41 lines
1.4 KiB
TypeScript
41 lines
1.4 KiB
TypeScript
// Copyright 2017-2021 @polkadot/api-derive authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { ApiInterfaceRx } from '@polkadot/api/types';
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import type { Option } from '@polkadot/types';
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import type { Hash, VoteThreshold } from '@polkadot/types/interfaces';
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import type { ITuple } from '@polkadot/types/types';
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import type { Observable } from '@polkadot/x-rxjs';
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import type { DeriveProposalExternal } from '../types';
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import { of } from '@polkadot/x-rxjs';
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import { map, switchMap } from '@polkadot/x-rxjs/operators';
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import { memo } from '../util';
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function withImage (api: ApiInterfaceRx, nextOpt: Option<ITuple<[Hash, VoteThreshold]>>): Observable<DeriveProposalExternal | null> {
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if (nextOpt.isNone) {
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return of(null);
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}
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const [imageHash, threshold] = nextOpt.unwrap();
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return api.derive.democracy.preimage(imageHash).pipe(
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map((image): DeriveProposalExternal => ({
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image,
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imageHash,
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threshold
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}))
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);
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}
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export function nextExternal (instanceId: string, api: ApiInterfaceRx): () => Observable<DeriveProposalExternal | null> {
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return memo(instanceId, (): Observable<DeriveProposalExternal | null> =>
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api.query.democracy?.nextExternal
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? api.query.democracy.nextExternal<Option<ITuple<[Hash, VoteThreshold]>>>().pipe(
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switchMap((nextOpt) => withImage(api, nextOpt))
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)
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: of(null)
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);
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}
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