import {
  type HotelListingHotelData,
  type HotelSortItem,
  HotelSortOption,
} from "@scandic-hotels/trpc/types/hotel"

import type {
  HotelFilter,
  HotelFilters,
} from "@scandic-hotels/trpc/routers/hotels/filters/output"

const HOTEL_SORTING_STRATEGIES: Partial<
  Record<
    HotelSortOption,
    (a: HotelListingHotelData, b: HotelListingHotelData) => number
  >
> = {
  [HotelSortOption.Name]: function (a, b) {
    return a.hotel.name.localeCompare(b.hotel.name)
  },
  [HotelSortOption.TripAdvisorRating]: function (a, b) {
    return (b.hotel.tripadvisor ?? 0) - (a.hotel.tripadvisor ?? 0)
  },
}

export function getFilteredHotels(
  hotels: HotelListingHotelData[],
  filters: HotelFilter[]
) {
  if (filters.length) {
    return hotels.filter(({ hotel }) =>
      filters.every((filter) => {
        const matchesFacility = hotel.detailedFacilities.some(
          (facility) => facility.id === Number(filter.id)
        )
        const matchesCountry = hotel.countryCode === filter.id
        return matchesFacility || matchesCountry
      })
    )
  }
  return hotels
}

export function getSortedHotels(
  hotels: HotelListingHotelData[],
  sortOption: HotelSortOption
) {
  const sortFn = HOTEL_SORTING_STRATEGIES[sortOption]
  return sortFn ? [...hotels].sort(sortFn) : hotels
}

export function isValidSortOption(
  value: string,
  sortItems: HotelSortItem[]
): value is HotelSortOption {
  return sortItems.map((item) => item.value).includes(value as HotelSortOption)
}

export function getFiltersWithHotelCount(
  hotelFilters: HotelFilters,
  hotels: HotelListingHotelData[]
): HotelFilters {
  const flattenedFilters = Object.values(hotelFilters).flat()
  const filterHotelCounts: Record<string, number> = {}

  hotels.forEach(({ hotel }) => {
    hotel.detailedFacilities.forEach((facility) => {
      filterHotelCounts[facility.id] = (filterHotelCounts[facility.id] || 0) + 1
    })

    if (hotel.countryCode) {
      filterHotelCounts[hotel.countryCode] =
        (filterHotelCounts[hotel.countryCode] || 0) + 1
    }
  })

  return flattenedFilters.reduce(
    (acc, filter) => {
      if (filter.filterType === "facility") {
        acc.facilityFilters.push({
          ...filter,
          hotelCount: filterHotelCounts[filter.id] ?? 0,
        })
      } else if (filter.filterType === "surroundings") {
        acc.surroundingsFilters.push({
          ...filter,
          hotelCount: filterHotelCounts[filter.id] ?? 0,
        })
      } else if (filter.filterType === "country") {
        acc.countryFilters.push({
          ...filter,
          filterType: "country",
          hotelCount: filterHotelCounts[filter.id] ?? 0,
        })
      }
      return acc
    },
    {
      facilityFilters: [],
      surroundingsFilters: [],
      countryFilters: [],
    } as HotelFilters
  )
}