M33: enforce booking readiness workflow

frontend/src/i18n/brusselsDateTime.ts

@@ -0,0 +1,46 @@
+const BRUSSELS_TIME_ZONE = "Europe/Brussels";
+
+const partsFormatter = new Intl.DateTimeFormat("en-CA", {
+  timeZone: BRUSSELS_TIME_ZONE,
+  year: "numeric",
+  month: "2-digit",
+  day: "2-digit",
+  hour: "2-digit",
+  minute: "2-digit",
+  second: "2-digit",
+  hourCycle: "h23",
+});
+
+function partsAt(value: Date): Record<string, string> {
+  return Object.fromEntries(
+    partsFormatter.formatToParts(value)
+      .filter((part) => part.type !== "literal")
+      .map((part) => [part.type, part.value]),
+  );
+}
+
+export function toBrusselsDateTimeLocal(value: Date): string {
+  const parts = partsAt(value);
+  return `${parts.year}-${parts.month}-${parts.day}T${parts.hour}:${parts.minute}`;
+}
+
+export function brusselsDateTimeFromNow(hours: number): string {
+  const value = new Date(Date.now() + hours * 60 * 60 * 1000);
+  value.setUTCMinutes(0, 0, 0);
+  return toBrusselsDateTimeLocal(value);
+}
+
+/** Convert a Fleet Ops Europe/Brussels wall-clock value to an unambiguous UTC instant. */
+export function brusselsLocalToIso(value: string): string {
+  const match = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})$/.exec(value);
+  if (!match) throw new Error("Invalid Brussels date-time");
+  const [, year, month, day, hour, minute] = match;
+  const wallClockUtc = Date.UTC(+year, +month - 1, +day, +hour, +minute);
+  let candidate = wallClockUtc;
+  for (let iteration = 0; iteration < 3; iteration += 1) {
+    const parts = partsAt(new Date(candidate));
+    const represented = Date.UTC(+parts.year, +parts.month - 1, +parts.day, +parts.hour, +parts.minute);
+    candidate += wallClockUtc - represented;
+  }
+  return new Date(candidate).toISOString();
+}