"""
Exercise 7.3 from "A primer on...
The main point of the exercise is to illustrate 
how encapsulation works in class programming. If
attributes are always accessed through methods
(getters/setters) we can change the internal 
data structure without any consequences for users
of the class. 
(A secondary point is to introduce the
useful datetime module.)
"""

from datetime import datetime

class AccountP:
    def __init__(self, name, account_number, initial_amount):
        self._name = name
        self._no = account_number
        self._transactions = [{'time':datetime.now(),'amount':initial_amount}]

    def deposit(self, amount):
        trans = {'time':datetime.now(),'amount':amount}
        self._transactions.append(trans)

    def withdraw(self, amount):
        trans = {'time':datetime.now(),'amount': -amount}
        self._transactions.append(trans)

    def get_balance(self):
        balance = sum([t['amount'] for t in self._transactions]) 
        return balance

    def dump(self):
        s = f'{self._name}, {self._no}, balance: {self._balance}'
        print(s)

    def print_transactions(self):
        for t in self._transactions:
            time = t['time'].strftime('%a %d %b %Y, %H:%M:%S')
            amount = t['amount']
            print(f'{time}: {amount}')

#example usage:
a1 = AccountP('John Olsson', 19371554951, 20000)
a1.withdraw(4000)

#print(a1._balance) # it works, but a convention is broken
print(a1.get_balance()) # correct way of viewing the balance

a1.print_transactions()