<?php

namespace App\Services\Crawl;

class ArxivListUrlParser
{
    /**
     * @return array{category: string, slice: string}|null
     */
    public static function parse(?string $url): ?array
    {
        $url = trim((string) $url);
        if ($url === '') {
            return null;
        }

        if (! preg_match('#arxiv\.org/list/([^/?\#]+)/([^/?\#]+)#i', $url, $matches)) {
            return null;
        }

        $category = trim($matches[1]);
        $slice = trim($matches[2]);
        if ($category === '' || $slice === '' || ! preg_match('/^[a-z0-9\-_.]+$/i', $category)) {
            return null;
        }

        return [
            'category' => $category,
            'slice' => $slice,
        ];
    }

    public static function isListUrl(?string $url): bool
    {
        return self::parse($url) !== null;
    }

    public static function buildCategorySearchQuery(?string $url): ?string
    {
        $parsed = self::parse($url);
        if ($parsed === null) {
            return null;
        }

        $category = $parsed['category'];
        if (str_contains($category, '.')) {
            return 'cat:'.$category;
        }

        return 'cat:'.$category.'*';
    }

    /**
     * @return array{sortBy: string, sortOrder: string}
     */
    public static function sortParams(?string $url): array
    {
        $parsed = self::parse($url);
        $slice = strtolower($parsed['slice'] ?? 'new');

        if ($slice === 'recent') {
            return [
                'sortBy' => 'lastUpdatedDate',
                'sortOrder' => 'descending',
            ];
        }

        return [
            'sortBy' => 'submittedDate',
            'sortOrder' => 'descending',
        ];
    }

    public static function buildListPageUrl(string $requestUrl, int $skip, int $show): string
    {
        $parts = parse_url($requestUrl);
        $scheme = $parts['scheme'] ?? 'https';
        $host = $parts['host'] ?? 'arxiv.org';
        $path = $parts['path'] ?? '/';
        $query = [];
        if (! empty($parts['query'])) {
            parse_str((string) $parts['query'], $query);
        }
        $query['skip'] = max(0, $skip);
        $query['show'] = min(2000, max(1, $show));

        return $scheme.'://'.$host.$path.'?'.http_build_query($query);
    }

}