Move some logic to order utils

2 files changed, 16 insertions, 8 deletions

diff --git a/packages/asset-buyer/src/utils/buy_quote_calculator.ts b/packages/asset-buyer/src/utils/buy_quote_calculator.ts
index 31823cc02..aa7159e6c 100644
--- a/packages/asset-buyer/src/utils/buy_quote_calculator.ts
+++ b/packages/asset-buyer/src/utils/buy_quote_calculator.ts
@@ -3,6 +3,7 @@ import { BigNumber } from '@0xproject/utils';
 import * as _ from 'lodash';
 
 import { constants } from '../constants';
+import { orderUtils } from './order_utils';
 import { AssetBuyerError, AssetBuyerOrdersAndFillableAmounts, BuyQuote } from '../types';
 
 export const buyQuoteCalculator = {
@@ -30,7 +31,7 @@ export const buyQuoteCalculator = {
         if (remainingFillAmount.gt(constants.ZERO_AMOUNT)) {
             throw new Error(AssetBuyerError.InsufficientAssetLiquidity);
         }
-        // TODO: optimization
+        // TODO(bmillman): optimization
         // update this logic to find the minimum amount of feeOrders to cover the worst case as opposed to
         // finding order that cover all fees, this will help with estimating ETH and minimizing gas usage
         const {
@@ -59,10 +60,11 @@ export const buyQuoteCalculator = {
         let maxEthAmount = constants.ZERO_AMOUNT;
         let cumulativeMakerAmount = constants.ZERO_AMOUNT;
         _.forEach(allOrders, (order, index) => {
-            // TODO: Move this logic to order_utils
             const remainingFillableMakerAssetAmount = allRemainingAmounts[index];
-            const orderRate = order.takerAssetAmount.div(order.makerAssetAmount);
-            const claimableTakerAssetAmount = orderRate.mul(remainingFillableMakerAssetAmount);
+            const claimableTakerAssetAmount = orderUtils.calculateRemainingTakerAssetAmount(
+                order,
+                remainingFillableMakerAssetAmount,
+            );
             // taker asset is always assumed to be WETH
             maxEthAmount = maxEthAmount.plus(claimableTakerAssetAmount);
             if (cumulativeMakerAmount.lessThan(assetBuyAmount)) {
diff --git a/packages/asset-buyer/src/utils/order_utils.ts b/packages/asset-buyer/src/utils/order_utils.ts
index bb0bdb80f..27db73257 100644
--- a/packages/asset-buyer/src/utils/order_utils.ts
+++ b/packages/asset-buyer/src/utils/order_utils.ts
@@ -10,10 +10,16 @@ export const orderUtils = {
         return order.expirationTimeSeconds.lessThan(currentUnixTimestampSec);
     },
     calculateRemainingMakerAssetAmount(order: SignedOrder, remainingTakerAssetAmount: BigNumber): BigNumber {
-        const result = remainingTakerAssetAmount.eq(0)
-            ? constants.ZERO_AMOUNT
-            : remainingTakerAssetAmount.times(order.makerAssetAmount).dividedToIntegerBy(order.takerAssetAmount);
-        return result;
+        if (remainingTakerAssetAmount.eq(0)) {
+            return constants.ZERO_AMOUNT;
+        }
+        return remainingTakerAssetAmount.times(order.makerAssetAmount).dividedToIntegerBy(order.takerAssetAmount);
+    },
+    calculateRemainingTakerAssetAmount(order: SignedOrder, remainingMakerAssetAmount: BigNumber): BigNumber {
+        if (remainingMakerAssetAmount.eq(0)) {
+            return constants.ZERO_AMOUNT;
+        }
+        return remainingMakerAssetAmount.times(order.takerAssetAmount).dividedToIntegerBy(order.makerAssetAmount);
     },
     isOpenOrder(order: SignedOrder): boolean {
         return order.takerAddress === constants.NULL_ADDRESS;