feat: chat list timestamp (#426)

src/lib/utils/format.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest'
-import { toDecimal, toSignificantString, toBigInt } from './format'
+import { toDecimal, toSignificantString, toBigInt, formatTimestamp } from './format'
 
 describe('toDecimal', () => {
 	const testValues = [
@@ -55,3 +55,24 @@ describe('toBigInt', () => {
 		})
 	})
 })
+
+describe('formatTimestamp', () => {
+	const currentDate = new Date(1695301187859)
+	const testValues = [
+		{ timestamp: 1695292194040, expectedOut: '12:29' },
+		{ timestamp: 1695292052039, expectedOut: '12:27' },
+		{ timestamp: 1695215231556, expectedOut: 'Wed' },
+		{ timestamp: 1695213720514, expectedOut: 'Wed' },
+		{ timestamp: 1695213620936, expectedOut: 'Wed' },
+		{ timestamp: 1695136556259, expectedOut: 'Tue' },
+		{ timestamp: 1695062899168, expectedOut: 'Mon' },
+		{ timestamp: 1694447288453, expectedOut: 'Sep 11' },
+		{ timestamp: 1694258558099, expectedOut: 'Sep 9' },
+	]
+
+	testValues.forEach(({ timestamp, expectedOut }) => {
+		it(`with timestamp=${timestamp} should return ${expectedOut}`, () => {
+			expect(formatTimestamp(timestamp, currentDate)).toEqual(expectedOut)
+		})
+	})
+})

src/lib/utils/format.ts

@@ -96,3 +96,57 @@ export function formatDateAndTime(timestamp: number) {
 	const dateTime = timeFormat.format(date)
 	return `${dateString} at ${dateTime}`
 }
+
+export function formatTimestamp(timestamp: number, currentDate = new Date()) {
+	if (timestamp <= 0) {
+		return ''
+	}
+
+	const locale = new Intl.DateTimeFormat().resolvedOptions().locale
+	const date = new Date(timestamp)
+
+	// today at 00:00
+	const today = new Date(
+		currentDate.getFullYear(),
+		currentDate.getMonth(),
+		currentDate.getDate(),
+		0,
+		0,
+		0,
+		0,
+	)
+
+	// a week before `today`
+	// this is used for the calculating a day, but it should not include
+	// the same day twice, hence we only count the last 6 days
+	const lastWeek = new Date(today.valueOf() - 6 * 24 * 60 * 60 * 1000)
+
+	// if it is today, show only the time with a 24 hour clock
+	if (timestamp >= today.valueOf()) {
+		const timeFormat = new Intl.DateTimeFormat(locale, {
+			hour: 'numeric',
+			minute: 'numeric',
+			hour12: false,
+		})
+		const dateTime = timeFormat.format(date)
+
+		return dateTime
+	}
+
+	// if it is last week, show only the day of the week
+	if (timestamp >= lastWeek.valueOf()) {
+		const dayFormat = new Intl.DateTimeFormat(locale, {
+			weekday: 'short',
+		})
+
+		return dayFormat.format(date)
+	}
+
+	// if it is older than a week, show the month and day
+	const dateFormat = new Intl.DateTimeFormat(locale, {
+		month: 'short',
+		day: 'numeric',
+	})
+
+	return dateFormat.format(date)
+}

src/routes/+page.svelte

@@ -20,6 +20,7 @@
 	import AuthenticatedOnly from '$lib/components/authenticated-only.svelte'
 	import Layout from '$lib/components/layout.svelte'
 	import Events from '$lib/components/icons/events.svelte'
+	import { formatTimestamp } from '$lib/utils/format'
 
 	$: orderedChats = Array.from($chats.chats)
 		.map(([, chat]) => chat)
@@ -184,6 +185,9 @@
 														</Badge>
 													{/if}
 												</span>
+												<span class="timestamp">
+													{formatTimestamp(lastMessage?.timestamp ?? 0)}
+												</span>
 											</div>
 											<p class={`message text-serif ${myMessage ? 'my-message' : ''}`}>
 												{#if chat.joined}