verify.js

import { onRequest } from 'firebase-functions/v2/https';
import { google } from 'googleapis';
import admin from 'firebase-admin';
import { setGlobalOptions } from 'firebase-functions/v2';

setGlobalOptions({
  maxInstances: 1
});

admin.initializeApp();

const auth = new google.auth.GoogleAuth({
  keyFile: 'YOUR_KEY.json',
  scopes: ['https://www.googleapis.com/auth/androidpublisher'],
});

const androidpublisher = google.androidpublisher({
  version: 'v3',
  auth,
});

const handleValidation = onRequest(async (request, response) => {
  const returnContent = {
    isValid: false,
    error: null,
  };

  try {
    const { packageName, subscriptionId, token } = request.body;
    const subscriptionRes = await checkSubscription(packageName, subscriptionId, token);
    if (subscriptionRes) {
      const { startTimeMillis, expiryTimeMillis } = subscriptionRes;
      const now = Date.now();
      const startTime = parseInt(startTimeMillis, 10);
      const expiryTime = parseInt(expiryTimeMillis, 10);
      const isValid = now >= startTime && now < expiryTime;

      if (isValid) {
        returnContent.isValid = true;
      }
    }
  } catch (error) {
    returnContent.error = error;
  }

  response.status(200).send(returnContent);
});


const checkSubscription = async (packageName, subscriptionId, token) => {
  try {
    const res = await androidpublisher.purchases.subscriptions.get({
      packageName,
      subscriptionId,
      token,
    });
    return res?.data;
  } catch (error) {
    console.log(error);
  }

  return null;
};

export default handleValidation;