127 lines
4.4 KiB
TypeScript
127 lines
4.4 KiB
TypeScript
// Copyright 2017-2020 @polkadot/react-hooks authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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// eslint-disable-next-line @typescript-eslint/no-unused-vars
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import type { Codec } from '@polkadot/types/types';
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import type { CallOptions, CallParam, CallParams } from './types';
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import { useEffect, useRef, useState } from 'react';
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import { isNull, isUndefined } from '@polkadot/util';
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import { MountedRef, useIsMountedRef } from './useIsMountedRef';
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type VoidFn = () => void;
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// This should be VoidFn, however the API actually does allow us to use any general single-shot queries with
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// a result callback, so `api.query.system.account.at(<blokHash>, <account>, (info) => {... })` does work
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// (The same applies to e.g. keys or entries). So where we actally use the unsub, we cast `unknown` to `VoidFn`
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// to cater for our usecase.
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type TrackFnResult = Promise<unknown>;
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interface TrackFn {
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(...params: CallParam[]): TrackFnResult;
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meta?: {
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type: {
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isDoubleMap: boolean;
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};
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};
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}
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interface Tracker {
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isActive: boolean;
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serialized: string | null;
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subscriber: TrackFnResult | null;
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}
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interface TrackerRef {
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current: Tracker;
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}
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// the default transform, just returns what we have
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function transformIdentity <T> (value: unknown): T {
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return value as T;
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}
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// extract the serialized and mapped params, all ready for use in our call
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function extractParams <T> (fn: unknown, params: unknown[], { paramMap = transformIdentity }: CallOptions<T> = {}): [string, CallParams | null] {
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return [
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JSON.stringify({ f: (fn as { name: string })?.name, p: params }),
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params.length === 0 || !params.some((param) => isNull(param) || isUndefined(param))
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? paramMap(params)
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: null
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];
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}
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// unsubscribe and remove from the tracker
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function unsubscribe (tracker: TrackerRef): void {
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tracker.current.isActive = false;
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if (tracker.current.subscriber) {
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tracker.current.subscriber.then((unsubFn) => (unsubFn as VoidFn)()).catch(console.error);
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tracker.current.subscriber = null;
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}
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}
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// subscribe, trying to play nice with the browser threads
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function subscribe <T> (mountedRef: MountedRef, tracker: TrackerRef, fn: TrackFn | undefined, params: CallParams, setValue: (value: T) => void, { transform = transformIdentity, withParams, withParamsTransform }: CallOptions<T> = {}): void {
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const validParams = params.filter((p) => !isUndefined(p));
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unsubscribe(tracker);
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setTimeout((): void => {
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if (mountedRef.current) {
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if (fn && (!fn.meta || !fn.meta.type?.isDoubleMap || validParams.length === 2)) {
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// swap to acive mode
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tracker.current.isActive = true;
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tracker.current.subscriber = (fn as (...params: unknown[]) => Promise<VoidFn>)(...params, (value: Codec): void => {
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// we use the isActive flag here since .subscriber may not be set on immediate callback)
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if (mountedRef.current && tracker.current.isActive) {
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mountedRef.current && tracker.current.isActive && setValue(
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withParams
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? [params, transform(value)] as any
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: withParamsTransform
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? transform([params, value])
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: transform(value)
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);
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}
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});
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} else {
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tracker.current.subscriber = null;
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}
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}
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}, 0);
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}
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// tracks a stream, typically an api.* call (derive, rpc, query) that
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// - returns a promise with an unsubscribe function
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// - has a callback to set the value
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// FIXME The typings here need some serious TLC
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export function useCall <T> (fn: TrackFn | undefined | null | false, params?: CallParams, options?: CallOptions<T>): T | undefined {
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const mountedRef = useIsMountedRef();
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const tracker = useRef<Tracker>({ isActive: false, serialized: null, subscriber: null });
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const [value, setValue] = useState<T | undefined>((options || {}).defaultValue);
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// initial effect, we need an un-subscription
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useEffect((): () => void => {
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return () => unsubscribe(tracker);
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}, []);
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// on changes, re-subscribe
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useEffect((): void => {
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// check if we have a function & that we are mounted
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if (mountedRef.current && fn) {
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const [serialized, mappedParams] = extractParams(fn, params || [], options);
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if (mappedParams && serialized !== tracker.current.serialized) {
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tracker.current.serialized = serialized;
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subscribe(mountedRef, tracker, fn, mappedParams, setValue, options);
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}
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}
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}, [fn, options, mountedRef, params]);
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return value;
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}
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