"""File manager with automatic cleanup for uploaded files"""

import os
import time
import threading
from pathlib import Path
from typing import Dict, List
import logging

logger = logging.getLogger(__name__)


class FileManager:
    """Manages uploaded files with automatic cleanup and tracking"""
    
    def __init__(self, upload_folder: str, max_age_seconds: int = 86400):
        """
        Initialize FileManager
        
        Args:
            upload_folder: Path to folder where files are uploaded
            max_age_seconds: Maximum age of files before cleanup (default: 24 hours)
        """
        self.upload_folder = upload_folder
        self.max_age = max_age_seconds
        self.session_files: Dict[str, List[dict]] = {}
        self.lock = threading.Lock()
        
        # Create upload folder if it doesn't exist
        os.makedirs(upload_folder, exist_ok=True)
        
        # Start cleanup thread
        self.cleanup_thread = threading.Thread(
            target=self._cleanup_loop,
            daemon=True
        )
        self.cleanup_thread.start()
        logger.info(f"FileManager initialized for {upload_folder}")
    
    def register_file(self, session_id: str, filepath: str):
        """
        Track a file for a specific session
        
        Args:
            session_id: Session that owns the file
            filepath: Full path to the file
        """
        with self.lock:
            if session_id not in self.session_files:
                self.session_files[session_id] = []
            
            self.session_files[session_id].append({
                'path': filepath,
                'created_at': time.time(),
                'size_bytes': os.path.getsize(filepath) if os.path.exists(filepath) else 0
            })
            logger.debug(f"File registered: {filepath} for session {session_id}")
    
    def cleanup_session_files(self, session_id: str) -> int:
        """
        Delete all files associated with a session
        
        Args:
            session_id: Session whose files to delete
            
        Returns:
            Number of files successfully deleted
        """
        deleted_count = 0
        total_bytes = 0
        
        with self.lock:
            if session_id not in self.session_files:
                return 0
            
            files = self.session_files[session_id]
            for file_data in files:
                try:
                    if os.path.exists(file_data['path']):
                        total_bytes += file_data['size_bytes']
                        os.remove(file_data['path'])
                        deleted_count += 1
                        logger.info(f"Deleted: {file_data['path']}")
                except Exception as e:
                    logger.error(f"Failed to delete {file_data['path']}: {e}")
            
            del self.session_files[session_id]
        
        if deleted_count > 0:
            logger.info(f"Cleaned {deleted_count} files ({total_bytes/1024/1024:.2f} MB) for session {session_id}")
        
        return deleted_count
    
    def cleanup_old_files(self) -> dict:
        """
        Remove files older than max_age
        
        Returns:
            Dictionary with cleanup statistics
        """
        deleted_count = 0
        deleted_bytes = 0
        current_time = time.time()
        
        try:
            if not os.path.exists(self.upload_folder):
                return {'deleted': 0, 'freed_bytes': 0}
            
            for filename in os.listdir(self.upload_folder):
                filepath = os.path.join(self.upload_folder, filename)
                
                if os.path.isfile(filepath):
                    try:
                        file_age = current_time - os.path.getmtime(filepath)
                        
                        if file_age > self.max_age:
                            file_size = os.path.getsize(filepath)
                            os.remove(filepath)
                            deleted_count += 1
                            deleted_bytes += file_size
                            logger.info(f"Deleted old file: {filepath}")
                    except Exception as e:
                        logger.error(f"Error processing {filepath}: {e}")
        
        except Exception as e:
            logger.error(f"Cleanup old files error: {e}")
        
        if deleted_count > 0:
            logger.info(f"Cleanup: Deleted {deleted_count} old files, freed {deleted_bytes/1024/1024:.2f} MB")
        
        return {
            'deleted': deleted_count,
            'freed_bytes': deleted_bytes
        }
    
    def _cleanup_loop(self):
        """Background cleanup thread that runs periodically"""
        while True:
            try:
                time.sleep(600)  # Check every 10 minutes
                self.cleanup_old_files()
            except Exception as e:
                logger.error(f"File cleanup loop error: {e}")
    
    def get_disk_usage(self) -> dict:
        """
        Get upload folder disk usage statistics
        
        Returns:
            Dictionary with file count and size information
        """
        total_size = 0
        file_count = 0
        files_by_age = {'recent': 0, 'day': 0, 'week': 0, 'old': 0}
        current_time = time.time()
        
        try:
            for filename in os.listdir(self.upload_folder):
                filepath = os.path.join(self.upload_folder, filename)
                if os.path.isfile(filepath):
                    file_size = os.path.getsize(filepath)
                    total_size += file_size
                    file_count += 1
                    
                    # Categorize by age
                    file_age = current_time - os.path.getmtime(filepath)
                    if file_age < 3600:  # 1 hour
                        files_by_age['recent'] += 1
                    elif file_age < 86400:  # 1 day
                        files_by_age['day'] += 1
                    elif file_age < 604800:  # 1 week
                        files_by_age['week'] += 1
                    else:
                        files_by_age['old'] += 1
        
        except Exception as e:
            logger.error(f"Error calculating disk usage: {e}")
        
        return {
            'file_count': file_count,
            'total_bytes': total_size,
            'total_mb': total_size / (1024 * 1024),
            'total_gb': total_size / (1024 * 1024 * 1024),
            'files_by_age': files_by_age,
            'max_age_seconds': self.max_age,
        }
    
    def get_session_files(self, session_id: str) -> list:
        """Get files associated with a session"""
        with self.lock:
            return self.session_files.get(session_id, [])
    
    def get_file_statistics(self) -> dict:
        """Get statistics about tracked files"""
        total_tracked = 0
        total_tracked_bytes = 0
        tracked_by_session = {}
        
        with self.lock:
            for session_id, files in self.session_files.items():
                total_tracked += len(files)
                session_bytes = sum(f['size_bytes'] for f in files)
                total_tracked_bytes += session_bytes
                tracked_by_session[session_id] = {
                    'file_count': len(files),
                    'total_bytes': session_bytes,
                    'total_mb': session_bytes / (1024 * 1024)
                }
        
        return {
            'total_tracked_files': total_tracked,
            'total_tracked_bytes': total_tracked_bytes,
            'total_tracked_mb': total_tracked_bytes / (1024 * 1024),
            'by_session': tracked_by_session
        }