initial commit of the paytime session frontend

discord_verificiation/playtime-frontend/lib/timezone.ts

@@ -0,0 +1,58 @@
+// The MySQL server stores/returns naive DATETIME strings (no timezone
+// attached) representing wall-clock time in this zone. Hardcoded here and
+// used via native Intl APIs rather than relying on the Node process's own
+// TZ environment variable — this makes date handling correct regardless of
+// how the process is deployed/restarted, sidestepping an entire class of
+// "did the env var actually reload" deployment issues.
+const DB_TIMEZONE = 'Europe/Berlin';
+
+const partsFormatter = new Intl.DateTimeFormat('en-US', {
+  timeZone: DB_TIMEZONE,
+  year: 'numeric',
+  month: '2-digit',
+  day: '2-digit',
+  hour: '2-digit',
+  minute: '2-digit',
+  second: '2-digit',
+  hour12: false,
+});
+
+function getParts(date: Date): Record<string, string> {
+  const parts: Record<string, string> = {};
+  for (const p of partsFormatter.formatToParts(date)) {
+    if (p.type !== 'literal') parts[p.type] = p.value;
+  }
+  if (parts.hour === '24') parts.hour = '00'; // some locales report midnight as 24
+  return parts;
+}
+
+/**
+ * Parses a MySQL DATETIME string (e.g. "2026-08-21 15:31:15"), which
+ * represents a wall-clock moment in DB_TIMEZONE, into the correct absolute
+ * Date/instant — regardless of the Node process's own configured timezone.
+ */
+export function parseDbDateTime(dbString: string): Date {
+  const naiveUTC = new Date(`${dbString.replace(' ', 'T')}Z`);
+  const parts = getParts(naiveUTC);
+  const asIfLocal = Date.UTC(
+    Number(parts.year),
+    Number(parts.month) - 1,
+    Number(parts.day),
+    Number(parts.hour),
+    Number(parts.minute),
+    Number(parts.second),
+  );
+  const offsetMs = naiveUTC.getTime() - asIfLocal;
+  return new Date(naiveUTC.getTime() + offsetMs);
+}
+
+/**
+ * Converts an absolute Date/instant into a MySQL DATETIME string
+ * ("YYYY-MM-DD HH:MM:SS") representing that instant's wall-clock time in
+ * DB_TIMEZONE — for building query parameters that compare correctly
+ * against stored DATETIME columns.
+ */
+export function formatDbDateTime(date: Date): string {
+  const parts = getParts(date);
+  return `${parts.year}-${parts.month}-${parts.day} ${parts.hour}:${parts.minute}:${parts.second}`;
+}