<?php

declare(strict_types=1);

namespace App\Services\Crawler;

use Illuminate\Support\Str;

class XPathExtractor
{
    /**
     * @param array<string, mixed> $extractorConfig
     * @return list<string>
     */
    public function extractListUrls(string $html, string $baseUrl, array $extractorConfig): array
    {
        $listXPath = (string) ($extractorConfig['list_link_xpath'] ?? '');

        if ($listXPath === '') {
            return [];
        }

        $xpath = $this->buildXPath($html);

        if ($xpath === null) {
            return [];
        }

        $nodes = $xpath->query($listXPath);

        if ($nodes === false) {
            return [];
        }

        $urls = [];
        foreach ($nodes as $node) {
            $value = trim($node->nodeValue ?? '');
            if ($value === '') {
                continue;
            }

            $absolute = $this->toAbsoluteUrl($value, $baseUrl);
            if ($absolute !== null) {
                $urls[] = $absolute;
            }
        }

        return array_values(array_unique($urls));
    }

    /**
     * @param array<string, mixed> $extractorConfig
     * @return array<string, mixed>
     */
    public function extractFields(string $html, array $extractorConfig): array
    {
        $fieldRules = $extractorConfig['fields'] ?? [];

        if (! is_array($fieldRules) || $fieldRules === []) {
            return [];
        }

        $xpath = $this->buildXPath($html);

        if ($xpath === null) {
            return [];
        }

        $result = [];

        foreach ($fieldRules as $field => $rule) {
            if (! is_string($field)) {
                continue;
            }

            $xpathExpr = '';
            $multiple = false;

            if (is_string($rule)) {
                $xpathExpr = $rule;
            } elseif (is_array($rule)) {
                $xpathExpr = (string) ($rule['xpath'] ?? '');
                $multiple = (bool) ($rule['multiple'] ?? false);
            }

            if ($xpathExpr === '') {
                continue;
            }

            $nodes = $xpath->query($xpathExpr);

            if ($nodes === false || $nodes->length === 0) {
                continue;
            }

            if ($multiple) {
                $values = [];
                foreach ($nodes as $node) {
                    $value = trim($node->nodeValue ?? '');
                    if ($value !== '') {
                        $values[] = $value;
                    }
                }

                if ($values !== []) {
                    $result[$field] = array_values(array_unique($values));
                }

                continue;
            }

            $value = trim($nodes->item(0)?->nodeValue ?? '');
            if ($value !== '') {
                $result[$field] = Str::squish($value);
            }
        }

        return $result;
    }

    private function buildXPath(string $html): ?\DOMXPath
    {
        $dom = new \DOMDocument('1.0', 'UTF-8');

        libxml_use_internal_errors(true);
        $loaded = $dom->loadHTML('<?xml encoding="UTF-8">'.$html, LIBXML_NOWARNING | LIBXML_NOERROR);
        libxml_clear_errors();

        if (! $loaded) {
            return null;
        }

        return new \DOMXPath($dom);
    }

    private function toAbsoluteUrl(string $url, string $baseUrl): ?string
    {
        if (Str::startsWith($url, ['http://', 'https://'])) {
            return $url;
        }

        if (Str::startsWith($url, '//')) {
            $scheme = parse_url($baseUrl, PHP_URL_SCHEME) ?: 'https';

            return sprintf('%s:%s', $scheme, $url);
        }

        $baseParts = parse_url($baseUrl);
        if (! is_array($baseParts) || ! isset($baseParts['scheme'], $baseParts['host'])) {
            return null;
        }

        $prefix = sprintf('%s://%s', $baseParts['scheme'], $baseParts['host']);
        if (isset($baseParts['port'])) {
            $prefix .= ':'.$baseParts['port'];
        }

        if (Str::startsWith($url, '/')) {
            return $prefix.$url;
        }

        $path = $baseParts['path'] ?? '/';
        $dir = rtrim(str_replace('\\', '/', dirname($path)), '/');
        if ($dir === '') {
            $dir = '/';
        }

        return rtrim($prefix, '/').'/'.ltrim($dir.'/'.$url, '/');
    }
}