# Script will change a user mailbox into a shared mailbox and prompt you if you want to add a delegate.
# define functions
function Get-UserInfo{
   [string]$script:mailbox = Read-Host "please enter the email address of the user you should like to convert"
}

function Set-SharedMbox {
    Write-Host "Checking if $mailbox is already shared type..."
    $state = $(Get-Mailbox -Identity $mailbox | Select-Object -ExpandProperty RecipientTypeDetails)

    if($state -eq "UserMailbox"){
        Set-Mailbox -identity $mailbox -Type Shared
        Write-Host "Successfully converted $mailbox to a shared mailbox."
    }
    elseif($state -eq "SharedMailbox"){
        Write-Host "Mailbox $mailbox is already a shared mailbox."
    }
}

function Edit-Delegates {
    param (
        [string[]]$delegate,
        [string[]]$rights
    )

    Add-MailboxPermission -Identity "$mailbox" -User "$delegate" -AccessRights FullAccess
    if ($?){
        Write-Host "Added user $delegate as a delegate of $mailbox."
    }

    if ($rights -eq 2){
        Add-RecipientPermission -Identity "$mailbox" -Trustee "$delegate" -AccessRights SendAs

        if ($?){
            Write-Host "Added sending rights for $delegate on mailbox $mailbox."
        }
    }
}

function Read-Choice {
   $script:choice = Read-Host "Would you like to add a delegate user now?"
}

# Actual script

$adminuser = Read-Host 'Enter the email address of an admin user'

Connect-ExchangeOnline -UserPrincipalName $adminuser

# clear the screen to avoid the cmdlet vomit
Clear-Host

Get-UserInfo

if([string]::IsNullOrWhiteSpace($mailbox)){
    Write-Host "You must enter an email address."
    Write-Host "Please try again."
    Get-UserInfo
    }
else{
    Set-SharedMbox
}

Read-Choice

if ($choice -eq "y"){
    $delegate = Read-Host "Please enter the email address for the delegated user"
    Write-Host "`n`n"
    Write-Host "Please enter the access rights you would like this user to have."
    Write-Host "1. FullAccess (full access to the mailbox, but cannot send.)"
    Write-Host "2. FullAccess + SendAs (Same as above, but allows sending from the delegated mailbox.)"
    $rights = Read-Host "Enter your choice"

    Clear-Host

    Edit-Delegates $delegate $rights

}
elseif ($choice -eq "n"){
    Write-Output "Goodbye."
}
else{
    Write-Output "Invalid entry. Please try again."
    Read-Choice
}