06/18 Phase 7

app/services/reviews.py

@@ -0,0 +1,48 @@
+"""Review business logic."""
+from sqlalchemy.exc import IntegrityError
+from app.extensions import db
+from app.models.review import Review
+
+
+class ReviewError(ValueError):
+    pass
+
+
+def create_review(listing, author, rating: int, body: str | None = None):
+    """Leave a review for a seller. Listing must be sold. Returns Review."""
+    from app.models.enums import ListingStatus
+    if listing.status != ListingStatus.sold:
+        raise ReviewError("can only review sold listings")
+    if listing.user_id == author.id:
+        raise ReviewError("cannot review your own listing")
+    if rating not in range(1, 6):
+        raise ReviewError("rating must be 1–5")
+
+    review = Review(
+        listing_id=listing.id,
+        author_id=author.id,
+        seller_id=listing.user_id,
+        rating=rating,
+        body=(body or "").strip() or None,
+    )
+    db.session.add(review)
+    try:
+        db.session.commit()
+    except IntegrityError:
+        db.session.rollback()
+        raise ReviewError("you have already reviewed this listing")
+    return review
+
+
+def seller_rating(user_id) -> dict:
+    """Return avg rating and count for a seller."""
+    from app.extensions import db
+    result = (db.session.query(
+        db.func.round(db.func.avg(Review.rating), 1).label("avg"),
+        db.func.count(Review.id).label("count"))
+        .filter(Review.seller_id == user_id)
+        .first())
+    return {
+        "avg": float(result.avg) if result.avg else None,
+        "count": result.count or 0,
+    }