PinEmail.ps1

function Connect-Exchange { 
    param( 
        [Parameter(Position = 0, Mandatory = $true)] [string]$MailboxName,        
        [Parameter(Position = 1, Mandatory = $false)] [string]$url,
        [Parameter(Position = 2, Mandatory = $false)] [string]$ClientId,
        [Parameter(Position = 3, Mandatory = $false)] [string]$redirectUrl,
        [Parameter(Position = 4, Mandatory = $false)] [string]$AccessToken,
        [Parameter(Position = 5, Mandatory = $false)] [switch]$basicAuth,
        [Parameter(Position = 6, Mandatory = $false)] [System.Management.Automation.PSCredential]$Credentials

    )  
    Begin {
        Invoke-LoadEWSManagedAPI
		
        $ExchangeVersion = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010_SP1      
		
        ## Create Exchange Service Object  
        $service = New-Object Microsoft.Exchange.WebServices.Data.ExchangeService($ExchangeVersion)  
		  
        ## Set Credentials to use two options are availible Option1 to use explict credentials or Option 2 use the Default (logged On) credentials  
        if ($basicAuth.IsPresent) {
            $creds = New-Object System.Net.NetworkCredential($Credentials.UserName.ToString(), $Credentials.GetNetworkCredential().password.ToString())  
            $service.Credentials = $creds    
        }
        else {
            if ([String]::IsNullOrEmpty($AccessToken)) {
                $Resource = "Outlook.Office365.com"    
                if ([String]::IsNullOrEmpty($ClientId)) {
                    $ClientId = "d3590ed6-52b3-4102-aeff-aad2292ab01c"
                }
                if ([String]::IsNullOrEmpty($redirectUrl)) {
                    $redirectUrl = "urn:ietf:wg:oauth:2.0:oob"  
                }
                $Script:Token = Get-EWSAccessToken -MailboxName $MailboxName -ClientId $ClientId -redirectUrl $redirectUrl  -ResourceURL $Resource -Prompt $Prompt -CacheCredentials   
                $OAuthCredentials = New-Object Microsoft.Exchange.WebServices.Data.OAuthCredentials((ConvertFrom-SecureStringCustom -SecureToken $Script:Token.access_token))
            }
            else {
                $OAuthCredentials = New-Object Microsoft.Exchange.WebServices.Data.OAuthCredentials($AccessToken)
            }    
            $service.Credentials = $OAuthCredentials
        }  
        #Credentials Option 1 using UPN for the windows Account  
        #$psCred = Get-Credential  
  
        #Credentials Option 2  
        #service.UseDefaultCredentials = $true  
        #$service.TraceEnabled = $true
        ## Choose to ignore any SSL Warning issues caused by Self Signed Certificates  
		  
        Invoke-HandleSSL	
		  
        ## Set the URL of the CAS (Client Access Server) to use two options are availbe to use Autodiscover to find the CAS URL or Hardcode the CAS to use  

        #CAS URL Option 1 Autodiscover  
        if ($url) {
            $uri = [system.URI] $url
            $service.Url = $uri    
        }
        else {
            $service.AutodiscoverUrl($MailboxName, { $true })  
        }
        #Write-host ("Using CAS Server : " + $Service.url)   
		   
        #CAS URL Option 2 Hardcoded  
		  
        #$uri=[system.URI] "https://casservername/ews/exchange.asmx"  
        #$service.Url = $uri    
		  
        ## Optional section for Exchange Impersonation  
		  
        #$service.ImpersonatedUserId = new-object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $MailboxName) 
        if (!$service.Url) {
            throw "Error connecting to EWS"
        }
        else {	
            $Name = $service.ResolveName($MailboxName)	
            Write-Verbose("Exchange Version " + $service.ServerInfo.MajorVersion)
            if ($service.ServerInfo.MajorVersion -ge 15) {
                $ExchangeVersion = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2013_SP1	
                if ($service.ServerInfo.MinorVersion -ge 20) {                    
                    if ([Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2016) {
                        $ExchangeVersion = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2016
                    }
                    else {
                        $ExchangeVersion = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2013_SP1
                    }   
                }
                $UpdatedService = New-Object Microsoft.Exchange.WebServices.Data.ExchangeService($ExchangeVersion)  
                $UpdatedService.Credentials = $service.Credentials
                $UpdatedService.Url = $service.Url;
                $service = $UpdatedService
                write-verbose("Update Version")
            }
            return, $service
        }
    }
}


function Invoke-LoadEWSManagedAPI {
    param( 
    )  
    Begin {
        if (Test-Path ($script:ModuleRoot + "/Microsoft.Exchange.WebServices.dll")) {
            Import-Module ($script:ModuleRoot + "/Microsoft.Exchange.WebServices.dll")
            $Script:EWSDLL = $script:ModuleRoot + "/Microsoft.Exchange.WebServices.dll"
            write-verbose ("Using EWS dll from Local Directory")
        }
        else {

        
            ## Load Managed API dll  
            ###CHECK FOR EWS MANAGED API, IF PRESENT IMPORT THE HIGHEST VERSION EWS DLL, ELSE EXIT
            $EWSDLL = (($(Get-ItemProperty -ErrorAction SilentlyContinue -Path Registry::$(Get-ChildItem -ErrorAction SilentlyContinue -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Web Services'|Sort-Object Name -Descending| Select-Object -First 1 -ExpandProperty Name)).'Install Directory') + "Microsoft.Exchange.WebServices.dll")
            if (Test-Path $EWSDLL) {
                Import-Module $EWSDLL
                $Script:EWSDLL = $EWSDLL 
            }
            else {
                "$(get-date -format yyyyMMddHHmmss):"
                "This script requires the EWS Managed API 1.2 or later."
                "Please download and install the current version of the EWS Managed API from"
                "http://go.microsoft.com/fwlink/?LinkId=255472"
                ""
                "Exiting Script."
                exit


            } 
        }
    }
}

function Invoke-HandleSSL {
    param( 
    )  
    Begin {
        ## Code From http://poshcode.org/624
        ## Create a compilation environment
        $Provider = New-Object Microsoft.CSharp.CSharpCodeProvider
        $Compiler = $Provider.CreateCompiler()
        $Params = New-Object System.CodeDom.Compiler.CompilerParameters
        $Params.GenerateExecutable = $False
        $Params.GenerateInMemory = $True
        $Params.IncludeDebugInformation = $False
        $Params.ReferencedAssemblies.Add("System.DLL") | Out-Null

        $TASource = @'
  namespace Local.ToolkitExtensions.Net.CertificatePolicy{
    public class TrustAll : System.Net.ICertificatePolicy {
      public TrustAll() { 
      }
      public bool CheckValidationResult(System.Net.ServicePoint sp,
        System.Security.Cryptography.X509Certificates.X509Certificate cert, 
        System.Net.WebRequest req, int problem) {
        return true;
      }
    }
  }
'@ 
        $TAResults = $Provider.CompileAssemblyFromSource($Params, $TASource)
        $TAAssembly = $TAResults.CompiledAssembly

        ## We now create an instance of the TrustAll and attach it to the ServicePointManager
        $TrustAll = $TAAssembly.CreateInstance("Local.ToolkitExtensions.Net.CertificatePolicy.TrustAll")
        [System.Net.ServicePointManager]::CertificatePolicy = $TrustAll

        ## end code from http://poshcode.org/624 ##

    }
}

function ConvertTo-String($ipInputString) {    
    $Val1Text = ""    
    for ($clInt = 0; $clInt -lt $ipInputString.length; $clInt++) {    
        $Val1Text = $Val1Text + [Convert]::ToString([Convert]::ToChar([Convert]::ToInt32($ipInputString.Substring($clInt, 2), 16)))    
        $clInt++    
    }    
    return $Val1Text    
}    

function Get-PinnedEmail  {
	    param( 
    	[Parameter(Position=0, Mandatory=$true)] [string]$MailboxName,
		[Parameter(Mandatory=$false)] [System.Management.Automation.PSCredential]$Credentials,
		[Parameter(Position=2, Mandatory=$false)] [switch]$useImpersonation,
		[Parameter(Position=3, Mandatory=$false)] [string]$url,
        [Parameter(Position=4, Mandatory=$false)] [string]$FolderPath,
        [Parameter(Position=5, Mandatory = $false)] [switch]$basicAuth,
        [Parameter(Position=6, Mandatory = $false)] [switch]$Archive
    )  
 	Process
	{
        if (!$basicAuth.IsPresent) {
            $service = Connect-Exchange -MailboxName $MailboxName -url $url
        }
        else {
            if (!$Credentials) {
                $Credentials = Get-Credential
            }
            $service = Connect-Exchange -MailboxName $MailboxName -url $url -basicAuth:$basicAuth.IsPresent -Credentials $Credentials
        } 
        $service.HttpHeaders.Add("X-AnchorMailbox", $MailboxName);
		if($useImpersonation.IsPresent){
			$service.ImpersonatedUserId = new-object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $MailboxName) 
        }
        $PR_RenewTime = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF01,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        $PR_RenewTime2 = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF02,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        $SfSearchFilter = new-object Microsoft.Exchange.WebServices.Data.SearchFilter+IsGreaterThanOrEqualTo($PR_RenewTime2, [DateTime]::Parse("4500-9-1"))
        $psPropset= new-object Microsoft.Exchange.WebServices.Data.PropertySet([Microsoft.Exchange.WebServices.Data.BasePropertySet]::FirstClassProperties)
        $psPropset.Add($PR_RenewTime)  
        $psPropset.Add($PR_RenewTime2)  
        
        $Folder = Get-FolderFromPath -FolderPath $FolderPath -SmtpAddress $MailboxName -service $service -archive:$Archive.IsPresent
		Write-Host ("Total Message Count : " + $Folder.TotalCount)
        $rptcnt = $true
            $ivItemView = New-Object Microsoft.Exchange.WebServices.Data.ItemView(1000)  
            $ivItemView.PropertySet = $psPropset
            $fiItems = $null
            do{ 
                $fiItems = $Folder.findItems($SfSearchFilter,$ivItemView)  
                if($rptcnt){
                    Write-Host ("Total Pinned Message Count : " + $fiItems.TotalCount)
                    $rptcnt = $false
                }
                foreach($Item in $fiItems.Items){
                     Write-Output $Item
                }
                $ivItemView.Offset += $fiItems.Items.Count    
             }while($fiItems.MoreAvailable -eq $true) 

    }
}
function Set-UnPinEmail  {
	    param( 
        [Parameter(Position=0, Mandatory=$true)] [Microsoft.Exchange.WebServices.Data.Item]$Item
    )  
 	Process
    {
        $PR_RenewTime = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF01,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        $PR_RenewTime2 = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF02,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        [void] $Item.RemoveExtendedProperty($PR_RenewTime)
        [void] $Item.RemoveExtendedProperty($PR_RenewTime2)
        $Item.Update([Microsoft.Exchange.WebServices.Data.ConflictResolutionMode]::AlwaysOverwrite)
    }
}

function Set-PinEmail  {
	    param( 
        [Parameter(Position=0, Mandatory=$true)] [Microsoft.Exchange.WebServices.Data.Item]$Item
    )  
 	Process
    {
        $PR_RenewTime = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF01,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        $PR_RenewTime2 = new-object Microsoft.Exchange.WebServices.Data.ExtendedPropertyDefinition(0xF02,[Microsoft.Exchange.WebServices.Data.MapiPropertyType]::SystemTime); 
        [void] $Item.SetExtendedProperty($PR_RenewTime,[DateTime]::Parse("4500-9-1T00:00:00Z"))
        [void] $Item.SetExtendedProperty($PR_RenewTime2,[DateTime]::Parse("4500-9-1T00:00:00Z"))
        $Item.Update([Microsoft.Exchange.WebServices.Data.ConflictResolutionMode]::AlwaysOverwrite)
    }
}

function Get-FolderFromPath{
	param (
	        [Parameter(Position=0, Mandatory=$true)] [string]$FolderPath,
			[Parameter(Position=1, Mandatory=$true)] [string]$SmtpAddress,
            [Parameter(Position=2, Mandatory=$true)] [Microsoft.Exchange.WebServices.Data.ExchangeService]$service,
            [Parameter(Position=3, Mandatory = $false)] [switch]$Archive
		  )
	process{
		## Find and Bind to Folder based on Path  
		#Define the path to search should be seperated with \  
		#Bind to the MSGFolder Root  
		$folderid = new-object Microsoft.Exchange.WebServices.Data.FolderId([Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::MsgFolderRoot,$SmtpAddress)   
        if($Archive.IsPresent){
            $folderid = new-object Microsoft.Exchange.WebServices.Data.FolderId([Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::ArchiveMsgFolderRoot,$SmtpAddress) 
        }
        $tfTargetFolder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service,$folderid)  
		#Split the Search path into an array  
		$fldArray = $FolderPath.Split("\") 
		 #Loop through the Split Array and do a Search for each level of folder 
		for ($lint = 1; $lint -lt $fldArray.Length; $lint++) { 
	        #Perform search based on the displayname of each folder level 
	        $fvFolderView = new-object Microsoft.Exchange.WebServices.Data.FolderView(1) 
	        $SfSearchFilter = new-object Microsoft.Exchange.WebServices.Data.SearchFilter+IsEqualTo([Microsoft.Exchange.WebServices.Data.FolderSchema]::DisplayName,$fldArray[$lint]) 
	        $findFolderResults = $service.FindFolders($tfTargetFolder.Id,$SfSearchFilter,$fvFolderView) 
	        if ($findFolderResults.TotalCount -gt 0){ 
	            foreach($folder in $findFolderResults.Folders){ 
	                $tfTargetFolder = $folder                
	            } 
	        } 
	        else{ 
	            Write-host ("Error Folder Not Found check path and try again")  
	            $tfTargetFolder = $null  
	            break  
	        }     
	    }  
		if($tfTargetFolder -ne $null){
			return [Microsoft.Exchange.WebServices.Data.Folder]::Bind($service,$tfTargetFolder.Id)
		}
		else{
			throw ("Folder Not found")
		}
	}
}

function Invoke-PinLastEmail  {
	    param( 
    	[Parameter(Position=0, Mandatory=$true)] [string]$MailboxName,
		[Parameter(Mandatory=$false)] [System.Management.Automation.PSCredential]$Credentials,
		[Parameter(Position=2, Mandatory=$false)] [switch]$useImpersonation,
		[Parameter(Position=3, Mandatory=$false)] [string]$url,
        [Parameter(Position=4, Mandatory=$false)] [string]$FolderPath,
        [Parameter(Position=5, Mandatory = $false)] [switch]$basicAuth,
        [Parameter(Position=6, Mandatory = $false)] [switch]$Archive

    )  
 	Process
	{
        if (!$basicAuth.IsPresent) {
            $service = Connect-Exchange -MailboxName $MailboxName -url $url
        }
        else {
            if (!$Credentials) {
                $Credentials = Get-Credential
            }
            $service = Connect-Exchange -MailboxName $MailboxName -url $url -basicAuth:$basicAuth.IsPresent -Credentials $Credentials
        } 
		if($useImpersonation.IsPresent){
			$service.ImpersonatedUserId = new-object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $MailboxName) 
        }
        
        $Folder = Get-FolderFromPath -FolderPath $FolderPath -SmtpAddress $MailboxName -service $service -archive:$Archive.IsPresent
		Write-Host ("Total Message Count : " + $Folder.TotalCount)
        $rptcnt = $true
        $ivItemView = New-Object Microsoft.Exchange.WebServices.Data.ItemView(1)  
        $fiItems = $Folder.findItems($ivItemView) 
        Set-PinEmail -Item $fiItems.items[0]
        Write-Host "Updated Message"

    }
}
function Invoke-ValidateToken {
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [Microsoft.Exchange.WebServices.Data.ExchangeService]$service
    
    )
    begin {
        $MailboxName = $Script:Token.mailbox
        $minTime = new-object DateTime(1970, 1, 1, 0, 0, 0, 0, [System.DateTimeKind]::Utc);
        $expiry = $minTime.AddSeconds($Script:Token.expires_on)
        if ($expiry -le [DateTime]::Now.ToUniversalTime().AddMinutes(10)) {
            if ([bool]($Script:Token.PSobject.Properties.name -match "refresh_token")) {
                write-host "Refresh Token"
                $Script:Token = Invoke-RefreshAccessToken -MailboxName $MailboxName -AccessToken $Script:Token
                $OAuthCredentials = New-Object Microsoft.Exchange.WebServices.Data.OAuthCredentials((ConvertFrom-SecureStringCustom -SecureToken $Script:Token.access_token))
                $service.Credentials = $OAuthCredentials
            }
            else {
                throw "App Token has expired"
            }        
        }
    }
}


function Get-EWSAccessToken {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [string]
        $MailboxName,
    
        [Parameter(Position = 1, Mandatory = $false)]
        [string]
        $ClientId,
    
        [Parameter(Position = 2, Mandatory = $false)]
        [string]
        $redirectUrl,
    
        [Parameter(Position = 3, Mandatory = $false)]
        [string]
        $ClientSecret,
    
        [Parameter(Position = 4, Mandatory = $false)]
        [string]
        $ResourceURL,
    
        [Parameter(Position = 5, Mandatory = $false)]
        [switch]
        $Beta,
    
        [Parameter(Position = 6, Mandatory = $false)]
        [String]
        $Prompt,

        [Parameter(Position = 7, Mandatory = $false)]
        [switch]
        $CacheCredentials
    
    )
    Begin {
        Add-Type -AssemblyName System.Web
        $HttpClient = Get-HTTPClient -MailboxName $MailboxName
        if ([String]::IsNullOrEmpty($ClientId)) {
            $ReturnToken = Get-ProfiledToken -MailboxName $MailboxName
            if ($ReturnToken -eq $null) {
                Write-Error ("No Access Token for " + $MailboxName)
            }
            else {				
                return $ReturnToken
            }
        }
        else {
            if ([String]::IsNullOrEmpty(($ClientSecret))) {
                $ClientSecret = $AppSetting.ClientSecret
            }
            if ([String]::IsNullOrEmpty($redirectUrl)) {
                $redirectUrl = [System.Web.HttpUtility]::UrlEncode("urn:ietf:wg:oauth:2.0:oob")
            }
            else {
                $redirectUrl = [System.Web.HttpUtility]::UrlEncode($redirectUrl)
            }
            if ([String]::IsNullOrEmpty($ResourceURL)) {
                $ResourceURL = $AppSetting.ResourceURL
            }
            if ([String]::IsNullOrEmpty($Prompt)) {
                $Prompt = "refresh_session"
            }
        
            $code = Show-OAuthWindow -Url "https://login.microsoftonline.com/common/oauth2/authorize?resource=https%3A%2F%2F$ResourceURL&client_id=$ClientId&response_type=code&redirect_uri=$redirectUrl&prompt=$Prompt&domain_hint=organizations&response_mode=form_post"
            $AuthorizationPostRequest = "resource=https%3A%2F%2F$ResourceURL&client_id=$ClientId&grant_type=authorization_code&code=$code&redirect_uri=$redirectUrl"
            if (![String]::IsNullOrEmpty($ClientSecret)) {
                $AuthorizationPostRequest = "resource=https%3A%2F%2F$ResourceURL&client_id=$ClientId&client_secret=$ClientSecret&grant_type=authorization_code&code=$code&redirect_uri=$redirectUrl"
            }
            $content = New-Object System.Net.Http.StringContent($AuthorizationPostRequest, [System.Text.Encoding]::UTF8, "application/x-www-form-urlencoded")
            $ClientReesult = $HttpClient.PostAsync([Uri]("https://login.windows.net/common/oauth2/token"), $content)
            $JsonObject = ConvertFrom-Json -InputObject $ClientReesult.Result.Content.ReadAsStringAsync().Result
            if ([bool]($JsonObject.PSobject.Properties.name -match "refresh_token")) {
                $JsonObject.refresh_token = (Get-ProtectedToken -PlainToken $JsonObject.refresh_token)
            }
            if ([bool]($JsonObject.PSobject.Properties.name -match "access_token")) {
                $JsonObject.access_token = (Get-ProtectedToken -PlainToken $JsonObject.access_token)
            }
            if ([bool]($JsonObject.PSobject.Properties.name -match "id_token")) {
                $JsonObject.id_token = (Get-ProtectedToken -PlainToken $JsonObject.id_token)
            }
            Add-Member -InputObject $JsonObject -NotePropertyName clientid -NotePropertyValue $ClientId
            Add-Member -InputObject $JsonObject -NotePropertyName redirectUrl -NotePropertyValue $redirectUrl
            Add-Member -InputObject $JsonObject -NotePropertyName mailbox -NotePropertyValue $MailboxName
            if ($Beta.IsPresent) {
                Add-Member -InputObject $JsonObject -NotePropertyName Beta -NotePropertyValue $True
            }
            return $JsonObject
        }
    }
}

function Show-OAuthWindow {
    [CmdletBinding()]
    param (
        [System.Uri]
        $Url
    
    )
    ## Start Code Attribution
    ## Show-AuthWindow function is the work of the following Authors and should remain with the function if copied into other scripts
    ## https://foxdeploy.com/2015/11/02/using-powershell-and-oauth/
    ## https://blogs.technet.microsoft.com/ronba/2016/05/09/using-powershell-and-the-office-365-rest-api-with-oauth/
    ## End Code Attribution
    Add-Type -AssemblyName System.Web
    Add-Type -AssemblyName System.Windows.Forms

    $form = New-Object -TypeName System.Windows.Forms.Form -Property @{ Width = 440; Height = 640 }
    $web = New-Object -TypeName System.Windows.Forms.WebBrowser -Property @{ Width = 420; Height = 600; Url = ($url) }
    $Navigated = {
   
        $formElements = $web.Document.GetElementsByTagName("input");  
        foreach ($element in $formElements) {
            if ($element.Name -eq "code") {
                $Script:oAuthCode = $element.GetAttribute("value");
                Write-Verbose $Script:oAuthCode
                $form.Close();
            }
        }   
    }
    
    $web.ScriptErrorsSuppressed = $true
    $web.Add_Navigated($Navigated)
    $form.Controls.Add($web)
    $form.Add_Shown( { $form.Activate() })
    $form.ShowDialog() | Out-Null
    return $Script:oAuthCode
}

function Get-ProtectedToken {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [String]
        $PlainToken
    )
    begin {
        $SecureEncryptedToken = Protect-String -String $PlainToken
        return, $SecureEncryptedToken
    }
}
function Get-HTTPClient {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [string]
        $MailboxName
    )
    process {
        Add-Type -AssemblyName System.Net.Http
        $handler = New-Object  System.Net.Http.HttpClientHandler
        $handler.CookieContainer = New-Object System.Net.CookieContainer
        $handler.AllowAutoRedirect = $true;
        $HttpClient = New-Object System.Net.Http.HttpClient($handler);
        #$HttpClient.DefaultRequestHeaders.Authorization = New-Object System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", "");
        $Header = New-Object System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json")
        $HttpClient.DefaultRequestHeaders.Accept.Add($Header);
        $HttpClient.Timeout = New-Object System.TimeSpan(0, 0, 90);
        $HttpClient.DefaultRequestHeaders.TransferEncodingChunked = $false
        if (!$HttpClient.DefaultRequestHeaders.Contains("X-AnchorMailbox")) {
            $HttpClient.DefaultRequestHeaders.Add("X-AnchorMailbox", $MailboxName);
        }
        $Header = New-Object System.Net.Http.Headers.ProductInfoHeaderValue("RestClient", "1.1")
        $HttpClient.DefaultRequestHeaders.UserAgent.Add($Header);
        return $HttpClient
    }
}

function Protect-String {
    <#
.SYNOPSIS
    Uses DPAPI to encrypt strings.

.DESCRIPTION
    Uses DPAPI to encrypt strings.

.PARAMETER String
    The string to encrypt.

.EXAMPLE
    PS C:\> Protect-String -String $secret

    Encrypts the content stored in $secret and returns it.
#>
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSAvoidUsingConvertToSecureStringWithPlainText", "")]
    [CmdletBinding()]
    Param (
        [Parameter(ValueFromPipeline = $true)]
        [string[]]
        $String
    )

    begin {
        Add-Type -AssemblyName System.Security -ErrorAction Stop
    }
    process {
        foreach ($item in $String) {
            $stringBytes = [Text.Encoding]::UTF8.GetBytes($item)
            $encodedBytes = [System.Security.Cryptography.ProtectedData]::Protect($stringBytes, $null, 'CurrentUser')
            [System.Convert]::ToBase64String($encodedBytes) | ConvertTo-SecureString -AsPlainText -Force
        }
    }
}

function Invoke-RefreshAccessToken {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [string]
        $MailboxName,
    
        [Parameter(Position = 1, Mandatory = $true)]
        [psobject]
        $AccessToken
    )
    process {
        Add-Type -AssemblyName System.Web
        $HttpClient = Get-HTTPClient -MailboxName $MailboxName
        $ClientId = $AccessToken.clientid
        # $redirectUrl = [System.Web.HttpUtility]::UrlEncode($AccessToken.redirectUrl)
        $redirectUrl = $AccessToken.redirectUrl
        $RefreshToken = (ConvertFrom-SecureStringCustom -SecureToken $AccessToken.refresh_token)
        $AuthorizationPostRequest = "client_id=$ClientId&refresh_token=$RefreshToken&grant_type=refresh_token&redirect_uri=$redirectUrl"
        $content = New-Object System.Net.Http.StringContent($AuthorizationPostRequest, [System.Text.Encoding]::UTF8, "application/x-www-form-urlencoded")
        $ClientResult = $HttpClient.PostAsync([Uri]("https://login.windows.net/common/oauth2/token"), $content)
        if (!$ClientResult.Result.IsSuccessStatusCode) {
            Write-Output ("Error making REST POST " + $ClientResult.Result.StatusCode + " : " + $ClientResult.Result.ReasonPhrase)
            Write-Output $ClientResult.Result
            if ($ClientResult.Content -ne $null) {
                Write-Output ($ClientResult.Content.ReadAsStringAsync().Result);
            }
        }
        else {
            $JsonObject = ConvertFrom-Json -InputObject $ClientResult.Result.Content.ReadAsStringAsync().Result
            if ([bool]($JsonObject.PSobject.Properties.name -match "refresh_token")) {
                $JsonObject.refresh_token = (Get-ProtectedToken -PlainToken $JsonObject.refresh_token)
            }
            if ([bool]($JsonObject.PSobject.Properties.name -match "access_token")) {
                $JsonObject.access_token = (Get-ProtectedToken -PlainToken $JsonObject.access_token)
            }
            if ([bool]($JsonObject.PSobject.Properties.name -match "id_token")) {
                $JsonObject.id_token = (Get-ProtectedToken -PlainToken $JsonObject.id_token)
            }
            Add-Member -InputObject $JsonObject -NotePropertyName clientid -NotePropertyValue $ClientId
            Add-Member -InputObject $JsonObject -NotePropertyName redirectUrl -NotePropertyValue $redirectUrl
            Add-Member -InputObject $JsonObject -NotePropertyName mailbox -NotePropertyValue $MailboxName
            if ($AccessToken.Beta) {
                Add-Member -InputObject $JsonObject -NotePropertyName Beta -NotePropertyValue True
            }
        }
        return $JsonObject		
    }
}

function ConvertFrom-SecureStringCustom {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [System.Security.SecureString]
        $SecureToken
    )
    process {
        #$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($SecureToken)
        $Token = Unprotect-String -String $SecureToken
        return, $Token
    }
}

function Unprotect-String {
    <#
.SYNOPSIS
    Uses DPAPI to decrypt strings.

.DESCRIPTION
    Uses DPAPI to decrypt strings.
    Designed to reverse encryption applied by Protect-String

.PARAMETER String
    The string to decrypt.

.EXAMPLE
    PS C:\> Unprotect-String -String $secret

    Decrypts the content stored in $secret and returns it.
#>
    [CmdletBinding()]
    Param (
        [Parameter(ValueFromPipeline = $true)]
        [System.Security.SecureString[]]
        $String
    )

    begin {
        Add-Type -AssemblyName System.Security -ErrorAction Stop
    }
    process {
        foreach ($item in $String) {
            $cred = New-Object PSCredential("irrelevant", $item)
            $stringBytes = [System.Convert]::FromBase64String($cred.GetNetworkCredential().Password)
            $decodedBytes = [System.Security.Cryptography.ProtectedData]::Unprotect($stringBytes, $null, 'CurrentUser')
            [Text.Encoding]::UTF8.GetString($decodedBytes)
        }
    }
}
$Script:EWSDLL = ""
$Script:Token = $null
$Script:MaxCount = 0
$Script:UseMaxCount = $false
$Script:MaxCountExceeded = $false
$script:ModuleRoot = $PSScriptRoot