61 lines
1.8 KiB
TypeScript
61 lines
1.8 KiB
TypeScript
// Copyright 2017-2019 @polkadot/react-query authors & contributors
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// This software may be modified and distributed under the terms
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// of the Apache-2.0 license. See the LICENSE file for details.
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import { Codec } from '@polkadot/types/types';
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import React, { useEffect, useState } from 'react';
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import { useApi } from '@polkadot/react-hooks';
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import { EventRecord } from '@polkadot/types/interfaces';
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import { stringToU8a } from '@polkadot/util';
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import { xxhashAsHex } from '@polkadot/util-crypto';
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interface KeyedEvent {
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key: string;
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record: EventRecord;
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}
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type Events = KeyedEvent[];
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interface Props {
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children: React.ReactNode;
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}
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const MAX_EVENTS = 25;
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const EventsContext: React.Context<Events> = React.createContext<Events>([]);
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function Events ({ children }: Props): React.ReactElement<Props> {
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const { api } = useApi();
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const [state, setState] = useState<Events>([]);
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useEffect((): void => {
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// TODO We should really unsub - but since this should just be used once,
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// atm I'm rather typing this than doing it the way it is supposed to be
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api.isReady.then((): void => {
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const prevEventHash = '';
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let events: Events = [];
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api.query.system.events((records: EventRecord[] & Codec): void => {
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const newEvents = records
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.filter(({ event }): boolean => event.section !== 'system')
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.map((record, index): KeyedEvent => ({ key: `${Date.now()}-${index}`, record }));
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const newEventHash = xxhashAsHex(stringToU8a(JSON.stringify(newEvents)));
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if (newEventHash !== prevEventHash) {
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events = [...newEvents, ...events].slice(0, MAX_EVENTS);
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setState(events);
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}
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});
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});
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}, []);
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return (
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<EventsContext.Provider value={state}>
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{children}
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</EventsContext.Provider>
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);
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}
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export { EventsContext, Events };
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