subscriptions.dunning-schedule

export function dunningSchedule(failedOn: string, retryOffsetsDays: readonly number[], businessDays: boolean, holidays: readonly string[]): readonly string[]

import { dunningSchedule } from "#fune/subscriptions.dunning-schedule@^1";

import { addDays } from "./dates_add_days.ts";  ← from dates.add-days ^1.0.0 · built alongside by fune
import { addBusinessDays } from "./dates_add_business_days.ts";  ← from dates.add-business-days ^1.0.0 · built alongside by fune

/**
 * The retry dates for a payment that failed on `failedOn`. Each offset counts
 * from the failure date, not from the previous retry, in calendar days or in
 * working days.
 */
export function dunningSchedule(failedOn: string, retryOffsetsDays: readonly number[], businessDays: boolean, holidays: readonly string[]): readonly string[] {
  let previous = 0;
  for (const offset of retryOffsetsDays) {
    if (!Number.isInteger(offset) || offset < 1) {
      throw new RangeError(`retry offsets must be whole days of 1 or more, received ${offset}`);
    }
    if (offset <= previous) {
      throw new RangeError(`retry offsets must be strictly increasing, received ${offset} after ${previous}`);
    }
    previous = offset;
  }
  // Validates the failure date even for an empty policy.
  addDays(failedOn, 0);
  return retryOffsetsDays.map((offset) => (businessDays ? addBusinessDays(failedOn, offset, holidays) : addDays(failedOn, offset)));
}

Install

fune build

With that line in your source, in a TypeScript project (language typescript in fune.project), fune build resolves it and its 2 dependencies, pins them in fune.lock, downloads only the TypeScript 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 TypeScript implementation. Install it without the registry with fune add ./subscriptions.dunning-schedule-1.0.0-typescript.fune, or fetch it from a terminal with fune pull subscriptions.dunning-schedule@1.0.0:typescript.

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