session.py

from __future__ import annotations
import random
from typing import List, Optional
from models import Card


class CardSession:
    
    def __init__(self, cards: List[Card], starting_side: str = 'front'):
        if not cards:
            raise ValueError("Cannot create session with empty card list")
        
        self.cards = cards[:]
        self.order: List[int] = list(range(len(self.cards)))
        random.shuffle(self.order)
        self.idx = 0
        self.side = starting_side
        self.starting_side = starting_side
    
    def current(self) -> Optional[Card]:
        if 0 <= self.idx < len(self.order):
            return self.cards[self.order[self.idx]]
        return None
    
    def flip(self) -> None:
        self.side = 'back' if self.side == 'front' else 'front'
    
    def next(self) -> bool:
        if self.idx < len(self.order) - 1:
            self.idx += 1
            self.side = self.starting_side
            return True
        return False
    
    def prev(self) -> bool:
        if self.idx > 0:
            self.idx -= 1
            self.side = self.starting_side
            return True
        return False
    
    def progress_text(self) -> str:
        if not self.order:
            return '0 / 0'
        return f'{self.idx + 1} / {len(self.order)}'
    
    def is_at_start(self) -> bool:
        return self.idx == 0
    
    def is_at_end(self) -> bool:
        return self.idx >= len(self.order) - 1