packages/api-derive/src/session/info.ts
// Copyright 2017-2024 @polkadot/api-derive authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { Observable } from 'rxjs';
import type { DeriveApi, DeriveSessionInfo } from '../types.js';
import { map } from 'rxjs';
import { objectSpread } from '@polkadot/util';
import { memo } from '../util/index.js';
/**
* @description Retrieves all the session and era query and calculates specific values on it as the length of the session and eras
*/
export function info (instanceId: string, api: DeriveApi): () => Observable<DeriveSessionInfo> {
return memo(instanceId, (): Observable<DeriveSessionInfo> =>
api.derive.session.indexes().pipe(
map((indexes) => {
const sessionLength = api.consts?.babe?.epochDuration || api.registry.createType('u64', 1);
const sessionsPerEra = api.consts?.staking?.sessionsPerEra || api.registry.createType('SessionIndex', 1);
return objectSpread({
eraLength: api.registry.createType('BlockNumber', sessionsPerEra.mul(sessionLength)),
isEpoch: !!api.query.babe,
sessionLength,
sessionsPerEra
}, indexes);
})
)
);
}