feat: add a function for transiting to a state

apps/fsm/utils.py

@@ -78,6 +78,12 @@ def transit_player_in_fsm(player: Player, source_state: State, target_state: Sta
     player.last_visit = transition_time
     player.save()
 
+    if edge is None:
+        edge = Edge.objects.filter(tail=source_state, head=target_state) or \
+            Edge.objects.filter(tail=target_state, head=source_state)
+        if edge.count() > 0:
+            edge = edge.first()
+
     player_transition = PlayerTransition.objects.create(
         player=player,
         source_state=source_state,

apps/fsm/views/fsm_view.py

@@ -113,7 +113,7 @@ def enter_fsm(self, request, pk=None):
             serializer.is_valid(raise_exception=True)
             player = serializer.save()
             transit_player_in_fsm(
-                player=player, source_state=None, target_state=fsm.first_state, edge=None)
+                player=player, source_state=None, target_state=fsm.first_state)
 
         # if any state has been deleted and player has no current state:
         if player.current_state is None:

apps/fsm/views/player_view.py

@@ -1,3 +1,4 @@
+from django.shortcuts import get_object_or_404
 from django.db import transaction
 from drf_yasg.utils import swagger_auto_schema
 from rest_framework import status
@@ -8,6 +9,7 @@
 from rest_framework.permissions import IsAuthenticated
 from rest_framework import viewsets
 
+from apps.fsm.models.fsm import State
 from errors.error_codes import serialize_error
 from errors.exceptions import InternalServerError
 from apps.fsm.models import FSM, Player
@@ -69,7 +71,7 @@ def go_backward(self, request, pk):
                 player = transit_player_in_fsm(
                     player, edge.head, edge.tail, edge)
             return Response(status=status.HTTP_202_ACCEPTED)
-        
+
         else:
             raise InternalServerError('Not implemented Yet😎')
 
@@ -92,3 +94,34 @@ def mentor_move_backward(self, request, pk):
 
         else:
             raise InternalServerError('Not implemented Yet😎')
+
+    @swagger_auto_schema(responses={200: PlayerSerializer}, tags=['player'])
+    @action(detail=True, methods=['get'], permission_classes=[IsAuthenticated], url_path='transit-to-state')
+    def transit_to_state(self, request):
+        state_id = request.data.get('state')
+        state = get_object_or_404(State, id=state_id)
+        player = Player.objects.filter(user=request.user, fsm=state.fsm)
+        if player is None:
+            Player.objects.create(
+                user=request.user,
+                fsm=state.fsm,
+                current_state=state,
+            )
+
+        if not is_transition_permitted(player.current_state, state):
+            # todo
+            pass
+
+        transit_player_in_fsm(
+            player=player,
+            source_state=player.current_state,
+            target_state=state,
+        )
+
+        return Response(status=status.HTTP_204_NO_CONTENT)
+
+
+def is_transition_permitted(source_state: State, target_state: State):
+    if source_state.id == target_state.id:
+        return True
+    return True