from datetime import datetime


class Transaction:
    def __init__(self, id, user_id, item_id, amount, timestamp=None) -> None:
        self.id = id
        self.user_id = user_id
        self.item_id = item_id
        self.amount = float(amount)
        self.timestamp = timestamp or datetime.now().isoformat()

    def to_json(self):
        return {
            "id": self.id,
            "user_id": self.user_id,
            "item_id": self.item_id,
            "amount": self.amount,
            "timestamp": self.timestamp,
        }

    @staticmethod
    def from_json(data):
        return Transaction(
            data["id"],
            data["user_id"],
            data["item_id"],
            data["amount"],
            data["timestamp"],
        )