Fix amount preview for scanned receipts (#227)

* no division of amount

* use gpt-4-turbo

* testing setup and naive test

* test multiple variants

* document

* correct locale names

* test large amounts

* test wth strings

* prettier

src/app/groups/[groupId]/expenses/create-from-receipt-button-actions.ts

@@ -12,7 +12,7 @@ export async function extractExpenseInformationFromImage(imageUrl: string) {
   const categories = await getCategories()
 
   const body: ChatCompletionCreateParamsNonStreaming = {
-    model: 'gpt-4-vision-preview',
+    model: 'gpt-4-turbo',
     messages: [
       {
         role: 'user',

src/lib/utils.test.ts

@@ -0,0 +1,66 @@
+import { formatCurrency } from './utils'
+
+describe('formatCurrency', () => {
+  const currency = 'CUR'
+  /** For testing decimals */
+  const partialAmount = 1.23
+  /** For testing small full amounts */
+  const smallAmount = 1
+  /** For testing large full amounts */
+  const largeAmount = 10000
+
+  /** Non-breaking space */
+  const nbsp = '\xa0'
+
+  interface variation {
+    amount: number
+    locale: string
+    result: string
+  }
+
+  /**
+   * Variations to be tested, chosen as follows
+   * - `en-US` is a very common i18n fallback
+   * - `de-DE` exhibited faulty behavior in previous versions
+   */
+  const variations: variation[] = [
+    {
+      amount: partialAmount,
+      locale: `en-US`,
+      result: `${currency}1.23`,
+    },
+    {
+      amount: smallAmount,
+      locale: `en-US`,
+      result: `${currency}1.00`,
+    },
+    {
+      amount: largeAmount,
+      locale: `en-US`,
+      result: `${currency}10,000.00`,
+    },
+    {
+      amount: partialAmount,
+      locale: `de-DE`,
+      result: `1,23${nbsp}${currency}`,
+    },
+    {
+      amount: smallAmount,
+      locale: `de-DE`,
+      result: `1,00${nbsp}${currency}`,
+    },
+    {
+      amount: largeAmount,
+      locale: `de-DE`,
+      result: `10.000,00${nbsp}${currency}`,
+    },
+  ]
+
+  for (const variation of variations) {
+    it(`formats ${variation.amount} in ${variation.locale}`, () => {
+      expect(formatCurrency(currency, variation.amount, variation.locale)).toBe(
+        variation.result,
+      )
+    })
+  }
+})

src/lib/utils.ts

@@ -40,7 +40,7 @@ export function formatCurrency(
     // '€' will be placed in correct position
     currency: 'EUR',
   })
-  const formattedAmount = format.format(amount / 100)
+  const formattedAmount = format.format(amount)
   return formattedAmount.replace('€', currency)
 }