Credit card utilities

CreditCardUtilities.ps1

Enum PaymentTypes
{
    Visa
    MasterCard
    AmericanExpress
    Discover
    JapanCreditBureau
    DinersClub
}


<#
 .SYNOPSIS
  Get the credit card type based off the card number.
  
 .PARAMETER creditCardNumber
  The card number youw want to get type for.
  
 .EXAMPLE
  Get-CreditCardType -creditCardNumber "4444333322221111"
#>
function Get-CreditCardType
{
    param (
        [Parameter(Mandatory=$True)]
        [string] $creditCardNumber
    )

    [string] $visaRegExPattern = "4[0-9]{12}(?:[0-9]{3})"
    [string] $masterCardRegExPattern = "(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}"
    [string] $americanExpressRegExPattern = "3[47][0-9]{13,14}"
    [string] $discoverRegExPattern = "6(?:011|5[0-9]{2})[0-9]{12}"
    [string] $jcbRegExPattern = "(?:2131|1800|35\d{3})\d{11}"
    [string] $dinersClubRegExPattern = "3(?:0[0-5]|[68][0-9])[0-9]{11}"

    switch -regex ($creditCardNumber)
    {
        $visaRegExPattern
        {
            return [PaymentTypes]::Visa
        }
        $masterCardRegExPattern
        {
            return [PaymentTypes]::MasterCard
        }
        $americanExpressRegExPattern
        {
            return [PaymentTypes]::AmericanExpress
        }
        $discoverRegExPattern
        {
            return [PaymentTypes]::Discover
        }
        $jcbRegExPattern
        {
            return [PaymentTypes]::JapanCreditBureau
        }
        $dinersClubRegExPattern
        {
            return [PaymentTypes]::DinersClub
        }
    }

    throw "Could not determine credit card type."
}

<#
 .SYNOPSIS
  Checks whether a given number was generated using the Luhn algorithm.
  
 .PARAMETER creditCardNumber
  The card number you want to validate.
  
 .EXAMPLE
  Test-ValidLuhn -creditCardNumber "4444333322221111"
#>
function Test-ValidLuhn {
    param (
        [Parameter(Mandatory=$True)]
        [string]$creditCardNumber
    )
    
    [char[]] $temp = $creditCardNumber.ToCharArray();
    [int[]] $numbers = @(0) * $creditCardNumber.Length;
    [bool] $alt = $false;
    [int] $sum = 0

    for($i = $temp.Length -1; $i -ge 0; $i--)
    {
       $numbers[$i] = [int]::Parse($temp[$i])
       if($alt) 
       {
           $numbers[$i] *= 2
           if($numbers[$i] -gt 9) 
           { 
               $numbers[$i] -= 9 
           }
       }
       $sum += $numbers[$i]
       $alt = !$alt
    }
    return ($sum % 10) -eq 0
}