90 lines
3.0 KiB
TypeScript
90 lines
3.0 KiB
TypeScript
// Copyright 2017-2021 @polkadot/react-query authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { IndexedEvent, KeyedEvent } from './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 { stringToU8a } from '@polkadot/util';
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import { xxhashAsHex } from '@polkadot/util-crypto';
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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 = 75;
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const EventsContext: React.Context<Events> = React.createContext<Events>([]);
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function EventsBase ({ 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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// No unsub, global context - destroyed on app close
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api.isReady.then((): void => {
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let prevBlockHash: string | null = null;
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let prevEventHash: string | null = null;
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api.query.system.events((records): void => {
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const newEvents: IndexedEvent[] = records
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.map((record, index) => ({ indexes: [index], record }))
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.filter(({ record: { event: { method, section } } }) => section !== 'system' && (method !== 'Deposit' || !['balances', 'treasury'].includes(section)))
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.reduce((combined: IndexedEvent[], e): IndexedEvent[] => {
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const prev = combined.find(({ record: { event: { method, section } } }) => e.record.event.section === section && e.record.event.method === method);
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if (prev) {
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prev.indexes.push(...e.indexes);
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} else {
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combined.push(e);
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}
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return combined;
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}, [])
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.reverse();
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const newEventHash = xxhashAsHex(stringToU8a(JSON.stringify(newEvents)));
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if (newEventHash !== prevEventHash && newEvents.length) {
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prevEventHash = newEventHash;
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// retrieve the last header, this will map to the current state
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api.rpc.chain.getHeader().then((header): void => {
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const blockNumber = header.number.unwrap();
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const blockHash = header.hash.toHex();
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if (blockHash !== prevBlockHash) {
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prevBlockHash = blockHash;
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setState((events) => [
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...newEvents.map(({ indexes, record }): KeyedEvent => ({
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blockHash,
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blockNumber,
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indexes,
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key: `${blockNumber.toNumber()}-${blockHash}-${indexes.join('.')}`,
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record
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})),
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// remove all events for the previous same-height blockNumber
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...events.filter((p) => !p.blockNumber?.eq(blockNumber))
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].slice(0, MAX_EVENTS));
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}
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}).catch(console.error);
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}
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}).catch(console.error);
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}).catch(console.error);
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// eslint-disable-next-line react-hooks/exhaustive-deps
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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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const Events = React.memo(EventsBase);
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export { EventsContext, Events };
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