fix: price calculation (#774)

RequestNetwork · Feb 16, 2022 · 6773e0c · 6773e0c
1 parent c047df3
commit 6773e0c
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Showing 2 changed files with 34 additions and 19 deletions.
diff --git a/packages/data-format/src/format/rnf_invoice/utils.ts b/packages/data-format/src/format/rnf_invoice/utils.ts
@@ -1,4 +1,4 @@
-import { BigNumber } from 'ethers';
+import { BigNumber, FixedNumber } from 'ethers';
 import { Invoice, InvoiceItem } from './types';
 
 export const getInvoiceTotal = (invoice: Invoice): BigNumber => {
@@ -9,11 +9,6 @@ export const getInvoiceTotal = (invoice: Invoice): BigNumber => {
 };
 
 export const getInvoiceLineTotal = (item: InvoiceItem): BigNumber => {
-  // Every amount in currency is a big number with the good number of decimals for this currency
-  // Tax percent is not an amount in currency. To allow a big number multiplication, we convert
-  //  it temporarily with preciselyOne (allows 6 decimals, ie 0.123456%)
-  const preciselyOne = 1000000;
-
   // Support for rnf_version < 0.0.3
   const tax = item.taxPercent
     ? { type: 'percentage', amount: String(item.taxPercent) }
@@ -24,18 +19,20 @@ export const getInvoiceLineTotal = (item: InvoiceItem): BigNumber => {
     tax.amount && tax.type === 'fixed' ? BigNumber.from(tax.amount) : BigNumber.from(0);
   const discount = item.discount ? BigNumber.from(item.discount) : BigNumber.from(0);
 
-  return (
-    BigNumber.from(item.unitPrice)
-      // account for floating quantities
-      .mul(Number(item.quantity * preciselyOne).toFixed(0))
-      .div(preciselyOne)
-      .sub(discount)
-      // Artificially offset the decimal to let the multiplication work
-      .mul(Number(taxPercent * preciselyOne).toFixed(0))
-      // Remove the decimal offset
-      .div(preciselyOne)
-      // Remove the percentage multiplier
-      .div(100)
-      .add(taxFixed)
+  return BigNumber.from(
+    // Removes the resulting decimal (.0)
+    Number(
+      FixedNumber.from(item.unitPrice)
+        // accounts for floating quantities
+        .mulUnsafe(FixedNumber.fromString(item.quantity.toString()))
+        .subUnsafe(FixedNumber.from(discount))
+        // accounts for floating taxes
+        .mulUnsafe(FixedNumber.fromString(taxPercent.toString()))
+        // Removes the percentage multiplier
+        .divUnsafe(FixedNumber.from(100))
+        .addUnsafe(FixedNumber.from(taxFixed))
+        .round(0)
+        .toString(),
+    ),
   );
 };
diff --git a/packages/data-format/test/rnf_invoice/utils.test.ts b/packages/data-format/test/rnf_invoice/utils.test.ts
@@ -174,4 +174,22 @@ describe('getInvoiceTotal', () => {
       }).toString(),
     ).toEqual('1515165');
   });
+
+  it('rounds the total correctly', () => {
+    expect(
+      getInvoiceTotal({
+        ...baseInvoice,
+        invoiceItems: [
+          {
+            ...baseInvoiceItem,
+            unitPrice: '3333',
+            tax: {
+              type: 'percentage',
+              amount: '20',
+            },
+          },
+        ],
+      }).toString(),
+    ).toEqual('4000');
+  });
 });