feat(BOOK-55): Listen to SEO filter slugs when navigating to such page

Approved-by: Chuma Mcphoy (We Ahead)
Approved-by: Matilda Landström

packages/trpc/lib/utils/getFiltersFromHotels.ts

@@ -1,5 +1,7 @@
+import type { FacilityEnum } from "@scandic-hotels/common/constants/facilities"
 import type { Lang } from "@scandic-hotels/common/constants/language"
 
+import type { SEOFilters } from "../types/destinationsData"
 import type {
   CategorizedHotelFilters,
   HotelFilter,
@@ -33,6 +35,39 @@ function sortFilters(filters: HotelFilter[]): HotelFilter[] {
   })
 }
 
+// Merges hotel and SEO filters, removing duplicates (by id).
+// In case of duplicates, the SEO filter takes precedence.
+function mergeAndDeduplicate(
+  hotelFilters: HotelFilter[],
+  seoFilters: HotelFilter[]
+): HotelFilter[] {
+  const map = new Map<FacilityEnum, HotelFilter>()
+  hotelFilters.forEach((filter) => map.set(filter.id, filter))
+  seoFilters.forEach((filter) => map.set(filter.id, filter))
+  return Array.from(map.values())
+}
+
+export function mergeHotelFiltersAndSeoFilters(
+  hotelFilters: CategorizedHotelFilters,
+  seoFilters: SEOFilters | null
+): CategorizedHotelFilters {
+  if (!seoFilters) {
+    return hotelFilters
+  }
+
+  return {
+    ...hotelFilters,
+    facilityFilters: mergeAndDeduplicate(
+      hotelFilters.facilityFilters,
+      seoFilters.facilityFilters
+    ),
+    surroundingsFilters: mergeAndDeduplicate(
+      hotelFilters.surroundingsFilters,
+      seoFilters.surroundingsFilters
+    ),
+  }
+}
+
 export function getFiltersFromHotels(
   hotels: HotelListingHotelData[],
   lang: Lang