This Firebase Cloud Function, using Express.js middleware, provides a remote procedure call (RPC) endpoint that accepts function names from requests, executes them, and returns the results as JSON responses. It also logs the results and handles cookies and CORS.

Run example

npm run import -- "google cloud function rpc wrapper"

google cloud function rpc wrapper

var cookie = require('cookie');
var cors = require('cors')({origin: true});
var importer = require('../Core');
var getResult = importer.import("rpc result");
var getEnvironment = importer.import("get environment");

var expressToResult = (req, res) => getResult({
    command: (req.body || {})['function'] || (req.query || {})['function'],
    result: importer.interpret((req.body || {})['function'] || (req.query || {})['function']),
    body: req.method === 'POST' ? req.body : req.query,
    circles: ['Public']
})

var logResult = (r) => {
    // TODO: call storeResult()?
    var result = typeof r === 'object'
        ? Object.keys(r).reduce((alt, key) => {
            alt[key] = r[key] + '';
            return alt;
        }, {})
        : ('' + r);
    console.log(result);
    return result;
}

function expressHandler(req, res) {
    getEnvironment();
    req.cookies = cookie.parse(req.get('cookie') || '');
    res.setHeader('Cache-Control', 'private');
    cors(req, res, () => {});
    return Promise.resolve()
        .then(() => expressToResult(req, res))
        .then(r => (res.status(200), r))
        .catch(e => (res.status(500), e))
        .then(r => logResult(r))
        .then(r => res.send(r));
}

module.exports.handler = expressHandler;

const cookie = require('cookie');
const cors = require('cors')({ origin: true });
const { importModule } = require('../Core');
const { getResult, interpret } = importModule(['rpc result', 'get environment']);

const expressToResult = (req, res) => {
  const func = req.body?.function || req.query?.function;
  const data = req.method === 'POST'? req.body : req.query;
  const result = getResult({
    command: func,
    result: interpret(func),
    body: data,
    circles: ['Public'],
  });

  return result;
};

const logResult = (r) => {
  let result;
  if (typeof r === 'object') {
    result = Object.fromEntries(Object.entries(r).map(([key, value]) => [key, value.toString()]));
  } else {
    result = r.toString();
  }

  console.log(result);
  return result;
};

const expressHandler = (req, res) => {
  getEnvironment();

  req.cookies = cookie.parse(req.get('cookie') || '');
  res.setHeader('Cache-Control', 'private');
  cors(req, res, () => {});

  return Promise.resolve()
   .then(() => expressToResult(req, res))
   .then((r) => {
      res.status(200);
      return r;
    })
   .catch((e) => {
      res.status(500);
      return e;
    })
   .then(logResult)
   .then((r) => res.send(r));
};

module.exports.handler = expressHandler;

This code sets up an Express.js middleware function for a Firebase Cloud Function that acts as a remote procedure call (RPC) endpoint.

Here's a breakdown:

1. Dependencies:

   • Imports cookie for parsing cookies, cors for handling cross-origin requests, and custom modules importer and getResult.

2. expressToResult Function:

   • Extracts the function name from the request body or query parameters.
   • Calls getResult to interpret the function name and execute the corresponding logic.
   • Returns the result object.

3. logResult Function:

   • Logs the result to the console.
   • (TODO) Should call storeResult to persist the result.

4. expressHandler Function:

   • Initializes the environment.
   • Parses cookies from the request headers.
   • Sets the Cache-Control header to private.
   • Enables CORS.
   • Calls expressToResult to process the request.
   • Sends the result back to the client as a JSON response.
   • Logs the result.

5. Export:

   • Exports the expressHandler function as the Cloud Function's handler.