<?php

declare(strict_types=1);

namespace App\Services\Academy;

use League\CommonMark\Environment\Environment;
use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
use League\CommonMark\Extension\GithubFlavoredMarkdownExtension;
use League\CommonMark\MarkdownConverter;

final class AcademyLessonMarkdownRenderer
{
    private ?MarkdownConverter $converter = null;

    public function render(?string $markdown): string
    {
        $trimmed = trim((string) $markdown);

        if ($trimmed === '') {
            return '';
        }

        return trim((string) $this->converter()->convert($trimmed)->getContent());
    }

    private function converter(): MarkdownConverter
    {
        if ($this->converter instanceof MarkdownConverter) {
            return $this->converter;
        }

        $environment = new Environment([
            'html_input' => 'strip',
            'allow_unsafe_links' => false,
        ]);
        $environment->addExtension(new CommonMarkCoreExtension());
        $environment->addExtension(new GithubFlavoredMarkdownExtension());

        return $this->converter = new MarkdownConverter($environment);
    }
}