"mews/purifier": "~2.0"

php artisan vendor:publish --provider="Mews\Purifier\PurifierServiceProvider"

"league/html-to-markdown": "^4.2",

"erusev/parsedown": "^1.6",

<?php

namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Services\Mention;
use Parsedown;
use League\HTMLToMarkdown\HtmlConverter;
use Purifier;

class Test extends Controller
{
protected $htmlParser;
    protected $markdownParser;

    public function __construct()
    {
        $this->htmlParser = new HtmlConverter([‘header_style‘ => ‘atx‘]);
        $this->markdownParser = new Parsedown();
    }

    public function t2(Request $request)
    {
        $mention = new Mention();
        $content = $request->input(‘content‘);
        $markdownContent = $mention->parse($content);

        $htmlContent = $this->convertMarkdownToHtml($markdownContent);
        var_dump($htmlContent);exit;
    }

    public function convertHtmlToMarkdown($html)
    {
        return $this->htmlParser->convert($html);
    }

    public function convertMarkdownToHtml($markdown)
    {
        $convertedHmtl = $this->markdownParser->setBreaksEnabled(true)->text($markdown);
        $convertedHmtl = Purifier::clean($convertedHmtl, ‘user_topic_body‘);
        $convertedHmtl = str_replace("<pre><code>", ‘<pre><code class=" language-php">‘, $convertedHmtl);

        return $convertedHmtl;
    }



}

<?php
namespace App\Services;

use App\Model\User;

class Mention
{
    public $body_parsed;
    public $users = [];
    public $usernames;
    public $body_original;

    public function getMentionedUsername()
    {
        preg_match_all("/(\S*)\@([^\r\n\s]*)/i", $this->body_original, $atlist_tmp);
        $usernames = [];
        foreach ($atlist_tmp[2] as $k=>$v) {
            if ($atlist_tmp[1][$k] || strlen($v) >25) {
                continue;
            }
            $usernames[] = $v;
        }
        return array_unique($usernames);
    }

    public function replace()
    {
        $this->body_parsed = $this->body_original;

        foreach ($this->users as $user) {
            $search = ‘@‘ . $user->name;
            //$place = ‘[‘.$search.‘](‘.route(‘users.show‘, $user->id).‘)‘;
            $place = ‘[‘.$search.‘](http://user?id=‘.$user->id.‘)‘;
            $this->body_parsed = str_replace($search, $place, $this->body_parsed);
        }
    }

    public function parse($body)
    {
        $this->body_original = $body;

        $this->usernames = $this->getMentionedUsername();
        count($this->usernames) > 0 && $this->users = User::whereIn(‘name‘, $this->usernames)->get();

        $this->replace();
        return $this->body_parsed;
    }
}