From 82e03978b89938219958032efb1448cc76baa181 Mon Sep 17 00:00:00 2001
From: Saumit <justsaumit@protonmail.com>
Date: Sat, 27 Sep 2025 02:14:26 +0530
Subject: Initial snapshot - OpenTelemetry demo 2.1.3 -f

---
 src/payment/charge.js | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 src/payment/charge.js

(limited to 'src/payment/charge.js')

diff --git a/src/payment/charge.js b/src/payment/charge.js
new file mode 100644
index 0000000..588cc07
--- /dev/null
+++ b/src/payment/charge.js
@@ -0,0 +1,88 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+const { context, propagation, trace, metrics } = require('@opentelemetry/api');
+const cardValidator = require('simple-card-validator');
+const { v4: uuidv4 } = require('uuid');
+
+const { OpenFeature } = require('@openfeature/server-sdk');
+const { FlagdProvider } = require('@openfeature/flagd-provider');
+const flagProvider = new FlagdProvider();
+
+const logger = require('./logger');
+const tracer = trace.getTracer('payment');
+const meter = metrics.getMeter('payment');
+const transactionsCounter = meter.createCounter('app.payment.transactions');
+
+const LOYALTY_LEVEL = ['platinum', 'gold', 'silver', 'bronze'];
+
+/** Return random element from given array */
+function random(arr) {
+  const index = Math.floor(Math.random() * arr.length);
+  return arr[index];
+}
+
+module.exports.charge = async request => {
+  const span = tracer.startSpan('charge');
+
+  await OpenFeature.setProviderAndWait(flagProvider);
+
+  const numberVariant =  await OpenFeature.getClient().getNumberValue("paymentFailure", 0);
+
+  if (numberVariant > 0) {
+    // n% chance to fail with app.loyalty.level=gold
+    if (Math.random() < numberVariant) {
+      span.setAttributes({'app.loyalty.level': 'gold' });
+      span.end();
+
+      throw new Error('Payment request failed. Invalid token. app.loyalty.level=gold');
+    }
+  }
+
+  const {
+    creditCardNumber: number,
+    creditCardExpirationYear: year,
+    creditCardExpirationMonth: month
+  } = request.creditCard;
+  const currentMonth = new Date().getMonth() + 1;
+  const currentYear = new Date().getFullYear();
+  const lastFourDigits = number.substr(-4);
+  const transactionId = uuidv4();
+
+  const card = cardValidator(number);
+  const { card_type: cardType, valid } = card.getCardDetails();
+
+  const loyalty_level = random(LOYALTY_LEVEL);
+
+  span.setAttributes({
+    'app.payment.card_type': cardType,
+    'app.payment.card_valid': valid,
+    'app.loyalty.level': loyalty_level
+  });
+
+  if (!valid) {
+    throw new Error('Credit card info is invalid.');
+  }
+
+  if (!['visa', 'mastercard'].includes(cardType)) {
+    throw new Error(`Sorry, we cannot process ${cardType} credit cards. Only VISA or MasterCard is accepted.`);
+  }
+
+  if ((currentYear * 12 + currentMonth) > (year * 12 + month)) {
+    throw new Error(`The credit card (ending ${lastFourDigits}) expired on ${month}/${year}.`);
+  }
+
+  // Check baggage for synthetic_request=true, and add charged attribute accordingly
+  const baggage = propagation.getBaggage(context.active());
+  if (baggage && baggage.getEntry('synthetic_request') && baggage.getEntry('synthetic_request').value === 'true') {
+    span.setAttribute('app.payment.charged', false);
+  } else {
+    span.setAttribute('app.payment.charged', true);
+  }
+
+  const { units, nanos, currencyCode } = request.amount;
+  logger.info({ transactionId, cardType, lastFourDigits, amount: { units, nanos, currencyCode }, loyalty_level }, 'Transaction complete.');
+  transactionsCounter.add(1, { 'app.payment.currency': currencyCode });
+  span.end();
+
+  return { transactionId };
+};
-- 
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