fix(mobile): shows asset datetime with original timezone (#4774)

mobile/lib/main.dart

@@ -7,6 +7,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_displaymode/flutter_displaymode.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:timezone/data/latest.dart';
 import 'package:immich_mobile/constants/locales.dart';
 import 'package:immich_mobile/modules/backup/background_service/background.service.dart';
 import 'package:immich_mobile/modules/backup/models/backup_album.model.dart';
@@ -77,6 +78,8 @@ Future<void> initApp() async {
     log.severe('Catch all error: ${error.toString()} - $error', error, stack);
     return true;
   };
+
+  initializeTimeZones();
 }
 
 Future<Isar> loadDb() async {

mobile/lib/modules/asset_viewer/ui/exif_bottom_sheet.dart

@@ -4,6 +4,7 @@ import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_map/flutter_map.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:timezone/timezone.dart';
 import 'package:immich_mobile/modules/asset_viewer/ui/description_input.dart';
 import 'package:immich_mobile/modules/map/ui/map_thumbnail.dart';
 import 'package:immich_mobile/shared/models/asset.dart';
@@ -26,12 +27,36 @@ class ExifBottomSheet extends HookConsumerWidget {
       exifInfo.latitude != 0 &&
       exifInfo.longitude != 0;
 
-  String get formattedDateTime {
-    final fileCreatedAt = asset.fileCreatedAt.toLocal();
-    final date = DateFormat.yMMMEd().format(fileCreatedAt);
-    final time = DateFormat.jm().format(fileCreatedAt);
+  String formatTimeZone(Duration d) =>
+      "GMT${d.isNegative ? '-': '+'}${d.inHours.abs().toString().padLeft(2, '0')}:${d.inMinutes.abs().remainder(60).toString().padLeft(2, '0')}";
 
-    return '$date • $time';
+  String get formattedDateTime {
+    DateTime dt = asset.fileCreatedAt.toLocal();
+    String? timeZone;
+    if (asset.exifInfo?.dateTimeOriginal != null) {
+      dt = asset.exifInfo!.dateTimeOriginal!;
+      if (asset.exifInfo?.timeZone != null) {
+        dt = dt.toUtc();
+        try {
+          final location = getLocation(asset.exifInfo!.timeZone!);
+          dt = TZDateTime.from(dt, location);
+        } on LocationNotFoundException {
+          RegExp re = RegExp(r'^utc(?:([+-]\d{1,2})(?::(\d{2}))?)?$', caseSensitive: false);
+          final m = re.firstMatch(asset.exifInfo!.timeZone!);
+          if (m != null) {
+            final duration = Duration(hours: int.parse(m.group(1) ?? '0'), minutes: int.parse(m.group(2) ?? '0'));
+            dt = dt.add(duration);
+            timeZone = formatTimeZone(duration);
+          }
+        }
+      }
+    }
+
+    final date = DateFormat.yMMMEd().format(dt);
+    final time = DateFormat.jm().format(dt);
+    timeZone ??= formatTimeZone(dt.timeZoneOffset);
+
+    return '$date • $time $timeZone';
   }
 
   Future<Uri?> _createCoordinatesUri(ExifInfo? exifInfo) async {

mobile/lib/shared/models/exif_info.dart

@@ -8,6 +8,8 @@ part 'exif_info.g.dart';
 class ExifInfo {
   Id? id;
   int? fileSize;
+  DateTime? dateTimeOriginal;
+  String? timeZone;
   String? make;
   String? model;
   String? lens;
@@ -47,6 +49,8 @@ class ExifInfo {
 
   ExifInfo.fromDto(ExifResponseDto dto)
       : fileSize = dto.fileSizeInByte,
+        dateTimeOriginal = dto.dateTimeOriginal,
+        timeZone = dto.timeZone,
         make = dto.make,
         model = dto.model,
         lens = dto.lensModel,
@@ -64,6 +68,8 @@ class ExifInfo {
   ExifInfo({
     this.id,
     this.fileSize,
+    this.dateTimeOriginal,
+    this.timeZone,
     this.make,
     this.model,
     this.lens,
@@ -82,6 +88,8 @@ class ExifInfo {
   ExifInfo copyWith({
     Id? id,
     int? fileSize,
+    DateTime? dateTimeOriginal,
+    String? timeZone,
     String? make,
     String? model,
     String? lens,
@@ -99,6 +107,8 @@ class ExifInfo {
       ExifInfo(
         id: id ?? this.id,
         fileSize: fileSize ?? this.fileSize,
+        dateTimeOriginal: dateTimeOriginal ?? this.dateTimeOriginal,
+        timeZone: timeZone ?? this.timeZone,
         make: make ?? this.make,
         model: model ?? this.model,
         lens: lens ?? this.lens,
@@ -119,6 +129,8 @@ class ExifInfo {
     if (other is! ExifInfo) return false;
     return id == other.id &&
         fileSize == other.fileSize &&
+        dateTimeOriginal == other.dateTimeOriginal &&
+        timeZone == other.timeZone &&
         make == other.make &&
         model == other.model &&
         lens == other.lens &&
@@ -139,6 +151,8 @@ class ExifInfo {
   int get hashCode =>
       id.hashCode ^
       fileSize.hashCode ^
+      dateTimeOriginal.hashCode ^
+      timeZone.hashCode ^
       make.hashCode ^
       model.hashCode ^
       lens.hashCode ^

mobile/pubspec.lock

@@ -1401,7 +1401,7 @@ packages:
     source: hosted
     version: "2.1.3"
   timezone:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: timezone
       sha256: "1cfd8ddc2d1cfd836bc93e67b9be88c3adaeca6f40a00ca999104c30693cdca0"

mobile/pubspec.yaml

@@ -52,6 +52,7 @@ dependencies:
   crypto: ^3.0.3 # TODO remove once native crypto is used on iOS
   wakelock_plus: ^1.1.1
   flutter_local_notifications: ^15.1.0+1
+  timezone: ^0.9.2
 
   openapi:
     path: openapi