Obtain the weekly list and weekly start time in a year-PHP source code

I searched for the weekly list and weekly start time for half a day on the Internet within a year. I did not find the list and wrote one myself.
Don't talk to me about the optimal algorithm. if you have several more CPU clock cycles, you won't be able to die.

public static function getWeeks($format="second",$year=null){if($year == null){$year=date('Y');}$second_of_day = 24*3600;$year_start = $year ."-01-01 00:00:00"; $year_end = $year ."-12-31 23:59:59"; $startday = strtotime($year_start); $day_of_week = date('N', $startday);$first_week_start=$startday;$first_week_end = $startday+(7-$day_of_week)*$second_of_day+$second_of_day-1;$week_array[0]=array($first_week_start,$first_week_end);$endday = strtotime($year_end); $day_of_week = date('N', $endday);$last_week_start=$endday-$day_of_week*$second_of_day+1;$last_week_end = $endday;$last_week=array($last_week_start,$last_week_end);$during = $last_week_start - $first_week_end;$during_total_week = intval($during/(7*$second_of_day));for($i=0;$i<$during_total_week;$i++){$week_array[$i+1]=array($first_week_end+(7*$i*$second_of_day)+1,$first_week_end+(($i+1)*$second_of_day*7));}$week_array[$during_total_week+1]=$last_week;if($format !="second"){foreach($week_array as $i => $week){$week_array_of_date_format[$i]=array(date($format,$week[0]),date($format,$week[1]));}return $week_array_of_date_format;}return $week_array;}