Date sorting ascending

  /*
   * Function for sorting time by converting each time type (Seconds, Hours, Days, Weeks, Months, Years) to Hours
   * Then stores the original value in a new temp array as a key, and the hour value as the actual value.
   * Next calls the asort() function to sort it low->high, clears the original array, and updates it with the sorted info.
   */
    function SortTime($a){
        $a_temp = [];
        $second = '/\d+\s+second(\s|s|)/i';
        $hour = '/\d+\s+hour(\s|s|)/i';
        $day = '/\d+\s+day(\s|s|)/i';
        $week = '/\d+\s+week(\s|s|)/i';
        $month = '/\d+\s+month(\s|s|)/i';
        $year = '/\d+\s+year(\s|s|)/i';
        $digit = '/\d+/i';
        foreach($a as $a_item){
            $valueTotal = 0;
                if(preg_match($year, $a_item,$yearARR)){
                    preg_match($digit,$yearARR[0],$yearNum);
                    $valueTotal += ($yearNum[0]*365*24);
                }
                if(preg_match($month, $a_item,$monthARR)){
                    preg_match($digit,$monthARR[0],$monthNum);
                    $valueTotal += ($monthNum[0]*30*24);
                }
                if(preg_match($week, $a_item,$weekARR)){
                    preg_match($digit,$weekARR[0],$weekNum);
                    $valueTotal += ($weekNum[0]*7*24);
                }
                if(preg_match($day, $a_item,$dayARR)){
                    preg_match($digit,$dayARR[0],$dayNum);
                    $valueTotal += ($dayNum[0]*24);
                }
                if(preg_match($hour, $a_item,$hourARR)){
                    preg_match($digit,$hourARR[0],$hourNum);
                    $valueTotal += $hourNum[0];
                }
                if(preg_match($second, $a_item,$secondARR)){
                    preg_match($digit,$secondARR[0],$secondNum);
                    $valueTotal += ($secondNum[0]/60/60);
                }
            $a_temp[$a_item] = $valueTotal;
        }
        asort($a_temp);
        $a=[];
        return($a_temp);
    }