Implemented receipt extraction

.gitignore

@@ -37,3 +37,4 @@ yarn-error.*
 *.tsbuildinfo
 
 app-example
+.env

backend/gemini-extractor.js

@@ -0,0 +1,53 @@
+import { GoogleGenAI } from "@google/genai";
+import fs from "fs";
+import dotenv from "dotenv";
+
+dotenv.config();
+
+const receiptExtractorPrompt = `
+    You are a receipt extractor. You are given a receipt image and you need to extract the following information:
+    - The name of the item and the price of the item in the receipt
+    extract all of those in the following format:
+    {
+        "item": "item name",
+        "upc": "item upc code",
+        "price": "item price"
+    }
+    - if there is no price, then the price should be 0
+    - if there is no item, then the item should be "No item"
+    - if there is no upc, then the upc should be "null"
+
+    IMPORTANT: Return ONLY the raw JSON array without any markdown formatting, code blocks, or additional text. 
+    Do not include \`\`\`json or \`\`\` markers. Just return the pure JSON array.
+`
+
+// The client gets the API key from the environment variable `GEMINI_API_KEY`.
+const ai = new GoogleGenAI({
+    apiKey: process.env.GEMINI_API_KEY,
+});
+
+const base64ImageFile = fs.readFileSync("./receipt.png", {
+    encoding: "base64",
+});
+
+const contents = [
+    {
+        inlineData: {
+            mimeType: "image/png",
+            data: base64ImageFile,
+        }
+    },
+    {
+        text: receiptExtractorPrompt
+    }
+]
+
+async function receiptExtractor() {
+  const response = await ai.models.generateContent({
+    model: "gemini-2.5-flash",
+    contents: contents,
+  });
+  console.log(response.text);
+}
+
+await receiptExtractor();

backend/index.js

@@ -0,0 +1,33 @@
+import express from "express";
+import dotenv from "dotenv";
+import cors from "cors";
+import sharp from "sharp";
+import Tesseract from "tesseract.js";
+import { receiptExtractor } from "./gemini-extractor.js";
+
+dotenv.config();
+
+const app = express();
+const port = 3000;
+
+app.use(express.json());
+app.use(express.urlencoded({ extended: true }));
+app.use(cors());
+
+
+app.post("/api/v1/receipts", async (req, res) => {
+    try {
+        const file = req.files?.file;
+        if (!file) return res.status(400).json({ error: "no_file" });
+
+        const result = await receiptExtractor(file);
+        res.json(result);
+      } catch (e) {
+        console.error(e);
+        res.status(500).json({ error: "extraction_failed" });
+      }
+});
+
+app.listen(port, () => {
+    console.log(`Server is running on port http://localhost:${port}`);
+});