PHP implements the function of converting week X to timestamp

To build an animation website, you need to update the list every week and call up the data from Monday to Sunday.
Write a function to implement key functions.

function getTimeFromWeek($dayNum){
 //$dayNum:0-6
 $curDayNum=date("w");
 if($dayNum>$curDayNum) $timeFlag="last " ;
 elseif($dayNum==$curDayNum) $timeFlag="";
 //If you want to use this week's day X when day X has not arrived this week else $timeFlag="next";
 else $timeFlag="last ";//If week X does not arrive this week, use last week's day 'Friday','Saturday');
 $timeStamp=strtotime("$timeFlag"."$arryWeekDay[$dayNum]");
 return $timeStamp;

}

echo date("Y-m-d l",getTimeFromWeek( 0));echo "";
echo date("Y-m-d l",getTimeFromWeek(1));echo "";
echo date("Y-m-d l",getTimeFromWeek(2)); echo "";
echo date("Y-m-d l",getTimeFromWeek(3));echo "";
echo date("Y-m-d l",getTimeFromWeek(4));echo "< br>";
echo date("Y-m-d l",getTimeFromWeek(5));echo "";
echo date("Y-m-d l",getTimeFromWeek(6));echo "";