feat:合并待办和提醒功能

lib/utils/todo_utils.dart

@@ -1,4 +1,5 @@
 import 'package:flisp_app/models/todo.dart';
+import 'package:intl/intl.dart';
 
 List<Todo> getActiveTodos(TodoTab currentTab, List<Todo> todos) {
   switch (currentTab) {
@@ -20,4 +21,25 @@ List<Todo> getActiveTodos(TodoTab currentTab, List<Todo> todos) {
     default:
       return todos;
   }
-}
+}
+
+// 格式化截止日期
+String formatDueDate(DateTime dueDate, bool isToday, bool isTomorrow) {
+  if (isToday) return '今天截止';
+  if (isTomorrow) return '明天截止';
+
+  final now = DateTime.now();
+  final difference = dueDate.difference(DateTime(now.year, now.month, now.day));
+
+  if (difference.inDays < 7) {
+    return '${difference.inDays}天后截止';
+  }
+
+  return DateFormat("MM-dd").format(dueDate);
+}
+
+bool isSameDay(DateTime date1, DateTime date2) {
+  return date1.year == date2.year &&
+      date1.month == date2.month &&
+      date1.day == date2.day;
+}