From bc1788db21424614bce2149be9cdab96537ff787 Mon Sep 17 00:00:00 2001
From: Ryan Ghods <ryan@ryanio.com>
Date: Tue, 2 Jan 2024 13:32:44 -0800
Subject: [PATCH] fix basis points rounding

---
 src/constants.ts   |  6 ++++--
 src/sdk.ts         |  7 ++++---
 src/utils/utils.ts | 13 ++++++++++---
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/src/constants.ts b/src/constants.ts
index ab6055113..afc8d9436 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -1,12 +1,14 @@
-import { ethers } from "ethers";
+import { FixedNumber, ZeroAddress } from "ethers";
 
+export const FIXED_NUMBER_100 = FixedNumber.fromValue(100);
 export const INVERSE_BASIS_POINT = 10_000; // 100 basis points per 1%
+export const INVERSE_BASIS_POINT_BIGINT = BigInt(INVERSE_BASIS_POINT);
 export const MAX_EXPIRATION_MONTHS = 1;
 
 export const API_BASE_MAINNET = "https://api.opensea.io";
 export const API_BASE_TESTNET = "https://testnets-api.opensea.io";
 
-export const DEFAULT_ZONE = ethers.ZeroAddress;
+export const DEFAULT_ZONE = ZeroAddress;
 export const ENGLISH_AUCTION_ZONE_MAINNETS =
   "0x110b2b128a9ed1be5ef3232d8e4e41640df5c2cd";
 export const ENGLISH_AUCTION_ZONE_TESTNETS =
diff --git a/src/sdk.ts b/src/sdk.ts
index e80d2bc4a..add6c7ed3 100644
--- a/src/sdk.ts
+++ b/src/sdk.ts
@@ -22,6 +22,7 @@ import { OpenSeaAPI } from "./api/api";
 import { CollectionOffer, Listing, NFT, Order } from "./api/types";
 import {
   INVERSE_BASIS_POINT,
+  INVERSE_BASIS_POINT_BIGINT,
   DEFAULT_ZONE,
   ENGLISH_AUCTION_ZONE_MAINNETS,
   ENGLISH_AUCTION_ZONE_TESTNETS,
@@ -248,7 +249,7 @@ export class OpenSeaSDK {
   ): string => {
     return (
       (amount * BigInt(basisPoints)) /
-      BigInt(INVERSE_BASIS_POINT)
+      INVERSE_BASIS_POINT_BIGINT
     ).toString();
   };
 
@@ -1106,10 +1107,10 @@ export class OpenSeaSDK {
 
     // Validation
     if (startAmount == null || startAmountWei < 0) {
-      throw new Error(`Starting price must be a number >= 0`);
+      throw new Error("Starting price must be a number >= 0");
     }
     if (isEther && orderSide === OrderSide.BID) {
-      throw new Error(`Offers must use wrapped ETH or an ERC-20 token.`);
+      throw new Error("Offers must use wrapped ETH or an ERC-20 token.");
     }
     if (priceDiffWei < 0) {
       throw new Error(
diff --git a/src/utils/utils.ts b/src/utils/utils.ts
index 42a5daedf..9ac3b6640 100644
--- a/src/utils/utils.ts
+++ b/src/utils/utils.ts
@@ -2,11 +2,12 @@ import {
   CROSS_CHAIN_SEAPORT_V1_5_ADDRESS,
   ItemType,
 } from "@opensea/seaport-js/lib/constants";
-import { ethers } from "ethers";
+import { ethers, FixedNumber } from "ethers";
 import {
   MAX_EXPIRATION_MONTHS,
   SHARED_STOREFRONT_LAZY_MINT_ADAPTER_CROSS_CHAIN_ADDRESS,
   SHARED_STOREFRONT_ADDRESSES,
+  FIXED_NUMBER_100,
 } from "../constants";
 import {
   Chain,
@@ -225,8 +226,14 @@ export const getAddressAfterRemappingSharedStorefrontAddressToLazyMintAdapterAdd
  * @returns sum of basis points
  */
 export const feesToBasisPoints = (fees: Fee[]): number => {
-  const feeBasisPoints = fees.map((fee) => fee.fee * 100);
-  return feeBasisPoints.reduce((sum, basisPoints) => basisPoints + sum, 0);
+  const feeBasisPoints = fees.map((fee) =>
+    Number(FixedNumber.fromValue(fee.fee).mul(FIXED_NUMBER_100).toString()),
+  );
+  const totalBasisPoints = feeBasisPoints.reduce(
+    (sum, basisPoints) => basisPoints + sum,
+    0,
+  );
+  return totalBasisPoints;
 };
 
 /**