feat:增加待办提醒功能

lib/widgets/task_dialog.dart

@@ -19,6 +19,7 @@ class _TaskDialogState extends State<TaskDialog> {
   late Priority _selectedPriority;
   DateTime? _selectedDueDate;
   DateTime? _selectedScheduleTime;
+  DateTime? _createTime;
   final _formKey = GlobalKey<FormState>();
 
   @override
@@ -29,6 +30,7 @@ class _TaskDialogState extends State<TaskDialog> {
     _selectedPriority = widget.task?.priority ?? Priority.medium;
     _selectedDueDate = widget.task?.dueDate;
     _selectedScheduleTime = widget.task?.scheduleTime;
+    _createTime = widget.task?.createTime;
   }
 
   @override
@@ -38,8 +40,22 @@ class _TaskDialogState extends State<TaskDialog> {
     super.dispose();
   }
 
-  void onConfirmClick() {
+  void onConfirmClick() async {
     if (_formKey.currentState!.validate()) {
+      if (_selectedScheduleTime != null &&
+          _selectedScheduleTime!.isBefore(DateTime.now())) {
+        await displayInfoBar(
+          context,
+          builder: (context, close) {
+            return InfoBar(
+              title: const Text('提醒时间不能早于当前时间'),
+              severity: InfoBarSeverity.error,
+            );
+          },
+        );
+        return;
+      }
+
       final task = Task(
         id: widget.task?.id,
         title: _titleController.text,
@@ -48,6 +64,7 @@ class _TaskDialogState extends State<TaskDialog> {
         scheduleTime: _selectedScheduleTime,
         priority: _selectedPriority,
         isCompleted: widget.task?.isCompleted ?? false,
+        createTime: _createTime,
       );
       widget.onSave(task);
       Navigator.pop(context);