Add initial project

backend/repositories/challenge_repository.py

@@ -0,0 +1,33 @@
+"""Challenge repository for data access operations."""
+from typing import List, Optional
+from sqlalchemy.orm import Session
+from sqlalchemy import func
+from backend.models.challenge import Challenge
+from backend.repositories.base import BaseRepository
+
+
+class ChallengeRepository(BaseRepository[Challenge]):
+    """Repository for Challenge model operations."""
+
+    def __init__(self, db: Session):
+        """Initialize challenge repository."""
+        super().__init__(Challenge, db)
+
+    def get_by_user_id(self, user_id: int) -> List[Challenge]:
+        """Get all challenges for a user ordered by display_order."""
+        return self.db.query(Challenge).filter(
+            Challenge.user_id == user_id
+        ).order_by(Challenge.display_order.asc()).all()
+
+    def get_by_user_and_id(self, user_id: int, challenge_id: int) -> Optional[Challenge]:
+        """Get a challenge by user ID and challenge ID."""
+        return self.db.query(Challenge).filter(
+            Challenge.id == challenge_id,
+            Challenge.user_id == user_id
+        ).first()
+
+    def get_max_display_order(self, user_id: int) -> Optional[int]:
+        """Get the maximum display_order for a user."""
+        return self.db.query(func.max(Challenge.display_order)).filter(
+            Challenge.user_id == user_id
+        ).scalar()