expephalon/core/models/billable.py

from django.db.models import Model, ForeignKey, CASCADE, TextField, PositiveIntegerField, BooleanField, DateField, ManyToManyField
from django.utils import timezone

from core.models.profiles import ClientProfile
from core.models.brands import Brand
from core.fields.base import LongCharField
from core.fields.numbers import CostField
from core.models.local import Currency
from core.mixins.billable import RecurMixin
from core.models.products import ProductGroup

from polymorphic.models import PolymorphicModel

class BaseBillable(PolymorphicModel):
    name = LongCharField()
    description = TextField(blank=True, null=True)
    amount = CostField()
    count = PositiveIntegerField(default=1)
    currency = ForeignKey(Currency, on_delete=CASCADE)
    taxable = BooleanField()
    client = ForeignKey(ClientProfile, on_delete=CASCADE)
    brand = ForeignKey(Brand, on_delete=CASCADE)

    @property
    def next_invoicing(self):
        raise NotImplementedError(f"{type(self)} does not implement property next_invoicing!")

    @property
    def can_invoice(self):
        raise NotImplementedError(f"{type(self)} does not implement property can_invoice!")

class Billable(RecurMixin, BaseBillable):
    product_groups = ManyToManyField(ProductGroup)