feat: complete realtime challenge matchmaking

backend/contest/models.py

@@ -77,6 +77,10 @@ class ContestQuestion(models.Model):
 
 
 class RealtimeMatch(models.Model):
+    class MatchType(models.TextChoices):
+        RANDOM = "random", "随机匹配"
+        CHALLENGE = "challenge", "联机码约战"
+
     class Status(models.TextChoices):
         WAITING = "waiting", "等待对手"
         ACTIVE = "active", "进行中"
@@ -85,6 +89,12 @@ class RealtimeMatch(models.Model):
 
     id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
     contest = models.ForeignKey(Contest, on_delete=models.PROTECT)
+    match_type = models.CharField(
+        max_length=16,
+        choices=MatchType.choices,
+        default=MatchType.RANDOM,
+    )
+    challenge_code = models.CharField(max_length=8, unique=True, null=True, blank=True)
     player_one = models.ForeignKey(
         settings.AUTH_USER_MODEL, on_delete=models.PROTECT, related_name="matches_as_player_one"
     )
@@ -106,13 +116,20 @@ class RealtimeMatch(models.Model):
         related_name="won_matches",
     )
     created_at = models.DateTimeField(auto_now_add=True)
+    expires_at = models.DateTimeField(null=True, blank=True)
     started_at = models.DateTimeField(null=True, blank=True)
     completed_at = models.DateTimeField(null=True, blank=True)
 
     class Meta:
         indexes = [
             models.Index(
-                fields=("contest", "status", "player_one_rating", "created_at"),
+                fields=(
+                    "contest",
+                    "match_type",
+                    "status",
+                    "player_one_rating",
+                    "created_at",
+                ),
                 name="matchmaking_lookup_idx",
             )
         ]