import datetime
import dejavu
from dejavu import Unit, UnitProperty, associate


class Zoo(Unit):
    Name = UnitProperty()
    Founded = UnitProperty(datetime.date)
    Opens = UnitProperty(datetime.time)
    LastEscape = UnitProperty(datetime.datetime)


class EscapeProperty(UnitProperty):
    def post(self, unit, value):
        z = unit.first(Zoo)
        if z:
            z.LastEscape = unit.LastEscape

class Animal(Unit):
    Name = UnitProperty()
    ZooID = UnitProperty(int, index=True)
    Legs = UnitProperty(int)
    Options = UnitProperty(dict)
    LastEscape = EscapeProperty(datetime.datetime)

associate(Zoo, 'ID', Animal, 'ZooID')


class Exhibit(Unit):
    ZooID = UnitProperty(int)
    Animals = UnitProperty(list)

associate(Zoo, 'ID', Exhibit, 'ZooID')

arena = dejavu.Arena()
arena.register_all(globals())