import getUrls from 'get-urls'
import { asyncMap, execPipe, map, findOr } from 'iter-tools'
import { mapNullable } from '/services/misc.js'

const LINK_RE = /<(.+?)>; rel="(\w+)"/gi

const YoutubeInstances = [
    'youtube.com', 'm.youtube.com', 'music.youtube.com',
    'invidio.us', 'redirect.invidious.io',
    'invidious.snopyta.org', 'yewtu.be', 'invidious.kavin.rocks', 'vid.puffyan.us', 'invidious.namazso.eu', 'inv.riverside.rocks', 'invidious.osi.kr', 'youtube.076.ne.jp', 'yt.artemislena.eu', 'tube.cthd.icu', 'invidious.flokinet.to', 'invidious.weblibre.org', 'invidious.esmailelbob.xyz', 'invidious.lunar.icu', 'invidious.mutahar.rocks', 'inv.bp.projectsegfau.lt', 'y.com.sb', 'invidious.sethforprivacy.com', 'invidious.tiekoetter.com', 'invidious.hub.ne.kr',
    'videos.arci.me', 'octt.ddns.net:48864',
    'c7hqkpkpemu6e7emz5b4vyz7idjgdvgaaa3dyimmeojqbgpea3xqjoid.onion', 'w6ijuptxiku4xpnnaetxvnkc5vqcdu7mgns2u77qefoixi63vbvnpnqd.onion', 'kbjggqkzv65ivcqj6bumvp337z6264huv5kpkwuv6gu5yjiskvan7fad.onion', 'grwp24hodrefzvjjuccrkw3mjq4tzhaaq32amf33dzpmuxe7ilepcmad.onion', 'osbivz6guyeahrwp2lnwyjk2xos342h4ocsxyqrlaopqjuhwn2djiiyd.onion', 'u2cvlit75owumwpy4dj2hsmvkq7nvrclkpht7xgyye2pyoxhpmclkrad.onion', 'euxxcnhsynwmfidvhjf6uzptsmh4dipkmgdmcmxxuo7tunp3ad2jrwyd.onion'
]

function parseLinkHeader(linkHeader) {
    const links = new Map()

    for (const [ , url, name ] of linkHeader.matchAll(LINK_RE)) {
        links.set(name, url)
    }

    return links
}

export const fetchStatus = (domain, id) => fetch(`https://${domain}/api/v1/statuses/${id}`)
    .then(response => response.json())

export async function* statusIterator({ domain, id }) {
    const partialTrack = processStatus(domain, await fetchStatus(domain, id))

    if (partialTrack !== null) {
        yield partialTrack
    }
}

export const hashtagStreamingStatusesObservable = (domain, hashtag) => {
    return new Observable(observer => {
        const onOpen = () => {
            console.log(`Streaming ${domain} #${hashtag} : open`)
        }

        const onStatus = event => {
            const status = JSON.parse(event.data)
            console.log(`Streaming ${domain} #${hashtag} : status ${status.id}`)
            observer.next(status)
        }

        const onError = error => {
            console.error(`Streaming ${domain} #${hashtag} : error`)
            console.error(error)
            observer.error(error)
        }

        const eventSource = new EventSource(`https://${domain}/api/v1/streaming/hashtag?tag=${hashtag}`)
        eventSource.addEventListener('open', onOpen)
        eventSource.addEventListener('update', onStatus)
        eventSource.addEventListener('error', onError)

        return () => {
            console.log(`Streaming ${domain} #${hashtag} : closed`)
            eventSource.removeEventListener('open', onOpen)
            eventSource.removeEventListener('update', onStatus)
            eventSource.removeEventListener('error', onError)
            eventSource.close()
        }
    })
}

export const hashtagStreamingObservable = (domain, hashtag) => {
    return new Observable(observer => {
        const subscription = hashtagStreamingStatusesObservable(domain, hashtag).subscribe({
            next: status => {
                const partialMedia = processStatus(domain, status)

                if (partialMedia !== null) {
                    observer.next(partialMedia)
                }
            },
            error: observer.error,
            complete: observer.complete
        })

        return () => {
            subscription.unsubscribe()
        }
    })
}

// don't handle correctly complete
export const hashtagsStreamingObservable = (domain, hashtags) => {
    return new Observable(observer => {
        const subscriptions = hashtags
            .map(hashtag => hashtagStreamingObservable(domain, hashtag))
            .map(observable => observable.subscribe(observer))

        return () => {
            subscriptions.forEach(subscription => subscription.unsubscribe())
        }
    })
}


export async function* hashtagTimelineStatusesIterator (domain, hashtag) {
    let nextLink = `https://${domain}/api/v1/timelines/tag/${hashtag}?limit=40`

    while (nextLink) {
        const response = await fetch(nextLink)

        nextLink = response.headers.has('link')
            ? parseLinkHeader(response.headers.get('link')).get('next')
            : null

        yield* await response.json()
    }
}

export const hashtagTimelineIterator = (domain, hashtag) => execPipe(
    hashtagTimelineStatusesIterator(domain, hashtag),
    asyncMap(status => processStatus(domain, status)),
    async function* (xs) {
        let c = 0

        for await (const x of xs) {
            if (x === null) {
                if (++c > 69) {
                    console.log(`Not found any viable media on #${hashtag}.`)
                    break
                }
            } else {
                c = 0
                yield x
            }
        }
    }
)

export async function* hashtagsTimelineIterator (domain, hashtags) {
    const iterators = hashtags.map(hashtag => hashtagTimelineIterator(domain, hashtag))
    const promises = iterators.map(iterator => iterator.next())

    while (true) {
        const results = (await Promise.all(promises))
            .map((result, index) => ({ index, result }))
            .filter(({ result }) => !result.done)

        if (results.length > 0) {
            const sorted = results.sort((a, b) => b.result.value.referer.date - a.result.value.referer.date)
            const { index, result: { value } } = sorted[0]

            promises[index] = iterators[index].next()
            yield value
        } else {
            break
        }
    }

}

export async function* hashtagsIterator(domain, hashtags) {
    const buffer = []

    const streamingSubscription = hashtagsStreamingObservable(domain, hashtags).subscribe({
        next: value => buffer.push(value),
        error: error => console.error(error),
        complete: () => console.log('complete')
    })

    const timelineGenerator = hashtagsTimelineIterator(domain, hashtags)

    try {
        while (true) {
            if (buffer.length > 0) {
                yield buffer.pop()
            } else {
                const { done, value } = await timelineGenerator.next()

                if (done) {
                    break
                } else {
                    yield value
                }
            }
        }
    } finally {
        streamingSubscription.unsubscribe()
        timelineGenerator.return()
    }
}

const processStatus = (domain, status) => mapNullable(findMedia(status), partialMedia => ({
    referer: {
        username: status.account.username,
        content: status.content,
        date: new Date(status.created_at),
        url: status.url,
        credentials: { type: 'mastodon', domain, id: status.id }
    },
    partialMedia
}))

const findMedia = status => execPipe(
    status.content,
    getUrls,
    map(url => {
        const { hostname, pathname, searchParams } = new URL(url)

        if (YoutubeInstances.includes(hostname) && searchParams.has('v')) {
            return { url, credentials: { type: 'youtube', id: searchParams.get('v') } }
        } else if (hostname === 'youtu.be') {
            return { url, credentials: { type: 'youtube', id: pathname.substring(1) } }
        } else {
            return null
        }
    }),
    findOr(null, x => x !== null)
)