import type { Trip } from '~/server/utils/flightics'

export type SortKey = 'price' | 'duration' | 'departure' | 'stops'

interface Filters {
  maxPrice: number | null
  maxStops: number | null
  airlines: string[]
  departureTimeRange: [number, number] // hours 0-24
}

function getTripDuration(trip: Trip): number {
  let total = 0
  for (const leg of trip.legs) {
    for (const seg of leg.segments) {
      total += (seg.arrivalUtcTimestamp ?? 0) - (seg.departureUtcTimestamp ?? 0)
    }
  }
  return total
}

function getTripStops(trip: Trip): number {
  return trip.legs.reduce((sum, leg) => sum + Math.max(0, leg.segments.length - 1), 0)
}

function getTripAirlines(trip: Trip): string[] {
  const codes = new Set<string>()
  for (const leg of trip.legs) {
    for (const seg of leg.segments) {
      if (seg.company?.code) codes.add(seg.company.code)
    }
  }
  return [...codes]
}

function getDepartureHour(trip: Trip): number {
  const dep = trip.legs[0]?.segments[0]?.departureDate
  return dep ? new Date(dep).getHours() : 0
}

export function useResultFilters(trips: Ref<Trip[]>) {
  const sortBy = ref<SortKey>('price')
  const filters = reactive<Filters>({
    maxPrice: null,
    maxStops: null,
    airlines: [],
    departureTimeRange: [0, 24]
  })
  const viewMode = ref<'full' | 'compact'>('full')

  // Extract available airlines from results
  const { resolve: resolveAirline } = useAirlineNames()
  const availableAirlines = computed(() => {
    const codes = new Set<string>()
    for (const trip of trips.value) {
      for (const leg of trip.legs) {
        for (const seg of leg.segments) {
          if (seg.company?.code) codes.add(seg.company.code)
        }
      }
    }
    return [...codes].sort().map(code => ({ code, name: resolveAirline(code) }))
  })

  // Price range in results
  const priceRange = computed(() => {
    if (!trips.value.length) return { min: 0, max: 1000 }
    const prices = trips.value.map(t => t.totalCost)
    return { min: Math.floor(Math.min(...prices)), max: Math.ceil(Math.max(...prices)) }
  })

  const filtered = computed(() => {
    let result = [...trips.value]

    // Filter by price
    if (filters.maxPrice != null) {
      result = result.filter(t => t.totalCost <= filters.maxPrice!)
    }

    // Filter by stops
    if (filters.maxStops != null) {
      result = result.filter(t => getTripStops(t) <= filters.maxStops!)
    }

    // Filter by airlines (exclusive: all airlines in the trip must be in the selected set)
    if (filters.airlines.length > 0) {
      result = result.filter(t => {
        const tripAirlines = getTripAirlines(t)
        return tripAirlines.every(a => filters.airlines.includes(a))
      })
    }

    // Filter by departure time
    if (filters.departureTimeRange[0] > 0 || filters.departureTimeRange[1] < 24) {
      result = result.filter(t => {
        const hour = getDepartureHour(t)
        return hour >= filters.departureTimeRange[0] && hour <= filters.departureTimeRange[1]
      })
    }

    // Sort
    if (sortBy.value === 'price') {
      result.sort((a, b) => a.totalCost - b.totalCost)
    } else if (sortBy.value === 'departure') {
      result.sort((a, b) => {
        const aTime = a.legs[0]?.segments[0]?.departureTimestamp ?? 0
        const bTime = b.legs[0]?.segments[0]?.departureTimestamp ?? 0
        return aTime - bTime
      })
    } else if (sortBy.value === 'duration') {
      result.sort((a, b) => getTripDuration(a) - getTripDuration(b))
    } else if (sortBy.value === 'stops') {
      result.sort((a, b) => getTripStops(a) - getTripStops(b))
    }

    return result
  })

  function resetFilters() {
    filters.maxPrice = null
    filters.maxStops = null
    filters.airlines = []
    filters.departureTimeRange = [0, 24]
  }

  const hasActiveFilters = computed(() =>
    filters.maxPrice != null ||
    filters.maxStops != null ||
    filters.airlines.length > 0 ||
    filters.departureTimeRange[0] > 0 ||
    filters.departureTimeRange[1] < 24
  )

  return {
    sortBy,
    filters,
    viewMode,
    filtered,
    availableAirlines,
    priceRange,
    hasActiveFilters,
    resetFilters
  }
}