internal/functions/oauth/Invoke-RefreshAccessToken.ps1

function Invoke-RefreshAccessToken {
    [CmdletBinding()]
    param (
        [Parameter(Position = 0, Mandatory = $true)]
        [string]
        $MailboxName,
        
        [Parameter(Position = 1, Mandatory = $true)]
        [psobject]
        $AccessToken,

        [Parameter(Position = 2, Mandatory = $false)]
        [string]
        $ResourceURL,
        
        [Parameter(Position = 3, Mandatory = $false)]
        [switch]
        $ucwa
    )
    process {
        Add-Type -AssemblyName System.Web
        $HttpClient = Get-HTTPClient -MailboxName $MailboxName
        $ClientId = $AccessToken.clientid
        # $redirectUrl = [System.Web.HttpUtility]::UrlEncode($AccessToken.redirectUrl)
        $redirectUrl = $AccessToken.redirectUrl
        $Cached = $AccessToken.Cached
        $RefreshToken = (ConvertFrom-SecureStringCustom -SecureToken $AccessToken.refresh_token)
        $AuthorizationPostRequest = "client_id=$ClientId&refresh_token=$RefreshToken&grant_type=refresh_token&redirect_uri=$redirectUrl"
        if ($ResourceURL) {
            $AuthorizationPostRequest = "resource=https%3A%2F%2F$ResourceURL&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 $JsonObject -NotePropertyName Beta -NotePropertyValue True
            }
            if ($Cached) {
                Add-Member -InputObject $JsonObject -NotePropertyName Cached -NotePropertyValue $true
                $HostDomain = (New-Object system.net.Mail.MailAddress($MailboxName)).Host.ToLower()
                $resourceURI = [URI]$JsonObject.resource
                $resource = $resourceURI.Host
                if ($ucwa.IsPresent) {
                    $Script:SK4BToken = $JsonObject
                }
                else {
                    if (!$Script:TokenCache[$resource].ContainsKey($HostDomain)) {            
                        $Script:TokenCache[$resource].Add($HostDomain, $JsonObject)
                    }
                    else {
                        $Script:TokenCache[$resource][$HostDomain] = $JsonObject
                    }
                }
                write-host ("Cached Token for " + $HostDomain)
            }

        }
        return $JsonObject        
    }
}