import useSWRSubscription from "swr/subscription"
import { getDynamicBuilder, getLookupFn } from "@polkadot-api/metadata-builders"
import { distinct, filter, map, mergeMap } from "rxjs"

import { useUnstableProvider } from "./UnstableProvider"
import { useMetadata } from "./MetadataProvider"

export const useValidators = ({ currentSession }) => {
    const { chainHead$, chainId } = useUnstableProvider()
    const metadata = useMetadata()
    const { data: slowClapValidators } = useSWRSubscription(
        chainHead$ && chainId && metadata
            ? ["slowClapValidators", chainHead$, currentSession, chainId, metadata]
            : null,
        ([_, chainHead$, currentSession, chainId, metadata], { next }) => {
            const { finalized$, storage$ } = chainHead$
            const subscription = finalized$.pipe(
                filter(Boolean),
                mergeMap((blockInfo) => {
                    const builder = getDynamicBuilder(getLookupFn(metadata))
                    const slowClapValidators = builder.buildStorage("GhostSlowClaps", "Validators")
                    return storage$(blockInfo?.hash, "value", () =>
                        slowClapValidators?.keys.enc(currentSession)
                    ).pipe(
                        filter(Boolean),
                        distinct(),
                        map((value) => slowClapValidators?.value.dec(value))
                    )
                }),
            )
            .subscribe({
                next(slowClapValidators) {
                    next(null, slowClapValidators)
                },
                error: next,
            })
            return () => subscription.unsubscribe()
        }
    )
    return slowClapValidators
}