From 6536504b246ef330eb5e0ec92d26eb13e39d8fdc Mon Sep 17 00:00:00 2001
From: RaviChauhan <1chauhanravi0@gmail.com>
Date: Wed, 25 Feb 2026 02:16:34 +0530
Subject: [PATCH] Fix: Remove floating-point precision loss in currency
 conversions using BigInt

---
 djed-sdk/src/helpers.js | 97 ++++++++++++++++++++++++++++++-----------
 1 file changed, 71 insertions(+), 26 deletions(-)

diff --git a/djed-sdk/src/helpers.js b/djed-sdk/src/helpers.js
index 6738053..c14e895 100644
--- a/djed-sdk/src/helpers.js
+++ b/djed-sdk/src/helpers.js
@@ -1,13 +1,14 @@
 export function web3Promise(contract, method, ...args) {
   return contract.methods[method](...args).call();
 }
+
 // Function to build a transaction
 // Set gas limit to 500,000 by default
 export function buildTx(from_, to_, value_, data_, setGasLimit = true) {
   const tx = {
     to: to_,
     from: from_,
-    value: "0x" + BigInt(value_).toString(16), // Use BigInt instead of BN
+    value: "0x" + BigInt(value_).toString(16),
     data: data_,
   };
   if (setGasLimit) {
@@ -15,6 +16,7 @@ export function buildTx(from_, to_, value_, data_, setGasLimit = true) {
   }
   return tx;
 }
+
 export function convertInt(promise) {
   return promise.then((value) => parseInt(value));
 }
@@ -52,7 +54,6 @@ export function decimalScaling(unscaledString, decimals, show = 6) {
   suffix = intersperseCommas(suffix);
 
   if (show <= decimals) {
-    // Remove commas after the decimal point
     suffix = suffix.replace(/,/g, "");
   }
 
@@ -71,14 +72,18 @@ export function decimalUnscaling(scaledString, decimals) {
   let s =
     scaledString.slice(0, pos) +
     scaledString.slice(pos + 1, pos + 1 + decimals);
+
   if (scaledString.length - pos - 1 < decimals) {
     s += "0".repeat(decimals - (scaledString.length - pos - 1));
   }
+
   return s;
 }
 
 export function scaledPromise(promise, scaling) {
-  return promise.then((value) => decimalScaling(value.toString(10), scaling));
+  return promise.then((value) =>
+    decimalScaling(value.toString(10), scaling)
+  );
 }
 
 export function scaledUnscaledPromise(promise, scaling) {
@@ -89,7 +94,11 @@ export function scaledUnscaledPromise(promise, scaling) {
 }
 
 export function percentageScale(value, scaling, showSymbol = false) {
-  const calculatedValue = decimalScaling(value.toString(10), scaling - 2, 2);
+  const calculatedValue = decimalScaling(
+    value.toString(10),
+    scaling - 2,
+    2
+  );
   if (showSymbol) {
     return calculatedValue + "%";
   }
@@ -97,35 +106,71 @@ export function percentageScale(value, scaling, showSymbol = false) {
 }
 
 export function percentScaledPromise(promise, scaling) {
-  return promise.then((value) => percentageScale(value, scaling, true));
+  return promise.then((value) =>
+    percentageScale(value, scaling, true)
+  );
 }
-// currency conversions:
-export function calculateBcUsdEquivalent(coinsDetails, amountFloat) {
-  const adaPerUsd = parseFloat(
-    coinsDetails?.scaledScExchangeRate.replaceAll(",", "")
+
+/* ============================================================
+   CURRENCY CONVERSIONS (BigInt Safe Version)
+   ============================================================ */
+
+// BC → USD
+export function calculateBcUsdEquivalent(coinsDetails, amount) {
+  if (!coinsDetails?.scaledScExchangeRate) return "0.000000";
+
+  const adaPerUsd = BigInt(
+    coinsDetails.scaledScExchangeRate.replaceAll(",", "")
   );
-  const eqPrice = (1e6 * amountFloat) / adaPerUsd;
-  return decimalScaling(eqPrice.toFixed(0).toString(10), 6);
+
+  const amountBig = BigInt(amount);
+
+  // scaled to 6 decimals
+  const eqPrice = (amountBig * 1_000_000n) / adaPerUsd;
+
+  return decimalScaling(eqPrice.toString(10), 6);
 }
 
-export function getBcUsdEquivalent(coinsDetails, amountFloat) {
-  return "$" + calculateBcUsdEquivalent(coinsDetails, amountFloat);
+export function getBcUsdEquivalent(coinsDetails, amount) {
+  return "$" + calculateBcUsdEquivalent(coinsDetails, amount);
 }
 
-export function calculateRcUsdEquivalent(coinsDetails, amountFloat) {
-  const adaPerRc = parseFloat(coinsDetails?.scaledSellPriceRc);
-  const adaPerUsd = parseFloat(
-    coinsDetails?.scaledScExchangeRate.replaceAll(",", "")
+// RC → USD
+export function calculateRcUsdEquivalent(coinsDetails, amount) {
+  if (
+    !coinsDetails?.scaledSellPriceRc ||
+    !coinsDetails?.scaledScExchangeRate
+  )
+    return "0.000000";
+
+  const adaPerRc = BigInt(coinsDetails.scaledSellPriceRc);
+  const adaPerUsd = BigInt(
+    coinsDetails.scaledScExchangeRate.replaceAll(",", "")
   );
-  const eqPrice = (1e6 * amountFloat * adaPerRc) / adaPerUsd;
-  return decimalScaling(eqPrice.toFixed(0).toString(10), 6);
-}
-export function getRcUsdEquivalent(coinsDetails, amountFloat) {
-  return "$" + calculateRcUsdEquivalent(coinsDetails, amountFloat);
+
+  const amountBig = BigInt(amount);
+
+  const eqPrice =
+    (amountBig * adaPerRc * 1_000_000n) / adaPerUsd;
+
+  return decimalScaling(eqPrice.toString(10), 6);
 }
 
-export function getScAdaEquivalent(coinsDetails, amountFloat) {
-  const adaPerSc = parseFloat(coinsDetails?.scaledPriceSc.replaceAll(",", ""));
-  const eqPrice = 1e6 * amountFloat * adaPerSc;
-  return decimalScaling(eqPrice.toFixed(0).toString(10), 6);
+export function getRcUsdEquivalent(coinsDetails, amount) {
+  return "$" + calculateRcUsdEquivalent(coinsDetails, amount);
 }
+
+// SC → ADA
+export function getScAdaEquivalent(coinsDetails, amount) {
+  if (!coinsDetails?.scaledPriceSc) return "0.000000";
+
+  const adaPerSc = BigInt(
+    coinsDetails.scaledPriceSc.replaceAll(",", "")
+  );
+
+  const amountBig = BigInt(amount);
+
+  const eqPrice = amountBig * adaPerSc * 1_000_000n;
+
+  return decimalScaling(eqPrice.toString(10), 6);
+}
\ No newline at end of file