Spatie\Backup\Tasks\Cleanup\Strategies\DefaultStrategy::calculateDateRanges PHP Method

    protected function calculateDateRanges() : Collection
    {
        $config = $this->config->get('laravel-backup.cleanup.defaultStrategy');
        $daily = new Period(Carbon::now()->subDays($config['keepAllBackupsForDays']), Carbon::now()->subDays($config['keepAllBackupsForDays'])->subDays($config['keepDailyBackupsForDays']));
        $weekly = new Period($daily->endDate(), $daily->endDate()->subWeeks($config['keepWeeklyBackupsForWeeks']));
        $monthly = new Period($weekly->endDate(), $weekly->endDate()->subMonths($config['keepMonthlyBackupsForMonths']));
        $yearly = new Period($monthly->endDate(), $monthly->endDate()->subYears($config['keepYearlyBackupsForYears']));
        return collect(compact('daily', 'weekly', 'monthly', 'yearly'));
    }