From fc4b18833ff3e38dfc820ce814d53ef822037e1a Mon Sep 17 00:00:00 2001
From: Brendon Votteler <bvotteler@users.noreply.github.com>
Date: Wed, 22 Nov 2023 11:12:31 +0200
Subject: [PATCH] chore: use monetary methods for usd conversion

---
 api/currency-utils.js | 30 ++++++++++++++++++++++--------
 api/package-lock.json |  1 +
 api/package.json      |  1 +
 api/tvl_dex.js        |  8 ++++----
 4 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/api/currency-utils.js b/api/currency-utils.js
index 58e9f86f3..9edbd9f70 100644
--- a/api/currency-utils.js
+++ b/api/currency-utils.js
@@ -1,14 +1,16 @@
 import {
+    MonetaryAmount,
+    ExchangeRate,
     Bitcoin,
-    InterBtc, // on Polkadot
-    Interlay, // On Polkadot
-    KBtc, // on Kusama
-    Kintsugi, // On Kusama
-    Kusama, // on Kusama
-    Polkadot // on Polkadot
+    InterBtc,
+    Interlay,
+    KBtc,
+    Kintsugi,
+    Kusama,
+    Polkadot
 } from '@interlay/monetary-js';
 import { isForeignAsset } from "@interlay/interbtc-api";
-
+import Big from "big.js";
 
 const COINGECKO_ID_BY_CURRENCY_TICKER = {
     [Bitcoin.ticker]: 'bitcoin',
@@ -40,4 +42,16 @@ const getCoingeckoQueryUrl = (vsId, coingeckoIds) => {
     return `https://api.coingecko.com/api/v3/simple/price?vs_currencies=${vsId}&ids=${idsString}`;
 };
 
-export { getCoingeckoId, getCoingeckoQueryUrl };
\ No newline at end of file
+const getUsdMonetaryAmount = (monetaryAmount, usdPrice) => {
+    const usdCurrency = {
+        name: "US Dollar",
+        decimals: 2,
+        ticker: "USD",
+        humanDecimals: 2
+    };
+
+    const xToUsd = new ExchangeRate(monetaryAmount.currency, usdCurrency, Big(usdPrice));
+    return xToUsd.toCounter(monetaryAmount);
+}
+
+export { getCoingeckoId, getCoingeckoQueryUrl, getUsdMonetaryAmount };
\ No newline at end of file
diff --git a/api/package-lock.json b/api/package-lock.json
index 124d156d0..12276b8ea 100644
--- a/api/package-lock.json
+++ b/api/package-lock.json
@@ -12,6 +12,7 @@
         "@interlay/interbtc-api": "2.6.0-rc.0",
         "@interlay/monetary-js": "0.7.3",
         "@polkadot/util-crypto": "12.6.1",
+        "big.js": "6.1.1",
         "pg": "^8.10.0"
       },
       "devDependencies": {
diff --git a/api/package.json b/api/package.json
index 03c5b5695..63f72574e 100644
--- a/api/package.json
+++ b/api/package.json
@@ -16,6 +16,7 @@
     "@interlay/interbtc-api": "2.6.0-rc.0",
     "@interlay/monetary-js": "0.7.3",
     "@polkadot/util-crypto": "12.6.1",
+    "big.js": "6.1.1",
     "pg": "^8.10.0"
   }
 }
diff --git a/api/tvl_dex.js b/api/tvl_dex.js
index 7f939e001..57fcabf15 100644
--- a/api/tvl_dex.js
+++ b/api/tvl_dex.js
@@ -1,5 +1,5 @@
 import { createInterBtcApi } from "@interlay/interbtc-api";
-import { getCoingeckoId, getCoingeckoQueryUrl } from "./currency-utils";
+import { getCoingeckoId, getCoingeckoQueryUrl, getUsdMonetaryAmount } from "./currency-utils";
 
 const tvlDex = async (request, response) => {
     if (request.method === 'GET') {
@@ -20,8 +20,8 @@ const tvlDex = async (request, response) => {
         const queryUrl = getCoingeckoQueryUrl("usd", Array.from(coingeckoIds));
         // return format: { <conigeckoId> : { <vs_id>: <price_as_number> }, ... }
         // eg. {"bitcoin":{"usd":36478},"interlay":{"usd":0.0240072},"voucher-dot":{"usd":6.12}}
-        const response = await fetch(queryUrl, { headers: { "accept": "application/json" } });
-        const cgData = await response.json();
+        const cgResponse = await fetch(queryUrl, { headers: { "accept": "application/json" } });
+        const cgData = await cgResponse.json();
         
         const amounts = pools.flatMap((pool) => pool.pooledCurrencies)
             .map((monetaryAmount) => {
@@ -33,7 +33,7 @@ const tvlDex = async (request, response) => {
                     ? cgData[cgId]["usd"]
                     : undefined;
                 
-                const monetaryAmountUsd = usdPrice ? monetaryAmount.mul(usdPrice) : undefined;
+                const monetaryAmountUsd = usdPrice ? getUsdMonetaryAmount(monetaryAmount) : undefined;
                 const amountUsd = monetaryAmountUsd?.toString(true);
                 const atomicAmountUsd = monetaryAmountUsd?.toString();
                 return {