domain.py

class Portfolio:
    def __init__(self, balance=1000000):
        self._portfolio = {}
        self._portfolio['**CASH**'] = {'Shares' : balance, 'Price' : 1.0, 'Updates' : 1}

    def update(self, price, ticker):
        if ticker in self._portfolio:
            self._portfolio[ticker]['Price'] = price
            self._portfolio[ticker]['Updates'] = self._portfolio[ticker]['Updates'] + 1
        else:
            self._portfolio[ticker] = {}
            self._portfolio[ticker]['Price'] = price
            self._portfolio[ticker]['Shares'] = 0
            self._portfolio[ticker]['Updates'] = 1

    @property
    def balance(self):
        return self._portfolio['**CASH**']['Shares']

    @balance.setter
    def balance(self, balance):
        self._portfolio['**CASH**']['Shares'] = balance

    def adjust_balance(self, delta):
        self._portfolio['**CASH**']['Shares'] = self.balance + delta

    def __contains__(self, item):
        return (item in self._portfolio)

    def value_summary(self, date):
        sum = self.get_total_value()
        return '%s : Stock value: %s, Cash: %s, Total %s' % (date, sum-self.balance, self.balance, sum)

    def get_total_value(self):
        sum = 0
        for stock in self._portfolio.values():
            sum += stock['Shares'] * stock['Price']
        return sum

    def get_value(self, ticker):
        return self.get_shares(ticker) * self.get_shares(ticker)

    def get_price(self, ticker):
        return self._portfolio[ticker]['Price']

    def get_shares(self, ticker):
        return self._portfolio[ticker]['Shares']

    def get_update_count(self, ticker):
        return self._portfolio[ticker]['Updates']

    def set_shares(self, ticker, shares):
        self._portfolio[ticker]['Shares'] = shares

    def update_shares(self, ticker, share_delta):
        self.set_shares(ticker, self.get_shares(ticker) + share_delta)

    def update_trade(self, ticker, share_delta, price, fee):
        # Assumes negative shares are sells, requires validation from Controller
        self.set_shares(ticker, self.get_shares(ticker) + share_delta)
        self.adjust_balance(-(price*share_delta + fee))

    def __str__(self):
        return self._portfolio.__str__()