def validate_input(query):
    """Validate and clean user input"""
    if not query or not query.strip():
        raise ValueError("Input cannot be empty")
    
    # Remove extra whitespace
    cleaned = query.strip()
    
    # Limit length to prevent abuse
    if len(cleaned) > 1000:
        raise ValueError("Input too long. Please limit to 1000 characters.")
    
    return cleaned