<?php

namespace App\Services;

use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;

class EasyListService
{
    private const EASYLIST_URL = 'https://easylist.to/easylist/easylist.txt';
    private const CACHE_KEY = 'easylist_filters';
    private const CACHE_TTL = 86400; // 24 hours

    public function getBlockedDomains(string $url): array
    {
        $filters = $this->getFilters();
        $domains = [];
        
        foreach ($filters as $filter) {
            if (strpos($filter, '||') === 0 && strpos($filter, '^') !== false) {
                $domain = trim(str_replace(['||', '^'], '', $filter));
                if ($this->isValidDomain($domain)) {
                    $domains[] = $domain;
                }
            }
        }
        
        // Limit to 50 most common ad domains to reduce timeout risk
        return array_slice(array_unique($domains), 0, 50);
    }

    public function getBlockedUrls(string $url): array
    {
        $filters = $this->getFilters();
        $urls = [];
        
        foreach ($filters as $filter) {
            if (strpos($filter, '||') !== 0 && strpos($filter, '#') !== 0 && strpos($filter, '!') !== 0) {
                $cleanFilter = trim($filter);
                if (strlen($cleanFilter) > 3 && strpos($cleanFilter, '*') !== false) {
                    $urls[] = str_replace('*', '', $cleanFilter);
                }
            }
        }
        
        // Limit to 25 URL patterns to reduce blocking overhead
        return array_slice(array_unique($urls), 0, 25);
    }

    private function getFilters(): array
    {
        return Cache::remember(self::CACHE_KEY, self::CACHE_TTL, function () {
            try {
                $response = Http::timeout(30)->get(self::EASYLIST_URL);
                
                if ($response->successful()) {
                    $content = $response->body();
                    $lines = explode("\n", $content);
                    
                    $filters = [];
                    foreach ($lines as $line) {
                        $line = trim($line);
                        if (!empty($line) && strpos($line, '!') !== 0) {
                            $filters[] = $line;
                        }
                    }
                    
                    Log::info('EasyList filters updated', ['count' => count($filters)]);
                    return $filters;
                }
                
                Log::warning('Failed to fetch EasyList filters');
                return $this->getFallbackFilters();
                
            } catch (\Exception $e) {
                Log::error('Error fetching EasyList filters: ' . $e->getMessage());
                return $this->getFallbackFilters();
            }
        });
    }

    private function getFallbackFilters(): array
    {
        return [
            '||googletagmanager.com^',
            '||google-analytics.com^',
            '||facebook.com/tr^',
            '||doubleclick.net^',
            '||googlesyndication.com^',
            '||amazon-adsystem.com^',
            '||adsystem.amazon.com^',
            '||googlesyndication.com^',
            '||googleadservices.com^'
        ];
    }

    private function isValidDomain(string $domain): bool
    {
        return filter_var($domain, FILTER_VALIDATE_DOMAIN) !== false;
    }
}