import { useCallback, useRef } from 'react'
import { Parcel } from './model/models'
import { useLatestCallback } from './useLatestCallback'

const weightsOf = (parcels: Array<Parcel>) =>
  parcels.map(parcel => parcel.weightInGrams)

export const useReviewedParcels = (
  setParcels: (parcels: Array<Parcel>) => void,
  onParcelCountReviewed: (parcelWeightsInGrams: Array<number>) => void
) => {
  const reviewedParcels = useRef<Array<Parcel> | undefined>(undefined)
  const numberOfParcels = useRef(0)
  const reportParcelCountReviewed = useLatestCallback(onParcelCountReviewed)

  const splitParcels = useCallback(
    (parcels: Array<Parcel>) => {
      reviewedParcels.current = undefined
      numberOfParcels.current = parcels.length
      setParcels(parcels)
    },
    [setParcels]
  )

  const reviewParcels = useCallback(
    (parcels: Array<Parcel>) => {
      const parcelCountChanged = parcels.length !== numberOfParcels.current
      reviewedParcels.current = parcels
      numberOfParcels.current = parcels.length
      setParcels(parcels)
      if (parcelCountChanged) {
        reportParcelCountReviewed(weightsOf(parcels))
      }
    },
    [setParcels, reportParcelCountReviewed]
  )

  const reviewedParcelWeights = useCallback(
    () => reviewedParcels.current && weightsOf(reviewedParcels.current),
    []
  )

  return { splitParcels, reviewParcels, reviewedParcelWeights }
}