697 lines
25 KiB
TypeScript
697 lines
25 KiB
TypeScript
/**
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* Client-side recurrence expansion for JSCalendar events.
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*
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* Implements JSCalendar 2.0 (draft-ietf-calext-jscalendarbis-15) §3.3.3.1
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* recurrence rule interpretation algorithm with full byX filtering,
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* implicit byX property addition, and bySetPosition support.
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*
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* Stalwart does not yet support mutations on the synthetic IDs produced by
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* CalendarEvent/query?expandRecurrences=true, so we fetch raw events (with
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* real, mutable IDs) and expand recurring series into individual occurrences
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* in the browser.
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*/
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import { parseISO, format, addDays, addWeeks, addMonths, addYears } from 'date-fns';
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import type { CalendarEvent, CalendarRecurrenceRule, CalendarNDay } from '@/lib/jmap/types';
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const DAY_INDEX: Record<string, number> = { su: 0, mo: 1, tu: 2, we: 3, th: 4, fr: 5, sa: 6 };
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const INDEX_TO_DAY: string[] = ['su', 'mo', 'tu', 'we', 'th', 'fr', 'sa'];
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/**
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* Given a master event and a date range, return an array of "virtual" occurrence
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* events. Each occurrence carries a synthetic `id` (for dedup in React) and a
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* `masterEventId` field that points back to the real server-side ID so the
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* store can use it for mutations.
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*
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* Non-recurring events are returned as-is. For recurring events the master is
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* **not** returned - only expanded instances within the range.
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*/
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export function expandRecurringEvents(
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events: CalendarEvent[],
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rangeStart: string,
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rangeEnd: string,
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): CalendarEvent[] {
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const start = parseISO(rangeStart);
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const end = parseISO(rangeEnd);
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const result: CalendarEvent[] = [];
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// Collect UIDs of master recurring events so we can skip their
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// server-returned override instances (which have recurrenceId set).
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// The master's recurrenceOverrides already accounts for them.
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const recurringUids = new Set<string>();
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for (const event of events) {
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if (event.recurrenceRules?.length && event.uid && !event.recurrenceId) {
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recurringUids.add(event.uid);
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}
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}
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for (const event of events) {
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// Skip override instances returned by the server - they belong to a
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// master recurring event and are already handled via recurrenceOverrides.
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if (event.recurrenceId && event.uid && recurringUids.has(event.uid)) {
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continue;
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}
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if (!event.recurrenceRules?.length) {
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result.push(event);
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continue;
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}
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const occurrences = expandEvent(event, start, end);
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result.push(...occurrences);
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}
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return result;
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}
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function expandEvent(
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master: CalendarEvent,
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rangeStart: Date,
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rangeEnd: Date,
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): CalendarEvent[] {
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const eventStart = parseISO(master.start);
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if (isNaN(eventStart.getTime())) return [];
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const rules = master.recurrenceRules || [];
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const overrides = master.recurrenceOverrides || {};
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const occurrences: CalendarEvent[] = [];
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const seenDates = new Set<string>();
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for (const rule of rules) {
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const dates = generateDates(eventStart, rule, rangeStart, rangeEnd);
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for (const date of dates) {
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const dateKey = master.showWithoutTime
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? format(date, 'yyyy-MM-dd')
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: date.toISOString();
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if (seenDates.has(dateKey)) continue;
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seenDates.add(dateKey);
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const recurrenceId = master.showWithoutTime
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? format(date, "yyyy-MM-dd'T'00:00:00")
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: format(date, "yyyy-MM-dd'T'HH:mm:ss");
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const override = overrides[recurrenceId] as (Partial<CalendarEvent> & { excluded?: boolean }) | undefined;
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if (override?.excluded) continue;
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occurrences.push(createOccurrence(master, date, recurrenceId, override));
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}
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}
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// Add overrides that define new dates not generated by rules (RDATE equivalent)
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for (const [recurrenceId, rawOverride] of Object.entries(overrides)) {
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const override = rawOverride as Partial<CalendarEvent> & { excluded?: boolean };
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if (override.excluded) continue;
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const overrideDate = parseISO(recurrenceId);
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if (isNaN(overrideDate.getTime())) continue;
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if (overrideDate < rangeStart || overrideDate >= rangeEnd) continue;
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const dateKey = master.showWithoutTime
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? format(overrideDate, 'yyyy-MM-dd')
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: overrideDate.toISOString();
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if (seenDates.has(dateKey)) continue;
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seenDates.add(dateKey);
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occurrences.push(createOccurrence(master, overrideDate, recurrenceId, override));
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}
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return occurrences;
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}
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function createOccurrence(
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master: CalendarEvent,
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date: Date,
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recurrenceId: string,
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override?: Partial<CalendarEvent>,
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): CalendarEvent {
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const startStr = master.showWithoutTime
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? format(date, "yyyy-MM-dd'T'00:00:00")
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: format(date, "yyyy-MM-dd'T'HH:mm:ss");
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// Compute utcStart/utcEnd for this occurrence so that getEventStartDate()
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// and getEventEndDate() (which prefer utcStart/utcEnd for timed events)
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// return the correct dates instead of the master's original UTC times.
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let utcStart: string | undefined;
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let utcEnd: string | undefined;
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if (!master.showWithoutTime && master.utcStart && master.start) {
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const masterLocal = parseISO(master.start);
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const masterUtc = parseISO(master.utcStart);
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const offsetMs = masterUtc.getTime() - masterLocal.getTime();
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utcStart = new Date(date.getTime() + offsetMs).toISOString();
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// Shift utcEnd by the same amount as utcStart
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if (master.utcEnd) {
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const masterUtcEnd = parseISO(master.utcEnd);
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const durationMs = masterUtcEnd.getTime() - masterUtc.getTime();
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utcEnd = new Date(date.getTime() + offsetMs + durationMs).toISOString();
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}
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}
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return {
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...master,
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...(override || {}),
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id: `${master.id}:${recurrenceId}`,
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originalId: master.originalId || master.id,
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uid: master.uid,
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calendarIds: master.calendarIds,
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start: (override?.start) || startStr,
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...(utcStart && !override?.utcStart ? { utcStart } : {}),
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...(utcEnd && !override?.utcEnd ? { utcEnd } : {}),
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recurrenceId,
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recurrenceRules: master.recurrenceRules,
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recurrenceOverrides: master.recurrenceOverrides,
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excludedRecurrenceRules: master.excludedRecurrenceRules,
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};
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}
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// ---------------------------------------------------------------------------
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// §3.3.3.1 - Implicit byX property addition
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// ---------------------------------------------------------------------------
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function addImplicitByX(
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rule: CalendarRecurrenceRule,
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eventStart: Date,
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): CalendarRecurrenceRule {
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const r = { ...rule };
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const freq = r.frequency;
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// bySecond
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if (freq !== 'secondly' && !r.bySecond?.length) {
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r.bySecond = [eventStart.getSeconds()];
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}
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// byMinute
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if (freq !== 'secondly' && freq !== 'minutely' && !r.byMinute?.length) {
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r.byMinute = [eventStart.getMinutes()];
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}
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// byHour
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if (freq !== 'secondly' && freq !== 'minutely' && freq !== 'hourly' && !r.byHour?.length) {
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r.byHour = [eventStart.getHours()];
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}
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// weekly: implicit byDay
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if (freq === 'weekly' && !r.byDay?.length) {
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r.byDay = [{ day: INDEX_TO_DAY[eventStart.getDay()] }];
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}
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// monthly: implicit byMonthDay
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if (freq === 'monthly' && !r.byDay?.length && !r.byMonthDay?.length) {
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r.byMonthDay = [eventStart.getDate()];
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}
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// yearly: implicit byMonth / byMonthDay / byDay
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if (freq === 'yearly' && !r.byYearDay?.length) {
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if (!r.byMonth?.length && !r.byWeekNo?.length && (r.byMonthDay?.length || !r.byDay?.length)) {
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r.byMonth = [String(eventStart.getMonth() + 1)];
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}
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if (!r.byMonthDay?.length && !r.byWeekNo?.length && !r.byDay?.length) {
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r.byMonthDay = [eventStart.getDate()];
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}
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if (r.byWeekNo?.length && !r.byMonthDay?.length && !r.byDay?.length) {
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r.byDay = [{ day: INDEX_TO_DAY[eventStart.getDay()] }];
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}
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}
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return r;
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}
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// ---------------------------------------------------------------------------
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// §3.3.3.1 - Generate occurrence dates
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// ---------------------------------------------------------------------------
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function generateDates(
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eventStart: Date,
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rawRule: CalendarRecurrenceRule,
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rangeStart: Date,
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rangeEnd: Date,
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): Date[] {
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const rule = addImplicitByX(rawRule, eventStart);
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const dates: Date[] = [];
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const interval = rule.interval || 1;
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const countLimit = rule.count || Infinity;
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const until = rule.until ? parseISO(rule.until) : null;
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let totalCount = 0;
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let current = new Date(eventStart);
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const maxIterations = 2000;
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const maxOccurrences = 500;
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let iterations = 0;
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while (iterations++ < maxIterations) {
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if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
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if (until && current > until) break;
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// For frequencies that produce one candidate per iteration at a time,
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// we can stop when we pass rangeEnd. But for frequencies that expand
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// into multiple candidates per period, we need the candidate generation.
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if (current >= rangeEnd && rule.frequency !== 'yearly' && rule.frequency !== 'monthly'
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&& rule.frequency !== 'weekly') break;
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// Generate candidates for the current period, then filter
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const candidates = generateCandidatesForPeriod(current, rule, eventStart);
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// Apply bySetPosition if present
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const filtered = rule.bySetPosition?.length
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? applyBySetPosition(candidates, rule.bySetPosition)
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: candidates;
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for (const d of filtered) {
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if (until && d > until) break;
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if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
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// Spec rule 4: eliminate dates before event start
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if (d < eventStart) continue;
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totalCount++;
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if (d >= rangeStart && d < rangeEnd) {
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dates.push(d);
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}
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if (d >= rangeEnd) break;
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}
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if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
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current = advancePeriod(current, rule.frequency, interval, rule.firstDayOfWeek || 'mo');
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if (current <= eventStart && iterations === 1) {
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// Safety: ensure we don't go backward
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current = advancePeriod(eventStart, rule.frequency, interval, rule.firstDayOfWeek || 'mo');
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}
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}
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// Spec rule 1: the initial start date-time is ALWAYS the first occurrence
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if (dates.length > 0 && dates[0].getTime() !== eventStart.getTime()) {
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if (eventStart >= rangeStart && eventStart < rangeEnd) {
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// Check it's not already in the list
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if (!dates.some(d => d.getTime() === eventStart.getTime())) {
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dates.unshift(eventStart);
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}
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}
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}
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return dates;
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}
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// ---------------------------------------------------------------------------
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// Generate all candidates within one period, filtered by byX properties
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// ---------------------------------------------------------------------------
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function generateCandidatesForPeriod(
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periodStart: Date,
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rule: CalendarRecurrenceRule,
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eventStart: Date,
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): Date[] {
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const freq = rule.frequency;
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let candidates: Date[];
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// Step 1: Generate base candidates based on frequency + expansion byX
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switch (freq) {
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case 'yearly':
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candidates = expandYearly(periodStart, rule, eventStart);
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break;
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case 'monthly':
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candidates = expandMonthly(periodStart, rule, eventStart);
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break;
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case 'weekly':
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candidates = expandWeekly(periodStart, rule, eventStart);
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break;
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case 'daily':
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case 'hourly':
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case 'minutely':
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case 'secondly':
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candidates = [new Date(periodStart)];
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break;
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default:
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candidates = [new Date(periodStart)];
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}
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// Step 2: Filter candidates by all applicable byX constraints
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candidates = candidates.filter(d => matchesByX(d, rule));
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candidates.sort((a, b) => a.getTime() - b.getTime());
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return candidates;
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}
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// ---------------------------------------------------------------------------
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// Yearly expansion
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// ---------------------------------------------------------------------------
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function expandYearly(
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periodStart: Date,
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rule: CalendarRecurrenceRule,
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eventStart: Date,
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): Date[] {
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const year = periodStart.getFullYear();
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const h = eventStart.getHours();
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const m = eventStart.getMinutes();
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const s = eventStart.getSeconds();
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let dates: Date[] = [];
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// Determine which months to iterate
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const months = rule.byMonth?.length
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? rule.byMonth.map(ms => parseInt(ms.replace('L', ''), 10) - 1)
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: [eventStart.getMonth()];
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if (rule.byWeekNo?.length) {
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// Expand by ISO week numbers
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for (const wn of rule.byWeekNo) {
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const weekDates = datesInISOWeek(year, wn, rule.firstDayOfWeek || 'mo');
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dates.push(...weekDates.map(d => { d.setHours(h, m, s, 0); return d; }));
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}
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} else if (rule.byYearDay?.length) {
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// Expand by day-of-year
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for (const yd of rule.byYearDay) {
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const d = dayOfYear(year, yd);
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if (d) { d.setHours(h, m, s, 0); dates.push(d); }
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}
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} else if (rule.byDay?.length && rule.byMonthDay?.length) {
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// Both byDay and byMonthDay: expand byMonthDay in each month, then byDay filters later
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for (const mo of months) {
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for (const md of rule.byMonthDay) {
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const d = resolveMonthDay(year, mo, md);
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if (d) { d.setHours(h, m, s, 0); dates.push(d); }
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}
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}
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} else if (rule.byDay?.length) {
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// byDay with nthOfPeriod in yearly context = nth weekday of year or month
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for (const mo of months) {
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const expanded = expandByDayInMonth(year, mo, rule.byDay, h, m, s);
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dates.push(...expanded);
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}
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} else if (rule.byMonthDay?.length) {
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for (const mo of months) {
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for (const md of rule.byMonthDay) {
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const d = resolveMonthDay(year, mo, md);
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if (d) { d.setHours(h, m, s, 0); dates.push(d); }
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}
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}
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} else {
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// Simple yearly: same date each year
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for (const mo of months) {
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const d = new Date(year, mo, eventStart.getDate(), h, m, s, 0);
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if (d.getMonth() === mo) dates.push(d);
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}
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}
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return dates;
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}
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// ---------------------------------------------------------------------------
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// Monthly expansion
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// ---------------------------------------------------------------------------
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function expandMonthly(
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periodStart: Date,
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rule: CalendarRecurrenceRule,
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eventStart: Date,
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): Date[] {
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const year = periodStart.getFullYear();
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const month = periodStart.getMonth();
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const h = eventStart.getHours();
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const m = eventStart.getMinutes();
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const s = eventStart.getSeconds();
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const dates: Date[] = [];
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if (rule.byDay?.length) {
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const expanded = expandByDayInMonth(year, month, rule.byDay, h, m, s);
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dates.push(...expanded);
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} else if (rule.byMonthDay?.length) {
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for (const md of rule.byMonthDay) {
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const d = resolveMonthDay(year, month, md);
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if (d) { d.setHours(h, m, s, 0); dates.push(d); }
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}
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} else {
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// Implicit byMonthDay already added, but as fallback:
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const d = new Date(year, month, eventStart.getDate(), h, m, s, 0);
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if (d.getMonth() === month) dates.push(d);
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}
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return dates;
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}
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// ---------------------------------------------------------------------------
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// Weekly expansion
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// ---------------------------------------------------------------------------
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function expandWeekly(
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periodStart: Date,
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rule: CalendarRecurrenceRule,
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eventStart: Date,
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): Date[] {
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const dates: Date[] = [];
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const baseDay = periodStart.getDay();
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const byDay = rule.byDay?.length ? rule.byDay : [{ day: INDEX_TO_DAY[eventStart.getDay()] }];
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for (const { day } of byDay) {
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const targetDay = DAY_INDEX[day];
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if (targetDay === undefined) continue;
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let diff = targetDay - baseDay;
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if (diff < 0) diff += 7;
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const d = addDays(periodStart, diff);
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d.setHours(eventStart.getHours(), eventStart.getMinutes(), eventStart.getSeconds(), 0);
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dates.push(d);
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}
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return dates.sort((a, b) => a.getTime() - b.getTime());
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}
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// ---------------------------------------------------------------------------
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// byX matching (Step 2 of §3.3.3.1)
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// ---------------------------------------------------------------------------
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function matchesByX(date: Date, rule: CalendarRecurrenceRule): boolean {
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if (rule.byMonth?.length) {
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const month = String(date.getMonth() + 1);
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if (!rule.byMonth.some(m => m.replace('L', '') === month)) return false;
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}
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if (rule.byWeekNo?.length) {
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const wn = getISOWeekNumber(date);
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const weeksInYear = getISOWeeksInYear(date.getFullYear());
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if (!rule.byWeekNo.some(w => (w > 0 ? w : weeksInYear + 1 + w) === wn)) return false;
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}
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if (rule.byYearDay?.length) {
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const yd = getDayOfYear(date);
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const daysInYear = isLeapYear(date.getFullYear()) ? 366 : 365;
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if (!rule.byYearDay.some(d => (d > 0 ? d : daysInYear + 1 + d) === yd)) return false;
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}
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if (rule.byMonthDay?.length) {
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const md = date.getDate();
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const daysInMonth = new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate();
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if (!rule.byMonthDay.some(d => (d > 0 ? d : daysInMonth + 1 + d) === md)) return false;
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}
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if (rule.byDay?.length) {
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const dayName = INDEX_TO_DAY[date.getDay()];
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const freq = rule.frequency;
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if (!rule.byDay.some(nd => {
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if (nd.day !== dayName) return false;
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if (nd.nthOfPeriod == null) return true;
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if (freq === 'monthly') {
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return nd.nthOfPeriod === nthWeekdayInMonth(date, nd.nthOfPeriod);
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}
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if (freq === 'yearly') {
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// When byMonth is present, nthOfPeriod scopes to the month (iCalendar semantics)
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|
if (rule.byMonth?.length) {
|
|
return nd.nthOfPeriod === nthWeekdayInMonth(date, nd.nthOfPeriod);
|
|
}
|
|
return nd.nthOfPeriod === nthWeekdayInYear(date, nd.nthOfPeriod);
|
|
}
|
|
return true;
|
|
})) return false;
|
|
}
|
|
if (rule.byHour?.length) {
|
|
if (!rule.byHour.includes(date.getHours())) return false;
|
|
}
|
|
if (rule.byMinute?.length) {
|
|
if (!rule.byMinute.includes(date.getMinutes())) return false;
|
|
}
|
|
if (rule.bySecond?.length) {
|
|
if (!rule.bySecond.includes(date.getSeconds())) return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// bySetPosition (Step 3 of §3.3.3.1)
|
|
// ---------------------------------------------------------------------------
|
|
function applyBySetPosition(dates: Date[], positions: number[]): Date[] {
|
|
if (!dates.length) return dates;
|
|
const result: Date[] = [];
|
|
const len = dates.length;
|
|
for (const pos of positions) {
|
|
const idx = pos > 0 ? pos - 1 : len + pos;
|
|
if (idx >= 0 && idx < len) {
|
|
result.push(dates[idx]);
|
|
}
|
|
}
|
|
return result.sort((a, b) => a.getTime() - b.getTime());
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Advance to the start of the next period
|
|
// ---------------------------------------------------------------------------
|
|
function advancePeriod(
|
|
date: Date,
|
|
frequency: CalendarRecurrenceRule['frequency'],
|
|
interval: number,
|
|
_firstDayOfWeek: string,
|
|
): Date {
|
|
switch (frequency) {
|
|
case 'daily': return addDays(date, interval);
|
|
case 'weekly': return addWeeks(date, interval);
|
|
case 'monthly': return addMonths(date, interval);
|
|
case 'yearly': return addYears(date, interval);
|
|
case 'hourly': return new Date(date.getTime() + interval * 3600000);
|
|
case 'minutely': return new Date(date.getTime() + interval * 60000);
|
|
case 'secondly': return new Date(date.getTime() + interval * 1000);
|
|
default: return addDays(date, interval);
|
|
}
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: expand byDay within a specific month (monthly or yearly context)
|
|
// ---------------------------------------------------------------------------
|
|
function expandByDayInMonth(
|
|
year: number,
|
|
month: number,
|
|
byDay: CalendarNDay[],
|
|
h: number, m: number, s: number,
|
|
): Date[] {
|
|
const dates: Date[] = [];
|
|
|
|
for (const { day, nthOfPeriod } of byDay) {
|
|
const targetDay = DAY_INDEX[day];
|
|
if (targetDay === undefined) continue;
|
|
|
|
if (nthOfPeriod != null && nthOfPeriod !== 0) {
|
|
const d = nthWeekdayOfMonth(year, month, targetDay, nthOfPeriod);
|
|
if (d) { d.setHours(h, m, s, 0); dates.push(d); }
|
|
} else {
|
|
// Every occurrence of this weekday in the month
|
|
let d = new Date(year, month, 1);
|
|
while (d.getDay() !== targetDay) d = addDays(d, 1);
|
|
while (d.getMonth() === month) {
|
|
const occ = new Date(d);
|
|
occ.setHours(h, m, s, 0);
|
|
dates.push(occ);
|
|
d = addDays(d, 7);
|
|
}
|
|
}
|
|
}
|
|
|
|
return dates;
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: find nth weekday of month
|
|
// ---------------------------------------------------------------------------
|
|
function nthWeekdayOfMonth(
|
|
year: number,
|
|
month: number,
|
|
weekday: number,
|
|
nth: number,
|
|
): Date | null {
|
|
if (nth > 0) {
|
|
let d = new Date(year, month, 1);
|
|
while (d.getDay() !== weekday) d = addDays(d, 1);
|
|
d = addDays(d, (nth - 1) * 7);
|
|
return d.getMonth() === month ? d : null;
|
|
} else {
|
|
let d = new Date(year, month + 1, 0); // last day of month
|
|
while (d.getDay() !== weekday) d = addDays(d, -1);
|
|
if (nth < -1) d = addDays(d, (nth + 1) * 7);
|
|
return d.getMonth() === month ? d : null;
|
|
}
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: check if date is the nth (or nth-last) weekday in its month
|
|
// ---------------------------------------------------------------------------
|
|
function nthWeekdayInMonth(date: Date, nth: number): number {
|
|
if (nth > 0) {
|
|
// Count from start: which occurrence of this weekday is it?
|
|
return Math.floor((date.getDate() - 1) / 7) + 1;
|
|
} else {
|
|
// Count from end
|
|
const daysInMonth = new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate();
|
|
return -(Math.floor((daysInMonth - date.getDate()) / 7) + 1);
|
|
}
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: check if date is the nth weekday in its year
|
|
// ---------------------------------------------------------------------------
|
|
function nthWeekdayInYear(date: Date, nth: number): number {
|
|
const yd = getDayOfYear(date);
|
|
const weekday = date.getDay();
|
|
if (nth > 0) {
|
|
// Find first occurrence of this weekday in the year
|
|
const jan1 = new Date(date.getFullYear(), 0, 1);
|
|
let first = jan1;
|
|
while (first.getDay() !== weekday) first = addDays(first, 1);
|
|
const firstYd = getDayOfYear(first);
|
|
return Math.floor((yd - firstYd) / 7) + 1;
|
|
} else {
|
|
const daysInYear = isLeapYear(date.getFullYear()) ? 366 : 365;
|
|
const dec31 = new Date(date.getFullYear(), 11, 31);
|
|
let last = dec31;
|
|
while (last.getDay() !== weekday) last = addDays(last, -1);
|
|
const lastYd = getDayOfYear(last);
|
|
return -(Math.floor((lastYd - yd) / 7) + 1);
|
|
}
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: resolve negative/positive byMonthDay to a real date
|
|
// ---------------------------------------------------------------------------
|
|
function resolveMonthDay(year: number, month: number, day: number): Date | null {
|
|
const daysInMonth = new Date(year, month + 1, 0).getDate();
|
|
const actualDay = day > 0 ? day : daysInMonth + 1 + day;
|
|
if (actualDay < 1 || actualDay > daysInMonth) return null;
|
|
return new Date(year, month, actualDay);
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: day of year (1-indexed)
|
|
// ---------------------------------------------------------------------------
|
|
function getDayOfYear(date: Date): number {
|
|
const start = new Date(date.getFullYear(), 0, 0);
|
|
const diff = date.getTime() - start.getTime();
|
|
return Math.floor(diff / 86400000);
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Helper: day-of-year to Date
|
|
// ---------------------------------------------------------------------------
|
|
function dayOfYear(year: number, yd: number): Date | null {
|
|
const daysInYear = isLeapYear(year) ? 366 : 365;
|
|
const actual = yd > 0 ? yd : daysInYear + 1 + yd;
|
|
if (actual < 1 || actual > daysInYear) return null;
|
|
const d = new Date(year, 0, actual);
|
|
return d;
|
|
}
|
|
|
|
function isLeapYear(year: number): boolean {
|
|
return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// ISO week helpers
|
|
// ---------------------------------------------------------------------------
|
|
function getISOWeekNumber(date: Date): number {
|
|
const d = new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()));
|
|
d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay() || 7));
|
|
const yearStart = new Date(Date.UTC(d.getUTCFullYear(), 0, 1));
|
|
return Math.ceil(((d.getTime() - yearStart.getTime()) / 86400000 + 1) / 7);
|
|
}
|
|
|
|
function getISOWeeksInYear(year: number): number {
|
|
const dec28 = new Date(Date.UTC(year, 11, 28));
|
|
return getISOWeekNumber(dec28);
|
|
}
|
|
|
|
function datesInISOWeek(year: number, weekNo: number, _firstDayOfWeek: string): Date[] {
|
|
const weeksInYear = getISOWeeksInYear(year);
|
|
const actual = weekNo > 0 ? weekNo : weeksInYear + 1 + weekNo;
|
|
if (actual < 1 || actual > weeksInYear) return [];
|
|
|
|
// Find Monday of ISO week 1
|
|
const jan4 = new Date(year, 0, 4);
|
|
const dayOfWeek = jan4.getDay() || 7; // Monday=1 ... Sunday=7
|
|
const week1Monday = addDays(jan4, 1 - dayOfWeek);
|
|
const targetMonday = addDays(week1Monday, (actual - 1) * 7);
|
|
|
|
const dates: Date[] = [];
|
|
for (let i = 0; i < 7; i++) {
|
|
dates.push(addDays(targetMonday, i));
|
|
}
|
|
return dates;
|
|
}
|