[mob] Add groupType with common extn methods

mobile/lib/ui/viewer/gallery/component/group/type.dart

@@ -0,0 +1,59 @@
+import "package:flutter/widgets.dart";
+import "package:intl/intl.dart";
+import "package:photos/generated/l10n.dart";
+import "package:photos/models/file/file.dart";
+import "package:photos/utils/date_time_util.dart";
+
+enum GroupType { day, week, month, size, year }
+
+extension GroupTypeExtension on GroupType {
+  String get name {
+    switch (this) {
+      case GroupType.day:
+        return "day";
+      case GroupType.week:
+        return "week";
+      case GroupType.month:
+        return "month";
+      case GroupType.size:
+        return "size";
+      case GroupType.year:
+        return "year";
+    }
+  }
+
+  String getTitle(BuildContext context, EnteFile file, {EnteFile? lastFile}) {
+    if (this == GroupType.day) {
+      return _getDayTitle(context, file.creationTime!);
+    }
+    throw UnimplementedError("not implemented for $this");
+  }
+
+  bool areFromSameGroup(EnteFile first, EnteFile second) {
+    switch (this) {
+      case GroupType.day:
+        return areFromSameDay(first.creationTime!, second.creationTime!);
+      default:
+        throw UnimplementedError("not implemented for $this");
+    }
+  }
+
+  String _getDayTitle(BuildContext context, int timestamp) {
+    final date = DateTime.fromMicrosecondsSinceEpoch(timestamp);
+    final now = DateTime.now();
+    if (date.year == now.year && date.month == now.month) {
+      if (date.day == now.day) {
+        return S.of(context).dayToday;
+      } else if (date.day == now.day - 1) {
+        return S.of(context).dayYesterday;
+      }
+    }
+    if (date.year != DateTime.now().year) {
+      return DateFormat.yMMMEd(Localizations.localeOf(context).languageCode)
+          .format(date);
+    } else {
+      return DateFormat.MMMEd(Localizations.localeOf(context).languageCode)
+          .format(date);
+    }
+  }
+}