Add mobile expenses and receipt OCR

lib/receipt-scan.ts

@@ -0,0 +1,135 @@
+import * as ImagePicker from "expo-image-picker";
+import { Alert } from "react-native";
+
+import {
+  applyReceiptOcrToForm,
+  recognizeReceiptFromImage,
+} from "@/lib/receipt-ocr";
+import type { ReceiptLineItem } from "@/lib/receipt-parse";
+
+export type ReceiptSuggestFn = (input: { text: string }) => Promise<{
+  amount: number | null;
+  date: Date | null;
+  description: string | null;
+}>;
+
+export type PickedReceiptImage = {
+  uri: string;
+  base64: string;
+  filename: string;
+  mimeType: string;
+};
+
+export type ReceiptScanResult = {
+  image: PickedReceiptImage;
+  description: string;
+  amountText: string;
+  date: Date;
+  ocrText: string;
+  items: ReceiptLineItem[];
+  subtotal: number | null;
+  tax: number | null;
+  total: number | null;
+};
+
+async function requestPermissions(fromCamera: boolean): Promise<boolean> {
+  const permission = fromCamera
+    ? await ImagePicker.requestCameraPermissionsAsync()
+    : await ImagePicker.requestMediaLibraryPermissionsAsync();
+
+  if (permission.granted) return true;
+
+  Alert.alert(
+    fromCamera ? "Camera access needed" : "Photos access needed",
+    fromCamera
+      ? "Allow camera access to scan receipts."
+      : "Allow photo library access to import receipt images.",
+  );
+  return false;
+}
+
+export async function pickReceiptImage(
+  fromCamera: boolean,
+): Promise<PickedReceiptImage | null> {
+  if (!(await requestPermissions(fromCamera))) return null;
+
+  const result = fromCamera
+    ? await ImagePicker.launchCameraAsync({
+        mediaTypes: ["images"],
+        quality: 0.9,
+        base64: true,
+      })
+    : await ImagePicker.launchImageLibraryAsync({
+        mediaTypes: ["images"],
+        quality: 0.9,
+        base64: true,
+      });
+
+  if (result.canceled || !result.assets[0]) return null;
+
+  const asset = result.assets[0];
+  if (!asset.uri || !asset.base64) {
+    Alert.alert(
+      "Could not read image",
+      "Try another photo or lower the image size.",
+    );
+    return null;
+  }
+
+  return {
+    uri: asset.uri,
+    base64: asset.base64,
+    filename:
+      asset.fileName ?? (fromCamera ? "receipt.jpg" : "receipt-import.jpg"),
+    mimeType: asset.mimeType ?? "image/jpeg",
+  };
+}
+
+export async function scanReceiptImage(
+  fromCamera: boolean,
+  current: { description: string; amountText: string; date: Date },
+  suggest?: ReceiptSuggestFn,
+): Promise<ReceiptScanResult | null> {
+  const image = await pickReceiptImage(fromCamera);
+  if (!image) return null;
+
+  try {
+    const ocr = await recognizeReceiptFromImage(image.uri);
+    let next = applyReceiptOcrToForm(ocr, current);
+    next = { ...next, ocrText: ocr.rawText || next.ocrText };
+
+    if (ocr.rawText && suggest) {
+      try {
+        const suggestion = await suggest({ text: ocr.rawText });
+        next = {
+          description: suggestion.description?.trim() || next.description,
+          amountText:
+            suggestion.amount != null
+              ? String(suggestion.amount)
+              : next.amountText,
+          date: suggestion.date ? new Date(suggestion.date) : next.date,
+          ocrText: ocr.rawText,
+        };
+      } catch {
+        // Local parse is enough when server suggest fails offline.
+      }
+    }
+
+    return {
+      image,
+      ...next,
+      items: ocr.items,
+      subtotal: ocr.subtotal,
+      tax: ocr.tax,
+      total: ocr.amount,
+    };
+  } catch (error) {
+    Alert.alert(
+      "OCR failed",
+      error instanceof Error
+        ? error.message
+        : "Could not read text from the receipt.",
+    );
+    return null;
+  }
+}