Host Android Sign in with Apple function on firebase

import * as functions from "firebase-functions";
import {logger} from "firebase-functions";
const firebaseAdmin = require('firebase-admin');

const express = require("express");
const bodyParser = require("body-parser");

const app = express();

app.use(bodyParser.urlencoded({ extended: false }));

const redirectUrl = function(body: any, ANDROID_PACKAGE_IDENTIFIER: string): string {
    return `intent://callback?${new URLSearchParams(
        body
    ).toString()}#Intent;package=${
        ANDROID_PACKAGE_IDENTIFIER
    };scheme=signinwithapple;end`;
}

// The callback route used for Android, which will send the callback parameters from Apple into the Android app.
// This is done using a deeplink, which will cause the Chrome Custom Tab to be dismissed and providing the parameters from Apple back to the app.
app.post("/callbacks/sign-in-with-apple",  (request: any, response: any) => {
    const ANDROID_PACKAGE_IDENTIFIER = "com.your.indentifier";
    const redirect = redirectUrl(request.body, ANDROID_PACKAGE_IDENTIFIER);

    logger.info(`Redirecting to ${redirect}`);

    response.redirect(307, redirect);
});

exports.auth = functions.https.onRequest(app);

exports.app = app;

      final appleCredential = await SignInWithApple.getAppleIDCredential(
        scopes: [
          AppleIDAuthorizationScopes.email,
          AppleIDAuthorizationScopes.fullName
        ],
        # This section below is for android.  clientId should match identifier made in apple console
        webAuthenticationOptions: WebAuthenticationOptions(
            clientId: "com.your.identifier.service",
            redirectUri: Uri.parse(appleRedirectUri)),
        nonce: nonce,
      );

const test = require('firebase-functions-test')({
   authDomain: "",
   projectId: "",
   storageBucket: "",
   messagingSenderId: ""
}, process.env.GOOGLE_APPLICATION_CREDENTIALS);

const supertest = require("supertest");
const {createServer} = require("http");

describe('Authentication', function () {
   let functionsToTest, request;

   // adds the functions to test
   before(function () {
       functionsToTest = require('../lib/index');
       request = supertest(createServer(functionsToTest.app));
   });
   // cleans up firebase after each test
   after(function () {
       test.cleanup();
   });

   describe('Sign in with apple on Android', function () {
       it('should return redirect to URI', function (done) {
           request.post('/callbacks/sign-in-with-apple')
               .send({domain: "test"})
               .set('Accept', 'application/json')
               .expect(307)
               .expect('Location', "intent://callback?#Intent;package=com.your.identifier;scheme=signinwithapple;end")
               .end(function(err) {
                   if (err) return done(err);
                   return done();
               });
       });
   });
});