packages/page-preimages/src/usePreimages.ts
// Copyright 2017-2024 @polkadot/app-preimages authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { Changes } from '@polkadot/react-hooks/useEventChanges';
import type { StorageKey } from '@polkadot/types';
import type { EventRecord, Hash } from '@polkadot/types/interfaces';
import type { HexString } from '@polkadot/util/types';
import { useMemo } from 'react';
import { createNamedHook, useApi, useEventChanges, useMapKeys } from '@polkadot/react-hooks';
const EMPTY_PARAMS: unknown[] = [];
const OPT_HASH = {
transform: (keys: StorageKey<[Hash]>[]): Hash[] =>
keys.map(({ args: [hash] }) => hash)
};
function filter (records: EventRecord[]): Changes<Hash> {
const added: Hash[] = [];
const removed: Hash[] = [];
records.forEach(({ event: { data: [hash], method } }): void => {
if (method === 'Noted') {
added.push(hash as Hash);
} else {
removed.push(hash as Hash);
}
});
return { added, removed };
}
function usePreimagesImpl (): HexString[] | undefined {
const { api } = useApi();
const startValueStatusFor = useMapKeys(api.query.preimage.statusFor, EMPTY_PARAMS, OPT_HASH);
const startvalueRequstStatusFor = useMapKeys(api.query.preimage.requestStatusFor, EMPTY_PARAMS, OPT_HASH);
const hashes = useEventChanges([
api.events.preimage.Cleared,
api.events.preimage.Noted
], filter, startValueStatusFor?.concat(startvalueRequstStatusFor || []));
return useMemo(
() => hashes?.map((h) => h.toHex()),
[hashes]
);
}
export default createNamedHook('usePreimages', usePreimagesImpl);