fix

apps/web/app/components/UpcomingReminders.tsx

@@ -37,6 +37,7 @@ export function UpcomingReminders({ reminders, className }: Props) {
             sortedReminders.map((reminder, index) => (
               <div key={index} className="flex flex-col gap-1 p-4 border rounded">
                 <div className="text-sm text-default-500">
+                  {reminder.sendAt}
                   {locale === 'ja'
                     ? `${dateTimeFormatter.format(parseISO(reminder.sendAt))}に通知`
                     : `Notify at ${dateTimeFormatter.format(parseISO(reminder.sendAt))}`}

packages/usecase/package.json

@@ -16,6 +16,7 @@
     "@synk-cal/core": "workspace:*",
     "@synk-cal/repository": "workspace:*",
     "date-fns": "^4.1.0",
+    "date-fns-tz": "^3.2.0",
     "eta": "^3.5.0"
   },
   "devDependencies": {

packages/usecase/src/get_remind_targets.test.ts

@@ -166,7 +166,7 @@ describe('getRemindTargets', () => {
 
     expect(targets).toEqual([
       {
-        sendAt: parseISO('2023-06-01T10:00:00Z'),
+        sendAt: parseISO('2023-06-01T19:00:00Z'),
         notificationType: 'console',
         target: '[email protected]',
         message: 'Custom reminder: Event 1 tomorrow at 01:00.',
@@ -211,13 +211,13 @@ describe('getRemindTargets', () => {
 
     expect(targets).toEqual([
       {
-        sendAt: parseISO('2023-06-01T10:00:00Z'),
+        sendAt: parseISO('2023-06-01T19:00:00Z'),
         notificationType: 'console',
         target: '[email protected]',
         message: 'Custom reminder: Event 1 tomorrow at 01:00.',
       },
       {
-        sendAt: parseISO('2023-06-01T10:00:00Z'),
+        sendAt: parseISO('2023-06-01T19:00:00Z'),
         notificationType: 'webhook',
         target: '[email protected]',
         message: 'Custom reminder: Event 1 tomorrow at 01:00.',

packages/usecase/src/get_remind_targets.ts

@@ -1,6 +1,7 @@
 import type { CalendarRepository, GroupRepository, ReminderSetting, ReminderSettingsRepository } from '@synk-cal/core'
 import { config } from '@synk-cal/core'
-import { parseISO, subDays, subMinutes } from 'date-fns'
+import { parseISO, setHours, setMinutes, subDays, subMinutes } from 'date-fns'
+import { fromZonedTime, toZonedTime } from 'date-fns-tz'
 import { Eta } from 'eta'
 import { getEvents } from './get_events'
 
@@ -14,32 +15,10 @@ export const getReminderTime = (eventStart: Date, setting: ReminderSetting) => {
   if ('minutesBefore' in setting) {
     return subMinutes(eventStart, setting.minutesBefore)
   } else {
-    const formatter = new Intl.DateTimeFormat('en-US', {
-      timeZone: config.TIMEZONE,
-      year: 'numeric',
-      month: '2-digit',
-      day: '2-digit',
-      hour: '2-digit',
-      minute: '2-digit',
-      second: '2-digit',
-      hour12: false,
-    })
-
-    const parts = formatter.formatToParts(eventStart)
-    // @ts-expect-error
-    const dateValues: Record<Intl.DateTimeFormatPartTypes, number> = {}
-    parts.forEach((part) => {
-      if (part.type !== 'literal') {
-        dateValues[part.type] = parseInt(part.value, 10)
-      }
-    })
-
-    let localDate = new Date(
-      Date.UTC(dateValues.year, dateValues.month - 1, dateValues.day, setting.hour, setting.minute, dateValues.second),
-    )
-    localDate = subDays(localDate, 1)
-    const offset = -new Date(new Date().toLocaleString('en-US', { timeZone: config.TIMEZONE })).getTimezoneOffset()
-    return new Date(localDate.getTime() - offset * 60 * 1000)
+    const zonedDate = toZonedTime(eventStart, config.TIMEZONE)
+    const previousDay = subDays(zonedDate, 1)
+    const previousDayAt = setMinutes(setHours(previousDay, setting.hour), setting.minute)
+    return fromZonedTime(previousDayAt, config.TIMEZONE)
   }
 }