Add Open Food Facts barcode lookup workflow

src/modules/openFoodFacts.test.ts

@@ -0,0 +1,80 @@
+import { http, HttpResponse } from 'msw';
+import { setupServer } from 'msw/node';
+import { afterAll, afterEach, beforeAll, describe, expect, it } from 'vitest';
+import { fetchProductFromOFF } from './openFoodFacts';
+
+const server = setupServer();
+
+beforeAll(() => server.listen());
+afterEach(() => server.resetHandlers());
+afterAll(() => server.close());
+
+describe('fetchProductFromOFF', () => {
+  const endpoint = 'https://world.openfoodfacts.org/api/v2/product/123456.json';
+
+  it('returns parsed product data when available', async () => {
+    server.use(
+      http.get(endpoint, () =>
+        HttpResponse.json({
+          status: 1,
+          product: {
+            product_name: 'Sparkling Water',
+            brands: 'Acme',
+            quantity: '500ml',
+            image_url: 'https://example.com/water.png',
+          },
+        }),
+      ),
+    );
+
+    const result = await fetchProductFromOFF('123456');
+
+    expect(result).toEqual({
+      name: 'Sparkling Water',
+      brand: 'Acme',
+      quantity: '500ml',
+      image: 'https://example.com/water.png',
+      source: 'openfoodfacts',
+    });
+  });
+
+  it('coerces missing optional fields to null', async () => {
+    server.use(
+      http.get(endpoint, () =>
+        HttpResponse.json({
+          status: 1,
+          product: {
+            product_name: 'Chocolate Bar',
+          },
+        }),
+      ),
+    );
+
+    const result = await fetchProductFromOFF('123456');
+
+    expect(result).toEqual({
+      name: 'Chocolate Bar',
+      brand: null,
+      quantity: null,
+      image: null,
+      source: 'openfoodfacts',
+    });
+  });
+
+  it('returns null when the product is not found', async () => {
+    server.use(http.get(endpoint, () => HttpResponse.json({ status: 0 })));
+
+    const result = await fetchProductFromOFF('123456');
+
+    expect(result).toBeNull();
+  });
+
+  it('returns null on network error', async () => {
+    server.use(http.get(endpoint, () => HttpResponse.error()));
+
+    const result = await fetchProductFromOFF('123456');
+
+    expect(result).toBeNull();
+  });
+});
+

src/modules/openFoodFacts.ts

@@ -0,0 +1,53 @@
+export interface ExternalProductInfo {
+  name: string | null;
+  brand?: string | null;
+  quantity?: string | null;
+  image?: string | null;
+  source: 'openfoodfacts';
+}
+
+const BASE_URL = 'https://world.openfoodfacts.org/api/v2/product';
+const REQUEST_TIMEOUT_MS = 5000;
+
+const isOffline = () => typeof navigator !== 'undefined' && 'onLine' in navigator && !navigator.onLine;
+
+export const fetchProductFromOFF = async (barcode: string): Promise<ExternalProductInfo | null> => {
+  if (!barcode || isOffline()) {
+    return null;
+  }
+
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
+
+  try {
+    const response = await fetch(`${BASE_URL}/${barcode}.json`, { signal: controller.signal });
+    if (!response.ok) return null;
+
+    const data = (await response.json()) as {
+      status?: number;
+      product?: {
+        product_name?: string | null;
+        brands?: string | null;
+        quantity?: string | null;
+        image_url?: string | null;
+      };
+    };
+
+    if (data?.status !== 1 || !data.product || !data.product.product_name) {
+      return null;
+    }
+
+    return {
+      name: data.product.product_name ?? null,
+      brand: data.product.brands ?? null,
+      quantity: data.product.quantity ?? null,
+      image: data.product.image_url ?? null,
+      source: 'openfoodfacts',
+    } satisfies ExternalProductInfo;
+  } catch (error) {
+    return null;
+  } finally {
+    clearTimeout(timeout);
+  }
+};
+