PiggyBank/piggybank/transaction.py

"""Transaction class implementation."""

from __future__ import annotations
from time import strftime, strptime, gmtime
from typing import Optional, List

__all__ = ["Transaction", "TYPE_INCOME", "TYPE_OUTCOME", "TIME_FORMAT"]

TYPE_INCOME = "in"
TYPE_OUTCOME = "out"
TIME_FORMAT = "%Y-%m-%dT%H:%M:%S"


class Transaction:
    """An object that holds a transaction.
    
    Arguments:
        - coins -- a list of numbers represent count for each face value;
        - direction -- is this income or outcome. Takes TYPE_INCOME
                       or TYPE_OUTCOME;
        - timestamp -- date and time formated accordingly to TIME_FORMAT."""
    def __init__(self, coins: List[int], direction: str = TYPE_INCOME,
                 timestamp: Optional[str] = None) -> None:
        self.coins = coins
        if direction in [TYPE_INCOME, TYPE_OUTCOME]:
            self.direction = direction
        else:
            raise ValueError(f"Direction may only be"
                             f"'{TYPE_INCOME}' or '{TYPE_OUTCOME}'")
        if timestamp is None:
            self.timestamp = strftime(TIME_FORMAT, gmtime())
        else:
            try:
                strptime(timestamp, TIME_FORMAT)
            except ValueError:
                raise ValueError(f"Timestamp {timestamp} has wrong format. "
                                 f"The right one is '{TIME_FORMAT}''")
            self.timestamp = timestamp

    @staticmethod
    def from_string(transaction: str) -> Transaction:
        """Makes a Transaction object from its string output."""
        timestamp, direction, coins = transaction.split()

        coins = list(map(int, coins.split(",")))
        return Transaction(coins, direction, timestamp)

    def __str__(self) -> str:
        return f"{self.timestamp} {self.direction} " \
            f"{','.join(str(c) for c in self.coins)}"

    def __repr__(self) -> str:
        return f"Transaction(coins={self.coins!r}," \
            f"direction={self.direction!r}, timestamp={self.timestamp!r})"