Add value field to MusicGameOrder and update score calculation logic

game/models.py

@@ -1,5 +1,6 @@
 from django.contrib.auth.models import User
 from django.db import models
+from django.db.models import F
 from django.db.models.functions import Lower
 from django.db.models.signals import post_delete, post_save
 from django.dispatch import receiver
@@ -106,6 +107,17 @@ class MusicGameOrder(models.Model):
     player = models.ForeignKey(User, on_delete=models.CASCADE)
     music_video = models.ForeignKey(MusicVideo, on_delete=models.CASCADE)
     order = models.PositiveIntegerField()
+    value = models.PositiveIntegerField(default=0)
+
+    def update_value(self):
+        n_right = self.musicgameanswer_set.filter(game__player=F("answer")).count()
+        if n_right == 0:
+            self.value = 1000
+        else:
+            self.value = 1000 / (
+                1 + ((n_right - 1) / (self.game.players.count() - 1)) ** 0.5
+            )
+        self.save()
 
     class Meta:
         constraints = [
@@ -117,6 +129,17 @@ class MusicGameOrder(models.Model):
         ordering = ["order"]
 
 
+class AnswerManager(models.Manager):
+    def score(self, game, player):
+        qs = self.filter(game__game=game, game__player=player)
+        return (
+            qs.filter(answer=F("game__player"))
+            .aggregate(score=models.Sum("game__value", default=0))
+            .get("score")
+            - 500 * qs.exclude(game__player=F("answer")).count()
+        )
+
+
 class MusicGameAnswer(models.Model):
     game = models.ForeignKey(MusicGameOrder, on_delete=models.CASCADE)
     player = models.ForeignKey(User, on_delete=models.CASCADE)
@@ -124,6 +147,8 @@ class MusicGameAnswer(models.Model):
         User, on_delete=models.SET_NULL, null=True, related_name="+"
     )
 
+    objects = AnswerManager()
+
     class Meta:
         constraints = [
             models.UniqueConstraint(fields=("game", "player"), name="unique_answer"),