// Copyright 2017-2020 @polkadot/react-hooks authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type BN from 'bn.js';
import type { Balance } from '@polkadot/types/interfaces';

import { useEffect, useState } from 'react';

import { DeriveBalancesAccount } from '@polkadot/api-derive/types';
import { BN_MILLION, BN_ZERO, stringToU8a } from '@polkadot/util';

import { useApi } from './useApi';
import { useCall } from './useCall';

const TREASURY_ACCOUNT = stringToU8a('modlpy/trsry'.padEnd(32, '\0'));

interface Result {
  value?: Balance;
  burn?: BN;
  spendPeriod: BN;
}

export function useTreasury (): Result {
  const { api } = useApi();
  const [result, setResult] = useState<Result>({
    spendPeriod: api.consts.treasury
      ? api.consts.treasury.spendPeriod
      : BN_ZERO
  });

  const treasuryBalance = useCall<DeriveBalancesAccount>(api.derive.balances?.account, [TREASURY_ACCOUNT]);

  useEffect(() => {
    if (!api.consts.treasury) {
      return;
    }

    setResult(({ spendPeriod }) => ({
      burn: treasuryBalance?.freeBalance.gtn(0) && !api.consts.treasury.burn.isZero()
        ? api.consts.treasury.burn.mul(treasuryBalance.freeBalance).div(BN_MILLION)
        : BN_ZERO,
      spendPeriod,
      value: treasuryBalance?.freeBalance.gtn(0)
        ? treasuryBalance.freeBalance
        : undefined
    }));
  }, [api, treasuryBalance]);

  return result;
}