"""MOC Number Generation Service for LEGO Instructions Manager"""

from app.models.set import Set
from app import db


class MOCNumberGenerator:
    """Service for auto-generating MOC (My Own Creation) set numbers"""
    
    DEFAULT_PREFIX = 'MOC'
    DEFAULT_START = 10000
    
    @staticmethod
    def generate_next_number(prefix=None, user_id=None):
        """
        Generate the next available MOC number
        
        Args:
            prefix: MOC prefix (default: 'MOC')
            user_id: Optional user ID to scope MOC numbers per user
            
        Returns:
            str: Next MOC number (e.g., 'MOC-10001')
        """
        if prefix is None:
            prefix = MOCNumberGenerator.DEFAULT_PREFIX
            
        # Build query for highest MOC number
        query = Set.query.filter(
            Set.is_moc == True,
            Set.set_number.like(f'{prefix}%')
        )
        
        # Optionally scope to user
        if user_id:
            query = query.filter_by(user_id=user_id)
            
        # Get highest MOC number
        highest_moc = query.order_by(Set.set_number.desc()).first()
        
        if highest_moc:
            try:
                # Extract number from format like "MOC-12345" or "MOC12345"
                number_part = highest_moc.set_number.replace(prefix, '').replace('-', '').strip()
                current_num = int(number_part)
                next_num = current_num + 1
            except (ValueError, AttributeError):
                # If parsing fails, start from default
                next_num = MOCNumberGenerator.DEFAULT_START
        else:
            next_num = MOCNumberGenerator.DEFAULT_START
            
        return f'{prefix}-{next_num}'
    
    @staticmethod
    def validate_moc_number(set_number, user_id=None):
        """
        Check if a MOC number is available
        
        Args:
            set_number: MOC number to validate
            user_id: Optional user ID to check user-specific availability
            
        Returns:
            bool: True if available, False if already in use
        """
        query = Set.query.filter_by(set_number=set_number)
        
        if user_id:
            query = query.filter_by(user_id=user_id)
            
        existing = query.first()
        return existing is None
    
    @staticmethod
    def is_moc_number(set_number, prefix=None):
        """
        Check if a set number follows MOC format
        
        Args:
            set_number: Set number to check
            prefix: MOC prefix to match (default: 'MOC')
            
        Returns:
            bool: True if it's a MOC number
        """
        if prefix is None:
            prefix = MOCNumberGenerator.DEFAULT_PREFIX
            
        return set_number.upper().startswith(prefix)