<?php

// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- ImportInvalid carries text for the REST response (JSON), never for HTML output.

namespace AOP\App\ImportExport;

/**
 * Reads an export file: size, JSON, version and shape are checked before anything else looks at the content.
 */
final class Package
{
    /**
     * @return int Bytes an import file may have.
     */
    public static function maxBytes(): int
    {
        /**
         * The largest export file that Import accepts.
         *
         * @since 1.0.0
         *
         * @param int $bytes Default 5 MB.
         */
        return (int) apply_filters('aop_import_max_bytes', 5 * MB_IN_BYTES);
    }

    /**
     * @param string $content The text of the file.
     *
     * @return array{aop_export_version: int, menus_and_pages: array, options: array, plugin_version?: string, generated?: string} The file in the current version.
     *
     * @throws ImportInvalid
     */
    public static function parse(string $content): array
    {
        if (strlen($content) > self::maxBytes()) {
            throw new ImportInvalid('too_large', __('The file is too large to import.', 'admin-options-pages'), [], 413);
        }

        // A byte order mark (some editors add one) is not part of the JSON.
        $content = preg_replace('/^\xEF\xBB\xBF/', '', $content);

        try {
            $data = json_decode($content, true, 32, JSON_THROW_ON_ERROR);
        } catch (\JsonException $exception) {
            throw new ImportInvalid('invalid_json', __('This is not a JSON file, or it is not valid UTF-8.', 'admin-options-pages'));
        }

        if (! is_array($data) || ($data !== [] && array_keys($data) === range(0, count($data) - 1))) {
            throw new ImportInvalid('invalid_file', __('This file does not look like an export of Admin Options Pages.', 'admin-options-pages'));
        }

        $data = self::toCurrentVersion($data);

        $errors = SchemaValidator::validate($data, self::schema());

        if ($errors) {
            throw new ImportInvalid(
                'invalid_file',
                __('This file does not look like an export of Admin Options Pages.', 'admin-options-pages'),
                $errors
            );
        }

        $data['options'] = (array) ($data['options'] ?? []);

        return $data;
    }

    /**
     * Files of a lower version are migrated, files of a higher version are refused.
     *
     * Version 0 is the file of 0.9.x: no version, and per menu also the row `id` and `time`, which mean nothing on
     * another site.
     *
     * @throws ImportInvalid
     */
    private static function toCurrentVersion(array $data): array
    {
        if (! array_key_exists('aop_export_version', $data)) {
            if (! isset($data['menus_and_pages']) || ! is_array($data['menus_and_pages'])) {
                throw new ImportInvalid('invalid_file', __('This file does not look like an export of Admin Options Pages.', 'admin-options-pages'));
            }

            $menus = [];

            foreach ($data['menus_and_pages'] as $item) {
                $menus[] = is_array($item)
                    ? array_intersect_key($item, ['menu_slug' => 1, 'page_value' => 1])
                    : $item;
            }

            return [
                'aop_export_version' => Exporter::VERSION,
                'menus_and_pages' => $menus,
                'options' => $data['options'] ?? [],
            ];
        }

        $version = $data['aop_export_version'];

        if (is_int($version) && $version > Exporter::VERSION) {
            throw new ImportInvalid(
                'newer_version',
                sprintf(
                    /* translators: 1: the version of the file, 2: the version this plugin reads */
                    __('This file has export format %1$d. This version of the plugin reads format %2$d. Update the plugin on this site and try again.', 'admin-options-pages'),
                    $version,
                    Exporter::VERSION
                )
            );
        }

        return $data;
    }

    private static function schema(): array
    {
        $file = \AOP\App\Plugin::root() . 'includes/schema/export.v1.json';

        return (array) json_decode((string) file_get_contents($file), true); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- a file of the plugin
    }
}