Managers

def during(self, year, month):
    """Return Charges between a certain time range based on `created`."""
    return self.filter(created__year=year, created__month=month)

def paid_totals_for(self, year, month):
    """
    Return paid Charges during a certain year, month with total amount,
    fee and refunded annotated.
    """
    return (
        self.during(year, month)
        .filter(paid=True)
        .aggregate(
            total_amount=models.Sum("amount"),
            total_refunded=models.Sum("amount_refunded"),
        )
    )

def active(self):
    """Return active Subscriptions."""
    return self.filter(status="active")

def active_plan_summary(self):
    """Return active Subscriptions with plan counts annotated."""
    return (
        self.active().values("plan").order_by().annotate(count=models.Count("plan"))
    )

def canceled(self):
    """Return canceled Subscriptions."""
    return self.filter(status="canceled")

def canceled_during(self, year, month):
    """Return Subscriptions canceled during a certain time range."""
    return self.canceled().filter(canceled_at__year=year, canceled_at__month=month)

def canceled_plan_summary_for(self, year, month):
    """
    Return Subscriptions canceled within a time range with plan counts annotated.
    """
    return (
        self.canceled_during(year, month)
        .values("plan")
        .order_by()
        .annotate(count=models.Count("plan"))
    )

def churn(self):
    """Return number of canceled Subscriptions divided by active Subscriptions."""
    canceled = self.canceled().count()
    active = self.active().count()
    return decimal.Decimal(str(canceled)) / decimal.Decimal(str(active))

def started_during(self, year, month):
    """Return Subscriptions not in trial status between a certain time range."""
    return self.exclude(status="trialing").filter(
        start_date__year=year, start_date__month=month
    )

def started_plan_summary_for(self, year, month):
    """Return started_during Subscriptions with plan counts annotated."""
    return (
        self.started_during(year, month)
        .values("plan")
        .order_by()
        .annotate(count=models.Count("plan"))
    )

def during(self, year, month):
    """Return Transfers between a certain time range."""
    return self.filter(created__year=year, created__month=month)

def paid_totals_for(self, year, month):
    """
    Return paid Transfers during a certain year, month with total amounts annotated.
    """
    return self.during(year, month).aggregate(total_amount=models.Sum("amount"))