Add filter values to roms query

backend/handler/database/roms_handler.py

@@ -1273,3 +1273,58 @@ class DBRomsHandler(DBBaseHandler):
             "regions": sorted(regions),
             "languages": sorted(languages),
         }
+
+    @begin_session
+    def with_filter_values(
+        self,
+        query: Query,
+        session: Session = None,  # type: ignore
+    ) -> dict:
+        ids_subq = query.with_only_columns(Rom.id).scalar_subquery()  # type: ignore
+
+        statement = (
+            select(
+                RomMetadata.genres,
+                RomMetadata.franchises,
+                RomMetadata.companies,
+                RomMetadata.game_modes,
+                RomMetadata.age_ratings,
+                RomMetadata.player_count,
+                Rom.regions,
+                Rom.languages,
+            )
+            .select_from(Rom)
+            .join(RomMetadata, Rom.id == RomMetadata.rom_id)
+            .where(Rom.id.in_(ids_subq))
+        )
+
+        genres = set()
+        franchises = set()
+        companies = set()
+        game_modes = set()
+        age_ratings = set()
+        player_counts = set()
+        regions = set()
+        languages = set()
+
+        for row in session.execute(statement):
+            g, f, c, gm, ar, pc, rg, lg = row
+            genres.update(g)
+            franchises.update(f)
+            companies.update(c)
+            game_modes.update(gm)
+            age_ratings.update(ar)
+            player_counts.update(pc)
+            regions.update(rg)
+            languages.update(lg)
+
+        return {
+            "genres": sorted(genres),
+            "franchises": sorted(franchises),
+            "companies": sorted(companies),
+            "game_modes": sorted(game_modes),
+            "age_ratings": sorted(age_ratings),
+            "player_counts": sorted(player_counts),
+            "regions": sorted(regions),
+            "languages": sorted(languages),
+        }