Crystal Report exclude time entries based on holiday rules - crystal-reports

Question

Working on report to determine an employees utilization (utilization is defined as number of billable versus non billable hours in a given report period).
The issue is I need to exclude holidays from my equation. While much has been written on identifying holidays, i need some additional help.
I do not have access to the backend MS. SQL database in order to create a holiday table, so I need to filter dates in the report.
Holidays I need to exclude are
New Year's Day (January 1)
Memorial Day (last Monday in May)
Independence Day (July 4)
Labor Day (first Monday in September)
Thanksgiving (fourth Thursday in November)
1/2 Day Christmas Eve (December 24)
Christmas (December 25)
1/2 Day New Year's Eve (December 31)
Here are the rules I need to follow:
A recognized holiday that falls on a Saturday will be observed on the preceding Friday.
A recognized holiday that falls on a Sunday will be observed on the following Monday.
currently I have the report working by calculating total available minutes (each workday = 480 minutes) so for normal holidays I need to remove them from total hours worked, and from the total hours available). For the half day holidays I need to remove 240 minutes from total available and to discard any minutes worked above 240).
I hope that makes sense.

Answer 1

Create a custom-function named 'Observance' with the following text:
//Correct date to match business rules
Function (Datevar value)
Select DayOfWeek(value)
//Sunday; add a day
Case 1: Date(DateAdd("d", 1, value))
//Saturday
Case 7: Date(DateAdd("d", -1, value))
//no change
Default: value
;
Create a custom-function named 'FullHolidays' with the following text:
//create a list of full-day holidays, calculated dynamically
Function (Numbervar yyyy)
Datevar Array holidays;
Datevar holiday;
//New Year's day
holiday:=Date(yyyy, 1, 1);
Redim Preserve holidays[Ubound(holidays)+1];
holidays[Ubound(holidays)]:=Observance(holiday);
//Memorial Day (last Monday in May)
//TODO
//Independence day
holiday:=Date(yyyy, 7, 4);
Redim Preserve holidays[Ubound(holidays)+1];
holidays[Ubound(holidays)]:=Observance(holiday);
//Labor Day (first Monday in September)
//TODO
//Thanksgiving (fourth Thursday in November)
//TODO
//xmas day
holiday:=Date(yyyy, 12, 25);
Redim Preserve holidays[Ubound(holidays)+1];
holidays[Ubound(holidays)]:=Observance(holiday);
holidays;
Create a custom-function named 'HalfHolidays' with the following text:
//create a list of half-day holidays, calculated dynamically
Function (Numbervar yyyy)
Datevar Array holidays;
Datevar holiday;
//xmas eve
holiday:=Date(yyyy, 12, 24);
Redim Preserve holidays[Ubound(holidays)+1];
holidays[Ubound(holidays)]:=Observance(holiday);
//new year's eve
holiday:=Date(yyyy, 12, 31);
Redim Preserve holidays[Ubound(holidays)+1];
holidays[Ubound(holidays)]:=Observance(holiday);
holidays;
Use in a formula like:
If {Table.DateField} IN FullHolidays(Year({Table.DateField})) Then
0
Else If {Table.DateField} IN HalfHolidays(Year({Table.DateField})) Then
240
Else
480
I'll leave the Thanksgiving (and other such holidays) calculation in your capable hands (I'm too busy watching House).