<?php

declare(strict_types=1);

namespace App\Services\Traffic;

use Illuminate\Http\Request;

final class BotClassifier
{
    /**
     * @return array{is_bot: bool, type: ?string, family: ?string}
     */
    public function classify(Request $request): array
    {
        $userAgent = trim((string) $request->userAgent());

        if ($userAgent === '') {
            return $this->bot('suspicious_bot', 'Empty UA');
        }

        $normalized = strtolower($userAgent);

        if ($family = $this->matchFamily($normalized, [
            'curl' => ['curl'],
            'wget' => ['wget'],
            'python-requests' => ['python-requests'],
            'libwww-perl' => ['libwww-perl'],
            'Go-http-client' => ['go-http-client'],
            'Java' => ['java/'],
            'scrapy' => ['scrapy'],
            'httpclient' => ['httpclient'],
            'masscan' => ['masscan'],
            'nikto' => ['nikto'],
            'sqlmap' => ['sqlmap'],
        ])) {
            return $this->bot('suspicious_bot', $family);
        }

        if ($family = $this->matchFamily($normalized, [
            'Googlebot' => ['googlebot'],
            'Bingbot' => ['bingbot'],
            'DuckDuckBot' => ['duckduckbot'],
            'YandexBot' => ['yandexbot'],
            'Baiduspider' => ['baiduspider'],
            'Applebot' => ['applebot'],
            'Slurp' => ['slurp'],
        ])) {
            return $this->bot('search_bot', $family);
        }

        if ($family = $this->matchFamily($normalized, [
            'GPTBot' => ['gptbot'],
            'ChatGPT-User' => ['chatgpt-user'],
            'OAI-SearchBot' => ['oai-searchbot'],
            'ClaudeBot' => ['claudebot'],
            'PerplexityBot' => ['perplexitybot'],
            'Bytespider' => ['bytespider'],
            'CCBot' => ['ccbot'],
            'Google-Extended' => ['google-extended'],
            'anthropic-ai' => ['anthropic-ai'],
            'cohere-ai' => ['cohere-ai'],
        ])) {
            return $this->bot('ai_bot', $family);
        }

        if ($family = $this->matchFamily($normalized, [
            'AhrefsBot' => ['ahrefsbot'],
            'SemrushBot' => ['semrushbot'],
            'MJ12bot' => ['mj12bot'],
            'DotBot' => ['dotbot'],
            'PetalBot' => ['petalbot'],
            'DataForSeoBot' => ['dataforseobot'],
            'BLEXBot' => ['blexbot'],
            'MauiBot' => ['mauibot'],
            'serpstatbot' => ['serpstatbot'],
        ])) {
            return $this->bot('seo_bot', $family);
        }

        if ($family = $this->matchFamily($normalized, [
            'facebookexternalhit' => ['facebookexternalhit'],
            'Twitterbot' => ['twitterbot'],
            'LinkedInBot' => ['linkedinbot'],
            'Slackbot' => ['slackbot'],
            'Discordbot' => ['discordbot'],
            'TelegramBot' => ['telegrambot'],
            'WhatsApp' => ['whatsapp'],
            'Pinterestbot' => ['pinterestbot'],
        ])) {
            return $this->bot('social_bot', $family);
        }

        if ($family = $this->matchFamily($normalized, [
            'UptimeRobot' => ['uptimerobot'],
            'Pingdom' => ['pingdom'],
            'StatusCake' => ['statuscake'],
            'Better Stack' => ['better stack', 'betterstack'],
            'BetterUptime' => ['betteruptime'],
        ])) {
            return $this->bot('monitoring_bot', $family);
        }

        if (strlen($userAgent) < 8) {
            return $this->bot('suspicious_bot', 'Short UA');
        }

        if ($this->containsAny($normalized, ['bot', 'crawler', 'spider', 'crawl', 'preview'])) {
            return $this->bot('unknown_bot', 'Unknown crawler');
        }

        return [
            'is_bot' => false,
            'type' => null,
            'family' => null,
        ];
    }

    /**
     * @param array<string, array<int, string>> $families
     */
    private function matchFamily(string $normalizedUserAgent, array $families): ?string
    {
        foreach ($families as $family => $keywords) {
            if ($this->containsAny($normalizedUserAgent, $keywords)) {
                return $family;
            }
        }

        return null;
    }

    /**
     * @param array<int, string> $keywords
     */
    private function containsAny(string $haystack, array $keywords): bool
    {
        foreach ($keywords as $keyword) {
            if ($keyword !== '' && str_contains($haystack, $keyword)) {
                return true;
            }
        }

        return false;
    }

    /**
     * @return array{is_bot: bool, type: string, family: string}
     */
    private function bot(string $type, string $family): array
    {
        return [
            'is_bot' => true,
            'type' => $type,
            'family' => $family,
        ];
    }
}