from bluechips import model
from bluechips.model import meta
-import sqlalchemy
+from bluechips.model.types import Currency
-from decimal import Decimal
+import sqlalchemy
class DirtyBooks(Exception):
"""
# house
users = meta.Session.query(model.User)
- debts = {}
+ debts_dict = dict((u, Currency(0)) for u in users)
# First, credit everyone for expenditures they've made
- for user in users:
- debts[user] = -sum(map((lambda x: x.amount), user.expenditures))
+ total_expenditures = meta.Session.query(model.Expenditure).\
+ add_column(sqlalchemy.func.sum(model.Expenditure.amount).label('total_spend')).\
+ group_by(model.Expenditure.spender_id)
+ for expenditure, total_spend in total_expenditures:
+ debts_dict[expenditure.spender] -= total_spend
# Next, debit everyone for expenditures that they have an
# investment in (i.e. splits)
group_by(model.Split.user_id)
for split, total_cents in total_splits:
- debts[split.user] += (total_cents / 100)
+ debts_dict[split.user] += total_cents
# Finally, move transfers around appropriately
#
total_credits = transfer_q.group_by(model.Transfer.creditor_id)
for transfer, total_amount in total_debits:
- debts[transfer.debtor] -= (total_amount / 100)
+ debts_dict[transfer.debtor] -= total_amount
for transfer, total_amount in total_credits:
- debts[transfer.creditor] += (total_amount / 100)
+ debts_dict[transfer.creditor] += total_amount
- return debts
+ return debts_dict
def settle(debts_dict):
# This algorithm has been shamelessly stolen from Nelson Elhage's
debts_list = [dict(who=user, amount=amount) for user, amount in \
debts_dict.iteritems()]
- debts_list.sort(reverse=True, key=(lambda x: abs(x['amount'])))
+ #debts_list.sort(reverse=True, key=(lambda x: abs(x['amount'])))
owes_list = [debt for debt in debts_list if debt['amount'] > 0]
owed_list = [debt for debt in debts_list if debt['amount'] < 0]
- settle = []
+ settle_list = []
while len(owes_list) > 0 and len(owed_list) > 0:
+ owes_list.sort(reverse=True, key=(lambda x: abs(x['amount'])))
+ owed_list.sort(reverse=True, key=(lambda x: abs(x['amount'])))
+
owes = owes_list[0]
owed = owed_list[0]
owes_list.pop(0)
val = owes['amount']
- settle.append((owes['who'], owed['who'], val))
+ settle_list.append((owes['who'], owed['who'], val))
if len(owes_list) > 0:
raise DirtyBooks, ("People still owe money", owes_list)
if len(owed_list) > 0:
raise DirtyBooks, ("People are still owed money", owed_list)
- return settle
+ return settle_list
__all__ = ['debts', 'settle']