Middleware to resize the image

operator-middleware.js

import urlJoin from "url-join";
import R from "ramda";
import request from "request";
import sharp from "sharp";

export const containMiddleware = (req, res, next) => {
  //Use pipe to pass in the results from one function to the next
  R.pipe(makeResizer('contain'), requestImage(req, res, next))(req, res, next);
};
export const coverMiddleware = (req, res, next) => {
  //Use pipe to pass in the results from one function to the next
  R.pipe(makeResizer('cover'), requestImage(req, res, next))(req, res, next);
};

const requestImage = (req, res, next)=>(resizer)=>{
  const {image, imageHost} = res.stash.params;
  const url: string = urlJoin(`http${req.secure ? "s": ""}://`,  imageHost, image);

  const stream = request(url);
  
  //We want to know when we have a 404 error
  stream.on('response', resp=> {
    if (resp.statusCode >= 400) {
      next(new Error( "Could not access image"))
    } else {
      //set the content type, if the original image had one
      res.set('Content-Type', resp.headers['content-type']);
      stream.pipe(resizer).pipe(res);
    }
  });
};


/**
 * Creates a resizer that accepts an input stream and can pipe out an output stream
 * @param type - must be one of "contain" or "cover"
 */
const makeResizer = (type:'contain'|'cover')=>(req, res) =>{
  const {width, height} = res.props;
  let resizer = sharp().resize(width, height).withoutEnlargement();

  if (width && height) {
    if (type === 'contain') {
      //Resize the image according to background-size contain
      resizer = resizer.max();
    } else if (type === 'cover') {
      //Resize the image according to background-size cover
      resizer = resizer.min();
    }
  }
  return resizer
};