Automatic Daylight Saving and Date Adjustments

pages/alarms.tsx

@@ -120,7 +120,7 @@ const Alarms: NextPage = () => {
   const [serverTime, setServerTime] = useState<DateTime>(
     currDate.setZone(regionTZ)
   )
-  const [selectedDate, setSelectedDate] = useState(currDate.setZone(regionTZ))
+  const [selectedDate, setSelectedDate] = useState(currDate.setZone(regionTZ).set({hour: 0, minute: 0, second: 0, millisecond: 0}))
 
   const [gameEvents, setGameEvents] = useState<Array<GameEvent> | undefined>(
     undefined
@@ -185,7 +185,7 @@ const Alarms: NextPage = () => {
     if (regionTZ !== undefined) {
       setMounted(true)
       setServerTime(currDate.setZone(regionTZ))
-      setSelectedDate(currDate.setZone(regionTZ))
+      setSelectedDate(currDate.setZone(regionTZ).set({hour: 0, minute: 0, second: 0, millisecond: 0}))
     }
   }, [regionTZ])
 
@@ -200,14 +200,14 @@ const Alarms: NextPage = () => {
   useEffect(() => {
     const timer = setInterval(() => {
       let now = DateTime.now()
-      if (currDate.endOf('day').diffNow().toMillis() < 0) setSelectedDate(now)
+      if (serverTime.endOf('day').diffNow().toMillis() < 0) setSelectedDate(now.setZone(regionTZ).set({hour: 0, minute: 0, second: 0, millisecond: 0}))
       setCurrDate(now)
       setServerTime(now.setZone(regionTZ))
     }, 1000)
     return () => {
       clearInterval(timer) // Return a function to clear the timer so that it will stop being called on unmount
     }
-  }, [regionTZ, view24HrTime, viewLocalizedTime, selectedDate])
+  }, [regionTZ, view24HrTime, viewLocalizedTime, selectedDate, serverTime.day])
 
   // clear disabled alarm when alarm expires
   useEffect(() => {
@@ -539,7 +539,7 @@ const Alarms: NextPage = () => {
             </button>
             <button
               className="btn relative text-2xl text-stone-200"
-              onClick={(e) => setSelectedDate(serverTime)}
+              onClick={(e) => setSelectedDate(serverTime.setZone(regionTZ).set({hour: 0, minute: 0, second: 0, millisecond: 0}))}
             >
               <span>
                 {selectedDate.monthLong} {selectedDate.day}

util/static.ts

@@ -1,9 +1,23 @@
 import { RegionKey } from './types/types'
+import { DateTime } from 'luxon'
+
+/* IANA Codes relative to approximate AWS server locations, as per http://ec2-reachability.amazonaws.com/
+  NA East: America/New_York (Herndon, VA, US)
+  NA West: America/Los_Angeles (San Francisco, CA, US)
+  EU Central: Europe/Berlin (Frankfurt, Germany)
+  EU West: Europe/Dublin (Dublin, Ireland)
+  South America: America/Sao_Paulo (São Paulo, Brazil)
+*/
+
+function DSTOffset(IANAString: string): string {
+  const offset = DateTime.now().setZone(IANAString).get('offset') / 60 || 0
+  return (`UTC${offset >= 0 ? "+" + offset : offset}`) // UTC+offset, UTC-offset
+}
 
 export const RegionTimeZoneMapping: { [K in RegionKey]: string } = {
-  'US West': 'UTC-7',
-  'US East': 'UTC-4',
-  'EU Central': 'UTC+1',
-  'EU West': 'UTC-0',
-  'South America': 'UTC-4',
+  'US West': DSTOffset('America/Los_Angeles'),
+  'US East': DSTOffset('America/New_York'),
+  'EU Central': DSTOffset('Europe/Berlin'),
+  'EU West': DSTOffset('Europe/Dublin'),
+  'South America': DSTOffset('America/Sao_Paulo'),
 }