42 lines
1.6 KiB
JavaScript
42 lines
1.6 KiB
JavaScript
import useSWRSubscription from "swr/subscription"
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import { getDynamicBuilder, getLookupFn } from "@polkadot-api/metadata-builders"
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import { distinct, filter, map, mergeMap } from "rxjs"
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import { useUnstableProvider } from "./UnstableProvider"
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import { useMetadata } from "./MetadataProvider"
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export const useCurrentIndex = () => {
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const { chainHead$, chainId } = useUnstableProvider()
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const metadata = useMetadata()
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const { data: currentIndex } = useSWRSubscription(
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chainHead$ && chainId && metadata
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? ["currentIndex", chainHead$, chainId, metadata]
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: null,
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([_, chainHead$, chainId, metadata], { next }) => {
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const { finalized$, storage$ } = chainHead$
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const subscription = finalized$.pipe(
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filter(Boolean),
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mergeMap((blockInfo) => {
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const builder = getDynamicBuilder(getLookupFn(metadata))
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const currentIndex = builder.buildStorage("Session", "CurrentIndex")
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return storage$(blockInfo?.hash, "value", () =>
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currentIndex?.keys.enc()
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).pipe(
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filter(Boolean),
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distinct(),
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map((value) => currentIndex?.value.dec(value))
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)
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}),
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)
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.subscribe({
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next(currentIndex) {
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next(null, currentIndex)
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},
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error: next,
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})
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return () => subscription.unsubscribe()
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}
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)
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return currentIndex
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}
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