service._is_running is True


class TestErrorHandling:
    """Test error handling in download service."""

    @pytest.mark.asyncio
    async def test_reorder_nonexistent_item(self, download_service):
        """Test reordering non-existent item raises error."""
        with pytest.raises(DownloadServiceError):
            await download_service.reorder_queue("nonexistent-id", 0)

    @pytest.mark.asyncio
    async def test_download_failure_moves_to_failed(self, download_service):
        """Test that download failures are handled correctly."""
        # Mock download to fail
        download_service._anime_service.download = AsyncMock(
            side_effect=Exception("Download failed")
        )

        await download_service.add_to_queue(
            serie_id="series-1",
            serie_name="Test Series",
            episodes=[EpisodeIdentifier(season=1, episode=1)],
        )

        # Process the download
        item = download_service._pending_queue.popleft()
        await download_service._process_download(item)

        # Item should be in failed queue
        assert len(download_service._failed_items) == 1
        assert (
            download_service._failed_items[0].status == DownloadStatus.FAILED
        )
        assert download_service._failed_items[0].error is not None