Integrate LiveKit SFU and harden booking workflow

lib/booking/slots.ts

@@ -1,10 +1,9 @@
 import type { Payload } from "payload";
 import { WEEKDAYS } from "@/collections/Availability";
+import { berlinParts, berlinWallTimeToUTC, type CalendarDate } from "@/lib/calendar/timezone";
 
 export type TimeSlot = { start: Date; end: Date };
 
-const BERLIN_TZ = "Europe/Berlin";
-
 const WEEKDAY_BY_INDEX = [
   "sunday",
   "monday",
@@ -15,44 +14,12 @@ const WEEKDAY_BY_INDEX = [
   "saturday",
 ] as const;
 
-type CalendarDate = { year: number; month: number; day: number };
-
 // Availability/AvailabilityOverrides times are entered by the admin in their
 // browser (Europe/Berlin) and stored as UTC instants. All wall-clock reads
 // and writes here go through Intl's Berlin timezone data (not local Date
 // accessors, and not manual UTC+1/+2 arithmetic), so the server process's
 // own timezone (this app runs in UTC in production) never leaks into the
 // computed availability — see lib/calendar/timezone.ts for the same pattern.
-function berlinParts(date: Date): CalendarDate & { hour: number; minute: number } {
-  const parts = new Intl.DateTimeFormat("en-US", {
-    timeZone: BERLIN_TZ,
-    year: "numeric",
-    month: "2-digit",
-    day: "2-digit",
-    hour: "2-digit",
-    minute: "2-digit",
-    hourCycle: "h23",
-  }).formatToParts(date);
-  const get = (type: string) => Number(parts.find((p) => p.type === type)?.value ?? "0");
-  return { year: get("year"), month: get("month"), day: get("day"), hour: get("hour"), minute: get("minute") };
-}
-
-function berlinOffsetMinutes(date: Date): number {
-  const tzName = new Intl.DateTimeFormat("en-US", { timeZone: BERLIN_TZ, timeZoneName: "shortOffset" })
-    .formatToParts(date)
-    .find((p) => p.type === "timeZoneName")?.value ?? "GMT+1";
-  const match = tzName.match(/GMT([+-]\d+)(?::(\d+))?/);
-  const hours = match ? Number(match[1]) : 1;
-  const minutes = match?.[2] ? Number(match[2]) : 0;
-  return hours * 60 + (hours < 0 ? -minutes : minutes);
-}
-
-/** Converts a Europe/Berlin wall-clock date+time into the UTC instant it represents. */
-function berlinWallTimeToUTC(date: CalendarDate, hour: number, minute: number): Date {
-  const guess = Date.UTC(date.year, date.month - 1, date.day, hour, minute);
-  return new Date(guess - berlinOffsetMinutes(new Date(guess)) * 60_000);
-}
-
 function dateKey(date: Date): string {
   const { year, month, day } = berlinParts(date);
   return `${year}-${String(month).padStart(2, "0")}-${String(day).padStart(2, "0")}`;