Referendum passing status (#2447)

* Referendum passing status

* WarmUp totalIssuance

* Optional balances

packages/apps/src/WarmUp.tsx

@@ -11,10 +11,11 @@ function WarmUp (): React.ReactElement {
   const indexes = useCall<unknown>(isApiReady && api.derive.accounts?.indexes, []);
   const registrars = useCall<unknown>(isApiReady && api.query.identity?.registrars, []);
   const staking = null; // useCall<unknown>(isApiReady && api.derive.staking?.overview, []);
+  const issuance = useCall<unknown>(isApiReady && api.query.balances?.totalIssuance, []);
   const [hasValues, setHasValues] = useState(false);
 
   useEffect((): void => {
-    setHasValues(!!fees || !!indexes || !!registrars || !!staking);
+    setHasValues(!!fees || !!indexes || !!issuance || !!registrars || !!staking);
   }, []);
 
   return (

packages/page-democracy/src/Overview/Referendum.tsx

@@ -5,17 +5,18 @@
 import { DerivedReferendum } from '@polkadot/api-derive/types';
 import { BlockNumber } from '@polkadot/types/interfaces';
 
-import React from 'react';
+import React, { useMemo } from 'react';
 import styled from 'styled-components';
-import { AddressMini, Button, Expander, LinkExternal } from '@polkadot/react-components';
+import { AddressMini, Badge, Button, Expander, Icon, LinkExternal } from '@polkadot/react-components';
 import { useApi, useCall } from '@polkadot/react-hooks';
 import { FormatBalance, BlockToTime } from '@polkadot/react-query';
-import { formatNumber } from '@polkadot/util';
+import { formatNumber, isBoolean } from '@polkadot/util';
 
 import { useTranslation } from '../translate';
 import PreImageButton from './PreImageButton';
 import ProposalCell from './ProposalCell';
 import Voting from './Voting';
+import useIsPassing from './useIsPassing';
 import useVotes from './useVotes';
 
 interface Props {
@@ -27,7 +28,12 @@ function Referendum ({ className, value }: Props): React.ReactElement<Props> | n
   const { t } = useTranslation();
   const { api } = useApi();
   const bestNumber = useCall<BlockNumber>(api.derive.chain.bestNumber, []);
+  const isPassing = useIsPassing(value);
   const { allAye, allNay, voteCountAye, voteCountNay, votedAye, votedNay } = useVotes(value);
+  const threshold = useMemo(
+    () => value.status.threshold.type.toString().replace('majority', ' majority '),
+    [value]
+  );
 
   if (!bestNumber || value.status.end.sub(bestNumber).lten(0)) {
     return null;
@@ -76,6 +82,17 @@ function Referendum ({ className, value }: Props): React.ReactElement<Props> | n
           )}
         </Expander>
       </td>
+      <td className='padtop top'>
+        {isBoolean(isPassing) && (
+          <Badge
+            hover={isPassing ? t('{{threshold}}, passing', { replace: { threshold } }) : t('{{threshold}}, not passing', { replace: { threshold } })}
+            info={<Icon name={isPassing ? 'check' : 'cancel'} />}
+            isInline
+            isTooltip
+            type={isPassing ? 'green' : 'brown'}
+          />
+        )}
+      </td>
       <td className='number together top'>
         <Button.Group>
           <Voting

packages/page-democracy/src/Overview/useIsPassing.ts

@@ -0,0 +1,65 @@
+// Copyright 2017-2020 @polkadot/app-democracy authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { DerivedReferendum } from '@polkadot/api-derive/types';
+import { ReferendumStatus } from '@polkadot/types/interfaces';
+
+import BN from 'bn.js';
+import { useState, useEffect } from 'react';
+import { useApi, useCall } from '@polkadot/react-hooks';
+
+function compareRationals (n1: BN, d1: BN, n2: BN, d2: BN): boolean {
+  while (true) {
+    const q1 = n1.div(d1);
+    const q2 = n2.div(d2);
+
+    if (q1.lt(q2)) {
+      return true;
+    } else if (q2.lt(q1)) {
+      return false;
+    }
+
+    const r1 = n1.mod(d1);
+    const r2 = n2.mod(d2);
+
+    if (r2.isZero()) {
+      return false;
+    } else if (r1.isZero()) {
+      return true;
+    }
+
+    n1 = d2;
+    n2 = d1;
+    d1 = r2;
+    d2 = r1;
+  }
+}
+
+export default function useIsPassing (referendum: DerivedReferendum): boolean | undefined {
+  const { api } = useApi();
+  const totalIssuance = useCall<BN>(api.query.balances.totalIssuance, []);
+  const [isPassing, setIsPassing] = useState<boolean | undefined>(undefined);
+
+  useEffect((): void => {
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
+    const { tally, threshold } = (referendum.status as ReferendumStatus);
+
+    if (totalIssuance && tally) {
+      const sqrtVoters = tally.turnout.toRed(BN.red('k256')).redSqrt().fromRed();
+      const sqrtElectorate = totalIssuance.toRed(BN.red('k256')).redSqrt().fromRed();
+
+      setIsPassing(
+        sqrtVoters.isZero()
+          ? false
+          : threshold.isSimplemajority
+            ? tally.ayes.gt(tally.nays)
+            : threshold.isSupermajorityapproval
+              ? compareRationals(tally.nays, sqrtVoters, tally.ayes, sqrtElectorate)
+              : compareRationals(tally.nays, sqrtElectorate, tally.ayes, sqrtVoters)
+      );
+    }
+  }, [referendum, totalIssuance]);
+
+  return isPassing;
+}