Business hours calculation using PHP

Most of ticketing alert projects needed SLA calculation to exclude holidays and weekends or Off business hours.
First of all, let us take a look at types of SLA we need to calculate.
For instance, few companies will work 24/7 shifts and 8x5, 8x7 etc.

So we need to consider business hours. In this example, I'm considering business hours which starts at 09:00 AM and ends at 06:00 PM. Also, using this code we can calculate 24/7 too.

Let's consider business hours started at 9:00 AM to 18:00 PM without weekends.

Now, take the actual work start period and end period.

                                                     Demo

 <?php 
 $incident_work_started = '2018-09-12 09:28:07';
 $incident_work_ended = '2018-09-19 17:45:00';
 $totalHours = round(get_working_hours($incident_work_started,$incident_work_ended),2)."\n";
 echo "Total hours: ".$totalHours;
 function get_working_hours($work_started,$work_ended)
 {
 // business  hours start at 9:00 AM to 18:00. Consider that in an array [hrs,mins]
 $buss_start = array(9,00); // hours, minutes
 $buss_end = array(18,00); // hours, minutes
 
 // Convert $work_started and $work_ended date into date object.
 // Reason to converting, To get difference of time "2018-09-12 09:28:00" to "2018-09-12 09:00:00". here will get 28 mins 
 $work_started_date_obj = date_create($work_started); // Date will converted to date object
 $work_ended_date_obj = date_create($work_ended); // Date will converted to date object
 
 //Now, set $work_started to $buss_start to get difference
 $ini_buss_start_time = date_time_set(date_create($work_started),$buss_start[0],$buss_start[1]); // "2018-09-12 09:28:00" to "2018-09-12 09:00:00"
 $ini_buss_end_time = date_time_set(date_create($work_ended),$buss_end[0],$buss_end[1]); // "2018-09-19 17:45:00" to "2018-09-19 18:00:00"
 
 // To get actual working days and skip weekends(Sat & Sun) and holidays.
 $actual_worked_days = get_workdays($work_started_date_obj,$work_ended_date_obj); 
 $actual_worked_days_count = count($actual_worked_days); 
 
 // convert business hours to seconds for calculating time difference
  $workday_seconds = (($buss_end[0] * 60 + $buss_end[1]) - ($buss_start[0] * 60 + $buss_start[1])) * 60;
 
 //echo $current->format('U')."";
 //echo date('Y/m/d H:i:s', $current->format('U'))."";
 
 //get time difference
  $ini_seconds = 0;
 $end_seconds = 0;
 
   if(in_array($work_started_date_obj->format('Y-m-d'),$actual_worked_days))
 {
  $ini_seconds = $work_started_date_obj->format('U') - $ini_buss_start_time->format('U');
  /* we will get 1687 seconds, beacuase we given date "2018-09-12 09:28:07" our business 
  hours start at 9:00:00 (h:m:s) so need take seconds from 9:00:00. Finally we get seconds
  of 9:00:00 to 09:28:07 is  1687. */
 } 
 
    if(in_array($work_ended_date_obj->format('Y-m-d'),$actual_worked_days))
 {
  $end_seconds = $ini_buss_end_time->format('U') - $work_ended_date_obj->format('U');
 } 
 
 
  $seconds_dif = $ini_seconds > 0 ? $ini_seconds : 0;
  
  if($end_seconds > 0)
  {
   $seconds_dif += $end_seconds;
  }
 
 /* Final Calculation, Hence we got total number of working days $actual_worked_days_count and $workday_seconds.
  business  start at 9:00:00 AM but here work started at 9:28:07 
  so we should subtraction the 28:07 (m:s) total 1687 seconds and business  ends at 18:00:00
  but here work closed at 17:45:00 then subtraction will get (15:00) total 900 seconds. so total 2587 seconds. */
 
 $working_seconds = ($actual_worked_days_count * $workday_seconds) - $seconds_dif; 
 /* here we get total number of working day seconds ($actual_worked_days_count * $workday_seconds)
  and subtraction none used seconds $seconds_dif will get actual working seconds. */

 echo 'Working Hours:'.($working_seconds / 3600)."\n";
 
    return $working_seconds / 3600; //return hrs 
 
 }
 
 
function get_workdays($work_started,$work_ended)
{
 //To skip saturday and sunday weekends
 $weekdays = [0,6]; // sunday:0 monday:1...saturday:6;
 $holidays = []; //eg: ['2018-12-25']; for public holidays
 
 $current = clone $work_started; // Clone is used to load date objects.
 
 // Get date format from $work_started and end date
 $start_date = $work_started->format('Y-m-d');
 $end_date = $work_ended->format('Y-m-d');
 
 // To store valid working days after avoid weekends and holidays
  $days_arr = [];
  
 //So we have $start_date, $end_date, $weekdays and $holidays. We need to take work dates between all these days.
 
 while($start_date <= $end_date){
        if(!in_array($current->format('w'),$weekdays) && !in_array($start_date,$holidays)){
            $days_arr[] = $start_date;
        }
        $current->add(new DateInterval('P1D')); //adds one day
        $start_date = $current->format('Y-m-d');
    }
    return $days_arr; // return the valid worked days 
}
?>