chore(utils): currency epsilon (#14225)

* chore(utils): currency epsilon

* pending diff

* getEpsilonFromDecimalPrecision

packages/core/utils/src/totals/big-number.ts

@@ -1,6 +1,7 @@
 import { BigNumberInput, BigNumberRawValue, IBigNumber } from "@medusajs/types"
 import { BigNumber as BigNumberConstructor } from "bignumber.js"
 import { isBigNumber } from "../common/is-big-number"
+import { isDefined } from "../common/is-defined"
 import { isString } from "../common/is-string"
 
 type BigNumberJS = InstanceType<typeof BigNumberConstructor>
@@ -150,3 +151,18 @@ export class BigNumber implements IBigNumber {
 export const MEDUSA_EPSILON = new BigNumber(
   process.env.MEDUSA_EPSILON || "0.0001"
 )
+
+export const MEDUSA_DEFAULT_CURRENCY_EPSILON = new BigNumber(
+  process.env.MEDUSA_DEFAULT_CURRENCY_EPSILON || "0.01"
+)
+
+export const getEpsilonFromDecimalPrecision = (decimalDigits?: number) => {
+  if (!isDefined(decimalDigits)) {
+    return MEDUSA_DEFAULT_CURRENCY_EPSILON
+  }
+
+  const epsilon = new BigNumberJS(1).dividedBy(
+    new BigNumberJS(10).pow(decimalDigits)
+  )
+  return new BigNumber(epsilon.toString())
+}

packages/core/utils/src/totals/cart/index.ts

@@ -1,5 +1,6 @@
 import { BigNumberInput, CartLikeWithTotals } from "@medusajs/types"
-import { BigNumber } from "../big-number"
+import { defaultCurrencies } from "../../defaults/currencies"
+import { BigNumber, getEpsilonFromDecimalPrecision } from "../big-number"
 import { calculateCreditLinesTotal } from "../credit-lines"
 import { GetItemTotalInput, getLineItemsTotals } from "../line-item"
 import { MathBN } from "../math"
@@ -14,6 +15,7 @@ interface TotalsConfig {
 }
 
 export interface DecorateCartLikeInputDTO {
+  currency_code?: string
   credit_lines?: {
     amount: BigNumberInput
   }[]
@@ -198,6 +200,7 @@ export function decorateCartTotals(
       creditLines,
       includesTax: false,
       taxRate: creditLinesSumTaxRate,
+      currencyCode: cartLike.currency_code,
     })
 
   const taxTotal = MathBN.add(itemsTaxTotal, shippingTaxTotal)
@@ -276,6 +279,11 @@ export function decorateCartTotals(
       ...(cart.items?.map((item) => item.return_requested_total ?? 0) ?? [0])
     )
 
+    const upperCurCode = cart.currency_code?.toUpperCase() as string
+    const currencyEpsilon = getEpsilonFromDecimalPrecision(
+      defaultCurrencies[upperCurCode]?.decimal_digits
+    )
+
     const pendingDifference = new BigNumber(
       MathBN.sub(
         MathBN.sub(cart.total, pendingReturnTotal),
@@ -283,7 +291,12 @@ export function decorateCartTotals(
       )
     )
 
-    cart.summary.pending_difference = pendingDifference
+    cart.summary.pending_difference = MathBN.lte(
+      MathBN.abs(pendingDifference),
+      currencyEpsilon
+    )
+      ? MathBN.convert(0)
+      : pendingDifference
   }
 
   return cart

packages/core/utils/src/totals/credit-lines/index.ts

@@ -1,16 +1,19 @@
 import { BigNumberInput } from "@medusajs/types"
 import { isDefined } from "../../common"
-import { BigNumber, MEDUSA_EPSILON } from "../big-number"
+import { defaultCurrencies } from "../../defaults/currencies"
+import { BigNumber, getEpsilonFromDecimalPrecision } from "../big-number"
 import { MathBN } from "../math"
 
 export function calculateCreditLinesTotal({
   creditLines,
   includesTax,
   taxRate,
+  currencyCode,
 }: {
   creditLines: { amount: BigNumberInput }[]
   includesTax?: boolean
   taxRate?: BigNumberInput
+  currencyCode?: string
 }) {
   // the sum of all creditLine amounts excluding tax
   let creditLinesSubtotal = MathBN.convert(0)
@@ -46,7 +49,12 @@ export function calculateCreditLinesTotal({
     }
   }
 
-  const isZero = MathBN.lte(creditLinesTotal, MEDUSA_EPSILON)
+  const upperCurCode = currencyCode?.toUpperCase() as string
+  const currencyEpsilon = getEpsilonFromDecimalPrecision(
+    defaultCurrencies[upperCurCode]?.decimal_digits
+  )
+
+  const isZero = MathBN.lte(creditLinesTotal, currencyEpsilon)
   return {
     creditLinesTotal: isZero ? MathBN.convert(0) : creditLinesTotal,
     creditLinesSubtotal: isZero ? MathBN.convert(0) : creditLinesSubtotal,