lightbox: Use a friendlier format for the date

assets/l10n/app_en.arb

@@ -680,5 +680,29 @@
   "emojiPickerSearchEmoji": "Search emoji",
   "@emojiPickerSearchEmoji": {
     "description": "Hint text for the emoji picker search text field."
+  },
+  "aFewSecondsAgo": "A few seconds ago",
+  "@aFewSecondsAgo": {
+    "description": "Message displayed when the difference between the current time and the given time is less than 60 seconds."
+  },
+  "oneMinuteAgo": "1 minute ago",
+  "@oneMinuteAgo": {
+    "description": "Message displayed when the difference between the current time and the given time is exactly 1 minute."
+  },
+  "minutesAgo": "{minutes} minutes ago",
+  "@minutesAgo": {
+    "description": "Message displayed when the difference between the current time and the given time is in minutes. The placeholder {minutes} will be replaced with the actual number of minutes."
+  },
+  "todayAt": "Today at {time}",
+  "@todayAt": {
+    "description": "Message displayed when the given time is from today. The placeholder {time} will be replaced with the formatted time."
+  },
+  "yesterdayAt": "Yesterday at {time}",
+  "@yesterdayAt": {
+    "description": "Message displayed when the given time is from yesterday. The placeholder {time} will be replaced with the formatted time."
+  },
+  "dateAtTime": "{date} at {time}",
+  "@dateAtTime": {
+    "description": "Message displayed when the given time is older than yesterday. The placeholder {date} will be replaced with the formatted date and {time} with the formatted time."
   }
 }

lib/generated/l10n/zulip_localizations.dart

@@ -1014,6 +1014,42 @@ abstract class ZulipLocalizations {
   /// In en, this message translates to:
   /// **'Search emoji'**
   String get emojiPickerSearchEmoji;
+
+  /// Message displayed when the difference between the current time and the given time is less than 60 seconds.
+  ///
+  /// In en, this message translates to:
+  /// **'A few seconds ago'**
+  String get aFewSecondsAgo;
+
+  /// Message displayed when the difference between the current time and the given time is exactly 1 minute.
+  ///
+  /// In en, this message translates to:
+  /// **'1 minute ago'**
+  String get oneMinuteAgo;
+
+  /// Message displayed when the difference between the current time and the given time is in minutes. The placeholder {minutes} will be replaced with the actual number of minutes.
+  ///
+  /// In en, this message translates to:
+  /// **'{minutes} minutes ago'**
+  String minutesAgo(Object minutes);
+
+  /// Message displayed when the given time is from today. The placeholder {time} will be replaced with the formatted time.
+  ///
+  /// In en, this message translates to:
+  /// **'Today at {time}'**
+  String todayAt(Object time);
+
+  /// Message displayed when the given time is from yesterday. The placeholder {time} will be replaced with the formatted time.
+  ///
+  /// In en, this message translates to:
+  /// **'Yesterday at {time}'**
+  String yesterdayAt(Object time);
+
+  /// Message displayed when the given time is older than yesterday. The placeholder {date} will be replaced with the formatted date and {time} with the formatted time.
+  ///
+  /// In en, this message translates to:
+  /// **'{date} at {time}'**
+  String dateAtTime(Object date, Object time);
 }
 
 class _ZulipLocalizationsDelegate extends LocalizationsDelegate<ZulipLocalizations> {

lib/generated/l10n/zulip_localizations_ar.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/generated/l10n/zulip_localizations_en.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/generated/l10n/zulip_localizations_fr.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsFr extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/generated/l10n/zulip_localizations_ja.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/generated/l10n/zulip_localizations_pl.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/generated/l10n/zulip_localizations_ru.dart

@@ -537,4 +537,30 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get aFewSecondsAgo => 'A few seconds ago';
+
+  @override
+  String get oneMinuteAgo => '1 minute ago';
+
+  @override
+  String minutesAgo(Object minutes) {
+    return '$minutes minutes ago';
+  }
+
+  @override
+  String todayAt(Object time) {
+    return 'Today at $time';
+  }
+
+  @override
+  String yesterdayAt(Object time) {
+    return 'Yesterday at $time';
+  }
+
+  @override
+  String dateAtTime(Object date, Object time) {
+    return '$date at $time';
+  }
 }

lib/widgets/lightbox.dart

@@ -152,11 +152,42 @@ class _LightboxPageLayoutState extends State<_LightboxPageLayout> {
 
     PreferredSizeWidget? appBar;
     if (_headerFooterVisible) {
-      // TODO(#45): Format with e.g. "Yesterday at 4:47 PM"
-      final timestampText = DateFormat
-        .yMMMd(/* TODO(#278): Pass selected language here, I think? */)
-        .add_Hms()
-        .format(DateTime.fromMillisecondsSinceEpoch(widget.message.timestamp * 1000));
+      final zulipLocalizations = ZulipLocalizations.of(context);
+
+      String formatLocalizedTimestamp(DateTime date) {
+        final now = DateTime.now();
+        final nowDateOnly = DateTime(now.year, now.month, now.day);
+        final messageDateOnly = DateTime(date.year, date.month, date.day);
+
+        final differenceInSeconds = now.difference(date).inSeconds;
+        final differenceInMinutes = now.difference(date).inMinutes;
+        final differenceInDays = nowDateOnly.difference(messageDateOnly).inDays;
+
+        if (differenceInSeconds < 60) {
+          return zulipLocalizations.aFewSecondsAgo;
+        } else if (differenceInMinutes < 60) {
+          return Intl.plural(
+            differenceInMinutes,
+            one: zulipLocalizations.oneMinuteAgo,
+            other: zulipLocalizations.minutesAgo(differenceInMinutes),
+            locale: zulipLocalizations.localeName,
+          );
+        } else if (differenceInDays == 0) {
+          final time = DateFormat.jm(zulipLocalizations.localeName).format(date);
+          return zulipLocalizations.todayAt(time);
+        } else if (differenceInDays == 1) {
+          final time = DateFormat.jm(zulipLocalizations.localeName).format(date);
+          return zulipLocalizations.yesterdayAt(time);
+        } else {
+          final dateStr = DateFormat('MMM d, yyyy', zulipLocalizations.localeName).format(date);
+          final timeStr = DateFormat('hh:mm a', zulipLocalizations.localeName).format(date);
+          return zulipLocalizations.dateAtTime(dateStr, timeStr);
+        }
+      }
+
+      final timestampText = formatLocalizedTimestamp(
+        DateTime.fromMillisecondsSinceEpoch(widget.message.timestamp * 1000),
+      );
 
       // We use plain [AppBar] instead of [ZulipAppBar], even though this page
       // has a [PerAccountStore], because:

test/widgets/lightbox_test.dart

@@ -249,7 +249,7 @@ void main() {
           matching: find.textContaining(findRichText: true,
             eg.otherUser.fullName)));
       check(labelTextWidget.text.toPlainText())
-        .contains('Jul 23, 2024 23:12:24');
+        .contains('Jul 23, 2024 at 11:12 PM');
 
       debugNetworkImageHttpClientProvider = null;
     });