initial commit of the paytime session frontend

discord_verificiation/playtime-frontend/lib/dates.ts

@@ -0,0 +1,14 @@
+import { parseDbDateTime } from './timezone';
+
+// Parses a MySQL DATETIME string correctly regardless of the Node
+// process's own timezone — see lib/timezone.ts.
+export function parseDbDate(s: string): Date {
+  return parseDbDateTime(s);
+}
+
+export function diffMinutes(startStr: string, endStr: string | null): number | null {
+  if (!endStr) return null;
+  const start = parseDbDate(startStr);
+  const end = parseDbDate(endStr);
+  return Math.round((end.getTime() - start.getTime()) / 60000);
+}