<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\BlockTree;

defined('ABSPATH') || exit;

/**
 * Turns a Document back into block markup. Unchanged blocks reuse their original
 * delimiters; changed or new blocks get delimiters generated exactly like WordPress'
 * get_comment_delimited_block_content() / serialize_block_attributes() do, which also
 * yields the escaping Divi expects inside $variable(…)$ payloads: json_encode()'s own
 * \" (an escaped quote inside a JSON string) is replaced by \u0022, see ESCAPES below.
 */
final class Serializer
{
    /** serialize_block_attributes() replacements (WordPress 7.0). */
    private const ESCAPES = [
        '\\\\' => '\\u005c',
        '--' => '\\u002d\\u002d',
        '<' => '\\u003c',
        '>' => '\\u003e',
        '&' => '\\u0026',
        '\\"' => '\\u0022',
    ];

    public static function document(Document $document): string
    {
        return self::parts($document->parts());
    }

    public static function block(Block $block): string
    {
        $open = $block->rawOpen() ?? self::opener($block);
        if ($block->isVoid()) {
            return $open;
        }

        return $open . self::parts($block->parts()) . ($block->rawClose() ?? self::closer($block));
    }

    /** @param array<string, mixed> $attrs */
    public static function attributes(array $attrs): string
    {
        return strtr(Json::encode($attrs), self::ESCAPES);
    }

    private static function opener(Block $block): string
    {
        $attrs = $block->attrs() === [] ? '' : self::attributes($block->attrs()) . ' ';

        return '<!-- wp:' . self::serializedName($block->name()) . ' ' . $attrs . ($block->isVoid() ? '/-->' : '-->');
    }

    private static function closer(Block $block): string
    {
        return '<!-- /wp:' . self::serializedName($block->name()) . ' -->';
    }

    private static function serializedName(string $name): string
    {
        return str_starts_with($name, 'core/') ? substr($name, 5) : $name;
    }

    /** @param list<string|Block> $parts */
    private static function parts(array $parts): string
    {
        $out = '';
        foreach ($parts as $part) {
            $out .= $part instanceof Block ? self::block($part) : $part;
        }

        return $out;
    }
}