af83/chouette-core

import { useEffect, useState } from 'react'
import useSWR from 'swr'
import { isArray, isEmpty } from 'lodash'

import geoJSON from '../geoJSON'

const useGeoJSONFeatures = (
    urls,
    callback = () => {}
) => {
    const [loadingStatus, setLoadingStatus] = useState(() =>
        new Map(urls.map(url => [url, true]))
    )
    const [features, setFeatures] = useState()

    const doneFetching = Array.from(loadingStatus.entries()).every(([_key, isFetching]) => !isFetching)

    const onSuccess = (data, key) => {
        const fetchFeatures = isArray(data) ? data : [data]

        !isEmpty(fetchFeatures) && setFeatures(prevFeatures => [
            ...(prevFeatures || []),
            ...fetchFeatures.map(featureCollection => geoJSON.readFeatures(featureCollection)).flat()
        ])

        setLoadingStatus(prevLoadingStatus =>
            new Map([
                ...prevLoadingStatus.entries(),
                [key, false]
            ])
        )
    }

    urls.forEach(url => {
        useSWR(url, { onSuccess, revalidateOnFocus: false })
    })

    useEffect(() => {
        doneFetching && callback(features)
    }, [doneFetching])

    return doneFetching ? features : null
}

export default useGeoJSONFeatures