packages/api-derive/src/session/indexes.ts
// Copyright 2017-2024 @polkadot/api-derive authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { Observable } from 'rxjs';
import type { Option, u32 } from '@polkadot/types';
import type { ActiveEraInfo, EraIndex, Moment, SessionIndex } from '@polkadot/types/interfaces';
import type { DeriveApi, DeriveSessionIndexes } from '../types.js';
import { map, of } from 'rxjs';
import { memo } from '../util/index.js';
// parse into Indexes
function parse ([currentIndex, activeEra, activeEraStart, currentEra, validatorCount]: [SessionIndex, EraIndex, Option<Moment>, EraIndex, u32]): DeriveSessionIndexes {
return {
activeEra,
activeEraStart,
currentEra,
currentIndex,
validatorCount
};
}
// query based on latest
function queryStaking (api: DeriveApi): Observable<DeriveSessionIndexes> {
return api.queryMulti<[SessionIndex, Option<ActiveEraInfo>, Option<EraIndex>, u32]>([
api.query.session.currentIndex,
api.query.staking.activeEra,
api.query.staking.currentEra,
api.query.staking.validatorCount
]).pipe(
map(([currentIndex, activeOpt, currentEra, validatorCount]): DeriveSessionIndexes => {
const { index, start } = activeOpt.unwrapOrDefault();
return parse([
currentIndex,
index,
start,
currentEra.unwrapOrDefault(),
validatorCount
]);
})
);
}
// query based on latest
function querySession (api: DeriveApi): Observable<DeriveSessionIndexes> {
return api.query.session.currentIndex().pipe(
map((currentIndex): DeriveSessionIndexes => parse([
currentIndex,
api.registry.createType('EraIndex'),
api.registry.createType('Option<Moment>'),
api.registry.createType('EraIndex'),
api.registry.createType('u32')
]))
);
}
// empty set when none is available
function empty (api: DeriveApi): Observable<DeriveSessionIndexes> {
return of(parse([
api.registry.createType('SessionIndex', 1),
api.registry.createType('EraIndex'),
api.registry.createType('Option<Moment>'),
api.registry.createType('EraIndex'),
api.registry.createType('u32')
]));
}
export function indexes (instanceId: string, api: DeriveApi): () => Observable<DeriveSessionIndexes> {
return memo(instanceId, (): Observable<DeriveSessionIndexes> =>
api.query.session
? api.query.staking
? queryStaking(api)
: querySession(api)
: empty(api)
);
}