<?php
defined('ABSPATH') || exit();

final class APEARI_Documents
{
    public static function get(string $ref)
    {
        if (preg_match('/^page:(\d+)$/', $ref, $matches)) {
            $post = get_post((int) $matches[1]);
            if (
                !$post ||
                'page' !== $post->post_type ||
                'trash' === $post->post_status ||
                !current_user_can('edit_post', $post->ID)
            ) {
                return new WP_Error('apeari_document', __('Nie możesz edytować tej strony.', 'apeari'), [
                    'status' => 403,
                ]);
            }
            return self::document($ref, get_the_title($post), $post->post_content, false);
        }
        return new WP_Error(
            'apeari_ref',
            __('Edytor zapisuje wyłącznie treść Gutenberga wybranej strony.', 'apeari'),
            [
                'status' => 403,
            ],
        );
    }

    private static function document(string $ref, string $title, string $original, bool $global): array
    {
        $content = self::editable_content($original);
        return [
            'ref' => $ref,
            'title' => $title,
            'content' => $content,
            'originalContent' => $original,
            'hash' => hash('sha256', $original . "\0" . $content),
            'version' => hash('sha256', $content),
            'global' => $global,
        ];
    }

    public static function editable_content(string $content): string
    {
        if (!str_contains($content, '<!-- wp:pattern ')) {
            return $content;
        }
        return serialize_blocks(self::expand_patterns(parse_blocks($content), [], 0));
    }

    private static function expand_patterns(array $blocks, array $seen, int $depth): array
    {
        if ($depth > 12) {
            return $blocks;
        }
        $result = [];
        foreach ($blocks as $block) {
            if ('core/pattern' === $block['blockName']) {
                $slug = $block['attrs']['slug'] ?? '';
                $registry = WP_Block_Patterns_Registry::get_instance();
                if ($slug && !in_array($slug, $seen, true) && $registry->is_registered($slug)) {
                    $pattern = $registry->get_registered($slug);
                    $expanded = self::expand_patterns(
                        parse_blocks($pattern['content']),
                        array_merge($seen, [$slug]),
                        $depth + 1,
                    );
                    array_push($result, ...$expanded);
                    continue;
                }
            }
            if ($block['innerBlocks']) {
                $children = [];
                $chunks = [];
                $index = 0;
                foreach ($block['innerContent'] as $chunk) {
                    if (is_string($chunk)) {
                        $chunks[] = $chunk;
                        continue;
                    }
                    $expanded = self::expand_patterns([$block['innerBlocks'][$index++]], $seen, $depth + 1);
                    foreach ($expanded as $child) {
                        $children[] = $child;
                        $chunks[] = null;
                    }
                }
                $block['innerBlocks'] = $children;
                $block['innerContent'] = $chunks;
            }
            $result[] = $block;
        }
        return $result;
    }

    public static function save(array $document, string $content)
    {
        $ref = (string) ($document['ref'] ?? '');
        if (!preg_match('/^page:[1-9][0-9]*$/', $ref)) {
            return new WP_Error('apeari_ref', __('Zapis poza treścią strony jest zabroniony.', 'apeari'), [
                'status' => 403,
            ]);
        }
        $current = self::get($ref);
        if (is_wp_error($current)) {
            return $current;
        }
        return wp_update_post(wp_slash(['ID' => (int) substr($ref, 5), 'post_content' => $content]), true);
    }

    public static function public_data(array $document): array
    {
        unset($document['template'], $document['originalContent']);
        return $document;
    }

    public static function mark(string $content, string $ref): string
    {
        $content = self::editable_content($content);
        $version = hash('sha256', $content);
        $blocks = parse_blocks($content);
        $walk = function (array &$items, array $parent) use (&$walk, $ref, $version) {
            $index = 0;
            foreach ($items as &$block) {
                if (!$block['blockName'] && '' === trim($block['innerHTML'])) {
                    continue;
                }
                $path = array_merge($parent, [$index]);
                if ($block['blockName']) {
                    $block['attrs']['apeariRef'] = $ref . '|' . implode('.', $path);
                    $block['attrs']['apeariVersion'] = $version;
                }
                $walk($block['innerBlocks'], $path);
                ++$index;
            }
        };
        $walk($blocks, []);
        return serialize_blocks($blocks);
    }
}