// Copyright 2017-2023 @polkadot/react-hooks authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type { ApiPromise } from '@polkadot/api';

import { useMemo } from 'react';

import { BN, BN_THOUSAND, BN_TWO, bnMin } from '@polkadot/util';

import { createNamedHook } from './createNamedHook';
import { useApi } from './useApi';
import { A_DAY } from './useBlocksPerDays';

// Some chains incorrectly use these, i.e. it is set to values such as 0 or even 2
// Use a low minimum validity threshold to check these against
const THRESHOLD = BN_THOUSAND.div(BN_TWO);
const DEFAULT_TIME = new BN(6_000);

function calcInterval (api: ApiPromise): BN {
  return bnMin(A_DAY, (
    // Babe, e.g. Relay chains (Substrate defaults)
    api.consts.babe?.expectedBlockTime ||
    // POW, eg. Kulupu
    api.consts.difficulty?.targetBlockTime ||
    // Subspace
    api.consts.subspace?.expectedBlockTime || (
      // Check against threshold to determine value validity
      api.consts.timestamp?.minimumPeriod.gte(THRESHOLD)
        // Default minimum period config
        ? api.consts.timestamp.minimumPeriod.mul(BN_TWO)
        : api.query.parachainSystem
          // default guess for a parachain
          ? DEFAULT_TIME.mul(BN_TWO)
          // default guess for others
          : DEFAULT_TIME
    )
  ));
}

function useBlockIntervalImpl (apiOverride?: ApiPromise | null): BN {
  const { api } = useApi();

  return useMemo(
    () => calcInterval(apiOverride || api),
    [api, apiOverride]
  );
}

export const useBlockInterval = createNamedHook('useBlockInterval', useBlockIntervalImpl);