from pydantic import BaseModel, ConfigDict
from typing import List, Optional
from decimal import Decimal

class UserCostShare(BaseModel):
    user_id: int
    user_identifier: str # Name or email
    items_added_value: Decimal = Decimal("0.00") # Total value of items this user added
    amount_due: Decimal # The user's share of the total cost (for equal split, this is total_cost / num_users)
    balance: Decimal # items_added_value - amount_due

    model_config = ConfigDict(from_attributes=True)

class ListCostSummary(BaseModel):
    list_id: int
    list_name: str
    total_list_cost: Decimal
    num_participating_users: int
    equal_share_per_user: Decimal
    user_balances: List[UserCostShare]

    model_config = ConfigDict(from_attributes=True)