<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Import;

use TYPO3\CMS\Core\Http\RequestFactory;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Reads posts and categories from a WordPress site through its REST API.
 *
 * The REST route was chosen over direct database access on purpose: the VITEC
 * blog happens to sit on the same server, but datapath.co.uk does not and its
 * MySQL is not reachable from here. One code path serves both, and nothing has
 * to store a database password.
 *
 * The trade-off is that `/wp/v2/posts` only exposes published posts. That is
 * what a content migration wants; drafts would need an application password.
 *
 * Read-only throughout - this class never writes to the source.
 */
final class WordPressClient
{
    /** WordPress caps per_page at 100. */
    private const PER_PAGE = 100;

    /** Generous: 358 posts with embedded media is a lot of JSON. */
    private const TIMEOUT = 120;

    /** Guard against a misconfigured source paginating forever. */
    private const MAX_PAGES = 50;

    /**
     * All published posts, newest first, with the featured image embedded so the
     * list does not need one extra request per post.
     *
     * @return array{posts:array<int,array<string,mixed>>, error:?string}
     */
    public function posts(string $baseUrl): array
    {
        $api = $this->apiBase($baseUrl);
        if ($api === null) {
            return ['posts' => [], 'error' => 'No usable URL.'];
        }

        $posts = [];
        for ($page = 1; $page <= self::MAX_PAGES; $page++) {
            $url = $api . '/posts?per_page=' . self::PER_PAGE . '&page=' . $page . '&_embed=wp:featuredmedia,wp:term';
            $batch = $this->get($url);
            if ($batch === null) {
                // Page 1 failing is a real error; later pages simply mean the end
                // (WordPress answers 400 rest_post_invalid_page_number past it).
                return $page === 1
                    ? ['posts' => [], 'error' => 'The source did not answer with a post list. Check the URL.']
                    : ['posts' => $posts, 'error' => null];
            }
            $posts = array_merge($posts, $batch);
            if (count($batch) < self::PER_PAGE) {
                break;
            }
        }

        return ['posts' => $posts, 'error' => null];
    }

    /**
     * Category id => name, for showing what a post was filed under over there.
     *
     * @return array<int,string>
     */
    public function categories(string $baseUrl): array
    {
        $api = $this->apiBase($baseUrl);
        if ($api === null) {
            return [];
        }
        $rows = $this->get($api . '/categories?per_page=' . self::PER_PAGE) ?? [];

        $map = [];
        foreach ($rows as $row) {
            $map[(int)($row['id'] ?? 0)] = html_entity_decode((string)($row['name'] ?? ''), ENT_QUOTES | ENT_HTML5, 'UTF-8');
        }
        return $map;
    }

    /**
     * Turns whatever the editor typed into the v2 API base.
     * "vitec.com/blog", "https://vitec.com/blog/" and a full ".../wp-json/wp/v2"
     * all end up the same.
     */
    public function apiBase(string $baseUrl): ?string
    {
        $baseUrl = trim($baseUrl);
        if ($baseUrl === '') {
            return null;
        }
        if (!preg_match('#^https?://#i', $baseUrl)) {
            $baseUrl = 'https://' . $baseUrl;
        }
        $baseUrl = rtrim($baseUrl, '/');
        if (str_contains($baseUrl, '/wp-json')) {
            return $baseUrl;
        }
        return $baseUrl . '/wp-json/wp/v2';
    }

    /** @return array<int,array<string,mixed>>|null */
    private function get(string $url): ?array
    {
        try {
            $response = GeneralUtility::makeInstance(RequestFactory::class)
                ->request($url, 'GET', ['timeout' => self::TIMEOUT, 'headers' => ['Accept' => 'application/json']]);
            if ($response->getStatusCode() !== 200) {
                return null;
            }
            $decoded = json_decode((string)$response->getBody(), true);
            return is_array($decoded) ? $decoded : null;
        } catch (\Throwable $e) {
            return null;
        }
    }
}