trpc on cloud function

trpc.ts

import { inferAsyncReturnType, initTRPC, TRPCError } from '@trpc/server';
import * as trpcExpress from '@trpc/server/adapters/express';
import express from 'express';
import dotenv from 'dotenv';
import { appRouter } from './router/server';
import cors, { CorsOptions } from 'cors';
import jsonwebtoken from 'jsonwebtoken';
// import * as functions from 'firebase-functions';
import type { HttpFunction } from '@google-cloud/functions-framework';

const { decode } = jsonwebtoken;
import { createExpressMiddleware } from '@trpc/server/adapters/express';

dotenv.config();

const port = process.env.PORT || '4000';

type RequestUser = {
  _id: string;
  firstName: string;
  lastName: string;
  displayName: string;
  email: string;
}

// created for each request
const createContext = ({
  req,
  res,
}: trpcExpress.CreateExpressContextOptions): { user : RequestUser | null } => {
  const auth = req.header('authorization') || '';
  const token = auth?.replace('Bearer ', '');
  // console.log('auth', auth);
  if (token) {
    const res = decode(token) as any;
    // console.log('jwt', res.user_data);

    const user = res?.user_data;
    return {
      user: {
        ...user,
      }
    }
  }
  
  return {
    user: null,
  }
}// no context

export type Context = inferAsyncReturnType<typeof createContext>;

const corsOptions: CorsOptions = {
  allowedHeaders: ['Content-Type', 'Authorization'],
  origin: (origin: string | undefined, callback: (err: Error | null, allow?: boolean) => void) => {
    const allowedOrigins = ['http://localhost', /\.xyz\.com$/];
    if (!origin || allowedOrigins.some(o => o instanceof RegExp ? o.test(origin) : o === origin)) {
      callback(null, true);
    } else {
      console.log('origin error', origin);
      callback(new Error('Not allowed by CORS'), false);
    }
  },
  methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
  preflightContinue: false,
  optionsSuccessStatus: 204,
  credentials: true,
};

export const setup = () => {
  const app = express();
  app.use('/', 
    cors(corsOptions),
    createExpressMiddleware({
    router: appRouter,
    createContext,
  }));

  return app;
};

export const trpcFunction: HttpFunction = (req, res) => {
  setup()(req, res);
};