<?php

declare(strict_types=1);

namespace UploadLogger\Detectors;

use UploadLogger\Core\Context;
use UploadLogger\Core\DetectorInterface;

final class FilenameDetector implements DetectorInterface
{
    public function getName(): string
    {
        return 'filename';
    }

    /**
     * @param array<string, mixed> $input
     * @return array<string, mixed>
     */
    public function detect(Context $context, array $input = []): array
    {
        $name = (string)($input['name'] ?? '');
        $origName = (string)($input['orig_name'] ?? $name);
        $suspicious = false;
        $reasons = [];

        if ($origName !== $name || strpos($origName, '/') !== false || strpos($origName, '\\') !== false) {
            $suspicious = true;
            $reasons[] = 'bad_name';
        }

        if ($this->isSuspiciousFilename($name)) {
            $suspicious = true;
            $reasons[] = 'bad_name';
        }

        return [
            'suspicious' => $suspicious,
            'reasons' => $reasons,
        ];
    }

    private function isSuspiciousFilename(string $name): bool
    {
        $n = strtolower($name);

        if (strpos($n, '../') !== false || strpos($n, '..\\') !== false || strpos($n, "\0") !== false) {
            return true;
        }

        if (preg_match('/\.(php|phtml|phar|php\d|pl|cgi|sh|asp|aspx|jsp)$/i', $n)) {
            return true;
        }

        if (preg_match('/\.(php|phtml|phar|php\d|pl|cgi|sh|asp|aspx|jsp)\./i', $n)) {
            return true;
        }

        if (preg_match('/^\.(php|phtml|phar|php\d)/i', $n)) {
            return true;
        }

        return false;
    }
}