Outlook und Exchange - wie perfekten Termin in den nächsten 30 Tagen finden?

# FQDN des Exchange Servers
$EXCHANGESERVER = 'ex.domain.tld'  
# Array der teilnehmenden User
$users = 'maxmuster@domain.tld','annamusterfrau@domain.tld'  
# Startzeit des Meetings
$starttime = [datetime]'11:00:00'  
# Dauer des Meetings
$duration = 60
# zu checkende Tage im Voraus
$daysinadvance = 30

if ($PSVersionTable.PSVersion.Major -lt 3){write-host "ERROR: Minimum Powershell Version 3.0 is required!" -F Yellow; return}  

# Funktion zum Verbinden mit dem Exchange EWS Dienst
function ConnectTo-EWS {
    param(
        [parameter(mandatory=$false)][bool]$UseScriptCredentials = $true,
        [parameter(mandatory=$false)][pscredential]$Credential,
        [parameter(mandatory=$false)][ValidateScript({Test-Path $_})][string]$ewsdll = "$psscriptroot\Microsoft.Exchange.WebServices.dll",  
        [parameter(mandatory=$false)][string]$mailbox = $null,
        [parameter(mandatory=$true)][string]$server
    )

    # Allen Zertifikaten vertrauen
    try{
        Add-Type '  
            using System.Net;
            using System.Security.Cryptography.X509Certificates;
            public class TrustAllCertsPolicy : ICertificatePolicy {
                public bool CheckValidationResult(
                    ServicePoint srvPoint, X509Certificate certificate,
                    WebRequest request, int certificateProblem) {
                    return true;
                }
            }
        '  
        # Trust all certs policy dem ServicePointManager zuweisen
        [System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy
    }catch{}

    # EWS DLL laden
    Add-Type -Path $ewsdll

    # EWS-Service Objekt erstellen
    $ews = new-object Microsoft.Exchange.WebServices.Data.ExchangeService([Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010)
    $ews.Url = "https://$server/ews/exchange.asmx"  
    $ews.UseDefaultCredentials = $UseScriptCredentials
    if (!$UseScriptCredentials){
        $ews.Credentials = $Credential.GetNetworkCredential()
    }
    if($mailbox){
        $ews.ImpersonatedUserId = New-Object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $mailbox)
    }
    return $ews
}


# Mit Service verbinden
$svc = ConnectTo-EWS -Server $EXCHANGESERVER
# collection für Teilnehmer erstellen
[Microsoft.Exchange.WebServices.Data.AttendeeInfo[]]$attendees = new-object "System.Collections.Generic.List[Microsoft.Exchange.WebServices.Data.AttendeeInfo]"  
# Teilnehmer der Collection hinzufügen
$users | %{
    $a = new-object Microsoft.Exchange.WebServices.Data.AttendeeInfo
    $a.SmtpAddress = $_
    $a.AttendeeType = [Microsoft.Exchange.WebServices.Data.MeetingAttendeeType]::Required
    $attendees += $a
}
# Availability Options festlegen
[Microsoft.Exchange.WebServices.Data.AvailabilityOptions]$options = New-Object Microsoft.Exchange.WebServices.Data.AvailabilityOptions
$options.GoodSuggestionThreshold = 49
$options.MaximumNonWorkHoursSuggestionsPerDay = 0
$options.MaximumSuggestionsPerDay = 24
$options.MeetingDuration = $duration
$options.MinimumSuggestionQuality = [Microsoft.Exchange.WebServices.Data.SuggestionQuality]::Good
$options.DetailedSuggestionsWindow = New-Object Microsoft.Exchange.WebServices.Data.TimeWindow((get-date),(get-date).AddDays($daysinadvance))
$options.CurrentMeetingTime = $starttime
$options.RequestedFreeBusyView = [Microsoft.Exchange.WebServices.Data.FreeBusyViewType]::FreeBusy

# FreeBusy mit den Optionen abfragen
$result = $svc.GetUserAvailability($attendees,$options.DetailedSuggestionsWindow,[Microsoft.Exchange.WebServices.Data.AvailabilityData]::FreeBusyAndSuggestions,$options)
# Vorschläge ausfiltern
$suggestions = $result.Suggestions.TimeSuggestions | ?{($_.Quality -eq 'Excellent' -or (($_.Conflicts.FreeBusyStatus | ?{$_ -eq 'Free'}).Count -ge $users.Count-1)) -and $_.MeetingTime.toString('HHmm') -eq $starttime.toString('HHmm') -and $_.MeetingTime.DayOfWeek -in 1..5}  | sort MeetingTime | select MeetingTime,@{n='Konflikte';e={($_.Conflicts.FreeBusyStatus | ?{$_ -ne 'Free'}).Count}}  
# und darstellen
$suggestions | ft -AutoSize