feat: printing module

stateflow/services.py

@@ -148,6 +148,37 @@ def reset_business_object_progress(business_object: 'models.BusinessObject') ->
 reset_order_progress = reset_business_object_progress
 
 
+def step_back_one_state(business_object: 'models.BusinessObject', user) -> Tuple[bool, str]:
+    """
+    回退一步（撤销最后一次完成的状态）
+    
+    这是 advance_to_next_state 的逆向操作
+    
+    返回: (是否成功, 消息)
+    """
+    from django.utils import timezone
+    
+    with transaction.atomic():
+        # 获取最后一条有效的状态流转记录（按完成时间倒序）
+        last_record = (
+            business_object.state_logs
+            .filter(is_cancelled=False)
+            .order_by('-completed_at', '-id')
+            .first()
+        )
+        
+        # 如果没有任何有效记录，说明当前没有任何状态流转，无需回退
+        if not last_record:
+            return False, "当前没有任何状态流转记录，无法回退"
+        
+        # 标记最后一条记录为已撤销
+        last_record.is_cancelled = True
+        last_record.cancelled_at = timezone.now()
+        last_record.save(update_fields=['is_cancelled', 'cancelled_at'])
+        
+        return True, f"已回退状态: {last_record.state.name}"
+
+
 def get_current_state_parameters(business_object: 'models.BusinessObject') -> List['models.StateParameter']:
     """获取订单当前状态的参数列表"""
     current_state = get_business_object_current_state(business_object)