feat: add "local time" default option to TimezonepickerInput (#1969)

packages/date/src/TimezonePickerInput.tsx

@@ -4,7 +4,6 @@ import { Select } from '@contentful/f36-components';
 
 import { zoneOffsets, defaultZoneOffset } from './utils/zoneOffsets';
 
-
 export type TimezonepickerProps = {
   disabled: boolean;
   onChange: (value: string) => void;
@@ -23,10 +22,11 @@ export const TimezonepickerInput = ({
       isDisabled={disabled}
       onChange={(e: ChangeEvent<HTMLSelectElement>) => {
         onChange(e.currentTarget.value);
-      }}>
+      }}
+    >
       {zoneOffsets.map((offset) => (
         <Select.Option key={offset} value={offset}>
-          UTC{offset}
+          {offset === defaultZoneOffset ? offset : `UTC${offset}`}
         </Select.Option>
       ))}
     </Select>

packages/date/src/utils/date.ts

@@ -1,13 +1,10 @@
 // eslint-disable-next-line -- TODO: move to date-fns
 import moment from 'moment';
 import { TimeResult } from '../types';
+import { defaultZoneOffset } from './zoneOffsets';
 
 const ZONE_RX = /(Z|[+-]\d{2}[:+]?\d{2})$/;
 
-function startOfToday(format: string) {
-  return moment().set({ hours: 0, minutes: 0 }).format(format);
-}
-
 function fieldValueToMoment(datetimeString: string | null | undefined): moment.Moment | null {
   if (!datetimeString) {
     return null;
@@ -42,9 +39,15 @@ function datetimeFromUserInput(input: TimeResult): {
   }
 
   const time = timeFromUserInput(input);
+  let utcOffset = input.utcOffset;
+
+  // If we have the default local offset, compute the local offset for the specified date
+  if (utcOffset === defaultZoneOffset) {
+    utcOffset = computeLocalZoneOffset(input.date, time);
+  }
 
   const date = moment
-    .parseZone(input.utcOffset, 'Z')
+    .parseZone(utcOffset, 'Z')
     .set(input.date.toObject())
     .set({ hours: time.hours(), minutes: time.minutes() });
 
@@ -93,7 +96,32 @@ export function getDefaultAMPM() {
 }
 
 export function getDefaultUtcOffset() {
-  return startOfToday('Z');
+  return defaultZoneOffset;
+}
+
+/**
+ * Compute the local zone offset for the specified date and time.
+ *
+ * @param date - The moment object for the date
+ * @param time - Optional moment with time
+ * @returns The offset as a string (e.g., "-08:00", "+05:30")
+ */
+export function computeLocalZoneOffset(date: moment.Moment, time?: moment.Moment): string {
+  let targetMoment = date.clone();
+  if (time) {
+    targetMoment = targetMoment.set({
+      hour: time.hour(),
+      minute: time.minute(),
+      second: 0,
+      millisecond: 0,
+    });
+  } else {
+    // Default to midnight
+    targetMoment = targetMoment.startOf('day');
+  }
+
+  // Format as string (e.g., "-08:00", "+05:30")
+  return targetMoment.format('Z');
 }
 
 /**
@@ -109,12 +137,17 @@ export function userInputFromDatetime({
   const datetime = fieldValueToMoment(value);
 
   if (datetime) {
+    let utcOffset = datetime.format('Z');
+    const localOffset = computeLocalZoneOffset(datetime);
+    if (utcOffset === localOffset) {
+      utcOffset = defaultZoneOffset;
+    }
     const timeFormat = uses12hClock ? 'hh:mm' : 'HH:mm';
     return {
       date: datetime,
       time: datetime.format(timeFormat),
       ampm: datetime.format('A'),
-      utcOffset: datetime.format('Z'),
+      utcOffset: utcOffset,
     };
   } else {
     return {

packages/date/src/utils/zoneOffsets.ts

@@ -1,6 +1,7 @@
-export const defaultZoneOffset = '+00:00';
+export const defaultZoneOffset = 'Local time';
 
 export const zoneOffsets = [
+  'Local time',
   '-12:00',
   '-11:00',
   '-10:00',