How to Integrate a Payment System for International Currencies in FlutterFlow

1// Cloud Function: updateExchangeRates
2const functions = require('firebase-functions');
3const admin = require('firebase-admin');
4const fetch = require('node-fetch');
5admin.initializeApp();
6
7exports.updateExchangeRates = functions.pubsub
8  .schedule('every 24 hours')
9  .onRun(async () => {
10    const apiKey = functions.config().exchange.key;
11    const base = 'USD';
12    const url = `https://api.exchangeratesapi.io/v1/latest?access_key=${apiKey}&base=${base}`;
13    const res = await fetch(url);
14    const data = await res.json();
15
16    if (data.success && data.rates) {
17      await admin.firestore()
18        .doc('config/exchange_rates')
19        .set({
20          base,
21          rates: data.rates,
22          updatedAt: admin.firestore.FieldValue
23            .serverTimestamp(),
24        });
25    }
26  });

1// Custom Function: formatPrice
2import 'package:intl/intl.dart';
3
4String formatPrice(
5  double baseAmount,
6  String targetCurrency,
7  Map<String, dynamic> rates,
8) {
9  final rate = (rates[targetCurrency] ?? 1.0).toDouble();
10  final converted = baseAmount * rate;
11
12  const zeroDecimal = {
13    'JPY', 'KRW', 'VND', 'CLP', 'ISK',
14    'UGX', 'RWF', 'BIF', 'GNF',
15  };
16
17  final decimals = zeroDecimal.contains(targetCurrency)
18      ? 0 : 2;
19
20  final formatter = NumberFormat.currency(
21    symbol: _currencySymbol(targetCurrency),
22    decimalDigits: decimals,
23  );
24
25  return formatter.format(converted);
26}
27
28String _currencySymbol(String code) {
29  const symbols = {
30    'USD': '\$', 'EUR': '\u20ac', 'GBP': '\u00a3',
31    'JPY': '\u00a5', 'CAD': 'CA\$', 'AUD': 'A\$',
32    'INR': '\u20b9', 'BRL': 'R\$',
33  };
34  return symbols[code] ?? code;
35}

1// Cloud Function: createCheckoutSession
2const functions = require('firebase-functions');
3const admin = require('firebase-admin');
4const stripe = require('stripe')(
5  functions.config().stripe.secret
6);
7
8exports.createCheckoutSession = functions.https
9  .onCall(async (data) => {
10    const { productName, baseAmountUsd,
11            currency, successUrl, cancelUrl } = data;
12
13    const ratesDoc = await admin.firestore()
14      .doc('config/exchange_rates').get();
15    const rates = ratesDoc.data().rates;
16    const rate = rates[currency.toUpperCase()] || 1;
17    const converted = baseAmountUsd * rate;
18
19    const zeroDecimal = ['jpy','krw','vnd','clp'];
20    const amount = zeroDecimal.includes(currency)
21      ? Math.round(converted)
22      : Math.round(converted * 100);
23
24    const session = await stripe.checkout.sessions
25      .create({
26        payment_method_types: ['card'],
27        line_items: [{
28          price_data: {
29            currency: currency.toLowerCase(),
30            product_data: { name: productName },
31            unit_amount: amount,
32          },
33          quantity: 1,
34        }],
35        mode: 'payment',
36        success_url: successUrl,
37        cancel_url: cancelUrl,
38      });
39
40    return { url: session.url };
41  });