Reorganize the cancel step code in order to make it more readable

Signed-off-by: Emmy D'Anello <emmy.danello@animath.fr>

draw/consumers.py

@@ -942,18 +942,34 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
         if not await Draw.objects.filter(tournament=self.tournament).aexists():
             return await self.alert(_("The draw has not started yet."), 'danger')
 
-        content_type = await ContentType.objects.aget(app_label=TeamDraw._meta.app_label,
-                                                      model=TeamDraw._meta.model_name)
-
         state = self.tournament.draw.get_state()
 
         self.tournament.draw.last_message = ""
         await self.tournament.draw.asave()
 
-        r = self.tournament.draw.current_round
-
         if state == 'DRAW_ENDED' or state == 'WAITING_FINAL':
-            td = self.tournament.draw.current_round.current_pool.current_team
+            await self.undo_end_draw()
+        elif state == 'WAITING_CHOOSE_PROBLEM':
+            await self.undo_draw_problem()
+        elif state == 'WAITING_DRAW_PROBLEM':
+            await self.undo_process_problem()
+        elif state == 'DICE_ORDER_POULE':
+            await self.undo_pool_dice()
+        elif state == 'DICE_SELECT_POULES':
+            await self.undo_order_dice()
+
+        await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
+                                            {'type': 'draw.set_info', 'draw': self.tournament.draw})
+        await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
+                                            {'type': 'draw.set_active', 'draw': self.tournament.draw})
+
+    async def undo_end_draw(self) -> None:
+        """
+        If the draw is ended, or if we are between the two rounds of the final,
+        then we cancel the last problem that was accepted.
+        """
+        r = self.tournament.draw.current_round
+        td = r.current_pool.current_team
         td.purposed = td.accepted
         td.accepted = None
         await td.asave()
@@ -971,7 +987,13 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
                                              'round': r.number,
                                              'team': td.participation.team.trigram,
                                              'problem': td.accepted})
-        elif state == 'WAITING_CHOOSE_PROBLEM':
+
+    async def undo_draw_problem(self):
+        """
+        A problem was drawn and we wait for the current team to accept or reject the problem.
+        Then, we just reset the problem draw.
+        :return:
+        """
         td = self.tournament.draw.current_round.current_pool.current_team
         td.purposed = None
         await td.asave()
@@ -984,7 +1006,24 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
                                             {'type': 'draw.box_visibility', 'visible': True})
         await self.channel_layer.group_send(f"volunteer-{self.tournament.id}",
                                             {'type': 'draw.box_visibility', 'visible': True})
-        elif state == 'WAITING_DRAW_PROBLEM':
+
+    async def undo_process_problem(self):
+        """
+        Now, a team must draw a new problem. Multiple cases are possible:
+        * In the same pool, a previous team accepted a problem ;
+        * In the same pool, a previous team rejected a problem ;
+        * The current team rejected a problem that was previously rejected ;
+        * The last team drawn its dice to choose the draw order.
+
+        In the two first cases, we explore the database history to fetch what team accepted or rejected
+        its problem at last.
+        The third case is ignored, because too hard and too useless to manage.
+        For the last case, we cancel the last dice.
+        """
+        content_type = await ContentType.objects.aget(app_label=TeamDraw._meta.app_label,
+                                                      model=TeamDraw._meta.model_name)
+
+        r = self.tournament.draw.current_round
         p = r.current_pool
         accepted_tds = {td.id: td async for td in p.team_draws.filter(accepted__isnull=False)
                         .prefetch_related('participation__team')}
@@ -1082,7 +1121,17 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
 
         await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
                                             {'type': 'draw.box_visibility', 'visible': False})
-        elif state == 'DICE_ORDER_POULE':
+
+    async def undo_pool_dice(self):
+        """
+        Teams of a pool are launching their dices to define the draw order.
+        We reset the last dice if possible, or we go to the last pool, or the last round,
+        or the passage dices.
+        """
+        content_type = await ContentType.objects.aget(app_label=TeamDraw._meta.app_label,
+                                                      model=TeamDraw._meta.model_name)
+
+        r = self.tournament.draw.current_round
         p = r.current_pool
         already_launched_tds = {td.id: td async for td in p.team_draws.filter(choice_dice__isnull=False)
                                 .prefetch_related('participation__team')}
@@ -1243,7 +1292,15 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
 
                 await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
                                                     {'type': 'draw.dice_visibility', 'visible': True})
-        elif state == 'DICE_SELECT_POULES':
+
+    async def undo_order_dice(self):
+        """
+        Undo the last dice for the passage order, or abort the draw if we are at the beginning.
+        """
+        content_type = await ContentType.objects.aget(app_label=TeamDraw._meta.app_label,
+                                                      model=TeamDraw._meta.model_name)
+
+        r = self.tournament.draw.current_round
         already_launched_tds = {td.id: td async for td in r.team_draws.filter(passage_dice__isnull=False)
                                 .prefetch_related('participation__team')}
 
@@ -1273,11 +1330,6 @@ class DrawConsumer(AsyncJsonWebsocketConsumer):
         else:
             await self.abort()
 
-        await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
-                                            {'type': 'draw.set_info', 'draw': self.tournament.draw})
-        await self.channel_layer.group_send(f"tournament-{self.tournament.id}",
-                                            {'type': 'draw.set_active', 'draw': self.tournament.draw})
-
     async def draw_alert(self, content):
         """
         Send alert to the current user.