How to add parameter to function counting working days in powershell?

Hello, This function is counting working days from specified date back in time. The question is : What is the proper way to add
parameter to this function so this function can be used for counting days in different countries.

Example :
Get-WorkingDay 5 "2015-01-01" Canada

Function is counting 5 working days from date "2015-01-01" using Canadian list of holidays.
If the parameter for holidays is not used, default setting should be US holiday.





##################################################################################

$Canada = @(
(Get-Date -Date '2014-01-01'),            # New_Years_Day_Canada2014
(Get-Date -Date '2014-02-17'),            # Family Day2014
(Get-Date -Date '2014-04-18'),            # Good Friday_Canada2014
(Get-Date -Date '2014-05-19'),            # Victoria Day2014
(Get-Date -Date '2014-07-01'),            # Canada Day2014
(Get-Date -Date '2014-08-04'),            # Civic Holiday2014
(Get-Date -Date '2014-09-01'),            # Labour Day2014
(Get-Date -Date '2014-10-13'),            # Thanksgiving Day_Canada2014
(Get-Date -Date '2014-12-25'),            # Christmas Day_Canada2014
(Get-Date -Date '2014-12-26'),            # Boxing Day2014
(Get-Date -Date '2015-01-01'),            # New_Years_Day_Canada2015
(Get-Date -Date '2015-02-16'),            # Family Day2015
(Get-Date -Date '2015-04-03'),            # Good Friday_Canada2015
(Get-Date -Date '2015-05-18'),            # Victoria Day2015
(Get-Date -Date '2015-07-01'),            # Canada Day2015
(Get-Date -Date '2015-08-03'),            # Civic Holiday2015
(Get-Date -Date '2015-09-07'),            # Labour Day2015
(Get-Date -Date '2015-10-12'),            # Thanksgiving Day_Canada2015
(Get-Date -Date '2015-12-25'),            # Christmas Day_Canada2015
(Get-Date -Date '2015-12-28')             # Boxing Day2015



#############################################################################


Function Get-WorkingDay{
param(
    [Parameter(Mandatory=$True,Position=1)]
    [int]$maxWorkingDays,
    [Parameter(Mandatory=$False,Position=2)]
    [datetime]$startDate = (Get-Date).Date
)

$holidays = @(
    (Get-Date -Date '2014-01-01'),            # New_Years_Day2014
    (Get-Date -Date '2014-01-20'),            # Martin_Luther_King2014
    (Get-Date -Date '2014-02-17'),            # Washingtons_Birthday2014
    (Get-Date -Date '2014-04-18'),            # Good_Friday2014 
    (Get-Date -Date '2014-05-26'),            # Memorial_Day2014 
    (Get-Date -Date '2014-07-04'),            # Independence_Day2014
    (Get-Date -Date '2014-09-01'),            # Labor_Day2014
    (Get-Date -Date '2014-11-27'),            # Thanksgiving_Day2014
    (Get-Date -Date '2014-12-25'),            # Christmas2014
    (Get-Date -Date '2015-01-01'),            # New_Years_Day2015
    (Get-Date -Date '2015-01-19'),            # Martin_Luther_King2015
    (Get-Date -Date '2015-02-16'),            # Washingtons_Birthday2015 
    (Get-Date -Date '2015-04-03'),            # Good_Friday2015 
    (Get-Date -Date '2015-05-25'),            # Memorial_Day2015 
    (Get-Date -Date '2015-07-03'),            # Independence_Day2015
    (Get-Date -Date '2015-09-07'),            # Labor_Day2015 
    (Get-Date -Date '2015-11-26'),            # Thanksgiving_Day2015
    (Get-Date -Date '2015-12-25')             # Christmas2015
)

# Count down the working days checking each date as we progress
$dateIndex = $startDate

For($workingDayIndex = $maxWorkingDays; $workingDayIndex -gt 0; $workingDayIndex--){
    # Assume the current day is not a working day
    $isWorkingDay = $False

    Do{
        If (("Sunday","Saturday" -contains $dateIndex.DayOfWeek) -or ($holidays -contains $dateIndex)){
            # This is not a working day. Check the next day.
            # Write-Host "$($dateIndex.Date) is a weekend or holiday" -ForegroundColor Red
            $dateIndex = $dateIndex.AddDays(-1)
        } Else {
            # Current $dateIndex is a working day.
            $isWorkingDay = $True
        }
    } While(!$isWorkingDay)

    # Write-Host "Current Date: $($dateIndex.Date). Number of working days left: $workingDayIndex."

    # Set the $dateIndex to the previous day.
    $dateIndex = $dateIndex.AddDays(-1)
}

  # The last date was the correct one. Re-add the day. 
  $dateIndex.AddDays(1)
}

Get-WorkingDay 5