subscriptions.dunning-schedule

def dunning_schedule(failed_on: str, retry_offsets_days: Sequence[int], business_days: bool, holidays: Sequence[str]) -> List[str]

from fune.subscriptions.dunning_schedule import dunning_schedule  # subscriptions.dunning-schedule@^1

from typing import List, Sequence

from .dates_add_business_days import add_business_days  ← from dates.add-business-days ^1.0.0 · built alongside by fune
from .dates_add_days import add_days  ← from dates.add-days ^1.0.0 · built alongside by fune


def dunning_schedule(
    failed_on: str, retry_offsets_days: Sequence[int], business_days: bool, holidays: Sequence[str]
) -> List[str]:
    """The retry dates for a payment that failed on ``failed_on``. Each offset
    counts from the failure date, not from the previous retry, in calendar days
    or in working days.
    """
    previous = 0
    for offset in retry_offsets_days:
        if isinstance(offset, bool) or not isinstance(offset, int) or offset < 1:
            raise ValueError("retry offsets must be whole days of 1 or more, received %r" % (offset,))
        if offset <= previous:
            raise ValueError(
                "retry offsets must be strictly increasing, received %d after %d" % (offset, previous)
            )
        previous = offset
    # Validates the failure date even for an empty policy.
    add_days(failed_on, 0)
    return [
        add_business_days(failed_on, offset, holidays) if business_days else add_days(failed_on, offset)
        for offset in retry_offsets_days
    ]

Install

fune build

With that line in your source, in a Python project (language python in fune.project), fune build resolves it and its 2 dependencies, pins them in fune.lock, downloads only the Python package of each, and builds the code above into your project’s .fune/build, one readable file per capability with a header linking back here. Or pin a range in fune.project and build in one step:

fune add subscriptions.dunning-schedule

The manifest, vectors and README with only the Python implementation. Install it without the registry with fune add ./subscriptions.dunning-schedule-1.0.0-python.fune, or fetch it from a terminal with fune pull subscriptions.dunning-schedule@1.0.0:python.

The whole function, every language, is one file too: subscriptions.dunning-schedule-1.0.0.fune, 9,946 bytes, sha256 29af783bacb57f016d8ee8462b19297e142602118f308f1cf84ac8beb18c75d1. It installs into a project of any language.

# fune: before subscriptions.dunning-schedule

# fune: after subscriptions.dunning-schedule

# fune: replace dates.add-business-days in subscriptions.dunning-schedule
# fune: replace dates.add-days in subscriptions.dunning-schedule

# fune: step subscriptions.dunning-schedule after <n|label>

More from the author

With `businessDays` true, the offsets are counted in working days using dates.add-business-days: weekends and the listed holidays are skipped, and a failure on a Saturday retried 1 business day later is retried on Monday. Pass bank holidays (dates.bank-holidays) when retries should land on days the banks process card and Direct Debit payments. With `businessDays` false the offsets are plain calendar days and `holidays` is ignored.

What happens after the last retry (cancel, mark unpaid, pause) is a policy decision for the caller; this only computes when the retries fall. An empty policy gives an empty schedule.

Errors: an offset below 1, offsets that do not increase, an impossible date, and (in business-day mode) a malformed holiday.

Files