feat: dateformat and timezone customization (#506)

packages/lib/constants/time-zones.ts

@@ -0,0 +1,44 @@
+import { rawTimeZones, timeZonesNames } from '@vvo/tzdb';
+
+export const TIME_ZONE_DATA = rawTimeZones;
+
+export const DEFAULT_DOCUMENT_TIME_ZONE = 'Etc/UTC';
+
+export type TimeZone = {
+  name: string;
+  rawOffsetInMinutes: number;
+};
+
+export const minutesToHours = (minutes: number): string => {
+  const hours = Math.abs(Math.floor(minutes / 60));
+  const min = Math.abs(minutes % 60);
+  const sign = minutes >= 0 ? '+' : '-';
+
+  return `${sign}${String(hours).padStart(2, '0')}:${String(min).padStart(2, '0')}`;
+};
+
+const getGMTOffsets = (timezones: TimeZone[]): string[] => {
+  const gmtOffsets: string[] = [];
+
+  for (const timezone of timezones) {
+    const offsetValue = minutesToHours(timezone.rawOffsetInMinutes);
+    const gmtText = `(${offsetValue})`;
+
+    gmtOffsets.push(`${timezone.name} ${gmtText}`);
+  }
+
+  return gmtOffsets;
+};
+
+export const splitTimeZone = (input: string | null): string => {
+  if (input === null) {
+    return '';
+  }
+  const [timeZone] = input.split('(');
+
+  return timeZone.trim();
+};
+
+export const TIME_ZONES_FULL = getGMTOffsets(TIME_ZONE_DATA);
+
+export const TIME_ZONES = ['Etc/UTC', ...timeZonesNames];