<?php
/**
 * Database transaction wrapper.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Infrastructure\Persistence;

use Throwable;
use wpdb;

/**
 * Runs a callable inside START TRANSACTION / COMMIT, rolling back on failure.
 *
 * @since 0.1.0
 */
final class TransactionManager {

	/**
	 * Backing field.
	 *
	 * @var wpdb
	 */
	private wpdb $db;

	/**
	 * Constructor.
	 *
	 * @param wpdb|null $db Database handle.
	 */
	public function __construct( ?wpdb $db = null ) {
		if ( null === $db ) {
			global $wpdb;
			$db = $wpdb;
		}
		$this->db = $db;
	}

	/**
	 * Execute $callback inside a transaction.
	 *
	 * Nested calls reuse the outer transaction (no savepoints in MySQL via wpdb by default).
	 *
	 * @template T
	 * @param callable(): T $callback Work to run.
	 * @return T
	 *
	 * @throws Throwable Re-throws after rollback.
	 *
	 * @since 0.1.0
	 */
	public function run( callable $callback ): mixed {
		$this->db->query( 'START TRANSACTION' );

		try {
			$result = $callback();
			$this->db->query( 'COMMIT' );
			return $result;
		} catch ( Throwable $e ) {
			$this->db->query( 'ROLLBACK' );
			throw $e;
		}
	}
}