<?php
/**
 * Manifest — describes a backup (site + environment + scope) for restore/migration.
 *
 * @package AI_SiteArk
 * Copyright (c) 2026 AtoZ INFOWAY INC.
 * Licensed under the GNU General Public License, version 2 or later.
 */

namespace AtoZ\SiteArk\Archive;

use AtoZ\SiteArk\Helpers\Crypto;

defined( 'ABSPATH' ) || exit;

/**
 * Class Manifest
 */
class Manifest {

	const FORMAT = 1;

	/**
	 * Build the manifest for the current site.
	 *
	 * @param array $scope     Selected backup scope (database/uploads/themes/…).
	 * @param array $enc       Optional encryption meta ({ key, salt }).
	 * @param array $inventory Optional { tables: string[], file_count: int } — what
	 *                         the backup will contain, so restore can detect a missing
	 *                         table/file before it touches the live site.
	 * @return array
	 */
	public static function build( array $scope, $enc = null, array $inventory = array(), array $extra = array() ) {
		global $wpdb;

		$crypto = array();
		if ( is_array( $enc ) && ! empty( $enc['key'] ) && ! empty( $enc['salt'] ) ) {
			$iv     = Crypto::iv();
			$crypto = array(
				'encrypted' => true,
				'kdf'       => array( 'algo' => 'pbkdf2-sha256', 'iter' => Crypto::ITER ),
				'salt'      => base64_encode( $enc['salt'] ),
				'verify_iv' => base64_encode( $iv ),
				// Lets restore reject a wrong password before touching anything.
				'verify'    => base64_encode( Crypto::enc( 'AISV-OK', $enc['key'], $iv ) ),
			);
		}

		$inv = array();
		if ( ! empty( $inventory ) ) {
			$inv['inventory'] = array(
				'tables'     => isset( $inventory['tables'] ) ? array_values( array_map( 'strval', (array) $inventory['tables'] ) ) : array(),
				'file_count' => isset( $inventory['file_count'] ) ? (int) $inventory['file_count'] : 0,
			);
		}

		// G1 incremental fields (cycle/sequence/base_file/deletions) when provided.
		$extra = is_array( $extra ) ? $extra : array();

		return $crypto + $inv + $extra + array(
			'format'         => self::FORMAT,
			'plugin'         => 'ai-siteark',
			'version'        => defined( 'AISITEARK_VERSION' ) ? AISITEARK_VERSION : '',
			'wp_version'     => get_bloginfo( 'version' ),
			'php_version'    => PHP_VERSION,
			// DB server so restore can flag a downgrade (e.g. MySQL 8 → MariaDB)
			// whose collations/syntax would break the import.
			'db_server_info' => is_object( $wpdb ) && method_exists( $wpdb, 'db_server_info' ) ? (string) $wpdb->db_server_info() : '',
			'db_version'     => is_object( $wpdb ) ? (string) $wpdb->db_version() : '',
			'site_url'       => site_url(),
			'home_url'       => home_url(),
			'abspath'        => ABSPATH,
			'content_dir'    => WP_CONTENT_DIR,
			'table_prefix'   => $wpdb->prefix,
			'multisite'      => is_multisite(),
			'charset'        => $wpdb->charset,
			'scope'          => $scope,
			'created_at'     => gmdate( 'c' ),
		);
	}

	/**
	 * The backup's declared inventory ({ tables, file_count }), or null when the
	 * manifest predates inventory support (older backups skip missing-item checks).
	 *
	 * @param array $m Manifest.
	 * @return array|null
	 */
	public static function inventory( array $m ) {
		return ( isset( $m['inventory'] ) && is_array( $m['inventory'] ) ) ? $m['inventory'] : null;
	}

	/**
	 * Validate a decoded manifest before a restore.
	 *
	 * @param mixed $m Decoded manifest.
	 * @return true|\WP_Error
	 */
	public static function validate( $m ) {
		// Accept backups from BOTH product ids: the current slug (ai-siteark) and the legacy
		// bridge slug (ai-sitevault). They are the same product — a site updated in place from
		// AI-SiteVault runs AI-SiteArk code under the old slug and tags its manifests
		// 'ai-sitevault' — so a backup (uploaded, URL-fetched, or pulled via site-to-site
		// migration) made on either build must restore on either build. Without this, a token
		// pull from an AI-SiteVault source failed with "missing a valid AI-SiteArk manifest".
		if ( ! is_array( $m ) || ! in_array( $m['plugin'] ?? '', array( 'ai-siteark', 'ai-sitevault' ), true ) ) {
			return new \WP_Error( 'aisiteark_manifest', __( 'This archive is missing a valid AI-SiteArk manifest.', 'ai-siteark' ) );
		}
		if ( (int) ( $m['format'] ?? 0 ) > self::FORMAT ) {
			return new \WP_Error( 'aisiteark_manifest_format', __( 'This backup was made by a newer version of AI-SiteArk. Please update first.', 'ai-siteark' ) );
		}
		return true;
	}

	/**
	 * Whether a manifest describes an encrypted backup.
	 *
	 * @param array $m Manifest.
	 * @return bool
	 */
	public static function is_encrypted( array $m ) {
		return ! empty( $m['encrypted'] );
	}

	/**
	 * Verify a password against the manifest's check token.
	 *
	 * @param array  $m        Manifest.
	 * @param string $password Password.
	 * @return string|false Derived key on success, false on wrong password.
	 */
	public static function verify_password( array $m, $password ) {
		if ( empty( $m['encrypted'] ) ) {
			return '';
		}
		if ( ! Crypto::available() || '' === (string) $password ) {
			return false;
		}
		$key = Crypto::key( $password, base64_decode( $m['salt'] ?? '' ) );
		$dec = Crypto::dec( base64_decode( $m['verify'] ?? '' ), $key, base64_decode( $m['verify_iv'] ?? '' ) );
		return ( 'AISV-OK' === $dec ) ? $key : false;
	}

	/**
	 * Whether restoring this manifest onto the current site is a cross-site
	 * migration (different URL or path), i.e. search-replace is needed.
	 *
	 * @param array $m Manifest.
	 * @return bool
	 */
	public static function is_migration( array $m ) {
		$src_url  = isset( $m['site_url'] ) ? untrailingslashit( (string) $m['site_url'] ) : '';
		$src_path = isset( $m['abspath'] ) ? (string) $m['abspath'] : '';
		return ( $src_url && untrailingslashit( site_url() ) !== $src_url )
			|| ( $src_path && ABSPATH !== $src_path );
	}
}