Function to generate samaccountname in PowerShell - powershell

Question

I am trying to write a PS function that can generate SamAccountName in a specific way, I have found another question here but it is not similar to what i'm trying to do.
I need the SamAccountName to be generated like this:
UNIT + initial_of_firstName + initial_of_lastName
for example employee Jane Doe in unit FLN could have FLNjd as SamAccountName, and the function should check if that ID is taken by another user and if true then SamAccountName should be:
UNIT + initial_of_firstName + first_two_initials_of_lastName such as FLNjdo
and if that is also taken then SamAccountName should be:
UNIT + first_two_initials_of_firstName + first_two_initials_of_lastName such as FLNjado
and if that is also taken then SamAccountName should be:
UNIT + first_two_initials_of_firstName + first_two_initials_of_lastName + 1 such as FLNjado1
and from here it starts adding numbers 2, 3, 4.... as long as the function finds that the ID exists.
I only managed to extract the initials needed:
$first_of_fname = ($_.Fname).Substring(0,1).ToLower()
$first_of_lname = ($_.Lname).Substring(0,1).ToLower()
$FirstandSecond_of_fname = ($_.Fname).Substring(0,2).ToLower()
$FirstandSecond_of_lname = ($_.Lname).Substring(0,2).ToLower()
I need now to know how to generate the the SamAccountName in the above form and order.
ANy help will be very much appreciated.

Answer 1

You can do the following:
Function Get-SamAccountName {
Param(
[Parameter(Position=0,ValueFromPipelineByPropertyName)]
$Unit,
[Parameter(Position=1,ValueFromPipelineByPropertyName)]
$First,
[Parameter(Position=2,ValueFromPipelineByPropertyName)]
$Last
)
$fcount = 1
$lcount = 1
$inc = 1
$Sam = "{0}{1}{2}" -f $unit,$first.substring(0,$fcount).ToLower(),$last.substring(0,$lcount++).ToLower()
while (Get-AdUser -Filter "SamAccountName -eq '$Sam'") {
if ($fcount -le 2) {
$Sam = "{0}{1}{2}" -f $unit,$first.substring(0,$fcount++).ToLower(),$last.substring(0,$lcount).ToLower()
} else {
$Sam = "{0}{1}{2}{3}" -f $unit,$first.substring(0,2).ToLower(),$last.substring(0,2).ToLower(),$inc++
}
}
$Sam
}
Usage Option 1: Using Named Parameters
Get-SamAccountName -Unit 'FLN' -First 'Sam' -Last 'Wise'
Usage Option 2: Using positional parameters (unnamed)
Get-SamAccountName 'FLN' 'Sam' 'Wise'
Usage Option 3: Having A Text List Of Units and Names
$users = Get-Content users.txt
$users
FLN,Sam,Wise
HRS,John,Doe
COM,Jane,Doe
$users | ConvertFrom-Csv -Header 'Unit','First','Last' | Foreach {
$_ | Get-SamAccountName
}
The pipe to ConvertFrom-Csv can be skipped here if your file is already a CSV with the proper headers.
Explanation:
The function returns a string that represents an available SamAccountName value.
$fcount is the first name character count that we want to retrieve. $lcount is the last name character count that we want to retrieve. $inc is the number we want to append to the username if needed.
$var++ notation increments the $var value by one after its line is executed. The timing of $fcount++ and $lcount++ allows us to retrieve (1,1),(1,2),(2,2) characters from (first,last) while minimizing code. $inc++ will increment after the current $inc value is retrieved.
-f is the string format operator.
The while loop will only execute if the current created SamAccountName value is found.
Note: The code shortening complexity may or may not be worth it. It does not gain much from a performance perspective, but I do feel code complexity on this level is merely relative.

Answer 2

To take a different approach, instead of multiple if statements, you can use the switch statement "backwards" to find out what is $null or not available, and fall back to the default switch which is the final while iteration loop incrementing the count.
#Get substrings
$first_of_fname = ($_.Fname).Substring(0,1).ToLower()
$first_of_lname = ($_.Lname).Substring(0,1).ToLower()
$FirstandSecond_of_fname = ($_.Fname).Substring(0,2).ToLower()
$FirstandSecond_of_lname = ($_.Lname).Substring(0,2).ToLower()
#create patters to match on
$pattern1 = $UNIT + $first_of_fname + $first_of_lname
$pattern2 = $UNIT + $first_of_fname + $FirstandSecond_of_lname
$pattern3 = $UNIT + $FirstandSecond_of_fname + $FirstandSecond_of_lname
#evaluate what is available
switch($null){
(Get-ADUser -Filter "samAccountName -like '$pattern1'"){
Write-Host "$pattern1 - Free"
break
}
(Get-ADUser -Filter "samAccountName -like '$pattern2'"){
Write-Host "$pattern2 - Free"
break
}
(Get-ADUser -Filter "samAccountName -like '$pattern3'"){
Write-Host "$pattern3 - Free"
break
}
default {
$cnt = 1
while (Get-ADUser -Filter "SamAccountName -like '$pattern3$cnt'") {
$cnt++
}
Write-Host "$pattern3$cnt - Free"
break
}
}