youtube-summarizer/backend/services/video_downloaders/base_downloader.py

"""
Base interface for video downloaders
"""
import asyncio
import logging
from abc import ABC, abstractmethod
from typing import Optional, Dict, Any
from pathlib import Path

from backend.models.video_download import (
    VideoDownloadResult, 
    DownloadPreferences,
    DownloadMethod,
    DownloadStatus,
    VideoMetadata,
    TranscriptData,
    DownloaderException
)


logger = logging.getLogger(__name__)


class BaseVideoDownloader(ABC):
    """Base class for all video downloaders"""
    
    def __init__(self, method: DownloadMethod, config: Optional[Dict[str, Any]] = None):
        self.method = method
        self.config = config or {}
        self.logger = logging.getLogger(f"{self.__class__.__name__}")
    
    @abstractmethod
    async def download_video(self, url: str, preferences: DownloadPreferences) -> VideoDownloadResult:
        """
        Download video with given preferences
        
        Args:
            url: YouTube video URL
            preferences: Download preferences
            
        Returns:
            VideoDownloadResult with download status and file paths
            
        Raises:
            DownloaderException: If download fails
        """
        pass
    
    @abstractmethod
    async def test_connection(self) -> bool:
        """
        Test if this downloader is working
        
        Returns:
            True if downloader is functional, False otherwise
        """
        pass
    
    async def extract_video_id(self, url: str) -> str:
        """Extract YouTube video ID from URL"""
        import re
        
        patterns = [
            r'(?:youtube\.com/watch\?v=|youtu\.be/)([a-zA-Z0-9_-]{11})',
            r'youtube\.com/embed/([a-zA-Z0-9_-]{11})',
            r'youtube\.com/v/([a-zA-Z0-9_-]{11})'
        ]
        
        for pattern in patterns:
            match = re.search(pattern, url)
            if match:
                return match.group(1)
        
        raise DownloaderException(f"Could not extract video ID from URL: {url}")
    
    def create_result(self, 
                     video_id: str, 
                     video_url: str, 
                     status: DownloadStatus = DownloadStatus.FAILED,
                     error_message: Optional[str] = None) -> VideoDownloadResult:
        """Create a basic download result"""
        return VideoDownloadResult(
            video_id=video_id,
            video_url=video_url,
            status=status,
            method=self.method,
            error_message=error_message
        )
    
    async def get_video_metadata(self, video_id: str) -> Optional[VideoMetadata]:
        """Get video metadata if supported by this downloader"""
        return None
    
    async def get_transcript(self, video_id: str) -> Optional[TranscriptData]:
        """Get video transcript if supported by this downloader"""
        return None
    
    def supports_audio_only(self) -> bool:
        """Check if this downloader supports audio-only downloads"""
        return False
    
    def supports_quality_selection(self) -> bool:
        """Check if this downloader supports quality selection"""
        return False
    
    def get_supported_formats(self) -> list[str]:
        """Get list of supported output formats"""
        return ["mp4"]
    
    async def cleanup_temp_files(self, temp_dir: Path):
        """Clean up temporary files"""
        if temp_dir.exists():
            import shutil
            try:
                shutil.rmtree(temp_dir)
                self.logger.debug(f"Cleaned up temp directory: {temp_dir}")
            except Exception as e:
                self.logger.warning(f"Failed to clean up temp directory {temp_dir}: {e}")


class DownloaderFactory:
    """Factory for creating video downloaders"""
    
    _downloaders = {}
    
    @classmethod
    def register(cls, method: DownloadMethod, downloader_class):
        """Register a downloader class"""
        cls._downloaders[method] = downloader_class
    
    @classmethod
    def create(cls, method: DownloadMethod, config: Optional[Dict[str, Any]] = None) -> BaseVideoDownloader:
        """Create a downloader instance"""
        if method not in cls._downloaders:
            raise ValueError(f"Unsupported download method: {method}")
        
        downloader_class = cls._downloaders[method]
        return downloader_class(method, config)
    
    @classmethod
    def get_available_methods(cls) -> list[DownloadMethod]:
        """Get list of available download methods"""
        return list(cls._downloaders.keys())


class DownloadTimeout:
    """Timeout context manager for download operations"""
    
    def __init__(self, timeout_seconds: int):
        self.timeout_seconds = timeout_seconds
        self.task = None
    
    async def __aenter__(self):
        return self
    
    async def __aexit__(self, exc_type, exc_val, exc_tb):
        if self.task and not self.task.done():
            self.task.cancel()
            try:
                await self.task
            except asyncio.CancelledError:
                pass
    
    async def run(self, coro):
        """Run coroutine with timeout"""
        try:
            self.task = asyncio.create_task(coro)
            return await asyncio.wait_for(self.task, timeout=self.timeout_seconds)
        except asyncio.TimeoutError:
            raise DownloaderException(f"Operation timed out after {self.timeout_seconds} seconds")