withBalance.js

// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.
//
// SPDX-License-Identifier: BSD-3-Clause

import abi from '@parity/shared/lib/contracts/abi/eip20';
import { empty } from 'rxjs';
import {
  defaultAccount$,
  isNullOrLoading,
  makeContract$,
  myBalance$
} from '@parity/light.js';
import { filter, map, switchMap } from 'rxjs/operators';
import { fromWei } from '@parity/api/lib/util/wei';
import light from 'light-hoc';

/**
 * A HOC on light.js to get the current balance.
 *
 * @example
 * @withBalance()
 * class MyComponent extends React.Component{
 *
 * }
 */
export default (propsSelector = ({ token }) => token) =>
  light({
    balance: ownProps => {
      // Find our token object in the props
      const token = propsSelector(ownProps);

      if (!token.address) {
        return empty();
      }
      return token.address === 'ETH'
        ? myBalance$().pipe(
          map(value => (isNullOrLoading(value) ? null : value)), // Transform loading state to null
          map(value => value && fromWei(value))
        )
        : defaultAccount$().pipe(
          filter(x => x),
          switchMap(defaultAccount =>
            makeContract$(token.address, abi).balanceOf$(defaultAccount)
          ),
          map(value => (isNullOrLoading(value) ? null : value)), // Transform loading state to null
          map(value => value && value.div(10 ** token.decimals))
        );
    }
  });