Script to delay an http resource for debugging

delay.php

<?php

namespace Aerticket\delay;
/**
 * Script for Delaying Content Delivery for certain Resources
 */
/**
 * Created by PhpStorm.
 * User: cwolff
 * Date: 05.12.2017
 * Time: 09:48
 */

class delay
{
    const HELP_MESSAGE_HTML = '<h1>Delay Script</h1>
            <pre>GET parameters:
    <b>url</b>         <i>required</i>  url which should be fetched.  
    <b>delay</b>       <i>optional</i>  delay in millisecond 1000 equals 1 Second.  
    <b>chunk_size</b>  <i>optional</i>  chunksize, in bytes, every chunk will be delayed by <i>delay</i>.  
            </pre>';
    /**
     * example usage:
     * http://extranet-aerticket-de.local/packit/delay.php?delay=10&src=http%3A%2F%2Fextranet-aerticket-de.local%2Fpackit%2Fscripts%2Fpackit.js
     */
    public function run()
    {
        $delay = isset($_GET['delay']) ? (int)$_GET['delay'] * 1000 : 0;
        $chunkLength = isset($_GET['chunk_size']) ? (int)$_GET['chunk_size'] : 0;
        $src = isset($_GET['url']) ? $_GET['url'] : null;

        /**
         * Main Programm
         */
        if (empty($src)) {
            http_response_code(400);
            echo self::HELP_MESSAGE_HTML;
            exit();
        } else {
            $response = $this->fetchHttpResource($src);
            usleep($delay);
            $body = $this->sendHeaderAndGetBody($response);

            $this->sendBodyPartsDelayed($body, $delay, $chunkLength);
        }
    }

    /**
     * Sends the HTTP headers and Returns the Body
     *
     * @param $httpResponse
     *
     * @return string
     */
    function sendHeaderAndGetBody($httpResponse)
    {

        // Split the headers from the body and fetch the headers
        $parts = explode("\r\n\r\n", $httpResponse);
        $headers = array_shift($parts);

        // Send headers
        foreach (explode("\r\n", $headers) as $header) {
            $header = trim($header);
            if ($header) header($header);
        }
        return implode("\r\n\r\n", $parts); // return body Part
    }

    /**
     * Sends the Body Parts with a delay if we send Multiple Parts
     *
     * @param $body
     * @param $delay
     * @param $chunkLength
     */
    function sendBodyPartsDelayed($body, $delay, $chunkLength = 0)
    {
        if ($chunkLength === 0) {
            echo $body;
        } else {
            $bodyChunks = str_split($body, $chunkLength);
            foreach ($bodyChunks as $chunk) {
                usleep($delay);
                echo $chunk;
            }

        }
    }


    /**
     * Fetches the Remote Resource
     *
     * @param $src
     *
     * @return mixed
     */
    function fetchHttpResource($src)
    {
        $curlHandle = curl_init();
        curl_setopt_array($curlHandle, [
            CURLOPT_URL => $src,
            CURLOPT_HEADER => true,
            CURLOPT_RETURNTRANSFER => true,
        ]);

        $response = curl_exec($curlHandle);
        return $response;
    }
}

$delay = new delay();
$delay->run();