Azure AD Users WriteBack to Active Directory On-Prem using PowerShell

#Connect to Azure AD
Connect-AzureAD

#Variables
$UsersToWB = Import-Csv -path "C:\Temp\AADUsers.csv" -Encoding UTF8 #file containing userprincipalname of Azure AD Users you want to writeback to AD on-prem
$ProxyAddresseUpdated = "C:\Temp\ProxyAddressesUpdated.csv" #Log file
$Path = "OU Distinguished name" #Example : $Path = "OU=Sales,OU=UserAccounts,DC=CONTOSO,DC=COM" #Distinghishedname of the organizational unit where user account are going to be created.
$ExistInADOnPrem = "C:\Temp\ExistInADOnPrem.csv"

$Server = (Get-ADDomainController -Discover -Service ADWS).Name #Find a domain controller 
$ADUsers = Get-ADUser -Filter * -Properties * -Server $Server   #Load all AD on-prem User accounts
$AADUsers = Get-AzureADUser -All $true -filter "UserType eq 'Member'" #Load all Azure AD User accounts of type Member

#Creating account in AD on-prem
foreach ($UserToWB in $UsersToWB){

    #Check that user account doesn't exist in your AD on-prem domain before creating them
    $adopUser = $ADUsers | where-object {($_.UserPrincipalName -eq $UserToWB.UserPrincipalName) -or ($UserToWB.UserPrincipalName -in $_.ProxyAddresses)}
    if(($adopUser | Measure-Object).count -ge 1){
        $adopUser | Select-Object UserPrincipalName, DistinguishedName | Export-Csv -Path $ExistInADOnPrem -Encoding UTF8 -Delimiter ";" -NoTypeInformation -Append
    }
    else{
        #Create user account. At this step, we are sure user account does not exist in AD on-prem
        Write-Host "Start Creation $($UserToWB.UserPrincipalName)" -ForegroundColor Yellow

        #Get Azure AD User data
        $AADUser = $AADUsers | Where-Object {$_.UserPrincipalName -eq $UserToWB.UserPrincipalName}        

        #Building samAccountName
        $samAccountName = ($AADUser.UserPrincipalName -split("@"))[0]
        if($samAccountName.Length -gt 20){
            $samAccountName = $samAccountName[0..19] -join ""
        }

        $DefaultPWD = ConvertTo-SecureString -AsPlainText $UserToWB.Password -force

        #Creating AD User account 
        New-ADUser $samAccountName -GivenName $AADUser.GivenName -Surname $AADUser.Surname `
            -Company $AADUser.CompanyName -Department $AADUser.department -EmployeeID $AADUser.ExtensionProperty.employeeId `
                -PostalCode $AADUser.postalCode -UserPrincipalName $AADUser.UserPrincipalName `
                    -EmailAddress $AADUser.mail -title $AADUser.JobTitle `
                        -StreetAddress $AADUser.StreetAddress -City $AADUser.City `
                            -Enabled $AADUser.AccountEnabled -ChangePasswordAtLogon $false `
                                -Office $AADUser.PhysicalDeliveryOfficeName -Path $Path `
                                    -AccountPassword $DefaultPWD -Server $Server
    
        #Set DisplayName and ProxyAddresses
        do{
            Start-Sleep -Seconds 1
            $NewUser = Get-ADUser -filter "UserPrincipalname -eq '$($AADUser.UserPrincipalName)'" -Properties * -Server $Server
        } while(-not $NewUser)

        #Set DisplayName
        Set-ADUser $NewUser.DistinguishedName -DisplayName $AADUser.DisplayName -Server $Server
        Rename-ADObject -Identity $NewUser.DistinguishedName -NewName $AADUser.DisplayName -Server $Server

        #Set ProxyAddresses 
        $Addresses = $AADUser | Select-Object -ExpandProperty ProxyAddresses | Where-Object {$_ -notlike "onmicrosoft.com"} 
        Start-Sleep -Seconds 2
        if($Addresses){
            ForEach($Address in $Addresses){
                Write-Host "Adding Proxy Address: $Address" -ForegroundColor White
                Set-ADUser -Identity $NewUser.ObjectGUID.Guid -Add @{ProxyAddresses="$Address"} -Server $Server
                if($?) {
                    Write-Host "Proxy OK: $Address" -ForegroundColor Green
                    $NewUser | Select-Object UserPrincipalName, @{Name ="Address"; Expression ={$Address}}, @{Name = "Added"; Expression = {$true}} | Export-Csv -Path $ProxyAddresseUpdated -Delimiter ";" -Encoding UTF8 -NotypeInformation -Append
                }
                else {
                    Write-Host "Proxy NOK: $Address" -ForegroundColor Red
                    $NewUser | Select-Object UserPrincipalName, @{Name ="Address"; Expression ={$Address}}, @{Name = "Added"; Expression = {$false}} | Export-Csv -Path $ProxyAddresseUpdated -Delimiter ";" -Encoding UTF8 -NotypeInformation -Append
                }
            }
        }
        Write-Host "Done: $($UserToWB.UserPrincipalName)" -ForegroundColor Green
    }
}