"""
File validation utilities
"""
from werkzeug.utils import secure_filename
from pathlib import Path
from typing import Optional, List, Tuple

def is_allowed_file(filename: str, allowed_extensions: List[str]) -> bool:
    """
    Check if file extension is allowed
    
    Args:
        filename: File name
        allowed_extensions: List of allowed extensions
        
    Returns:
        True if extension is allowed, False otherwise
    """
    if '.' not in filename:
        return False
    ext = filename.rsplit('.', 1)[1].lower()
    return ext in allowed_extensions

def validate_file_size(file_size: int, max_size: int) -> Tuple[bool, Optional[str]]:
    """
    Validate file size
    
    Args:
        file_size: File size in bytes
        max_size: Maximum allowed size in bytes
        
    Returns:
        Tuple of (is_valid, error_message)
    """
    if file_size > max_size:
        max_size_mb = max_size / (1024 * 1024)
        return False, f"File size exceeds maximum allowed size of {max_size_mb:.1f}MB"
    return True, None

def secure_file_path(filename: str, upload_folder: Path) -> Path:
    """
    Generate secure file path
    
    Args:
        filename: Original filename
        upload_folder: Upload folder path
        
    Returns:
        Secure file path
    """
    secure_name = secure_filename(filename)
    return upload_folder / secure_name