chore(trading): update fee factor with discount calculation (#5138)

apps/trading/components/fees-container/fees-container.tsx

@@ -7,7 +7,7 @@ import {
   NetworkParams,
 } from '@vegaprotocol/network-parameters';
 import { useMarketList } from '@vegaprotocol/markets';
-import { formatNumber } from '@vegaprotocol/utils';
+import { formatNumber, formatNumberRounded } from '@vegaprotocol/utils';
 import { useDiscountProgramsQuery, useFeesQuery } from './__generated__/Fees';
 import { FeeCard } from './fees-card';
 import { MarketFees } from './market-fees';
@@ -284,7 +284,7 @@ export const CurrentVolume = ({
   return (
     <div>
       <Stat
-        value={formatNumber(windowLengthVolume)}
+        value={formatNumberRounded(new BigNumber(windowLengthVolume))}
         text={t('Past %s epochs', epochs.toString())}
       />
       {requiredForNextTier > 0 && (

apps/trading/components/fees-container/utils.spec.ts

@@ -0,0 +1,74 @@
+import BigNumber from 'bignumber.js';
+import { getAdjustedFee } from './utils';
+
+describe('getAdjustedFee', () => {
+  it('simple', () => {
+    const volumeDiscount = 0.5;
+    const referralDiscount = 0.5;
+
+    const infraFee = 0.1;
+    const makerFee = 0.1;
+    const liqFee = 0.1;
+
+    const fees = [
+      new BigNumber(infraFee),
+      new BigNumber(makerFee),
+      new BigNumber(liqFee),
+    ];
+
+    const discounts = [
+      new BigNumber(volumeDiscount),
+      new BigNumber(referralDiscount),
+    ];
+
+    // 1 - 0.5 - 0.5
+    const v = new BigNumber(1).minus(new BigNumber(volumeDiscount));
+
+    // 1 - 0.5 = 0.5
+    const r = new BigNumber(1).minus(new BigNumber(referralDiscount));
+
+    // 0.5 * 0.5 = 0.25
+    // 1 - 0.25 = 0.75
+    const factor = new BigNumber(1).minus(v.times(r));
+
+    // 0.1 + 0.1 + 0.1 = 0.3
+    const totalFees = fees.reduce((sum, x) => sum.plus(x), new BigNumber(0));
+
+    // 0.3 * 0.75 = 0.225
+    const expected = new BigNumber(totalFees).times(factor).toNumber();
+
+    expect(getAdjustedFee(fees, discounts)).toBe(expected);
+  });
+
+  it('combines discount factors multiplicativly', () => {
+    const volumeDiscount = 0.4;
+    const referralDiscount = 0.1;
+
+    const infraFee = 0.0005;
+    const makerFee = 0.0002;
+    const liqFee = 0.01;
+
+    const fees = [
+      new BigNumber(infraFee),
+      new BigNumber(makerFee),
+      new BigNumber(liqFee),
+    ];
+
+    const discounts = [
+      new BigNumber(volumeDiscount),
+      new BigNumber(referralDiscount),
+    ];
+
+    // formula for calculating adjusted fees
+    const v = new BigNumber(1).minus(new BigNumber(volumeDiscount));
+    const r = new BigNumber(1).minus(new BigNumber(referralDiscount));
+    const factor = new BigNumber(1).minus(v.times(r));
+
+    // summed fees
+    const totalFees = fees.reduce((sum, x) => sum.plus(x), new BigNumber(0));
+
+    const expected = new BigNumber(totalFees).times(factor).toNumber();
+
+    expect(getAdjustedFee(fees, discounts)).toBe(expected);
+  });
+});

apps/trading/components/fees-container/utils.ts

@@ -88,14 +88,18 @@ export const getReferralBenefitTier = (
 /**
  * Given a set of fees and a set of discounts return
  * the adjusted fee factor
+ *
+ * Formula for calculating the adjusted fees
+ *  total_discount_factor = 1 - (1 - volumeDiscount) * (1 - referralDiscount)
  */
 export const getAdjustedFee = (fees: BigNumber[], discounts: BigNumber[]) => {
   const totalFee = fees.reduce((sum, f) => sum.plus(f), new BigNumber(0));
-  const totalDiscount = discounts.reduce(
-    (sum, d) => sum.plus(d),
-    new BigNumber(0)
-  );
-  return totalFee
-    .times(BigNumber.max(0, new BigNumber(1).minus(totalDiscount)))
-    .toNumber();
+
+  const combinedFactors = discounts.reduce((acc, d) => {
+    return acc.times(new BigNumber(1).minus(d));
+  }, new BigNumber(1));
+
+  const totalFactor = new BigNumber(1).minus(combinedFactors);
+
+  return totalFee.times(BigNumber.max(0, totalFactor)).toNumber();
 };

libs/utils/src/lib/format/number.ts

@@ -179,3 +179,33 @@ export const toNumberParts = (
 export const isNumeric = (
   value?: string | number | BigNumber | bigint | null
 ): value is NonNullable<number | string> => /^-?\d*\.?\d+$/.test(String(value));
+
+/**
+ * Format a number greater than 1 million with m for million, b for billion
+ * and t for trillion
+ */
+export const formatNumberRounded = (num: BigNumber) => {
+  let value = '';
+
+  const format = (divisor: string) => {
+    const result = num.dividedBy(divisor);
+    return result.isInteger() ? result.toString() : result.toFixed(1);
+  };
+
+  if (num.isGreaterThan(new BigNumber('1e14'))) {
+    value = '>100t';
+  } else if (num.isGreaterThanOrEqualTo(new BigNumber('1e12'))) {
+    // Trillion
+    value = `${format('1e12')}t`;
+  } else if (num.isGreaterThanOrEqualTo(new BigNumber('1e9'))) {
+    // Billion
+    value = `${format('1e9')}b`;
+  } else if (num.isGreaterThanOrEqualTo(new BigNumber('1e6'))) {
+    // Million
+    value = `${format('1e6')}m`;
+  } else {
+    value = formatNumber(num);
+  }
+
+  return value;
+};