# Import modules
Import-Module -Name MSAL.PS
Import-Module -Name ExchangeOnlineManagement
Import-Module -Name AzureADPreview
Import-Module -Name Microsoft.Graph.PersonalContacts
Import-Module -Name Microsoft.Graph.Authentication
Import-Module -Name Microsoft.Graph.Applications

# Variables
$thumbprint = XXXXXX
$appId = XXXXXX
$tenant = XXXXXXXX
$serviceId = XXXXXXXXX
$appSecret = XXXXXXXX
$tenantId = XXXXXXXXXX
$dlOrgContactId = XXXXXXXXXXXXXXXXXXXXXXX
$folderName = XXXXXXXXXXXXXXXXXXXX
$folderId = XXXXXXXXXXXXXXX
$Now = Get-Date -format D
$OrgNotes = "Organization contact created " + $Now

# Oauth connection to EXO
try { 
	Connect-ExchangeOnline -CertificateThumbprint $thumbprint -AppId $appId -Organization $tenant
	write-host -ForegroundColor Green "Connection Successfull to EXO"
}
catch {
  	write-host -ForegroundColor Red "Connection Error to EXO"
}
# Oauth connection to AAD
try { 
	Connect-AzureAD -TenantId $tenantId -CertificateThumbprint $thumbprint -ApplicationId $appId
	write-host -ForegroundColor Green "Connection Successfull to AAD"
}
catch {
  	write-host -ForegroundColor Red "Connection Error to AAD"
}

# Find the set of organization contacts from DL All Staff Contact
[array]$OrgContacts = [array]$OrgContacts = Get-AzureADGroupMember -ObjectId $dlOrgContactId -All:$true
If (!($OrgContacts)) {Write-Host "No organization contacts found - exiting" ; break }
Write-Host ("Found {0} organization contacts - continuing..." -f $OrgContacts.count)

# Look for target mailboxes. In this example, we get the mailboxes created in the last month
$LastMonth = (Get-Date).AddDays(-30)
[array]$Mailboxes = Get-ExoMailbox -Filter "WhenMailboxCreated -gt '$LastMonth'" -RecipientTypeDetails UserMailbox | Select ExternalDirectoryObjectId, DisplayName, UserPrincipalName
If (!($Mailboxes)) { Write-Host "No mailboxes found to process - exiting" ; break }
Write-Host ("Found {0} mailboxes to process - continuing..." -f $Mailboxes.count)

# Grant Full Access to Org Contacts Mailboxes
ForEach ($m in $OrgContacts) {
	# Grant Full Acces to Mailbox
	Add-MailboxPermission -Identity $m.Mail -User $serviceId -AccessRights FullAccess -InheritanceType All
}

# Get Token for Graph Api
$MsalResponse = Get-MsalToken -ClientId $appId -TenantId $tenant -ClientSecret (ConvertTo-SecureString $appSecret -AsPlainText -Force) -Scopes "https://graph.microsoft.com/.default" -ForceRefresh
$GraphToken  = $MsalResponse.AccessToken

# Connect Graph API
Connect-MgGraph -AccessToken $GraphToken

ForEach ($Mbx in $Mailboxes) {
	# Populate email addresses for existing contacts
	$folderStaffDirectory = Get-MgUserContactFolder -UserId $Mbx.UserPrincipalName | Where-Object {$_.DisplayName -eq $folderName}

	# Create contacts folder if does not exists
	if(!($folderStaffDirectory))
	{
		$paramsFolder = @{
			ParentFolderId = $folderId
			DisplayName = $folderName
		}
		# Create folder
		$folderStaffDirectory = New-MgUserContactFolder -UserId $Mbx.UserPrincipalName -BodyParameter $paramsFolder
	}
	# Get contacts from folder
	[array]$ContactsInMbx = Get-MgUserContactFolderContact -UserId $Mbx.UserPrincipalName -ContactFolderId $folderStaffDirectory.Id -All

	If ($ContactsInMbx.Count -gt 0) { $ContactsInMbx = $ContactsInMbx | Select emailaddresses }
	$CheckTable = [System.Collections.Generic.List[Object]]::new()
	ForEach ($C in $ContactsInMbx) { $CheckTable.Add($C[0].EmailAddresses[0].Address.toString()) }
	Write-Host "Processing mailbox" $Mbx.DisplayName

	ForEach ($Contact in $OrgContacts) {

		Write-Host "Processing contact" $Contact.DisplayName
		# Check if the contact is already there. If not, we go ahead and add the contact
		If ($Email -in $CheckTable) {
			Write-Host ("Contact record for {0} is already present in the mailbox" -f $Contact.Maill) }
		Else {
			Write-Host "Proceeding $($Contact.Mail)..."
			# Build the contact object
			$params = @{
				GivenName = "$($Contact.GivenName)"
				Surname = "$($Contact.Surname)"
				EmailAddresses = @(
					@{
						Address = "$($Contact.Mail)"
						Name = "$($Contact.DisplayName)"
					}
				)
				BusinessPhones = @(
					"$($Contact.TelephoneNumber)"
				)
			}
			# And add the new contact
			Try {
				New-MgUserContactFolderContact -UserId $Mbx.UserPrincipalName -BodyParameter $params -ContactFolderId $folderStaffDirectory.Id -DisplayName $Contact.DisplayName -CompanyName $Contact.CompanyName -Department $Contact.Department -JobTitle $Contact.JobTitle -PersonalNotes $OrgNotes -MobilePhone $Contact.Mobile
			}
			catch {
				Write-Host "Error creating contact $($Contact.Mail) for $($Mbx.UserPrincipalName) $($_.Exception.Message)"
			}
		} #End Else
 	} #End ForEach OrgContacts
} #End ForEach Mailboxes