<?php
/**
 * Rollback: snapshots of previously applied bundles.
 *
 * Before a new bundle version is applied, the current bundle + version are
 * pushed onto the option `aeo_connect_history` (the last 3 entries are
 * kept). Restoring an entry simply sets it back as the current bundle and
 * version — the plugin never writes to the site's content or database
 * tables, so a restore is instant and side-effect free.
 *
 * @package AEO_Tool_Connect
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Class AEO_Connect_Rollback
 */
class AEO_Connect_Rollback {

	/**
	 * Number of history entries kept.
	 */
	const MAX_ENTRIES = 3;

	/**
	 * Snapshot the currently applied bundle into the history.
	 *
	 * No-op when nothing is applied yet, or when the head of the history
	 * already holds the same version.
	 *
	 * @return void
	 */
	public static function snapshot() {
		$bundle  = AEO_Connect_Cache::get_bundle();
		$version = AEO_Connect_Cache::get_version();

		if ( null === $bundle || $version <= 0 ) {
			return;
		}

		$history = self::get_history();

		if ( ! empty( $history ) && isset( $history[0]['version'] ) && (int) $history[0]['version'] === $version ) {
			return; // Already snapshotted.
		}

		array_unshift(
			$history,
			array(
				'version'     => $version,
				'bundle'      => $bundle,
				'snapshot_at' => time(),
			)
		);

		$history = array_slice( $history, 0, self::MAX_ENTRIES );

		update_option( 'aeo_connect_history', $history, false );
	}

	/**
	 * Return the snapshot history (newest first).
	 *
	 * @return array[]
	 */
	public static function get_history() {
		$history = get_option( 'aeo_connect_history', array() );

		return is_array( $history ) ? array_values( $history ) : array();
	}

	/**
	 * Restore a history entry: set it back as the current bundle/version.
	 *
	 * Note: the next sync may re-apply the latest version published on
	 * everlange.com (the SaaS stays the source of truth).
	 *
	 * @param int $index Zero-based history index (0 = most recent snapshot).
	 * @return true|WP_Error
	 */
	public static function restore( $index ) {
		$index   = (int) $index;
		$history = self::get_history();

		if ( ! isset( $history[ $index ] ) || ! is_array( $history[ $index ] ) ) {
			return new WP_Error( 'aeo_connect_no_snapshot', __( 'The requested snapshot no longer exists.', 'aeo-tool-connect' ) );
		}

		$entry = $history[ $index ];

		if ( empty( $entry['bundle'] ) || ! is_array( $entry['bundle'] ) || empty( $entry['version'] ) ) {
			return new WP_Error( 'aeo_connect_bad_snapshot', __( 'The requested snapshot is corrupted.', 'aeo-tool-connect' ) );
		}

		update_option( 'aeo_connect_bundle', $entry['bundle'], false );
		update_option( 'aeo_connect_version', (int) $entry['version'], false );

		return true;
	}
}