update: integrate ics calendar

src/lib/calendarAvailability.js

@@ -0,0 +1,57 @@
+const { parisWallClockToUTC } = require('./calendarDates');
+
+// Default rehearsal-availability windows, Europe/Paris local time — used
+// whenever no admin-configured slotConfig is passed in (and by the pure-logic
+// tests below, so those keep testing this exact default without needing to
+// know about the DB-backed override path in calendarRepo/calendarSync).
+const DEFAULT_SLOT_CONFIG = {
+  weekday: { startHour: 18, startMinute: 30, endHour: 21, endMinute: 0 },
+  weekend: { startHour: 15, startMinute: 0, endHour: 19, endMinute: 0 },
+};
+const MAX_WEEKS = 3;
+
+// One slot per day for the next `weeks` weeks (capped at 3, same as the rest
+// of the calendar feature), starting from today's Paris-local calendar date
+// — not the server's own timezone, which may not be Europe/Paris.
+function generateSlots(weeks = MAX_WEEKS, slotConfig = DEFAULT_SLOT_CONFIG) {
+  const days = Math.min(weeks || MAX_WEEKS, MAX_WEEKS) * 7;
+  const parisToday = new Intl.DateTimeFormat('en-CA', { timeZone: 'Europe/Paris' }).format(new Date());
+  const [ty, tm, td] = parisToday.split('-').map(Number);
+  const anchor = Date.UTC(ty, tm - 1, td);
+
+  const slots = [];
+  for (let i = 0; i < days; i++) {
+    // This is only ever used to walk calendar dates one day at a time, never
+    // treated as a real instant — the actual Paris-local conversion happens
+    // below via parisWallClockToUTC, so there's no timezone ambiguity here.
+    const dayAnchor = new Date(anchor + i * 86400000);
+    const year = dayAnchor.getUTCFullYear();
+    const month = dayAnchor.getUTCMonth() + 1;
+    const day = dayAnchor.getUTCDate();
+    const isWeekend = dayAnchor.getUTCDay() === 0 || dayAnchor.getUTCDay() === 6;
+    const spec = isWeekend ? slotConfig.weekend : slotConfig.weekday;
+
+    slots.push({
+      lower: parisWallClockToUTC(year, month, day, spec.startHour, spec.startMinute),
+      upper: parisWallClockToUTC(year, month, day, spec.endHour, spec.endMinute),
+    });
+  }
+  return slots;
+}
+
+// intervals: [{start: Date, end: Date}] — flat, already-expanded busy blocks
+// (recurring events expanded, all-day events resolved to a concrete local-day
+// span) so this stays a plain half-open-interval overlap check.
+function isBusyDuring(intervals, slotLower, slotUpper) {
+  return intervals.some((interval) => interval.start < slotUpper && interval.end > slotLower);
+}
+
+// Widens a slot by `marginMinutes` on each side — used only for the busy/free
+// check (to account for travel time between back-to-back calendar events),
+// never for the slot that actually gets stored/displayed.
+function widenWindow(lower, upper, marginMinutes) {
+  const marginMs = (marginMinutes || 0) * 60000;
+  return { lower: new Date(lower.getTime() - marginMs), upper: new Date(upper.getTime() + marginMs) };
+}
+
+module.exports = { generateSlots, isBusyDuring, widenWindow, DEFAULT_SLOT_CONFIG };