def determine_debts(session):
#TODO(rpearl) ...actual arg parsing
dry_run = len(sys.argv) == 2 and sys.argv[1] == '--dry-run'
if dry_run:
print "This is a dry run. Not sending messages."
# Compute aggregate debt
debts = model.get_unresolved_transactions(session)
users = [u.username for u in model.get_users(session)]
rent = {user: 0 for user in users}
for debt in debts:
rent[debt.to_user] -= debt.amount
rent[debt.from_user] += debt.amount
assert sum(rent.values()) == 0
# Find users who have properties of Shakespeare
need_paid = []
can_pay = []
for u, r in rent.iteritems():
if r <= -THRESHOLD:
need_paid.append((r, u))
elif r > 0:
can_pay.append((-r, u))
# Begin paying users to zero
can_pay = [u for _, u in sorted(can_pay)]
payments = defaultdict(list)
for _, u in sorted(need_paid):
print "Finding money for %s (need %s)" % (u, format_cents(None, rent[u]))
for u2 in can_pay:
if rent[u2] > 0:
to_pay = min(rent[u2], -rent[u])
rent[u2] -= to_pay
rent[u] += to_pay
payments[u2].append((u, to_pay))
if rent[u] >= 0:
break
assert rent[u] == 0
# Inform users of their debts and reconcile ledger
for f, txns in payments.iteritems():
fu = session.query(User).get(f)
for t, amount in txns:
tu = session.query(User).get(t)
print "%s pays %s %s" % (f, t, format_cents(None, amount))
if not dry_run:
model.create_transaction(session, t, f, amount, '[automatic] resolving debt')
msg = debt_message(f, txns)
if not dry_run:
model.send_mail(from_user='******', to_user=f, message=msg)
else:
print msg
def debt_message(person, amount):
if amount > 0:
say = "%s more than" % (format_cents(None, amount))
elif amount == 0:
say = 'just'
else:
say = "%s less than" % (format_cents(None, -amount))
msg = '''\
To: %s
Subject: End-of-month rent is due
You should pay %s your regular rent.
''' % (person, say)
return msg
def debt_message(person, amount):
if amount > 0:
say = "%s more than" % (format_cents(None, amount))
elif amount == 0:
say = 'just'
else:
say = "%s less than" % (format_cents(None, -amount))
msg = '''\
To: %s
Subject: End-of-month rent is due
You should pay %s your regular rent.
''' % (person, say)
return msg
def debt_message(person, txns):
bullets = '\n'.join(' - %s to %s' % (format_cents(None, a), d) for d, a in txns)
msg = '''\
To: %s
Subject: Rent rebalance required
You should pay the following:
%s
''' % (person, bullets)
return msg
def create_transaction(self, session, from_user, to_user, amount, comment):
date = datetime.now()
txn = Transaction(date=date,
from_user=from_user,
to_user=to_user,
amount=amount,
comment=comment,
settled=False)
session.add(txn)
self.send_mail(from_user, [to_user], '''\
To: %s
Subject: %s sent you %s
for %s
''' % (to_user, from_user, format_cents(None, amount), comment))
