// Copyright 2017-2021 @polkadot/app-democracy authors & contributors
// SPDX-License-Identifier: Apache-2.0

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

import { useMemo } from 'react';

import { BN, BN_ONE, BN_THOUSAND, BN_TWO, bnToBn, extractTime } from '@polkadot/util';

import { createNamedHook } from './createNamedHook';
import { useTranslation } from './translate';
import { useApi } from './useApi';

type Result = [number, string, Time];

const DEFAULT_TIME = new BN(6_000);

// Some chains incorrectly use these, i.e. it is se 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);

function useBlockTimeImpl (blocks: number | BN = BN_ONE, apiOverride?: ApiPromise | null): Result {
  const { t } = useTranslation();
  const { api } = useApi();

  return useMemo(
    (): Result => {
      const a = apiOverride || api;
      const blockTime = (
        // Babe
        a.consts.babe?.expectedBlockTime ||
        // POW, eg. Kulupu
        a.consts.difficulty?.targetBlockTime ||
        // Subspace
        a.consts.subspace?.expectedBlockTime || (
          // Check against threshold to determine value validity
          a.consts.timestamp?.minimumPeriod.gte(THRESHOLD)
            // Default minimum period config
            ? a.consts.timestamp.minimumPeriod.mul(BN_TWO)
            : a.query.parachainSystem
              // default guess for a parachain
              ? DEFAULT_TIME.mul(BN_TWO)
              // default guess for others
              : DEFAULT_TIME
        )
      );
      const value = blockTime.mul(bnToBn(blocks)).toNumber();
      const time = extractTime(Math.abs(value));
      const { days, hours, minutes, seconds } = time;
      const timeStr = [
        days ? (days > 1) ? t<string>('{{days}} days', { replace: { days } }) : t<string>('1 day') : null,
        hours ? (hours > 1) ? t<string>('{{hours}} hrs', { replace: { hours } }) : t<string>('1 hr') : null,
        minutes ? (minutes > 1) ? t<string>('{{minutes}} mins', { replace: { minutes } }) : t<string>('1 min') : null,
        seconds ? (seconds > 1) ? t<string>('{{seconds}} s', { replace: { seconds } }) : t<string>('1 s') : null
      ]
        .filter((s): s is string => !!s)
        .slice(0, 2)
        .join(' ');

      return [
        blockTime.toNumber(),
        `${value < 0 ? '+' : ''}${timeStr}`,
        time
      ];
    },
    [api, apiOverride, blocks, t]
  );
}

export const useBlockTime = createNamedHook('useBlockTime', useBlockTimeImpl);