katas/bank

gistfile1.txt

import datetime
from dataclasses import dataclass

# exceptions.py
class NoMoneyException(Exception):
    pass

class InvalidValueException(Exception):
    pass



@dataclass
class TransactionLog:
    created_at: datetime.datetime
    amount: int 

    # 14/01/2012 || -500   || 2500
    def print(self, current_balance):
        return f"{self.created_at} || {self.amount} || {current_balance}\n"


NO_TRANSACTIONS_MSG = "no transactions yet"

class AccountService:

    transactionLog : list[TransactionLog]
    blanace : int # RO: current balance; to speed up validation

    def __init__(self):
        self.transactionLog = []
        self.blanace = 0

    def deposit(self, amount:int):
        if amount <= 0:
            raise InvalidValueException(f"amount must be positive; got: {amount}")

        self._update_balance(amount)

    def withdraw(self, amount:int):
        if amount <= 0:
            raise InvalidValueException(f"amount must be positive; got: {amount}")

        if amount > self.blanace:
            raise NoMoneyException(f"not enough money on the accout; want: {amount} got {self.blanace}")

        self._update_balance(-amount)

    def printStatement(self):
        # TODO: max transactions
        # TODO: print from latest

        if len(self.transactionLog) == 0:
            return NO_TRANSACTIONS_MSG

        self._prepre_for_print()

        log = self.transactionLog # deepcopy
        log.reverse()
        out = "Date || Amount || Balance\n"

        current_balance = self.blanace
        for tl in log:
            out += tl.print(current_balance)
            current_balance += -tl.amount

        return out
        
    def _update_balance(self, amount:int):
        # TODO: wrap for test with static time
        time_now = datetime.datetime.now()

        tl = TransactionLog(
            created_at=time_now,
            amount=amount,
        )

        self.transactionLog.append(tl)
        self.blanace += amount



def test_NoTransactions():
    ac = AccountService()

    got = ac.printStatement()
    want = NO_TRANSACTIONS_MSG

    assert got == want

def test_NoMoneyValidation():
    ac = AccountService()

    ac.deposit(100)

    # assert NoMoneyException:
    #     ac.withdraw(300)

def test_SingleTransaction():
    ac = AccountService()

    ac.deposit(100)

    want = """
Date || Amount || Balance
14/01/2012 || 100 || 100
    """
    got = ac.printStatement()

    assert got == want

def test_ProvidedInput():
    ac = AccountService()

    ac.deposit(1000)
    ac.deposit(2000)
    ac.withdraw(500)

    want = """
Date || Amount || Balance
14/01/2012 || -500 || 2500
13/01/2012 || 2000 || 3000
10/01/2012 || 1000 || 1000
    """
    got = ac.printStatement()

    assert got == want


# #2: validation: not an int; float, "above limit" (max-int), ...        
# #3: possive scenario: 10x deposits, 10x withdraw, print - expect 0 balance left; expect 20 lines in print...