PalletsStakingProgressController.ts

import { ApiPromise } from '@polkadot/api';
import { RequestHandler } from 'express';

import { PalletsStakingProgressService } from '../../services';
import AbstractController from '../AbstractController';

/**
 * GET progress on the general Staking pallet system.
 *
 * Query params:
 * - (Optional)`at`: Block at which to retrieve runtime version information at. Block
 * 		identifier, as the block height or block hash. Defaults to most recent block.
 *
 * Returns:
 * - `at`: Block number and hash at which the call was made.
 * - `activeEra`: `EraIndex` of the era being rewarded.
 * - `forceEra`: Current status of era forcing.
 * - `nextActiveEraEstimate`: **Upper bound estimate** of the block height at which the next
 *   active era will start. Not included in response when `forceEra.isForceNone`.
 * - `nextSessionEstimate`: **Upper bound estimate** of the block height at which the next
 *   session will start.
 * - `unappliedSlashes`: Array of upcoming `UnappliedSlash` indexed by era. Each `UnappliedSlash`
 *   contains:
 * 		- `validator`: Stash account ID of the offending validator.
 *		- `own`: The amount the validator will be slashed.
 *		- `others`: Array of tuples of (accountId, amount) representing all the stashes of other
 *     slashed stakers and the amount they will be slashed.
 *		- `reporters`: Array of account IDs of the reporters of the offense.
 *		- `payout`: Amount of bounty payout to reporters.
 * - `electionStatus`: Information about the off-chain election. Not included in response when
 *   `forceEra.isForceNone`. Response includes:
 *		- `status`: Era election status; either `Close: null` or `Open: <BlockNumber>`. A status of
 *		`Close` indicates that the submission window for solutions from off-chain Phragmen is not
 *		open. A status of `Open` indicates the submission window for off-chain Phragmen solutions
 *		has been open since BlockNumber. N.B. when the submission window is open, certain
 *		extrinsics are not allowed because they would mutate the state that the off-chain Phragmen
 * 		calculation relies on for calculating results.
 *		- `toggleEstimate`: **Upper bound estimate** of the block height at which the `status` will
 *    switch.
 * - `idealValidatorCount`: Upper bound of validator set size; considered the ideal size. Not
 *   included in response when `forceEra.isForceNone`.
 * - `validatorSet`: Stash account IDs of the validators for the current session. Not included in
 *   response when `forceEra.isForceNone`.
 *
 * Note about 'active' vs. 'current' era: The _active_ era is the era currently being rewarded.
 * That is, an elected validator set will be in place for an entire active era, as long as none
 * are kicked out due to slashing. Elections take place at the end of each _current_ era, which
 * is the latest planned era, and may not equal the active era. Normally, the current era index
 * increments one session before the active era, in order to perform the election and queue the
 * validator set for the next active era. For example:
 *
 * ```
 * Time: --------->
 * CurrentEra:            1              |              2              |
 * ActiveEra:   |              1              |              2              |
 * SessionIdx:  |  1 |  2 |  3 |  4 |  5 |  6 |  7 |  8 |  9 | 10 | 11 | 12 | 13 | 14 |
 * Elections:                           ^                             ^
 * Set Changes:                               ^                             ^
 * ```
 *
 * Substrate Reference:
 * - Staking Pallet: https://crates.parity.io/pallet_staking/index.html
 * - Session Pallet: https://crates.parity.io/pallet_session/index.html
 * - `Forcing`: https://crates.parity.io/pallet_staking/enum.Forcing.html
 * - `ElectionStatus`: https://crates.parity.io/pallet_staking/enum.ElectionStatus.html
 */
export default class PalletsStakingProgressController extends AbstractController<PalletsStakingProgressService> {
	constructor(api: ApiPromise) {
		super(
			api,
			'/pallets/staking/progress',
			new PalletsStakingProgressService(api)
		);
		this.initRoutes();
	}

	protected initRoutes(): void {
		this.safeMountAsyncGetHandlers([['', this.getPalletStakingProgress]]);
	}

	/**
	 * Get the progress of the staking pallet system.
	 *
	 * @param _req Express Request
	 * @param res Express Response
	 */
	private getPalletStakingProgress: RequestHandler = async (
		{ query: { at } },
		res
	): Promise<void> => {
		const hash = await this.getHashFromAt(at);

		PalletsStakingProgressController.sanitizedSend(
			res,
			await this.service.derivePalletStakingProgress(hash)
		);
	};
}