from decimal import Decimal

class Trade:
    """
    Represents a cryptocurrency trade, including the amount traded, total cost, and the date of trade.
    Provides methods to modify the trade and access various attributes.
    """
    def __init__(self, amount: float|Decimal, total_cost: float|Decimal, date: str) -> None:
        """
        Initialize a new Trade instance.

        Args:
            amount (Decimal): The amount of cryptocurrency traded.
            total_cost (Decimal): The total cost of the trade.
            date (str): The date of the trade, formatted as a string.
        """

        if amount <= 0 or total_cost <= 0:
            raise ValueError("Amount and total cost must be > 0")

        self.__amount: Decimal = Decimal(amount)
        self.__total_cost: Decimal = Decimal(total_cost)
        self.__date: str = date

    def remove_coins(self, amount: float|Decimal) -> None:
        """
        Reduce the amount of cryptocurrency in the trade by a specified amount.

        This effectively "loses" coins. The price-per-coin remains the same.

        Args:
            amount (Decimal): The amount of cryptocurrency to remove.

        Raises:
            ValueError: If the amount to remove exceeds the current amount in the trade.
        """
        if amount > self.__amount:
            raise ValueError(f"Can't remove more than {self.__amount}")
        
        amount = Decimal(amount)
        self.__total_cost -= amount * self.price_per_coin
        self.__amount -= amount

    @property
    def amount(self) -> Decimal:
        """
        Get the current amount of cryptocurrency in the trade.

        Returns:
            Decimal: The amount of cryptocurrency.
        """
        return self.__amount

    @property
    def total_cost(self) -> Decimal:
        """
        Get the total cost of the trade.

        Returns:
            Decimal: The total cost of the trade.
        """
        return self.__total_cost

    @property
    def date(self) -> str:
        """
        Get the date of the trade.

        Returns:
            str: The trade date as a string.
        """
        return self.__date

    @property
    def price_per_coin(self) -> Decimal:
        """
        Calculate the price per coin based on the total cost and current amount.

        Returns:
            Decimal: The price per coin.

        Raises:
            ZeroDivisionError: If the current amount is zero.
        """
        if self.amount == 0:
            raise ZeroDivisionError("Price per coin cannot be calculated when the amount is zero")

        return self.total_cost / self.amount

    def __repr__(self) -> str:
        """
        Get a string representation of the Trade instance.

        Returns:
            str: A formatted string displaying the trade details.
        """
        return f"Trade(amount={self.amount:.2f}, price_per_coin={self.price_per_coin:.2f}, total_cost={self.total_cost:.2f}, date={self.date})"