gc_function_get_server_notification_and_parse_data.js

file.js

const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp();

exports.v2 = functions.https.onRequest(async (req, res) => {
  // Ensure the request method is POST
  if (req.method !== "POST") {
    return res.status(400).send("Only POST requests are accepted");
  }

  // Save data to Firestore
  try {
    // Extract data from POST request body
    const data = req.body;
    if (!data.signedPayload) {
      res.status(500).send("Necessary Data is not provided");
      return;
    }
    await admin
      .firestore()
      .collection("ios-iap-server-notifications")
      .add(data);

    const transaction = generateTransaction(data.signedPayload);
    if (!transaction) {
      res.status(500).send("Failed to generate transaction");
      return;
    }

    await admin.firestore().collection("ios-iap-transactions").add(transaction);

    res.status(200).send("Success!");
  } catch (error) {
    console.error("Error saving data:", error);
    res.status(500).send("Failed to save data");
  }
});

function generateTransaction(signedPayload) {
  const decodedNotification = decode(signedPayload).payload;

  if (!decodedNotification) {
    return null;
  }

  const decodedSignedTransactionInfo = decode(
    decodedNotification.data.signedTransactionInfo
  ).payload;

  if (!decodedSignedTransactionInfo) {
    return null;
  }

  const decodedSignedRenewalInfo = decode(
    decodedNotification.data.signedRenewalInfo
  ).payload;

  if (!decodedSignedRenewalInfo) {
    return null;
  }

  return {
    notification: {
      signedPayload: signedPayload,
      data: decodedNotification.data,
    },
    transactionInfo: {
      signedTransactionInfo: decodedNotification.data.signedTransactionInfo,
      data: decodedSignedTransactionInfo,
    },
    renewalInfo: {
      signedRenewalInfo: decodedNotification.data.signedRenewalInfo,
      data: decodedSignedRenewalInfo,
    },
  };
}

function decode(signedPayload) {
  // Split the JWS transaction into its components
  const [encodedHeader, encodedPayload, signature] = signedPayload.split(".");
  const header = base64UrlDecode(encodedHeader);
  const payload = base64UrlDecode(encodedPayload);
  return { header, payload };
}

// Base64 URL decode the header and payload
function base64UrlDecode(str) {
  const base64 = str.replace(/-/g, "+").replace(/_/g, "/");
  const json = Buffer.from(base64, "base64").toString("utf-8");
  return JSON.parse(json);
}