Extension to spatie/laravel-backup DefaultStrategy

DefaultStrategyButKeepOnlyOneLocalBackup.php

<?php

namespace App\Helpers;

use Illuminate\Filesystem\Filesystem;
use Spatie\Backup\BackupDestination\Backup;
use Spatie\Backup\BackupDestination\BackupCollection;
use Spatie\Backup\Tasks\Cleanup\Strategies\DefaultStrategy;

class DefaultStrategyButKeepOnlyOneLocalBackup extends DefaultStrategy
{
    public function deleteOldBackups(BackupCollection $backups)
    {
        try {
            /** @var Backup $latest */
            $latest = $backups->shift();
            $reflection = new \ReflectionClass($latest);
            /** @var Filesystem $filesystem */
            $property = $reflection->getProperty('disk');
            $property->setAccessible(true);
            $filesystem = $property->getValue($latest);
            $driver = $filesystem->getDriver();
            if ($driver instanceof \League\Flysystem\Filesystem){
                $adapter = $driver->getAdapter();
                if ($adapter instanceof \League\Flysystem\Adapter\Local){
                    // Delete remaining backups
                    $backups->each(function (Backup $backup){
                        $backup->delete();
                    });
                    return;
                }
            }
        } catch (\ReflectionException $e) {
        }
        parent::deleteOldBackups($backups);
    }
}

Useful if you store your backups on both local and remote storage, and you want to save disk space on the local file system.
Only the latest backup file is kept on local storage. Other storages are unaffected.