diff --git a/attributes.json b/attributes.json
index 969da03..85dc730 100644
--- a/attributes.json
+++ b/attributes.json
@@ -36,16 +36,5 @@
             "ingredient": ["tomato", "tuna", "onion", "cheese"],
             "price": 40
         }
-    },
-    "size": {
-        "m": {
-            "price_multiplier": 1
-        },
-        "l": {
-            "price_multiplier": 1.2
-        },
-        "xl": {
-            "price_multiplier": 1.4
-        }
     }
 }
\ No newline at end of file
diff --git a/src/service/dialog_state_monitor.py b/src/service/dialog_state_monitor.py
index b01e808..abebbea 100644
--- a/src/service/dialog_state_monitor.py
+++ b/src/service/dialog_state_monitor.py
@@ -10,19 +10,52 @@ def normalize(value):
 class DialogStateMonitor:
     def __init__(self):
         self.__initial_state = dict(belief_state={
-                                        'order': [],
-                                        'address': {},
-                                        'order-complete': False,
-                                        'phone': {},
-                                        'delivery': {},
-                                        'payment': {},
-                                        'time': {},
-                                        'name': {},
-                                    },
-                                    history=[])
+            'order': [],
+            'address': {},
+            'order-complete': False,
+            'phone': {},
+            'delivery': {},
+            'payment': {},
+            'time': {},
+            'name': {},
+        },
+            stages=[
+                {'completed': False, 'name': 'collect_food'},
+                {'completed': False, 'name': 'collect_drinks'},
+                {'completed': False, 'name': 'collect_address'},
+            ],
+            constraints={
+                'order': [
+                    'sauce',
+                    'pizza',
+                ],
+            },
+            history=[])
         self.state = copy.deepcopy(self.__initial_state)
 
-    def update(self, frame: Frame):
+    def get_last_order_missing_fields(self) -> list[str]:
+        result = []
+        try:
+            last_order = self.state['belief_state']['order'][-1]
+        except IndexError:
+            raise RuntimeError('No orders are placed')
+        for constraint in self.state['constraints']['order']:
+            if constraint not in last_order:
+                result.append(constraint)
+        return result
+
+    def get_current_active_stage(self) -> str | None:
+        for stage in self.state['stages']:
+            if stage['completed'] is False:
+                return stage['name']
+
+    def mark_current_stage_completed(self) -> None:
+        for stage in self.state['stages']:
+            if stage['completed'] is False:
+                stage['completed'] = True
+                return
+
+    def update(self, frame: Frame) -> None:
         self.state['history'].append(frame)
         if frame.source != 'user':
             return
@@ -52,5 +85,5 @@ class DialogStateMonitor:
             for slot in frame.slots:
                 self.state['belief_state']['name'][slot.name] = normalize(slot.value)
 
-    def reset(self):
+    def reset(self) -> None:
         self.state = copy.deepcopy(self.__initial_state)
diff --git a/src/test/dialog_state_monitor.py b/src/test/dialog_state_monitor.py
index 8614126..f6509d4 100644
--- a/src/test/dialog_state_monitor.py
+++ b/src/test/dialog_state_monitor.py
@@ -2,24 +2,35 @@ from src.service.dialog_state_monitor import DialogStateMonitor
 from src.model.frame import Frame
 from src.model.slot import Slot
 
-dst = DialogStateMonitor()
+dsm = DialogStateMonitor()
 
 frame1 = Frame('user', 'inform/order', [Slot('pizza', 'margaritta'), Slot('sauce', 'ketchup')])
+dsm.update(frame1)
+assert dsm.get_last_order_missing_fields() == []
 frame2 = Frame('user', 'inform/order', [Slot('pizza', 'carbonara')])
+dsm.update(frame2)
+assert dsm.get_last_order_missing_fields() == ['sauce']
 frame3 = Frame('user', 'inform/order-complete', [])
-dst.update(frame1)
-dst.update(frame2)
-dst.update(frame3)
+dsm.update(frame3)
 
-assert dst.state['belief_state']['order'][0]['pizza'] == 'margaritta'
-assert dst.state['belief_state']['order'][0]['sauce'] == 'ketchup'
-assert dst.state['belief_state']['order-complete'] is True
-assert dst.state['history'][0] == frame1
-assert dst.state['history'][1] == frame2
-assert dst.state['history'][2] == frame3
+assert dsm.state['belief_state']['order'][0]['pizza'] == 'margaritta'
+assert dsm.state['belief_state']['order'][0]['sauce'] == 'ketchup'
+assert dsm.state['belief_state']['order-complete'] is True
+assert dsm.state['history'][0] == frame1
+assert dsm.state['history'][1] == frame2
+assert dsm.state['history'][2] == frame3
 
-dst.reset()
+assert dsm.get_current_active_stage() == 'collect_food'
+dsm.mark_current_stage_completed()
+assert dsm.get_current_active_stage() == 'collect_drinks'
+dsm.mark_current_stage_completed()
+assert dsm.get_current_active_stage() == 'collect_address'
+dsm.mark_current_stage_completed()
+assert dsm.get_current_active_stage() is None
 
-assert dst.state['belief_state']['order'] == []
-assert dst.state['belief_state']['order-complete'] is False
-assert len(dst.state['history']) == 0
+dsm.reset()
+
+assert dsm.get_current_active_stage() == 'collect_food'
+assert dsm.state['belief_state']['order'] == []
+assert dsm.state['belief_state']['order-complete'] is False
+assert len(dsm.state['history']) == 0