from collections import defaultdict
import datetime


def per_manager(timesheets):
    per_manager = defaultdict(list)
    # filter timesheets per manager
    for timesheet in [t for t in timesheets if not t.is_done()]:
        manager_id = timesheet.approver
        per_manager[manager_id].append(timesheet)
    return per_manager


def employees(timesheets):
    return dict([(t.employee.id, t.employee) for t in timesheets])


def previous_monday(date=None):
    today = date or datetime.date.today()
    return today + datetime.timedelta(days=-today.weekday(), weeks=-1)