Get username from full name - PowerShell function

Question

I would like your opinion of my PowerShell function. Does it follow conventions, and what could can I do to improve it. It is made to create LDAP friendly username from a full name in Serbian language.

function Get-UsernameFromFullName
{
    [CmdletBinding()]
    param
    (
        [Parameter(Position = 0, Mandatory = $true, ValueFromPipelineByPropertyName = $true)]
        [string]
        $FullName,

        [Parameter(Position = 1, Mandatory = $false, ValueFromPipelineByPropertyName = $true)]
        [ValidateSet('First', 'Last')]
        [string]
        $LastNamePosition = 'First'
    )
    
    $usernameComponents = $FullName.ToLower().Split(" ")

    switch ($LastNamePosition)
    {
        'First' { $firstName = $usernameComponents.Length -1; $lastName = 0 }
        'Last'  { $firstName = 0; $lastName = $usernameComponents.Length -1 }
        Default { $firstName = $usernameComponents.Length -1; $lastName = 0 }
    }

    $chars = ($usernameComponents.Get($firstName) + "." + $usernameComponents.Get($lastName)).ToCharArray()

    foreach($char in $chars)
    {
        switch($char)
        {
            'ć' { $segment = "c" }
            'č' { $segment = "c" }
            'đ' { $segment = "dj" }
            'š' { $segment = "s" }
            'ž' { $segment = "z" }
            default { $segment = $char }
        }
        $Username += $segment
    }
    return $Username
}

Here is a link to GitHub page of the actual .psm1 file.

This is an example of the function usage:

Get-UsernameFromFullName -FullName "Čedomir Đorđević"

cedomir.djordjevic

Get-UsernameFromFullName -FullName "JANKOV ZORAN" 

zoran.jankov

Get-UsernameFromFullName -FullName "Stojić Gradimir"

gradimir.stojic

Get-UsernameFromFullName -FullName "Vučićević R Željko"

zeljko.vucicevic

Get-UsernameFromFullName -FullName "Magda Boškić" -LastNamePosition Last

magda.boskic

Answer 1

i think the comments cover the why of things, but please feel free to ask if you have any questions. [grin]

#region >>> fake reading in a list of names
#    in real life, use Get-Content
$InStuff = @'
Čedomir Đorđević
JANKOV ZORAN 
Stojić Gradimir
Vučićević R Željko
Magda Boškić
'@ -split [System.Environment]::NewLine

<# intended output
cedomir.djordjevic
zoran.jankov
gradimir.stojic
zeljko.vucicevic 
magda.boskic [lastname @ end]
#>
#endregion >>> fake reading in a list of names



function Get-UserNameFromFullName
    # your "Get-UsernameFromFullName" name leaves the "N" in "Username" in lowercase
    #    that is not consistent with your use of that in other names of items
    {

    <#
    where is the Comment Based Help?
    #>

    [CmdletBinding ()]
    Param
        (
        [Parameter (
            Position = 0,
            # the following are switches that default to "$False"
            #    that means there is no need to add "= $True"
            #    the simple presense of the attribute flips it to "$True"
            Mandatory,
            ValueFromPipeline,
            # the following requres the pipeline object contain a property named ".FullName"
            #    is that always going to be the case?
            #    if not, then the "ValueFromPipeline" above will handle bare values
            ValueFromPipelineByPropertyName
            )]
            [string]
            $FullName,

        [Parameter (
            Position = 1,
            # making this mandatory makes little sense when a default is supplied
            #Mandatory,
            # does it make any sense to use the following attribute?
            ValueFromPipelineByPropertyName
            )]
            # don't use "First" and "Last" for _position_ info when the same words are used for the name parts
            #    it's needlessly confusing
            #[ValidateSet ('First', 'Last')]
            [ValidateSet ('Start', 'End')]
            [string]
            $LastNamePosition = 'Start'
        )

    begin {}

    process
        {
        # properly supporting the pipeline requires one to have a "process" block.
        #    otherwise all code is run in a virtual "end" block ... and that does not correctly support pipeline input

        # mixing camelCase and PascalCase for variable names is confusing [*grin*] 
        #    the recommended style for PoSh is PascalCase
        #$usernameComponents = $FullName.ToLower().Split(" ")
        # the 2nd sample name has a trailing space
        #    the ".Trim()" removes that
        # good practice in PoSh is to avoid using double quotes since that can trigger unwanted expansion of $Vars
        $UserNameComponents = $FullName.Trim().ToLower().Split(' ')

        switch ($LastNamePosition)
            {
            'Start' {
                # "index -1, index 0" for the $UserNameComponents skips any middle name or initial
                $UserName = '{0}.{1}' -f $UserNameComponents[-1], $UserNameComponents[0]
                }
            'End' {
                $UserName = '{0}.{1}' -f $UserNameComponents[0], $UserNameComponents[-1]
                }
            # this is a binary choice, so the "default" is not needed
            #Default { $firstName = $UserNameComponents.Length -1; $lastName = 0 }
            }

        # there is no need to assign the output to anything
        #    whatever is left unassigned will be sent out
        # there is also no need for "return"
        #    that is disrecommeded since it gives the false impression that ONLY the item to its right will be returned
        # the "-replace" operator can be chained. so can the ".Replace()" method
        #    that allows us to skip breaking things into an array of chars
        $UserName -replace 
            'č', 'c' -replace
            'ć', 'c' -replace
            'đ', 'dj' -replace
            'š', 's' -replace
            'ž', 'z'

        } # end >>> process

    end {}

    } # end >>> function Get-UserNameFromFullName

run with all names, no parameters, and using the pipeline ...

$InStuff |
    Get-UserNameFromFullName

output ...

djordjevic.cedomir
zoran.jankov
gradimir.stojic
zeljko.vucicevic
boskic.magda

run with all parameters listed and only one input value ...

Get-UserNameFromFullName -FullName $InStuff[-1] -LastNamePosition End

output = magda.boskic

Answer 2

I have created a new version of my function based on Lee_Dailey suggestions.

function Get-UserNameFromFullName
{
    [CmdletBinding()]
    param
    (
        [Parameter(Position = 0, Mandatory, ValueFromPipeline, ValueFromPipelineByPropertyName)]
        [string]
        $FullName,

        [Parameter(Position = 1, ValueFromPipelineByPropertyName)]
        [switch]
        $ReverseNamePositions = $false
    )
    
    process
    {    
        if ($ReverseNamePositions)
        {
            $Front = -1
            $End = 0
        }
        else
        {
            $Front = 0
            $End = -1
        }

        $UserNameComponents = $FullName.Trim().ToLower().Split(' ')

        $UserName = '{0}.{1}' -f $UserNameComponents[$Front], $UserNameComponents[$End]

        $UserName -replace 'č', 'c' `
                  -replace 'č', 'c' `
                  -replace 'ć', 'c' `
                  -replace 'đ', 'dj' `
                  -replace 'š', 's' `
                  -replace 'ž', 'z'
    }
}

If someone thinks that the function is lacking something feel free to tell me. I would be grateful.