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

import type {
  HotelFilter,
  HotelFilters,
} from "@scandic-hotels/trpc/routers/hotels/filters/output"
import type { DestinationCityListItem } from "@scandic-hotels/trpc/types/destinationCityPage"
import type { DestinationFilter } from "@scandic-hotels/trpc/types/destinationsData"

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)
  },
  [HotelSortOption.Distance]: function (a, b) {
    return a.hotel.location.distanceToCentre - b.hotel.location.distanceToCentre
  },
}

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

export function getFilteredCities(
  filteredHotels: HotelListingHotelData[],
  cities: DestinationCityListItem[]
) {
  const filteredCityIdentifiers = filteredHotels.map(
    (hotel) => hotel.hotel.cityIdentifier
  )

  return cities.filter(
    (city) =>
      city.destination_settings.city &&
      filteredCityIdentifiers.includes(city.destination_settings.city)
  )
}

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 getBasePathNameWithoutFilters(
  pathname: string,
  filterSlugs: string[]
) {
  if (!filterSlugs.length) {
    return pathname
  }

  const lastSlashIndex = pathname.lastIndexOf("/")
  const lastSegment = pathname.slice(lastSlashIndex + 1)

  if (filterSlugs.includes(lastSegment)) {
    return pathname.slice(0, lastSlashIndex) || "/"
  }

  return pathname
}

export function getActiveDestinationFilter(
  filterFromUrl: HotelFilter | null,
  allSeoFilters: DestinationFilter[]
) {
  if (!filterFromUrl) {
    return null
  }
  return allSeoFilters.find((f) => f.filter.id === filterFromUrl.id) || null
}

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

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

      if (!filterCityIdentifiers[facility.id]) {
        filterCityIdentifiers[facility.id] = new Set()
      }
      if (hotel.cityIdentifier) {
        filterCityIdentifiers[facility.id].add(hotel.cityIdentifier)
      }
    })

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

      if (!filterCityIdentifiers[hotel.countryCode]) {
        filterCityIdentifiers[hotel.countryCode] = new Set()
      }
      if (hotel.cityIdentifier) {
        filterCityIdentifiers[hotel.countryCode].add(hotel.cityIdentifier)
      }
    }
  })

  // Count cities that match the cityIdentifiers for each filter
  const filterCityCounts: Record<string, number> = {}
  Object.entries(filterCityIdentifiers).forEach(
    ([filterId, cityIdentifiers]) => {
      filterCityCounts[filterId] = cities.filter(
        (city) =>
          city.destination_settings.city &&
          cityIdentifiers.has(city.destination_settings.city)
      ).length
    }
  )

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