interface WatchlistItem {
  id: string
  booking_token: string
  route_summary: string
  departure_code: string
  arrival_code: string
  departure_date: string
  original_price: number
  current_price: number | null
  price_status: string
  passengers_adult: number
  passengers_child: number
  passengers_infant: number
  last_checked_at: string | null
  created_at: string
}

export function useWatchlist() {
  const supabase = useSupabaseClient()
  const user = useSupabaseUser()

  const items = ref<WatchlistItem[]>([])
  const loading = ref(false)

  async function fetchAll() {
    if (!user.value) return
    loading.value = true
    const { data } = await supabase
      .from('watchlist')
      .select('*')
      .order('created_at', { ascending: false })
    items.value = (data as WatchlistItem[]) || []
    loading.value = false
  }

  async function add(params: {
    bookingToken: string
    routeSummary: string
    departureCode: string
    arrivalCode: string
    departureDate: string
    price: number
    passengers: { adult: number; child: number; infant: number }
  }) {
    if (!user.value) return false
    const { error } = await supabase.from('watchlist').insert({
      user_id: user.value.id,
      booking_token: params.bookingToken,
      route_summary: params.routeSummary,
      departure_code: params.departureCode,
      arrival_code: params.arrivalCode,
      departure_date: params.departureDate,
      original_price: params.price,
      current_price: params.price,
      passengers_adult: params.passengers.adult,
      passengers_child: params.passengers.child,
      passengers_infant: params.passengers.infant
    })
    if (!error) await fetchAll()
    return !error
  }

  async function remove(id: string) {
    const { error } = await supabase.from('watchlist').delete().eq('id', id)
    if (!error) items.value = items.value.filter(i => i.id !== id)
    return !error
  }

  async function checkPrice(item: WatchlistItem) {
    try {
      const data = await $fetch<any>('/api/check', {
        method: 'POST',
        body: {
          bookingToken: item.booking_token,
          local: 'en',
          passengersCount: {
            adult: item.passengers_adult,
            child: item.passengers_child,
            infant: item.passengers_infant
          }
        }
      })

      const newPrice = data.trip.totalCost
      let status = 'available'
      if (newPrice < item.original_price) status = 'price_down'
      else if (newPrice > item.original_price) status = 'price_up'

      await supabase.from('watchlist').update({
        current_price: newPrice,
        price_status: status,
        last_checked_at: new Date().toISOString()
      }).eq('id', item.id)

      // Update local state
      const idx = items.value.findIndex(i => i.id === item.id)
      if (idx >= 0) {
        items.value[idx] = { ...items.value[idx], current_price: newPrice, price_status: status, last_checked_at: new Date().toISOString() }
      }
      return { price: newPrice, status }
    } catch {
      await supabase.from('watchlist').update({
        price_status: 'unavailable',
        last_checked_at: new Date().toISOString()
      }).eq('id', item.id)

      const idx = items.value.findIndex(i => i.id === item.id)
      if (idx >= 0) {
        items.value[idx] = { ...items.value[idx], price_status: 'unavailable', last_checked_at: new Date().toISOString() }
      }
      return { price: null, status: 'unavailable' }
    }
  }

  async function checkAll() {
    for (const item of items.value) {
      await checkPrice(item)
    }
  }

  function isWatched(bookingToken: string) {
    return items.value.some(i => i.booking_token === bookingToken)
  }

  function getWatchedItem(bookingToken: string) {
    return items.value.find(i => i.booking_token === bookingToken)
  }

  watch(user, (u) => {
    if (u) fetchAll()
    else items.value = []
  }, { immediate: true })

  return { items, loading, fetchAll, add, remove, checkPrice, checkAll, isWatched, getWatchedItem }
}