packages/api-derive/src/session/progress.ts
// Copyright 2017-2024 @polkadot/api-derive authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { Observable } from 'rxjs';
import type { Option, u64 } from '@polkadot/types';
import type { BlockNumber, SessionIndex } from '@polkadot/types/interfaces';
import type { DeriveApi, DeriveSessionInfo, DeriveSessionProgress } from '../types.js';
import { combineLatest, map, of, switchMap } from 'rxjs';
import { objectSpread } from '@polkadot/util';
import { memo } from '../util/index.js';
type ResultSlotsNoSession = [u64, u64, u64];
type ResultSlots = [u64, u64, u64, Option<SessionIndex>];
type ResultSlotsFlat = [u64, u64, u64, SessionIndex];
function withProgressField (field: 'eraLength' | 'eraProgress' | 'sessionProgress'): (instanceId: string, api: DeriveApi) => () => Observable<BlockNumber> {
return (instanceId: string, api: DeriveApi) =>
memo(instanceId, (): Observable<BlockNumber> =>
api.derive.session.progress().pipe(
map((info) => info[field])
)
);
}
function createDerive (api: DeriveApi, info: DeriveSessionInfo, [currentSlot, epochIndex, epochOrGenesisStartSlot, activeEraStartSessionIndex]: ResultSlotsFlat): DeriveSessionProgress {
const epochStartSlot = epochIndex.mul(info.sessionLength).iadd(epochOrGenesisStartSlot);
const sessionProgress = currentSlot.sub(epochStartSlot);
const eraProgress = info.currentIndex.sub(activeEraStartSessionIndex).imul(info.sessionLength).iadd(sessionProgress);
return objectSpread({
eraProgress: api.registry.createType('BlockNumber', eraProgress),
sessionProgress: api.registry.createType('BlockNumber', sessionProgress)
}, info);
}
function queryAura (api: DeriveApi): Observable<DeriveSessionProgress> {
return api.derive.session.info().pipe(
map((info): DeriveSessionProgress =>
objectSpread({
eraProgress: api.registry.createType('BlockNumber'),
sessionProgress: api.registry.createType('BlockNumber')
}, info)
)
);
}
function queryBabe (api: DeriveApi): Observable<[DeriveSessionInfo, ResultSlotsFlat]> {
return api.derive.session.info().pipe(
switchMap((info): Observable<[DeriveSessionInfo, ResultSlots | ResultSlotsNoSession]> =>
combineLatest([
of(info),
// we may have no staking, but have babe (permissioned)
api.query.staking?.erasStartSessionIndex
? api.queryMulti<ResultSlots>([
api.query.babe.currentSlot,
api.query.babe.epochIndex,
api.query.babe.genesisSlot,
[api.query.staking.erasStartSessionIndex, info.activeEra]
])
: api.queryMulti<ResultSlotsNoSession>([
api.query.babe.currentSlot,
api.query.babe.epochIndex,
api.query.babe.genesisSlot
])
])
),
map(([info, [currentSlot, epochIndex, genesisSlot, optStartIndex]]): [DeriveSessionInfo, ResultSlotsFlat] => [
info, [currentSlot, epochIndex, genesisSlot, optStartIndex && optStartIndex.isSome ? optStartIndex.unwrap() : api.registry.createType('SessionIndex', 1)]
])
);
}
/**
* @description Retrieves all the session and era query and calculates specific values on it as the length of the session and eras
*/
export function progress (instanceId: string, api: DeriveApi): () => Observable<DeriveSessionProgress> {
return memo(instanceId, (): Observable<DeriveSessionProgress> =>
api.query.babe
? queryBabe(api).pipe(
map(([info, slots]: [DeriveSessionInfo, ResultSlotsFlat]): DeriveSessionProgress =>
createDerive(api, info, slots)
)
)
: queryAura(api)
);
}
export const eraLength = /*#__PURE__*/ withProgressField('eraLength');
export const eraProgress = /*#__PURE__*/ withProgressField('eraProgress');
export const sessionProgress = /*#__PURE__*/ withProgressField('sessionProgress');