param($DomainController = [String]::Empty)

function Main
{
	#Script Logic flow
	#1. Pull User Info from cloud.csv file in the current directory
	#2. Lookup AD Info (DN, mail, proxyAddresses, and legacyExchangeDN) using the SMTP address from the CSV file
	#3. Save existing proxyAddresses
	#4. Add existing legacyExchangeDN's to proxyAddresses
	#5. Delete Mailbox
	#6. Mail-Enable the user using the cloud email address as the targetAddress
	#7. Disable RUS processing
	#8. Add proxyAddresses and mail attribute back to the object
	#9. Add msExchMailboxGUID from cloud.csv to the user object (for offboarding support)
	
	if($DomainController -eq [String]::Empty)
	{
		Write-Host "You must supply a value for the -DomainController switch" -ForegroundColor Red
		Exit
	}
	
	$CSVInfo = Import-Csv ".\cloud.csv"
	foreach($User in $CSVInfo)
	{
		Write-Host "Processing user" $User.OnPremiseEmailAddress -ForegroundColor Green
		Write-Host "Calling LookupADInformationFromSMTPAddress" -ForegroundColor Green
		$UserInfo = LookupADInformationFromSMTPAddress($User)
		
		#Check existing proxies for On-Premise and Cloud Legacy DN's as x500 proxies.  If not present add them.
		$CloudLegacyDNPresent = $false
		$LegacyDNPresent = $false
		foreach($Proxy in $UserInfo.ProxyAddresses)
		{
			if(("x500:$UserInfo.CloudLegacyDN") -ieq $Proxy)
			{
				$CloudLegacyDNPresent = $true
			}
			if(("x500:$UserInfo.LegacyDN") -ieq $Proxy)
			{
				$LegacyDNPresent = $true
			}
		}
		if(-not $CloudLegacyDNPresent)
		{
			$X500Proxy = "x500:" + $UserInfo.CloudLegacyDN
			Write-Host "Adding $X500Proxy to EmailAddresses" -ForegroundColor Green
			$UserInfo.ProxyAddresses += $X500Proxy
		}
		if(-not $LegacyDNPresent)
		{
			$X500Proxy = "x500:" + $UserInfo.LegacyDN
			Write-Host "Adding $X500Proxy to EmailAddresses" -ForegroundColor Green
			$UserInfo.ProxyAddresses += $X500Proxy
		}
		
		#Disable Mailbox
		Write-Host "Disabling Mailbox" -ForegroundColor Green
		Disable-Mailbox -Identity $UserInfo.OnPremiseEmailAddress -DomainController $DomainController -Confirm:$false
		
		#Mail Enable
		Write-Host "Enabling Mailbox" -ForegroundColor Green
		Enable-MailUser  -Identity $UserInfo.Identity -ExternalEmailAddress $UserInfo.CloudEmailAddress -DomainController $DomainController
		
		#Disable RUS
		Write-Host "Disabling RUS" -ForegroundColor Green
		Set-MailUser -Identity $UserInfo.Identity -EmailAddressPolicyEnabled $false -DomainController $DomainController
		
		#Add Proxies and Mail
		Write-Host "Adding EmailAddresses and WindowsEmailAddress" -ForegroundColor Green
		Set-MailUser -Identity $UserInfo.Identity -EmailAddresses $UserInfo.ProxyAddresses -WindowsEmailAddress $UserInfo.Mail -DomainController $DomainController
		
		#Set Mailbox GUID.  Need to do this via S.DS as Set-MailUser doesn't expose this property.
		$ADPath = "LDAP://" + $DomainController + "/" + $UserInfo.DistinguishedName
		$ADUser = New-Object -TypeName System.DirectoryServices.DirectoryEntry -ArgumentList $ADPath
		$MailboxGUID = New-Object -TypeName System.Guid -ArgumentList $UserInfo.MailboxGUID
		[Void]$ADUser.psbase.invokeset('msExchMailboxGUID',$MailboxGUID.ToByteArray())
		Write-Host "Setting Mailbox GUID" $UserInfo.MailboxGUID -ForegroundColor Green
		$ADUser.psbase.CommitChanges()
		
		Write-Host "Migration Complete for" $UserInfo.OnPremiseEmailAddress -ForegroundColor Green
		Write-Host ""
		Write-Host ""
	}
}

function LookupADInformationFromSMTPAddress($CSV)
{
	$Mailbox = Get-Mailbox $CSV.OnPremiseEmailAddress -ErrorAction SilentlyContinue
	
	if($Mailbox -eq $null)
	{
		Write-Host "Get-Mailbox failed for" $CSV.OnPremiseEmailAddress -ForegroundColor Red
		continue
	}
	
	$UserInfo = New-Object System.Object
	
	$UserInfo | Add-Member -Type NoteProperty -Name OnPremiseEmailAddress -Value $CSV.OnPremiseEmailAddress
	$UserInfo | Add-Member -Type NoteProperty -Name CloudEmailAddress -Value $CSV.CloudEmailAddress
	$UserInfo | Add-Member -Type NoteProperty -Name CloudLegacyDN -Value $CSV.LegacyExchangeDN
	$UserInfo | Add-Member -Type NoteProperty -Name LegacyDN -Value $Mailbox.LegacyExchangeDN
	$ProxyAddresses = @()
	foreach($Address in $Mailbox.EmailAddresses)
	{
		$ProxyAddresses += $Address
	}
	$UserInfo | Add-Member -Type NoteProperty -Name ProxyAddresses -Value $ProxyAddresses
	$UserInfo | Add-Member -Type NoteProperty -Name Mail -Value $Mailbox.WindowsEmailAddress
	$UserInfo | Add-Member -Type NoteProperty -Name MailboxGUID -Value $CSV.MailboxGUID
	$UserInfo | Add-Member -Type NoteProperty -Name Identity -Value $Mailbox.Identity
	$UserInfo | Add-Member -Type NoteProperty -Name DistinguishedName -Value (Get-User $Mailbox.Identity).DistinguishedName
	
	$UserInfo
}

Main