<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\Pages;

use Closure;
use LIT\MCP\Integrations\Divi\Compose\LinkTargets;
use WP_Post;

defined('ABSPATH') || exit;

/**
 * {{link:<ID>}} and post_link_url_* targets from WordPress (rulings P10, Q14): the entry exists,
 * lives (no trash, auto-draft or revision), is no attachment (whatever its status), its type has a
 * Divi link option post_link_url_<type> (never the library et_pb_layout or an internal "_" type) and
 * the current user may read it (read_post, like select_post settings, S37). Missing, unreadable and
 * unlinkable entries give the same null (no existence or type oracle).
 */
final class WpLinkTargets implements LinkTargets
{
    private const DEAD = ['trash', 'auto-draft', 'inherit'];

    /** Never link targets, whatever Divi lists: attachments and the Divi Library (ruling Q14). */
    private const NEVER = ['attachment', 'et_pb_layout'];

    /** @var Closure(string): bool */
    private Closure $linkable;

    /**
     * @param (Closure(string): bool)|null $linkable Whether Divi offers post_link_url_<type> (tests);
     *        null = Divi's et_builder_get_public_post_types(), the list its link option uses.
     */
    public function __construct(?Closure $linkable = null)
    {
        $this->linkable = $linkable ?? self::diviLinkable(...);
    }

    public function postTypeOf(int $id): ?string
    {
        $post = get_post($id);
        if (! $post instanceof WP_Post || in_array((string) $post->post_status, self::DEAD, true)) {
            return null;
        }

        $type = (string) $post->post_type;
        if (in_array($type, self::NEVER, true) || str_starts_with($type, '_') || ! ($this->linkable)($type)) {
            return null;
        }

        return current_user_can('read_post', $id) ? $type : null;
    }

    /** Fail closed: without Divi's list no type has a link option. */
    private static function diviLinkable(string $type): bool
    {
        if (! function_exists('et_builder_get_public_post_types')) {
            return false;
        }

        $types = et_builder_get_public_post_types();

        return is_array($types) && array_key_exists($type, $types);
    }
}