<?php

namespace App\Services;

use App\Models\Article;
use App\Models\Category;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Str;

class HelpdeskImportService
{
    private const DEFAULT_BASE_URL = 'https://www.internettoday.nl/helpdesk';

    public function import(?string $baseUrl = null, bool $dryRun = false, ?int $limit = null, ?callable $progress = null): array
    {
        $baseUrl = rtrim($baseUrl ?: self::DEFAULT_BASE_URL, '/');

        $rootHtml = $this->fetch($baseUrl);
        $categories = $this->extractCategories($rootHtml);

        $categoryMap = $this->syncCategories($categories, $dryRun);
        $sections = $this->buildSections($baseUrl, $categories);

        $articleUrlMap = $this->collectArticleUrls($baseUrl, $rootHtml, $sections);
        if ($limit !== null && $limit > 0) {
            $articleUrlMap = array_slice($articleUrlMap, 0, $limit, true);
        }

        $total = count($articleUrlMap);
        $imported = 0;
        $updated = 0;
        $skipped = 0;
        $processed = 0;

        foreach ($articleUrlMap as $articleUrl => $meta) {
            $processed++;
            $parsed = $this->parseArticlePage($articleUrl);
            if ($parsed === null) {
                $skipped++;
                $progress && $progress($processed, $total, $articleUrl, 'skipped');

                continue;
            }

            if ($dryRun) {
                $imported++;
                $progress && $progress($processed, $total, $articleUrl, 'dry-run');

                continue;
            }

            [$title, $content, $sourceArticleId] = $parsed;

            $categoryId = $this->resolveCategoryId($meta['category_external_id'] ?? null, $categoryMap);
            $subcategoryId = $this->resolveCategoryId($meta['subcategory_external_id'] ?? null, $categoryMap);

            $result = Article::query()->updateOrCreate(
                ['source' => 'internettoday_helpdesk', 'source_article_id' => $sourceArticleId],
                [
                    'title' => $title,
                    'content' => $content,
                    'source_url' => $articleUrl,
                    'category_id' => $categoryId,
                    'subcategory_id' => $subcategoryId,
                ]
            );

            if ($result->wasRecentlyCreated) {
                $imported++;
                $progress && $progress($processed, $total, $articleUrl, 'imported');
            } else {
                $updated++;
                $progress && $progress($processed, $total, $articleUrl, 'updated');
            }
        }

        return [
            'categories' => count($categories),
            'sections' => count($sections),
            'article_urls' => $total,
            'imported' => $imported,
            'updated' => $updated,
            'skipped' => $skipped,
            'dry_run' => $dryRun,
        ];
    }

    private function fetch(string $url): string
    {
        return Http::timeout(30)->retry(2, 300)->get($url)->throw()->body();
    }

    private function extractCategories(string $html): array
    {
        if (! preg_match('/const\s+categories\s*=\s*(\[.*?\]);/s', $html, $matches)) {
            return [];
        }

        $decoded = json_decode($matches[1], true);

        return is_array($decoded) ? $decoded : [];
    }

    private function syncCategories(array $categories, bool $dryRun): array
    {
        $map = [];
        foreach ($categories as $category) {
            if (! isset($category['id'], $category['title'], $category['slug'])) {
                continue;
            }

            $parentId = null;
            if (! $dryRun) {
                $model = Category::query()->updateOrCreate(
                    ['external_id' => (int) $category['id']],
                    ['name' => (string) $category['title'], 'slug' => (string) $category['slug'], 'parent_id' => null]
                );
                $parentId = $model->id;
            }

            $map[(int) $category['id']] = $parentId;

            foreach (($category['children'] ?? []) as $child) {
                if (! isset($child['id'], $child['title'], $child['slug'])) {
                    continue;
                }

                if (! $dryRun && $parentId !== null) {
                    $childModel = Category::query()->updateOrCreate(
                        ['external_id' => (int) $child['id']],
                        ['name' => (string) $child['title'], 'slug' => (string) $child['slug'], 'parent_id' => $parentId]
                    );
                    $map[(int) $child['id']] = $childModel->id;
                } else {
                    $map[(int) $child['id']] = null;
                }
            }
        }

        return $map;
    }

    private function buildSections(string $baseUrl, array $categories): array
    {
        $sections = [];
        foreach ($categories as $category) {
            if (! isset($category['id'], $category['slug'])) {
                continue;
            }

            $sections[] = [
                'url' => sprintf('%s/%d/%s', $baseUrl, (int) $category['id'], (string) $category['slug']),
                'category_external_id' => (int) $category['id'],
                'subcategory_external_id' => null,
            ];

            foreach (($category['children'] ?? []) as $child) {
                if (! isset($child['id'], $child['slug'])) {
                    continue;
                }

                $sections[] = [
                    'url' => sprintf('%s/%d/%s', $baseUrl, (int) $child['id'], (string) $child['slug']),
                    'category_external_id' => (int) $category['id'],
                    'subcategory_external_id' => (int) $child['id'],
                ];
            }
        }

        return $sections;
    }

    private function collectArticleUrls(string $baseUrl, string $rootHtml, array $sections): array
    {
        $result = [];
        $sources = array_merge([
            ['url' => $baseUrl, 'category_external_id' => null, 'subcategory_external_id' => null, 'html' => $rootHtml],
        ], $sections);

        foreach ($sources as $source) {
            try {
                $html = $source['html'] ?? $this->fetch($source['url']);
            } catch (\Throwable) {
                continue;
            }

            preg_match_all('/https:\/\/www\.internettoday\.nl\/helpdesk\/(\d+)-[a-z0-9\-]+/i', $html, $matches);
            foreach (($matches[0] ?? []) as $match) {
                $url = strtolower($match);
                if (! isset($result[$url])) {
                    $result[$url] = [
                        'category_external_id' => $source['category_external_id'],
                        'subcategory_external_id' => $source['subcategory_external_id'],
                    ];
                }
            }
        }

        return $result;
    }

    private function parseArticlePage(string $url): ?array
    {
        try {
            $html = $this->fetch($url);
        } catch (\Throwable) {
            return null;
        }

        if (! preg_match('/<h1[^>]*>(.*?)<\/h1>/is', $html, $titleMatch)) {
            return null;
        }

        $title = $this->sanitizeText($titleMatch[1]);
        if ($title === '') {
            return null;
        }

        if (! preg_match('/<div\s+class="main_1_column">\s*(<p.*?<\/p>)\s*<\/div>/is', $html, $contentMatch)) {
            return null;
        }

        $contentRaw = $contentMatch[1];
        $contentRaw = preg_replace('/<\s*br\s*\/?\s*>/i', "\n", $contentRaw) ?? $contentRaw;
        $contentRaw = preg_replace('/<\/p>\s*<p[^>]*>/i', "\n\n", $contentRaw) ?? $contentRaw;
        $content = $this->sanitizeText($contentRaw);

        if ($content === '') {
            return null;
        }

        if (! preg_match('/\/helpdesk\/(\d+)-/', $url, $idMatch)) {
            return null;
        }

        return [$title, Str::limit($content, 64000, ''), (int) $idMatch[1]];
    }

    private function resolveCategoryId(?int $externalId, array $map): ?int
    {
        if ($externalId === null) {
            return null;
        }

        return $map[$externalId] ?? Category::query()->where('external_id', $externalId)->value('id');
    }

    private function sanitizeText(string $value): string
    {
        $decoded = html_entity_decode(strip_tags($value), ENT_QUOTES | ENT_HTML5, 'UTF-8');
        $decoded = preg_replace('/\s+/', ' ', $decoded) ?? $decoded;

        return trim($decoded);
    }
}