Calculate Business Hours

// ----------------------------------------------------------------------
public void CalculateBusinessHoursSample()
{
  CalendarTimeRange testPeriod = new CalendarTimeRange( 
    new DateTime( 2011, 3, 1 ), new DateTime( 2011, 5, 1 ) );
  Console.WriteLine( "period: {0}", testPeriod );
  // > period: 01.03.2011 00:00:00 - 30.04.2011 23:59:59 | 60.23:59

  TimePeriodCollection holidays = new TimePeriodCollection();
  Console.WriteLine( "business hours without holidays: {0}", 
    CalculateBusinessHours( testPeriod, holidays ) );
  // > business hours without holidays: 396

  holidays.Add( new Day( 2011, 3, 9 ) );       // day 3/9/2011
  Console.WriteLine( "business hours with holidays: {0}", 
    CalculateBusinessHours( testPeriod, holidays ) );
  // > business hours with holidays: 387

  holidays.Add( new Days( 2011, 3, 16, 2 ) );  // days 16/9/2011 and 17/9/2011
  Console.WriteLine( "business hours with more holidays: {0}", 
    CalculateBusinessHours( testPeriod, holidays ) );
  // > business hours with more holidays: 369

  holidays.Add( new Week( 2011, 13 ) );        // w/c 13 2011
  Console.WriteLine( "business hours with even more holidays: {0}", 
    CalculateBusinessHours( testPeriod, holidays ) );
  // > business hours with even more holidays: 324
} // CalculateBusinessHoursSample

// ----------------------------------------------------------------------
public double CalculateBusinessHours( CalendarTimeRange testPeriod, ITimePeriodCollection holidays = null )
{
  CalendarPeriodCollectorFilter filter = new CalendarPeriodCollectorFilter();
  filter.AddWorkingWeekDays(); // only working days
  filter.CollectingHours.Add( new HourRange( 8, 12 ) );  // opening hours morning
  filter.CollectingHours.Add( new HourRange( 13, 18 ) ); // opening hours afternoon
  if ( holidays != null )
  {
    filter.ExcludePeriods.AddAll( holidays );
  }
 
  CalendarPeriodCollector collector = new CalendarPeriodCollector( 
    filter, testPeriod );
  collector.CollectHours();
 
  double businessHours = 0.0;
  foreach ( ICalendarTimeRange period in collector.Periods )
  {
    businessHours += Math.Round( period.Duration.TotalHours, 2 );
  }
  return businessHours;
} // CalculateBusinessHours