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#!/usr/bin/env python3 

 

## Imports 

import datetime 

import os 

import shlex 

import sqlalchemy 

import subprocess 

import re 

 

from contextlib import contextmanager 

from sqlalchemy.orm import * 

from sqlalchemy.schema import * 

from sqlalchemy.types import * 

from sqlalchemy.ext.declarative import declarative_base 

 

from . import banks 

 

## Schema Types 

Session = sessionmaker() 

Base = declarative_base() 

Dollars = Float 

DollarsPerDay = Float 

 

 

seconds_per_day = 86400 

days_per_month = 356 / 12 

days_per_year = 356 

 

class Budget (Base): 

    __tablename__ = 'budgets' 

 

    id = Column(Integer, primary_key=True, autoincrement=True) 

    name = Column(String, nullable=False, unique=True) 

    balance = Column(Dollars, nullable=False) 

    allowance = Column(DollarsPerDay, nullable=False) 

    last_update = Column(DateTime, nullable=False) 

 

    def __init__(self, name, balance=None, allowance=None): 

        self.name = name 

        self.balance = int(balance or 0) 

        self.allowance = parse_allowance(allowance or '') 

        self.last_update = now() 

 

        if name in ('skip', 'ignore'): 

            raise UserError("can't name a budget 'skip' or 'ignore'") 

 

    def __repr__(self):  # pragma: no cover 

        repr = '<budget name={0.name} balance={0.balance}' + \ 

                (' allowance={0.allowance}>' if self.allowance else '>') 

        return repr.format(self) 

 

    @property 

    def pretty_balance(self): 

        return format_dollars(self.balance) 

 

    @property 

    def pretty_allowance(self): 

        return format_dollars(self.allowance * days_per_month) + '/mo' 

 

    @property 

    def recovery_time(self): 

        """ 

        Return the number of days it will take this account to reach a positive  

        balance, assuming no more payments are made.  If the account is already  

        positive, return 0.  If the account will never become positive (i.e. it  

        has no allowance), return -1. 

        """ 

        from math import ceil 

 

        if self.balance >= 0: 

            return 0 

 

        if self.allowance <= 0: 

            return -1 

 

        return int(ceil(abs(self.balance / self.allowance))) 

 

    def update_allowance(self): 

        this_update = now() 

        last_update = self.last_update 

 

        dollars_per_second = self.allowance / seconds_per_day 

        seconds_elapsed = (this_update - last_update).total_seconds() 

 

        self.balance += dollars_per_second * seconds_elapsed 

        self.last_update = this_update 

 

 

def get_budget(session, name): 

    try: 

        return session.query(Budget).filter_by(name=name).one() 

    except sqlalchemy.orm.exc.NoResultFound: 

        raise NoSuchBudget(name) 

 

def get_budgets(session, *names): 

    budgets = session.query(Budget).all() 

    print(budgets, names) 

    if names: budgets = [x for x in budgets if x.name in names] 

    return budgets 

 

def get_num_budgets(session): 

    return session.query(Budget).count() 

 

def budget_exists(session, name): 

    return session.query(Budget).filter_by(name=name).count() > 0 

 

 

class Payment (Base): 

    __tablename__ = 'payments' 

 

    id = Column(Integer, primary_key=True, autoincrement=True) 

    bank_id = Column(Integer, ForeignKey('banks.id')) 

    account_id = Column(String) 

    transaction_id = Column(String) 

    date = Column(Date, nullable=False) 

    value = Column(Dollars, nullable=False) 

    description = Column(Text) 

    assignment = Column(String) 

 

    def __init__(self, acct_id, txn_id, date, value, description): 

        self.account_id = acct_id 

        self.transaction_id = txn_id 

        self.date = date 

        self.value = parse_dollars(value) 

        self.description = description 

 

    def __repr__(self):  # pragma: no cover 

        date = format_date(self.date) 

        value = format_dollars(self.value) 

        assignment = self.assignment or 'unassigned' 

        return '<Payment id={} date={} value={} assignment={}>'.format( 

                self.id, date, value, assignment) 

 

    def __eq__(self, other): 

        self_id = self.account_id, self.transaction_id 

        other_id = other.account_id, other.transaction_id 

        return self_id == other_id 

 

    def assign(self, assignment): 

        """ 

        Specify which budget should cover this payment.  If the payment was  

        already assigned before this call, the old budget will be credited and  

        the new budgets will be debited as appropriate. 

        """ 

 

        session = Session.object_session(self) 

 

        # Warn the user if the new assignment is the same as the old one. 

 

        if assignment == self.assignment: 

            raise AssignmentError("Payment #{} is already assigned to '{}'".format(self.id, assignment)) 

 

        # Make sure the new assignment actually exists. 

 

        try: 

            new_budget = get_budget(session, assignment) 

        except NoSuchBudget: 

            raise NoSuchBudget(assignment) 

 

        # If this payment was already assigned to another budget, make sure  

        # that budget still exists.  If it doesn't, raise an exception because  

        # there's no way to credit the value of this payment.  If it does, then  

        # credit it the value of this payment. 

 

        if self.assignment not in (None, 'ignore'): 

            try: 

                old_budget = get_budget(session, self.assignment) 

            except NoSuchBudget: 

                raise AssignmentError("Payment #{} assigned to '{}', which no longer exists.".format(self.id, self.assignment)) 

 

            old_budget.balance -= self.value 

 

        # Debit the new assignment the value of this payment. 

 

        new_budget.balance += self.value 

        self.assignment = assignment 

 

    def ignore(self): 

        if self.assignment is None: 

            self.assignment = 'ignore' 

        else: 

            raise AssignmentError("Payment can't be ignored because it's already assigned to '{}'.".format(self.assignment)) 

 

 

def get_payment(session, id): 

    payment = session.query(Payment).get(id) 

    if payment is None: raise NoSuchPayment(id) 

    else: return payment 

 

def get_payments(session, budget_name=None): 

    if budget_name is not None: 

        return session.query(Payment).filter_by(assignment=budget_name).all() 

    else: 

        return session.query(Payment).all() 

 

def get_unassigned_payments(session): 

    return session.query(Payment).filter_by(assignment=None).all() 

 

def get_num_unassigned_payments(session): 

    return session.query(Payment).filter_by(assignment=None).count() 

 

 

class Bank (Base): 

    __tablename__ = 'banks' 

 

    id = Column(Integer, primary_key=True, autoincrement=True) 

    scraper_key = Column(String, unique=True, nullable=False) 

    username_command = Column(String) 

    password_command = Column(String) 

    payments = relationship("Payment", backref="bank") 

    last_update = Column(DateTime) 

 

    def __init__(self, session, scraper_key): 

        if bank_exists(session, scraper_key): 

            raise UserError("Bank '{}' already exists.".format(scraper_key)) 

        if scraper_key not in scraper_classes: 

            raise NoSuchScraper(scraper_key) 

 

        self.scraper_key = scraper_key 

        self.username_command = None 

        self.password_command = None 

        self.last_update = now() 

 

    def download_payments(self, username_callback, password_callback): 

        """ 

        Download new transactions from this bank. 

        """ 

 

        # Get a username and password the scraper can use to download data from  

        # this bank.  Commands to generate user names and passwords can be  

        # stored in the database, so use those if they're present.  Otherwise  

        # prompt the user for the needed information. 

 

        def get_user_info(command, interactive_prompt): 

            error_message = "" 

 

            if command: 

                try: 

                    with open(os.devnull, 'w') as devnull: 

                        user_info = subprocess.check_output( 

                                shlex.split(command), stderr=devnull) 

                        return user_info.decode('ascii').strip('\n') 

                except subprocess.CalledProcessError as error: 

                    error_message = "Command '{}' returned non-zero exit status {}".format(command, error.returncode) 

 

            return interactive_prompt(self.title, error_message) 

 

        username = get_user_info(self.username_command, username_callback) 

        password = get_user_info(self.password_command, password_callback) 

 

        # Scrape new transactions from the bank website, and store those  

        # transactions in the database as payments. 

 

        session = Session.object_session(self) 

        scraper_class = scraper_classes[self.scraper_key] 

        scraper = scraper_class(username, password) 

        start_date = self.last_update - datetime.timedelta(days=30) 

 

        for account in scraper.download(start_date): 

            for transaction in account.statement.transactions: 

                payment = Payment( 

                        account.number, 

                        transaction.id, 

                        transaction.date, 

                        transaction.amount, 

                        transaction.payee + ' ' + transaction.memo) 

 

                if payment not in self.payments: 

                    self.payments.append(payment) 

 

        self.last_update = now() 

 

    @property 

    def title(self): 

        return scraper_titles[self.scraper_key] 

 

 

def get_bank(session, key): 

    try: 

        return session.query(Bank).filter_by(scraper_key=key).one() 

    except sqlalchemy.orm.exc.NoResultFound: 

        raise NoSuchBank(key) 

 

def get_banks(session): 

    return session.query(Bank).all() 

 

def get_num_banks(session): 

    return session.query(Bank).count() 

 

def bank_exists(session, key): 

    return session.query(Bank).filter_by(scraper_key=key).count() > 0 

 

 

scraper_classes = { 

        'wells_fargo': banks.WellsFargo, 

} 

 

scraper_titles = { 

        'wells_fargo': 'Wells Fargo', 

} 

 

 

@contextmanager 

def open_db(path): 

    # Make sure the database directory exists. 

 

    path = os.path.abspath(os.path.expanduser(path)) 

    if not os.path.isdir(os.path.dirname(path)): 

        os.makedirs(os.path.dirname(path)) 

 

    # Create an database session.  Currently the whole program is hard-coded to  

    # use SQLite, but in the future I may want to use MySQL to make budgets  

    # accessible from many devices. 

 

    engine = sqlalchemy.create_engine('sqlite:///' + path) 

    Base.metadata.create_all(engine) 

    session = sqlalchemy.orm.sessionmaker(bind=engine)() 

 

    # Return the session to the calling code.  If the calling code completes  

    # without error, commit and close the session.  Otherwise, rollback the  

    # session to prevent bad data from being written to the database. 

 

    try: 

        yield session 

        session.commit() 

    except: 

        session.rollback() 

        raise 

    finally: 

        session.close() 

 

def download_payments(session, username_callback, password_callback): 

    for bank in get_banks(session): 

        bank.download_payments(username_callback, password_callback) 

 

def update_allowances(session): 

    for budget in get_budgets(session): 

        budget.update_allowance() 

 

def suggest_allowance(session, budget): 

    """ 

    Suggest a reasonable allowance for the given account its rate of spending  

    to date.  More specifically, this function calculates the average amount of  

    spending for the given account and returns that information in units of  

    dollars per month. 

    """ 

    payments = get_payments(session, budget.name) 

 

    if not payments: 

        return 0 

 

    elapsed_money = sum(x.value for x in payments) 

    elapsed_time = now().date() - min(x.date for x in payments) 

 

    if not elapsed_time.days: 

        return 0 

 

    return -elapsed_money / elapsed_time.days * days_per_month 

 

def transfer_money(dollars, from_budget, to_budget): 

    from_budget.balance -= dollars 

    to_budget.balance += dollars 

 

def transfer_allowance(allowance, from_budget, to_budget): 

    dollars_per_day = parse_allowance(allowance) 

    from_budget.allowance -= dollars_per_day 

    to_budget.allowance += dollars_per_day 

 

def parse_dollars(value): 

    """ 

    Convert the input dollar value to a numeric value. 

 

    The input may either be a numeric value or a string.  If it's a string, a  

    leading dollar sign may or may not be present. 

    """ 

    try: value = value.replace('$', '') 

    except AttributeError: pass 

 

    try: dollars = float(value) 

    except: raise MoneyError(value) 

 

    from math import isfinite 

    if not isfinite(dollars): raise MoneyError(value) 

 

    return dollars 

 

def parse_allowance(allowance): 

    """ 

    Convert the given allowance to dollars per day. 

 

    An allowance is a string that represents some amount of money per time.   

    Each allowance is expected to have three tokens.  The first is a dollar  

    amount (which may be preceded by a dollar sign), the second is either "/"  

    or " per ", and the third is one of "day", "month", "mo", or "year".  If  

    the given allowance is properly formatted, this function returns a float in  

    units of dollars per day.  Otherwise an AllowanceError is raised. 

    """ 

 

    if allowance == '': 

        return 0 

 

    allowance_pattern = re.compile('(\$?[0-9.]+)(/| per )(day|month|mo|year)') 

    allowance_match = allowance_pattern.match(allowance) 

 

    if not allowance_match: 

        raise AllowanceError(allowance, "doesn't match '<money> per <day|month|year>'") 

 

    money_token, sep, time_token = allowance_match.groups() 

 

    dollars = parse_dollars(money_token) 

 

    if time_token == 'day': 

        days = 1 

    elif time_token in ('month', 'mo'): 

        days = days_per_month 

    elif time_token == 'year': 

        days = days_per_year 

    else: 

        raise AssertionError    # pragma: no cover 

 

    return dollars / days 

 

def format_date(date): 

    return date.strftime('%m/%d/%y') 

 

def format_dollars(value): 

    if value < 0: 

        value = abs(value) 

        return '-${:.2f}'.format(value) 

    else: 

        return '${:.2f}'.format(value) 

 

def now(): 

    """ 

    Return today's date.  This function is important because it can be  

    monkey-patched during testing make the whole program deterministic.  It's  

    also a bit more convenient than the function in datetime. 

    """ 

    return datetime.datetime.now() 

 

 

class UserError (Exception): 

 

    def __init__(self, message=''): 

        self.message = message 

 

    def __str__(self): 

        return self.message 

 

 

class AllowanceError (UserError): 

 

    def __init__(self, allowance, message): 

        if allowance is not None: 

            self.message = "'{}': {}".format(allowance, message) 

        else: 

            self.message = message 

 

 

class AssignmentError (UserError): 

    pass 

 

class MoneyError (UserError): 

 

    def __init__(self, value): 

        self.message = "Expected a dollar value, not '{}'.".format(value) 

 

 

class NoSuchBudget (UserError): 

 

    def __init__(self, name): 

        self.message = "No budget named '{}'.".format(name) 

 

 

class NoSuchPayment (UserError): 

 

    def __init__(self, payment_id): 

        self.message = "No payment with id='{}'.".format(payment_id) 

 

 

class NoSuchBank (UserError): 

 

    def __init__(self, scraper_key): 

        self.message = "No bank named '{}'.".format(scraper_key) 

 

 

class NoSuchScraper (UserError): 

 

    def __init__(self, scraper_key): 

        self.message = "Bank '{}' is not supported.\n".format(scraper_key) 

        if len(scraper_classes) == 1: 

            self.message += "Only '{}' is supported at present.".format(list(scraper_classes.keys())[0]) 

        else: 

            self.message += "Supported banks: " + ', '.join("'{}'".format(x) for x in scraper_classes)