Download remote file with progress bar (PHP, curl)

downloader.php

#!/usr/bin/php
<?php

/**
 * Usage:
 * php downloader.php http://path.to/remote/file.ext /local/file/path
 *
 * Output:
 * [###############################################################################################     ] 96%
 */

/**
 * Class Downloader
 */
class Downloader
{
    /**
     * @var string
     */
    private $url;
    /**
     * @var string
     */
    private $destination;

    /**
     * Downloader constructor.
     * @param string $url
     * @param string $destination
     */
    public function __construct(string $url, string $destination)
    {
        $this->url = $this->prepareUrl($url);
        $this->destination = $this->prepareDestination($destination);
    }

    /**
     * @param string $url
     * @return string
     */
    private function prepareUrl(string $url): string
    {
        if (!filter_var($url, FILTER_VALIDATE_URL)) {
            $this->stderr('Invalid URL');
            die;
        }

        return $url;
    }

    /**
     * @param string $output
     */
    private function stderr(string $output): void
    {
        fwrite(STDERR, $output);
    }

    /**
     * @param string $destination
     * @return string
     */
    private function prepareDestination(string $destination): string
    {
        $fileName = basename($destination);
        $dirName = realpath(dirname($destination));
        if (!$dirName) {
            $this->stderr('Check the destination path of file');
            die;
        }

        return $dirName . DIRECTORY_SEPARATOR . $fileName;
    }

    /**
     *
     */
    public function download(): void
    {
        $ch = curl_init();
        $fp = fopen($this->destination, 'wb');

        curl_setopt_array($ch, [
            CURLOPT_URL => $this->url,
            CURLOPT_HEADER => false,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_FILE => $fp,
            CURLOPT_PROGRESSFUNCTION => [$this, 'progress'],
            CURLOPT_NOPROGRESS => false,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_FAILONERROR => true
        ]);

        curl_exec($ch);

        if (curl_errno($ch)) {
            $this->stderr('Error: ' . curl_error($ch));
            die;
        }

        curl_close($ch);
        fclose($fp);
    }

    /**
     * @param $resource
     * @param int $download_size
     * @param int $downloaded
     * @param int $upload_size
     * @param int $uploaded
     */
    private function progress($resource, $download_size = 0, $downloaded = 0, $upload_size = 0, $uploaded = 0): void
    {
        $percent = $download_size > 0 && $downloaded > 0 ? ceil($downloaded * 100 / $download_size) : 0;
        $this->stdout('[' . str_pad('', $percent, '#') . str_pad('', 100 - $percent) . "] $percent%\r");
    }

    /**
     * @param string $output
     */
    private function stdout(string $output): void
    {
        fwrite(STDOUT, $output);
    }
}

$dw = new Downloader($argv[1], $argv[2]);
$dw->download();