expephalon/core/mixins/billable.py

from django.db.models import PositiveIntegerField, DateField, IntegerChoices, Model

from dateutil.relativedelta import relativedelta

class ActionChoices(IntegerChoices):
    WAIT = 0, "Do not invoice for now"
    NEXT = 1, "Add to client's next invoice"
    CRON = 2, "Invoice at next cron run"
    DATE = 3, "Invoice at date"


class CycleChoices(IntegerChoices):
    DAYS = 0, "Days"
    WEEKS = 1, "Weeks"
    MONTHS = 2, "Months"
    YEARS = 3, "Years"

class RecurMixin(Model):
    class Meta:
        abstract = True

    date = DateField()
    recur_action = PositiveIntegerField(choices=ActionChoices.choices)
    recur_cycle = PositiveIntegerField(choices=CycleChoices.choices)
    recur_count = PositiveIntegerField()

    def next_invoicing(self):
        from core.models.invoices import InvoiceItem, Invoice

        if not (self.recur_action == ActionChoices.DATE) or self.recur_cycle:
            return False

        try:
            invoiceitems = InvoiceItem.objects.filter(billable=self)

            if invoiceitems and not self.recur_cycle:
                return False

            invoice = Invoice.objects.filter(invoiceitem_set__contains=invoiceitems).latest("created")
            delta = relativedelta(days=self.recur_count if self.recur_cycle == CycleChoices.DAYS else 0, 
                                  weeks=self.recur_count if self.recur_cycle == CycleChoices.WEEKS else 0,
                                  months=self.recur_count if self.recur_cycle == CycleChoices.MONTHS else 0, 
                                  years=self.recur_count if self.recur_cycle == CycleChoices.YEARS else 0)

            return invoice.created + delta
        except InvoiceItem.DoesNotExist:
            return self.date