06/15 Phase 3 codes

app/services/favorites.py

@@ -0,0 +1,33 @@
+"""Favorites: toggle save/unsave, check status, list."""
+from sqlalchemy.exc import IntegrityError
+from app.extensions import db
+from app.models.favorite import Favorite
+
+
+def is_favorited(user_id: int, listing_id: int) -> bool:
+    return Favorite.query.filter_by(
+        user_id=user_id, listing_id=listing_id).first() is not None
+
+
+def toggle_favorite(user_id: int, listing_id: int) -> bool:
+    """Add if not present; remove if present. Returns True if now favorited."""
+    existing = Favorite.query.filter_by(
+        user_id=user_id, listing_id=listing_id).first()
+    if existing:
+        db.session.delete(existing)
+        db.session.commit()
+        return False
+    fav = Favorite(user_id=user_id, listing_id=listing_id)
+    db.session.add(fav)
+    try:
+        db.session.commit()
+    except IntegrityError:
+        db.session.rollback()
+    return True
+
+
+def user_favorites(user_id: int, page=1, per_page=20):
+    return (Favorite.query
+            .filter_by(user_id=user_id)
+            .order_by(Favorite.created_at.desc())
+            .paginate(page=page, per_page=per_page, error_out=False))