/* eslint-disable @typescript-eslint/no-non-null-assertion */
import express from 'express';
import * as http from 'http';
import type {AddressInfo} from 'net';
import {expect} from 'chai';

export type FakeAppServer = {
  url: undefined | URL;
  handler: (req: express.Request, res: express.Response) => void;
  server: undefined | http.Server;
};

// To use the fake server, replace its handler with a function that
// implements your test expectations.
export async function newFakeAppServer(path: string): Promise<FakeAppServer> {
  const fakeAppServer: FakeAppServer = {
    url: undefined,
    handler: (_0: express.Request, _1: express.Response) => {
      throw new Error('programmer error, set this function');
    },
    server: undefined,
  };

  const app = express();
  app.use(express.json());
  app.use(
    path,
    (
      req: express.Request,
      res: express.Response,
      next: express.NextFunction,
    ) => {
      fakeAppServer.handler(req, res);
      next();
    },
  );
  await new Promise<void>(resolve => {
    fakeAppServer.server = app.listen(
      {
        port: 0,
        host: '127.0.0.1', // using 'localhost' can return an ipv6 address
      },
      () => resolve(),
    );
    expect(fakeAppServer.server).to.be.an.instanceOf(http.Server);
  });

  const serverAddress: AddressInfo = (
    fakeAppServer.server as http.Server
  ).address() as AddressInfo;
  fakeAppServer.url = new URL(`http://${serverAddress.address}`);
  fakeAppServer.url.port = serverAddress.port.toString();
  return fakeAppServer;
}

export function s(obj: unknown) {
  return JSON.stringify(obj, null, 1).replace(/\n/g, '');
}