"""Module for bank website scraping interfaces and base classes."""

from selenium.webdriver.remote.webdriver import WebDriver


class BankWebAuthenticator(object):

    def login(self, driver, credentials):
        """Logs a user in using the given credentials.

        :return: Whether the login was successful
        """
        raise NotImplementedError("Must extend BankWebAuthenticator")


class BankScraper(object):
    """Generic interface for a Web scraper that pulls information from
    bank websites."""

    def __init__(self, driver, authenticator):
        """Initializes the BankScraper

        :param driver: A Selenium web driver
        :param authenticator: A BankWebAuthenticator
        """
        assert isinstance(authenticator, BankWebAuthenticator)
        self.driver = driver
        self.authenticator = authenticator

    def get_data(self, credentials, refresh=False):
        """Returns some data structure with the information parsed.
        Locally caches if possible.

        :param credentials: Credentials for the authenticator
            two-tuple of (username ,password)
        :param refresh: Forces the scraper to ignore local cache

        :return: The data retrieved
        """
        if self.authenticator.login(self.driver, credentials):
            accounts = self.get_accounts()
            return {
                'accounts': self.get_transactions(accounts)
            }
        else:
            # should maybe raise an exception here instead of silently
            # failing
            return []

    def get_accounts(self):
        """Retrieves account information such as bank balance

        :return: List of dicts that contain the keys 'name' and
            'balance'.
        """
        raise NotImplementedError("Must extend BankScraper")

    def get_transactions(self, accounts):
        """Gets the transactions associated with each account.

        :param accounts: List of dicts with the key 'name'

        :return: List of the same dicts but with a new key:
            'transactions', which is itself a list of dicts
        """
        return [
            self.get_transactions_for_account(account)
            for account in accounts
        ]

    def get_transactions_for_account(self, account):
        """Gets the transactions for one account.

        :param: dict with key 'name'

        :return: dict with keys 'name' and 'transactions', whose value
            is a list of the transactions for this account
        """
        raise NotImplementedError("Must extend BankScraper")