feat: add timezone support to logs explorer chart (built with Chartjs)

frontend/src/components/Graph/index.tsx

@@ -1,4 +1,5 @@
 import {
+	_adapters,
 	BarController,
 	BarElement,
 	CategoryScale,
@@ -18,8 +19,10 @@ import {
 } from 'chart.js';
 import annotationPlugin from 'chartjs-plugin-annotation';
 import { generateGridTitle } from 'container/GridPanelSwitch/utils';
+import dayjs from 'dayjs';
 import { useIsDarkMode } from 'hooks/useDarkMode';
 import isEqual from 'lodash-es/isEqual';
+import { useTimezone } from 'providers/Timezone';
 import {
 	forwardRef,
 	memo,
@@ -62,6 +65,17 @@ Chart.register(
 
 Tooltip.positioners.custom = TooltipPositionHandler;
 
+// Map of Chart.js time formats to dayjs format strings
+const formatMap = {
+	'HH:mm:ss': 'HH:mm:ss',
+	'HH:mm': 'HH:mm',
+	'MM/DD HH:mm': 'MM/DD HH:mm',
+	'MM/dd HH:mm': 'MM/DD HH:mm',
+	'MM/DD': 'MM/DD',
+	'YY-MM': 'YY-MM',
+	YY: 'YY',
+};
+
 const Graph = forwardRef<ToggleGraphProps | undefined, GraphProps>(
 	(
 		{
@@ -80,11 +94,13 @@ const Graph = forwardRef<ToggleGraphProps | undefined, GraphProps>(
 			dragSelectColor,
 		},
 		ref,
+		// eslint-disable-next-line sonarjs/cognitive-complexity
 	): JSX.Element => {
 		const nearestDatasetIndex = useRef<null | number>(null);
 		const chartRef = useRef<HTMLCanvasElement>(null);
 		const isDarkMode = useIsDarkMode();
 		const gridTitle = useMemo(() => generateGridTitle(title), [title]);
+		const { timezone } = useTimezone();
 
 		const currentTheme = isDarkMode ? 'dark' : 'light';
 		const xAxisTimeUnit = useXAxisTimeUnit(data); // Computes the relevant time unit for x axis by analyzing the time stamp data
@@ -112,6 +128,22 @@ const Graph = forwardRef<ToggleGraphProps | undefined, GraphProps>(
 			return 'rgba(231,233,237,0.8)';
 		}, [currentTheme]);
 
+		// Override Chart.js date adapter to use dayjs with timezone support
+		useEffect(() => {
+			_adapters._date.override({
+				format(time: number | Date, fmt: string) {
+					const dayjsTime = dayjs(time).tz(timezone?.value);
+					const format = formatMap[fmt as keyof typeof formatMap];
+					if (!format) {
+						console.warn(`Missing datetime format for ${fmt}`);
+						return dayjsTime.format('YYYY-MM-DD HH:mm:ss'); // fallback format
+					}
+
+					return dayjsTime.format(format);
+				},
+			});
+		}, [timezone]);
+
 		const buildChart = useCallback(() => {
 			if (lineChartRef.current !== undefined) {
 				lineChartRef.current.destroy();
@@ -132,6 +164,7 @@ const Graph = forwardRef<ToggleGraphProps | undefined, GraphProps>(
 					isStacked,
 					onClickHandler,
 					data,
+					timezone,
 				);
 
 				const chartHasData = hasData(data);
@@ -166,6 +199,7 @@ const Graph = forwardRef<ToggleGraphProps | undefined, GraphProps>(
 			isStacked,
 			onClickHandler,
 			data,
+			timezone,
 			name,
 			type,
 		]);

frontend/src/components/Graph/utils.ts

@@ -1,5 +1,6 @@
 import { Chart, ChartConfiguration, ChartData, Color } from 'chart.js';
 import * as chartjsAdapter from 'chartjs-adapter-date-fns';
+import { Timezone } from 'components/CustomTimePicker/timezoneUtils';
 import dayjs from 'dayjs';
 import { MutableRefObject } from 'react';
 
@@ -50,6 +51,7 @@ export const getGraphOptions = (
 	isStacked: boolean | undefined,
 	onClickHandler: GraphOnClickHandler | undefined,
 	data: ChartData,
+	timezone: Timezone,
 	// eslint-disable-next-line sonarjs/cognitive-complexity
 ): CustomChartOptions => ({
 	animation: {
@@ -97,7 +99,7 @@ export const getGraphOptions = (
 			callbacks: {
 				title(context): string | string[] {
 					const date = dayjs(context[0].parsed.x);
-					return date.format('MMM DD, YYYY, HH:mm:ss');
+					return date.tz(timezone?.value).format('MMM DD, YYYY, HH:mm:ss');
 				},
 				label(context): string | string[] {
 					let label = context.dataset.label || '';

frontend/src/hooks/useTimezoneFormatter/useTimezoneFormatter.ts

@@ -39,24 +39,39 @@ function useTimezoneFormatter({
 		cache.clear();
 	}, [cache, userTimezone]);
 
-	const clearExpiredEntries = useCallback(() => {
+	const clearCacheEntries = useCallback(() => {
 		if (cache.size <= CACHE_SIZE_LIMIT) return;
 
 		// Sort entries by timestamp (oldest first)
 		const sortedEntries = Array.from(cache.entries()).sort(
 			(a, b) => a[1].timestamp - b[1].timestamp,
 		);
 
-		// Calculate how many entries to remove
-		const entriesToRemove = Math.floor(cache.size * CACHE_CLEANUP_PERCENTAGE);
+		// Calculate how many entries to remove (50% or overflow, whichever is larger)
+		const entriesToRemove = Math.max(
+			Math.floor(cache.size * CACHE_CLEANUP_PERCENTAGE),
+			cache.size - CACHE_SIZE_LIMIT,
+		);
 
 		// Remove oldest entries
 		sortedEntries.slice(0, entriesToRemove).forEach(([key]) => cache.delete(key));
 	}, [cache]);
 
+	/**
+	 * Formats a timestamp with the user's timezone and caches the result
+	 * @param {TimestampInput} input - The timestamp to format (string, number, or Date)
+	 * @param {string} [format='YYYY-MM-DD HH:mm:ss'] - The desired output format
+	 * @returns {string} The formatted timestamp string in the user's timezone
+	 * @example
+	 * // Input: UTC timestamp
+	 * // User timezone: 'UTC - 4'
+	 * // Returns: "2024-03-14 15:30:00"
+	 * formatTimezoneAdjustedTimestamp('2024-03-14T19:30:00Z')
+	 */
 	const formatTimezoneAdjustedTimestamp = useCallback(
 		(input: TimestampInput, format = 'YYYY-MM-DD HH:mm:ss'): string => {
-			const cacheKey = `${input}_${format}_${userTimezone?.value}`;
+			const timestamp = dayjs(input).valueOf();
+			const cacheKey = `${timestamp}_${userTimezone?.value}`;
 
 			// Check cache first
 			const cachedValue = cache.get(cacheKey);
@@ -74,22 +89,12 @@ function useTimezoneFormatter({
 
 			// Clear expired entries and enforce size limit
 			if (cache.size > CACHE_SIZE_LIMIT) {
-				clearExpiredEntries();
-
-				// If still over limit, remove oldest entries
-				const entriesToDelete = cache.size - CACHE_SIZE_LIMIT;
-				if (entriesToDelete > 0) {
-					const entries = Array.from(cache.entries());
-					entries
-						.sort((a, b) => a[1].timestamp - b[1].timestamp)
-						.slice(0, entriesToDelete)
-						.forEach(([key]) => cache.delete(key));
-				}
+				clearCacheEntries();
 			}
 
 			return formattedValue;
 		},
-		[cache, clearExpiredEntries, userTimezone],
+		[cache, clearCacheEntries, userTimezone],
 	);
 
 	return { formatTimezoneAdjustedTimestamp };