Parse (get) all links from a website

ParseLinks.php

<?php

namespace App\Util;

class ParseLinks
{
    private $rootLink;

    private $links = [];
    private $deep = 0;
    private $domain = '';
    private $scheme = '';
    private $assets;

    public function __construct($rootLink, $assets = false)
    {
        $this->rootLink = $rootLink;
        $this->assets = $assets;

        if (!filter_var($this->rootLink, FILTER_VALIDATE_URL)) {
            throw new \Exception('Not a valid URL');
        }

        $d = parse_url($this->rootLink);

        $this->domain = $d['host'];
        $this->scheme = $d['scheme'];

        $this->recParseLink($this->rootLink);
    }

    public function getLinks()
    {
        ksort($this->links);

        return $this->links;
    }

    private function recParseLink($link)
    {
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_AUTOREFERER, true);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_URL, $link);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

        $html = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $mimeType = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);

        curl_close($ch);

        if (!$this->assets &&
            (
                strpos($mimeType, 'image') !== false ||
                strpos($mimeType, 'video') !== false ||
                strpos($mimeType, 'pdf') !== false)
        ) {
            return;
        }

        $this->links[$link] = $httpCode;

        if ($httpCode != 200) {
            return;
        }

        $this->deep++;
        $doc = new \DOMDocument();
        $doc->loadHTML($html);
        $elements = $doc->getElementsByTagName('a');

        foreach ($elements as $element) {
            if (!$link = $element->getAttribute('href')) {
                continue;
            }
            if ($link[0] == '/' || $link[0] == '?') {
                $link = $this->scheme . '://' . $this->domain . $link;
            }

            $p_links = parse_url($link);

            if (!isset($p_links['host']) || $p_links['host'] != $this->domain) {
                continue;
            }

            if ($link && !isset($this->links[$link])) {
//                if ($this->deep < 4) { // Maximum deep restriction
                    $this->recParseLink($link);
//                }
            }
        }

        $this->deep--;
    }
}