Fix timezone conversion logic (#11444)

* Fix timezone conversion logic

* Use function for consistency

* Cleanup

web/src/components/player/PreviewPlayer.tsx

@@ -10,7 +10,7 @@ import useSWR from "swr";
 import { FrigateConfig } from "@/types/frigateConfig";
 import { Preview } from "@/types/preview";
 import { PreviewPlayback } from "@/types/playback";
-import { getUTCOffset, isCurrentHour } from "@/utils/dateUtil";
+import { getTimestampOffset, isCurrentHour } from "@/utils/dateUtil";
 import { baseUrl } from "@/api/baseUrl";
 import { isAndroid, isChrome, isMobile } from "react-device-detect";
 import { TimeRange } from "@/types/timeline";
@@ -41,8 +41,7 @@ export default function PreviewPlayer({
   const [currentHourFrame, setCurrentHourFrame] = useState<string>();
 
   const currentPreview = useMemo(() => {
-    const timeRangeOffset =
-      (getUTCOffset(new Date(timeRange.before * 1000)) % 60) * 60;
+    const timeRangeOffset = getTimestampOffset(timeRange.before);
 
     return cameraPreviews.find(
       (preview) =>
@@ -233,8 +232,8 @@ function PreviewVideoPlayer({
       return;
     }
 
-    const timeRangeOffset =
-      getUTCOffset(new Date(timeRange.before * 1000)) % 60;
+    // account for minutes offset in timezone
+    const timeRangeOffset = getTimestampOffset(timeRange.before);
 
     const preview = cameraPreviews.find(
       (preview) =>

web/src/components/player/dynamic/DynamicVideoPlayer.tsx

@@ -12,7 +12,7 @@ import ActivityIndicator from "@/components/indicators/activity-indicator";
 import { VideoResolutionType } from "@/types/live";
 import axios from "axios";
 import { cn } from "@/lib/utils";
-import { getUTCOffset } from "@/utils/dateUtil";
+import { getTimestampOffset } from "@/utils/dateUtil";
 
 /**
  * Dynamically switches between video playback and scrubbing preview player.
@@ -149,8 +149,7 @@ export default function DynamicVideoPlayer({
   // state of playback player
 
   const recordingParams = useMemo(() => {
-    const timeRangeOffset =
-      (getUTCOffset(new Date(timeRange.before * 1000)) % 60) * 60;
+    const timeRangeOffset = getTimestampOffset(timeRange.before);
 
     return {
       before: timeRange.before + timeRangeOffset,

web/src/pages/Events.tsx

@@ -11,7 +11,7 @@ import {
   ReviewSeverity,
   ReviewSummary,
 } from "@/types/review";
-import { getUTCOffset } from "@/utils/dateUtil";
+import { getTimestampOffset } from "@/utils/dateUtil";
 import EventView from "@/views/events/EventView";
 import { RecordingView } from "@/views/events/RecordingView";
 import axios from "axios";
@@ -167,7 +167,8 @@ export default function Events() {
       return undefined;
     }
 
-    const timezoneMinuteOffset = (getUTCOffset(new Date()) % 60) * 60;
+    // offset by timezone minutes
+    const timestampOffset = getTimestampOffset(Date.now() / 1000);
 
     const startDate = new Date();
     startDate.setMinutes(0, 0, 0);
@@ -176,8 +177,8 @@ export default function Events() {
     endDate.setHours(0, 0, 0, 0);
 
     return {
-      after: startDate.getTime() / 1000 + timezoneMinuteOffset,
-      before: endDate.getTime() / 1000 + timezoneMinuteOffset,
+      after: startDate.getTime() / 1000 + timestampOffset,
+      before: endDate.getTime() / 1000 + timestampOffset,
     };
   }, [reviews]);
 

web/src/utils/dateUtil.ts

@@ -269,6 +269,15 @@ export const getUTCOffset = (
   );
 };
 
+/**
+ * Gets the minute offset in seconds of the current timezone from UTC.
+ * Any timezones with an offset in hours will return 0,
+ * any timezones with an offset of 30 or 45 minutes will return that amount in seconds.
+ */
+export function getTimestampOffset(timestamp: number) {
+  return (getUTCOffset(new Date(timestamp * 1000)) % 60) * 60;
+}
+
 export function getRangeForTimestamp(timestamp: number) {
   const date = new Date(timestamp * 1000);
   date.setMinutes(0, 0, 0);

web/src/utils/timelineUtil.tsx

@@ -20,7 +20,7 @@ import {
   MdOutlinePictureInPictureAlt,
 } from "react-icons/md";
 import { FaBicycle } from "react-icons/fa";
-import { endOfHourOrCurrentTime, getUTCOffset } from "./dateUtil";
+import { endOfHourOrCurrentTime } from "./dateUtil";
 import { TimeRange, Timeline } from "@/types/timeline";
 
 export function getTimelineIcon(timelineItem: Timeline) {
@@ -131,25 +131,13 @@ export function getChunkedTimeDay(timeRange: TimeRange): TimeRange[] {
   endOfThisHour.setSeconds(0, 0);
   const data: TimeRange[] = [];
   const startDay = new Date(timeRange.after * 1000);
-  const timezoneMinuteOffset =
-    getUTCOffset(new Date(timeRange.before * 1000)) % 60;
-
-  if (timezoneMinuteOffset == 0) {
-    startDay.setMinutes(0, 0, 0);
-  } else {
-    startDay.setSeconds(0, 0);
-  }
+  startDay.setMinutes(0, 0, 0);
 
   let start = startDay.getTime() / 1000;
   let end = 0;
 
   for (let i = 0; i < 24; i++) {
-    startDay.setHours(
-      startDay.getHours() + 1,
-      Math.abs(timezoneMinuteOffset),
-      0,
-      0,
-    );
+    startDay.setHours(startDay.getHours() + 1, 0, 0, 0);
 
     if (startDay > endOfThisHour) {
       break;