Custom period ranges for recurring events does not affect the starting date

[fabiodrg]

Suppose an event on 1st March (Tuesday) that recurs weekly. If the user selects a later starting date, e.g. 23rd March (Wednesday), the starting date for the event should be shifted to 29th March (the first Tuesday from the selected period). Regarding the ending date, that works fine as the user input is directly used for the recurring rule.

[fabiodrg]

Initial experiment with Luxon

const luxon = require("luxon");

const d1 = luxon.DateTime.local(2022, 03, 01, 15, 00);

const from1 = luxon.DateTime.local(2022, 02, 02);
const from2 = luxon.DateTime.local(2022, 02, 27);
const from3 = luxon.DateTime.local(2022, 03, 21);
const from4 = luxon.DateTime.local(2022, 03, 23);

const shiftDate = ((from, d) => {
  if (from > d) {
    const weeksDiff = from.diff(d, "weeks").toObject().weeks;
    return d.plus({weeks: Math.floor(weeksDiff) + 1});
  }

  return d;
});

console.log(shiftDate(from1, d1).toString());
console.log(shiftDate(from2, d1).toString());
console.log(shiftDate(from3, d1).toString());
console.log(shiftDate(from4, d1).toString());

2022-03-01T15:00:00.000+00:00
2022-03-01T15:00:00.000+00:00
2022-03-22T15:00:00.000+00:00
2022-03-29T15:00:00.000+01:00