指定された日付の月曜日から次の月曜日までの日付を返す

getThisWeek.php

    public function getThisWeek($day = null) {

        $day = !empty($day) ? strtotime($day) : strtotime(date('Y-m-d'));
        $monday = strtotime('this monday', $day);
        if ($day == $monday) {
            $from = date('Y-m-d', $monday);
            $to   = date('Y-m-d', strtotime('next monday', $monday));   
        } else {
            $from = date('Y-m-d', strtotime('last monday', $monday));
            $to   = date('Y-m-d', $monday); 
        }
        return array('from'=>$form, 'to'=>$to);
    }