wallets.py

"A Singleton Dictionary of User Wallets"
from decimal import Decimal
from reports import Reports


class Wallets():
    "A Singleton Dictionary of User Wallets"
    _wallets: dict[str, Decimal] = {}  # Python 3.9
    # _wallets = {}  # Python 3.8 or earlier

    def __new__(cls):
        return cls

    @classmethod
    def create_wallet(cls, user_id: str) -> bool:
        "A method to initialize a users wallet"
        if not user_id in cls._wallets:
            cls._wallets[user_id] = Decimal('0')
            Reports.log_event(
                f"wallet for `{user_id}` created and set to 0")
            return True
        return False

    @classmethod
    def get_balance(cls, user_id: str) -> Decimal:
        "A method to check a users balance"
        Reports.log_event(
            f"Balance check for `{user_id}` = {cls._wallets[user_id]}")
        return cls._wallets[user_id]

    @classmethod
    def adjust_balance(cls, user_id: str, amount: Decimal) -> Decimal:
        "A method to adjust a user balance up or down"
        cls._wallets[user_id] = cls._wallets[user_id] + Decimal(amount)
        Reports.log_event(
            f"Balance adjustment for `{user_id}`. "
            f"New balance = {cls._wallets[user_id]}"
        )
        return cls._wallets[user_id]