ExchangeDsc

2.0.0-preview0001

DSCResources/DSC_ExchMaintenanceMode/TransportMaintenance.psm1

#region Globals from all three scripts
# Service Names
$TransportServiceName = 'MsExchangeTransport'
$MessageTracing = 'MSMessageTracingClient'
$EdgeSync = 'MsExchangeEdgeSync'
$Script:OriginalPref = $ErrorActionPreference

$Script:ExchangeServer = $null
$Script:TransportService = $null
$Script:HubTransport = $null
$Script:Entered = $false

$Component = 'HubTransport'
$Requester = 'Maintenance'

$Target = $env:COMPUTERNAME

$Script:LogFileName = $null
$Script:TransportMaintenanceLogPrefix = 'TransportMaintenance'
$Script:TransportMaintenanceLogNameFormat = '{0}\TransportMaintenance-{1}-{2}.log'
$Script:ServerInMM = 'ServerInMM'
$Script:AllotedTimeExceeded = 'AllotedTimeExceeded'
$Script:NoProgressTimeout = 'NoProgressTimeout'
$Script:UnredirectedMessageEventId = 100
$Script:UndrainedDiscardEventEventId = 101
$Script:MaxWaitForOtherWorkflow = New-TimeSpan -Minutes 30
$Script:TransportMaintenanceSync = $null
$Script:ExchangeVersion = ''

$ServiceState = $null
#endregion

#region New Code or Wrappers

<#
    .SYNOPSIS
        Begin maintenance script for HUB components.
 
    .PARAMETER Target
        The name of the machine being put into maintenance.
#>
function Start-TransportMaintenance
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    [CmdletBinding()]
    param
    (
        [Parameter()]
        [System.String]
        $Target = $env:COMPUTERNAME,

        [Parameter()]
        [Switch]
        $ExcludeLocalSiteFromMessageRedirect,

        [Parameter()]
        [System.Boolean]
        $LoadLocalShell = $false,

        [Parameter()]
        [System.String[]]
        $MessageRedirectExclusions
    )

    if ($LoadLocalShell -eq $true)
    {
        Add-ExchangeSnapin
    }

    $Script:LogInfo = @{
        Target = $Target
    }

    try
    {
        Write-Verbose -Message "Starting non-fatal Transport maintenance tasks for '$Target' on $($env:ComputerName)"
        if (-not (Initialize-TransportMaintenance -Target $Target))
        {
            return
        }

        # Log the BeginTM/start event
        $beginTMLog = New-LogEntry -Source $Target -Stage BeginTM
        Write-EventOfEntry -Event Start -Entry $beginTMLog -Reason $Script:LogInfo

        Invoke-RemoteMaintenance -Target $Target -MessageRedirectExclusions $MessageRedirectExclusions -ExcludeLocalSiteFromMessageRedirect:$ExcludeLocalSiteFromMessageRedirect

    }
    catch
    {
        Write-Warning -Message "At least one non-fatal tasked failed. Ignoring and continuing deployment. Error was $_"
    }
    finally
    {
        Remove-ExchangeSnapin

        if ($beginTMLog)
        {
            Write-EventOfEntry -Event Completed -Entry $beginTMLog -Reason $Script:LogInfo
        }
    }
}

<#
    .SYNOPSIS
        Performs End Maintenance of HubTransport
 
    .PARAMETER LoadLocalShell
        Whether the Exchange snapin should be loaded. Defaults to False.
#>
function Stop-TransportMaintenance
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseDeclaredVarsMoreThanAssignments", "")]
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    [CmdletBinding()]
    param
    (
        [Parameter()]
        [System.Boolean]
        $LoadLocalShell = $false
    )

    if ($LoadLocalShell -eq $true)
    {
        Add-ExchangeSnapin
    }

    $ServiceState = 'Online'

    Start-HUBEndMaintenance

    Remove-ExchangeSnapin
}

<#
    .SYNOPSIS
        Adds the Exchange PowerShell snapin if it hasn't already been loaded.
#>
function Add-ExchangeSnapin
{
    if ($null -eq (Get-PSSnapin -Name 'Microsoft.Exchange.Management.PowerShell.E2010' -ErrorAction SilentlyContinue))
    {
        Add-PSSnapin -Name 'Microsoft.Exchange.Management.PowerShell.E2010' -ErrorAction SilentlyContinue
    }
}

<#
    .SYNOPSIS
        Removes the Exchange PowerShell snapin if it is loaded.
#>
function Remove-ExchangeSnapin
{
    if ($null -ne (Get-PSSnapin -Name 'Microsoft.Exchange.Management.PowerShell.E2010' -ErrorAction SilentlyContinue))
    {
        Remove-PSSnapin -Name 'Microsoft.Exchange.Management.PowerShell.E2010' -ErrorAction SilentlyContinue
    }
}
#endregion

#region From TransportBeginMaintenance.ps1
# .DESCRIPTION
# Initializes logging, validates if the current server
#
# .PARAMETER Target
# Target server for the operation.
#
# .RETURN
# True if the initialization is successful and caller should continue the MM process.
# Else, returns false and caller should NOT continue with the MM.
function Initialize-TransportMaintenance
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Target
    )

    $ErrorActionPreference = 'Stop'
    $Error.Clear()

    Initialize-TransportMaintenanceLog -Server $Target

    $Script:ExchangeServer = Get-ExchangeServer $Target
    if (-not $Script:ExchangeServer)
    {
        Write-Verbose -Message "$Target is not an exchange server"

        $Script:LogInfo.Add('ExchangeServer', 'False')
        Write-SkippedEvent -Source $Target -Stage BeginTM -Reason $Script:LogInfo

        return $false
    }

    $Script:TransportService = Get-Service `
        -ComputerName $Script:ExchangeServer.Fqdn `
        -Name $TransportServiceName `
        -ErrorAction SilentlyContinue

    if (-not $Script:TransportService)
    {
        Write-Verbose -Message "MSExchangeTransport service is not found on $Target"

        $Script:LogInfo.Add($TransportServiceName, 'NotFound')
        Write-SkippedEvent -Source $Target -Stage BeginTM -Reason $Script:LogInfo

        return $false
    }

    $Script:HubTransport = Get-ComponentState -Server $Target
    if (-not $Script:HubTransport)
    {
        Write-Verbose -Message "Unable to find HubTransport's ServerComponentState from $($env:ComputerName) for $Target."

        $Script:LogInfo.Add('HubTransport', 'NotFound')
        Write-SkippedEvent -Source $Target -Stage BeginTM -Reason $Script:LogInfo

        return $false
    }

    $Script:Entered = $true
    return $true
}

# .DESCRIPTION
# Fully drains the Transport and put HubTransport component state to Inactive
#
# .PARAMETER Target
# Target server for the operation.
#
# .RETURN
# None
function Invoke-FullyDrainTransport
{
    param
    (
        [Parameter()]
        [System.String]
        $Target = $env:COMPUTERNAME,

        [Parameter()]
        [switch]
        $ExcludeLocalSiteFromMessageRedirect,

        [Parameter()]
        [System.String[]]
        $MessageRedirectExclusions
    )

    # drain active messages
    Clear-ActiveMessage -Server $Target -TransportService $script:TransportService

    # redirect the remaining messages
    $activeServers = Send-MessagesToNewServer -Server $Target -MessageRedirectExclusions $MessageRedirectExclusions -ExcludeLocalSite:$ExcludeLocalSiteFromMessageRedirect

    # Drain the discard events
    if ($activeServers)
    {
        Clear-DiscardEvent -Primary $Target -ShadowServers $activeServers | Out-Null
    }
    else
    {
        Write-Verbose -Message 'Unable to find other active servers in this DAG. Skip draining of discard event.'
    }

    Write-Verbose -Message 'Setting HubTransport component state to Inactive'
    Set-ComponentState -Server $Target -State Inactive
    Write-InfoEvent -Source $Target -Stage RestartTransport -Reason @{
        ComponentState = 'Inactive'
    }
}

# .DESCRIPTION
# Perform the Remote Maintenance stage
#
# .PARAMETER Target
# Target server for the operation.
#
function Invoke-RemoteMaintenance
{
    param
    (
        [Parameter()]
        [System.String]
        $Target = $env:COMPUTERNAME,

        [Parameter()]
        [switch]
        $ExcludeLocalSiteFromMessageRedirect,

        [Parameter()]
        [System.String[]]
        $MessageRedirectExclusions
    )

    if (($Script:TransportService.Status -ne 'Running') -or `
        ($Script:HubTransport.State -ne 'Active'))
    {
        $Script:LogInfo.Add('MsExchangeTransport', $Script:TransportService.Status)
        $Script:LogInfo.Add('HubTransport', $Script:HubTransport.State)
        $Script:LogInfo.Add('Reason', 'Skipped')
    }
    else
    {
        Invoke-FullyDrainTransport -Target $Target -MessageRedirectExclusions $MessageRedirectExclusions -ExcludeLocalSiteFromMessageRedirect:$ExcludeLocalSiteFromMessageRedirect
    }
}


#endregion

#region From TransportEndMaintenance.ps1
# Main entry point for the script.
function Start-HUBEndMaintenance
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param ()

    $reasons = @{
        ServiceState = $ServiceState
    }
    try
    {
        Initialize-TransportMaintenanceLog -Server $Target

        $TransportService = Get-Service $TransportServiceName -errorAction silentlyContinue
        if (-not $TransportService)
        {
            Write-Verbose -Message 'MSExchangeTransport service is not found'

            $reasons.Add('MsExchangeTransport', 'NotFound')
            Write-SkippedEvent -Source $Target -Stage EndTM -Reason $reasons
            return;
        }

        $endMMLog = New-LogEntry -Source $Target -Stage EndTM

        Write-EventOfEntry -Event Start -Entry $endMMLog -Reason $reasons

        if ($ServiceState -eq 'Online')
        {
            Set-TransportActive
            return
        }

        # All other parameter combinations indicate 'Inactive' state.
        Set-TransportInactive
    }
    finally
    {
        if ($endMMLog)
        {
            Write-EventOfEntry -Event Completed -Entry $endMMLog -Reason $reasons
        }
    }
}

# checks and enable the submission queue if needed. This should be successful in
# the first iteration. However, we allow the service to have up to 5 minutes to return
# the submission queue.
function Enable-SubmissionQueue
{
    param
    (
        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5)
    )

    $endTime = (Get-Date) + $Timeout
    $submissionQName = $env:COMPUTERNAME + '\Submission'

    while ($true)
    {
        $submissionQ = Get-Queue $submissionQName -ErrorAction 'SilentlyContinue'
        if ($submissionQ)
        {
            if ($submissionQ.Status -eq 'Suspended')
            {
                try
                {
                    Resume-Queue $submissionQName -confirm:$false
                    Write-InfoEvent -source $env:COMPUTERNAME -stage SubmissionQueueCheck -Reason @{
                        EnableSubmissionQueue = 'Succeeded'
                    }
                    return $true
                }
                catch
                {
                    Write-InfoEvent -source $env:COMPUTERNAME -stage SubmissionQueueCheck -Reason @{
                        EnableSubmissionQueue = 'Failed'
                    }
                    return $false
                }
            }

            Write-SkippedEvent -source $env:COMPUTERNAME -stage SubmissionQueueCheck -Reason @{
                EnableSubmissionQueue = $submissionQ.Status
            }
            return $true
        }

        if ((Get-Date) -gt $endTime)
        {
            Write-InfoEvent -source $env:COMPUTERNAME -stage SubmissionQueueCheck -Reason @{
                EnableSubmissionQueue = 'QueueNotFound'
            }
            return $false
        }
        else
        {
            Start-Sleep -Seconds $PollingFrequency.Seconds
        }
    }
}

# Sets the Transport Component State to 'Active' and starts the appropriate services.
function Set-TransportActive
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param ()

    Write-Output 'Enter [Set-TransportActive]'

    $currentServerComponentState = Get-ServerComponentState -Identity $env:COMPUTERNAME -Component $Component
    $transportService = Get-CimInstance -ClassName win32_service -filter "name = 'MSExchangeTransport'"

    if ($currentServerComponentState.State -eq 'Active' `
            -and $null -ne $transportService `
            -and $transportService.StartMode -eq 'Auto' `
            -and $transportService.State -eq 'Running')
    {
        Write-SkippedEvent -Source $env:COMPUTERNAME -Stage StartTransport -Reason @{
            ComponentState = 'Active'
        }
    }
    else
    {
        # Set component state to 'Active'
        Set-ComponentState -Component $Component -State 'Active' -Requester $Requester | Out-Null

        # Restart transport
        Set-ServiceState -ServiceName $TransportServiceName -State 'Stopped' -LoggingStage StopTransport -StartMode 'Auto' -ThrowOnFailure
        Set-ServiceState -ServiceName $TransportServiceName -State 'Running' -LoggingStage StartTransport -ThrowOnFailure
    }

    # Enable the submission queue if needed. In case of failure, we will have to put
    # the service back to inactive
    if (-not (Enable-SubmissionQueue))
    {
        Set-TransportInactive
        return
    }

    # Set MSExchangeEdgeSync service start mode to Auto and restart.
    Set-ServiceState -ServiceName $EdgeSync -State 'Stopped' -LoggingStage StopEdgeSync -StartMode 'Auto'
    Set-ServiceState -ServiceName $EdgeSync -State 'Running' -LoggingStage StartEdgeSync

    # Do not change the start mode for MSMessageTracingClient
    # MSMessageTracingClient service is disabled in some test topologies
    # so only start the service, if it is NOT Disabled.
    Set-ServiceState -ServiceName $MessageTracing -State 'Running' -LoggingStage StartMessageTrace

    Write-Output 'Exit [Set-TransportActive]'
}

# Sets the Transport Component State to 'Inactive' and starts the appropriate services.
function Set-TransportInactive
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param ()

    Write-Output 'Enter [Set-TransportInactive]'

    $currentServerComponentState = Get-ServerComponentState -Identity $env:COMPUTERNAME -Component $Component
    $transportService = Get-CimInstance -ClassName win32_service -filter "name = 'MSExchangeTransport'"

    if ($currentServerComponentState.State -eq 'Inactive' `
            -and $null -ne $transportService `
            -and $transportService.StartMode -eq 'Auto' `
            -and $transportService.State -eq 'Running')
    {
        Write-SkippedEvent -Source $env:COMPUTERNAME -Stage StartTransport -Reason @{
            ComponentState = 'Inactive'
        }
    }
    else
    {
        # Set component state to 'Inactive'
        Set-ComponentState -Component $Component -State 'Inactive' -Requester $Requester | Out-Null
        Set-ServiceState -ServiceName $TransportServiceName -State 'Running' -LoggingStage StopTransport -StartMode 'Auto' -ThrowOnFailure
    }

    Write-Output 'Exit [Set-TransportInactive]'
}
#endregion

#region From DatacenterDeploymentTransportLibrary.ps1

# .DESCRIPTION
# Get servers in the dag that contains the specified server
#
# .PARAMETER server
# Server whose dag's members is retrieving.
#
# .PARAMETER ExcludeLocalSite
# Whether to exclude the servers on the same site
#
# .RETURN
# array of servers in the dag.
#
function Get-ServersInDag
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $server,

        [Parameter(Mandatory = $true)]
        [Switch]
        $ExcludeLocalSite,

        [Parameter()]
        [System.String[]]
        $AdditionalExclusions
    )

    Write-Verbose -Message "$server - Retrieving the DAG for the target server"
    $exchangeServer = (Get-ExchangeServer $server)
    if ($null -eq $exchangeServer)
    {
        Write-Warning -Message 'Could not get the exchange server. Skipping redirect.'
        return $null
    }

    if ($exchangeServer.IsMailboxServer -eq $false)
    {
        Write-Warning -Message 'Could not find the mailbox server. Skipping redirect.'
        return $null
    }

    $dag = (Get-MailboxServer $server).DatabaseAvailabilityGroup
    if ($null -eq $dag)
    {
        Write-Warning -Message 'Could not find the DAG for the target server. Skipping redirect.'
        return $null
    }

    Write-Verbose -Message "$server - Retrieving other hub transport servers in the DAG - $dag"

    $dagServers = @((Get-DatabaseAvailabilityGroup $dag).Servers | ForEach-Object {
            if ($null -ne $_.Name)
            {
                $_.Name
            }
            else
            {
                $_
            }
        } | Where-Object { $_ -ne $server })

    if ($null -ne $dagServers)
    {
        # Filter out servers who are in the local site, if $ExcludeLocalSite
        if ($ExcludeLocalSite)
        {
            for ($i = $dagServers.Count - 1; $i -ge 0; $i--)
            {
                $dagServerProps = $null
                $dagServerProps = Get-ExchangeServer $dagServers[$i]

                if ($null -ne $dagServerProps -and $dagServerProps.Site -eq $exchangeServer.Site)
                {
                    $dagServers = $dagServers | Where-Object { $_ -ne $dagServers[$i] }
                }
            }
        }

        # Filter out additional exclusions
        if ($null -ne $AdditionalExclusions)
        {
            foreach ($exclusion in $AdditionalExclusions)
            {
                $dagServers = $dagServers | Where-Object { $_ -notlike $exclusion }
            }
        }
    }

    if (-not $dagServers)
    {
        Write-Warning -Message 'Could not find servers in the DAG that do not meeting exclusion criteria.'
    }

    return $dagServers
}

# .DESCRIPTION
# Selects the active servers from the specified array of servers.
# Active servers are those that have EdgeTransport running.
#
# .PARAMETER $Servers
# Array of servers
#
# .RETURN
# Array of active servers
function Get-ActiveServer
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String[]]
        $Servers
    )

    $activeServers = $Servers |
        Where-Object { (Get-ServerComponentState -Identity $_ -Component HubTransport).State -eq 'Active' } |
        ForEach-Object {
            $xml = [xml] (Get-ExchangeDiagnosticInfo -Process 'EdgeTransport' -server $_ -ErrorAction SilentlyContinue)

            if ($xml -and $xml.Diagnostics.ProcessInfo)
            {
                Write-Output $_
            }
        }

    return $activeServers
}

# .DESCRIPTION
# Get version for exchange installed on the server
#
# .PARAMETER server
# Server whose version is being retrieved.
#
# .RETURN
# version string.
#
function Get-ExchangeVersion
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $server
    )

    Write-Verbose -Message "$server - Retrieving version for the target server"

    $serverVersion = (Get-ExchangeServer $server).AdminDisplayVersion

    if ($null -eq $serverVersion)
    {
        Write-Warning -Message 'Could not find exchange version.'
        return $null
    }

    $versionString = [System.String]::Format('{0}.{1}.{2}.{3}', `
            $serverVersion.Major.ToString('D2'), `
            $serverVersion.Minor.ToString('D2'), `
            $serverVersion.Build.ToString('D4'), `
            $serverVersion.Revision.ToString('D3'))
    return $versionString
}

# .DESCRIPTION
# Get the list of files that are in the Maintenance Log folder
#
# .PARAMETER $TransportService
# Transport Service object retrieved from Get-TransportService of the current server
# This object holds configuration and size limits of the Maintenance Log folder
#
# .PARAMETER $LogPath
# The path to the log folder adjusted for remote logging.
#
# .RETURN
# Array of file objects of files that are in the Maintenance Log folder
function Get-TransportMaintenanceLogFileList()
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Object]
        $TransportService,

        [Parameter(Mandatory = $true)]
        [System.String]
        $LogPath
    )

    $logFilesMatch = '{0}\{1}*.log' -f $LogPath, $Script:TransportMaintenanceLogPrefix
    return @(Get-Item $logFilesMatch -ErrorAction SilentlyContinue)
}

# .DESCRIPTION
# Ensures the current Maintenance log file stay within the limit specified in the TransportService object.
# Creates and initializes the log file to be ready for accepting logs.
#
# .PARAMETER $LogPath
# The path to the log folder adjusted for remote logging.
#
# .PARAMETER $TransportService
# Transport Service object retrieved from Get-TransportService of the current server
# This object holds configuration and size limits of the Maintenance Log folder
function Register-TransportMaintenanceLog
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Object]
        $TransportService,

        [Parameter(Mandatory = $true)]
        [System.String]
        $LogPath
    )

    $maxFileSize = $TransportService.TransportMaintenanceLogMaxFileSize.Value.ToBytes()

    if ($Script:LogFileName -and $Script:LogStream)
    {
        if ((Get-Item $Script:LogFileName).Length -lt $maxFileSize)
        {
            return
        }
        else
        {
            $Script:LogFileName = $null
            $newestLog = $null
        }
    }
    else
    {
        $newestLog = Get-TransportMaintenanceLogFileList -TransportService $TransportService -LogPath $LogPath |
            Sort-Object LastWriteTime -Descending |
            Select-Object -First 1
    }

    if (-not $newestLog -or $newestLog.Length -ge $maxFileSize)
    {
        $instance = 0
        while ($true)
        {
            $newLogFileName = $Script:TransportMaintenanceLogNameFormat -f `
                $LogPath, `
                [System.DateTime]::Now.ToString('yyyyMMdd'), $instance

            $existedLogFile = Get-Item -Path $newLogFileName -ErrorAction SilentlyContinue
            if (-not $existedLogFile)
            {
                break;
            }
            $instance++
        }
    }
    else
    {
        $newLogFileName = $newestLog.FullName
    }

    $Script:LogFileName = $newLogFileName
}

# .DESCRIPTION
# Removes old log files from the Maintenance Log directory to stay within the age limit specified
# in the TransportService object
#
# .PARAMETER $LogPath
# The path to the log folder adjusted for remote logging.
#
# .PARAMETER $TransportService
# Transport Service object retrieved from Get-TransportService of the current server
# This object holds configuration and size limits of the Maintenance Log folder
function Remove-TransportMaintenanceLogsOverMaxAge
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Object]
        $TransportService,

        [Parameter(Mandatory = $true)]
        [System.String]
        $LogPath
    )

    $maxLogAge = [TimeSpan] $TransportService.TransportMaintenanceLogMaxAge
    [DateTime] $rolloutTime = (Get-Date) - $maxLogAge

    Get-TransportMaintenanceLogFileList -TransportService $TransportService -LogPath $LogPath |
        Where-Object { $_.LastWriteTime -lt $rolloutTime } |
        ForEach-Object { Remove-Item -Path $_.FullName }
}

# .DESCRIPTION
# Removes old log files from the Maintenance Log directory to stay within total size limit specified
# in the TransportService object
#
# .PARAMETER $LogPath
# The path to the log folder adjusted for remote logging.
#
# .PARAMETER $TransportService
# Transport Service object retrieved from Get-TransportService of the current server
# This object holds configuration and size limits of the Maintenance Log folder
function Remove-TransportMaintenanceLogsOverMaxDirectorySize
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Object]
        $TransportService,

        [Parameter(Mandatory = $true)]
        [System.String]
        $LogPath
    )

    $maxDirectorySize = $TransportService.TransportMaintenanceLogMaxDirectorySize.Value.ToBytes()
    $maxFileSize = $TransportService.TransportMaintenanceLogMaxFileSize.Value.ToBytes()

    $files = Get-TransportMaintenanceLogFileList -TransportService $TransportService -LogPath $LogPath | Sort-Object LastWriteTime
    $directorySize = $files | Measure-Object Length -Sum | ForEach-Object { $_.Sum }

    $i = 0
    $desiredSize = $maxDirectorySize - $maxFileSize
    while ($directorySize -ge $desiredSize)
    {
        try
        {
            if ($files[$i].FullName -ne $Script:LogFileName)
            {
                $directorySize -= $files[$i].Length
                Remove-Item -Path $files[$i].FullName
                $i++
            }
        }
        catch
        {
            continue
        }
    }
}

# .DESCRIPTION
# Get the adjusted logging path for remote or local logging.
#
# .PARAMETER $TransportService
# Transport Service object retrieved from Get-TransportService of the current server
# This object holds configuration and size limits of the Maintenance Log folder
#
# .PARAMETER $Server
# Server name of the log folder
#
# .RETURN
# The path to the log folder adjusted for remote or local logging depending on the specified $Server.
function Get-MaintenanceLogPath
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Object]
        $TransportService,

        [Parameter()]
        [System.String]
        $Server = $env:ComputerName
    )

    if (-not $TransportService.TransportMaintenanceLogPath)
    {
        $logPath = Join-Path (Split-Path ($TransportService.QueueLogPath) -Parent) 'TransportMaintenance'
    }
    else
    {
        $logPath = $TransportService.TransportMaintenanceLogPath.PathName
    }

    if ($server -eq $env:ComputerName)
    {
        return $logPath
    }

    $drive = [IO.Path]::GetPathRoot($logPath)
    $share = Get-CimInstance -ClassName Win32_Share -ComputerName $server -Filter "Path = '$drive\'" -ErrorAction SilentlyContinue
    if ($share)
    {
        $remotePath = '\\{0}\{1}\{2}' -f `
            $server, `
            $share.Name, `
            $logPath.SubString($drive.Length)
        return $remotePath
    }
    else
    {
        return $logPath
    }
}

# .DESCRIPTION
# Initializes the Maintenance Log and ensures the log directory conforms with limits
# set in Transport Service. This function must be called by Begin/End MM script before
# performing any MM tasks to ensure log file is created properly.
#
# .PARAMETER Server
# Name of Server to write the maintenance log to
function Initialize-TransportMaintenanceLog()
{
    param
    (
        [Parameter()]
        [System.String]
        $Server = $env:ComputerName
    )

    # read MM log limits
    $transportService = Get-TransportService -Identity $Server

    # only configure the logging if we have the setting from Transport Service
    $hasMaintenanceSettings = $transportService.PsObject.Properties.Match('TransportMaintenance*')
    if ($hasMaintenanceSettings.Count -gt 0)
    {
        if (-not $transportService.TransportMaintenanceLogEnabled)
        {
            $Script:LogFileName = $null
            return
        }

        $logPath = Get-MaintenanceLogPath -Server $Server -TransportService $transportService

        if (Test-Path $logPath)
        {
            Remove-TransportMaintenanceLogsOverMaxAge -TransportService $transportService -LogPath $logPath
            Remove-TransportMaintenanceLogsOverMaxDirectorySize -TransportService $transportService -LogPath $logPath
        }
        else
        {
            try
            {
                New-Item $logPath -Item Directory -ErrorAction Stop | Out-Null
            }
            catch
            {
                Write-Verbose -Message $_.Exception.Message
                $Script:LogFileName = $null
                return
            }
        }

        $Script:ExchangeVersion = Get-ExchangeVersion $Server
        Register-TransportMaintenanceLog -TransportService $transportService -LogPath $logPath
    }
}

# .DESCRIPTION
# Change the running state of a service
#
# .PARAMETER $ServiceName
# Name of the service to change the state of
#
# .PARAMETER $Server
# Server where the service is running on
#
# .PARAMETER $State
# New state of the service, can be Stopped, Running, Paused, or NoChange
#
# .PARAMETER $StartMode
# Change the startMode if necessary before changing its running state
#
# .PARAMETER $WaitTime
# Maximum wait time for the service to change its state
#
# .PARAMETER $LoggingStage
# If provide, a log entry is added to MM log on start and complete of the state change
#
# .PARAMETER $ThrowOnFailure
# Whether to throw on failures
#
# .RETURN
# True if successful, false otherwise.
function Set-ServiceState
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $ServiceName,

        [Parameter()]
        [System.String]
        $Server = $env:COMPUTERNAME,

        [Parameter()]
        [ValidateSet('NoChange', 'Stopped', 'Running', 'Paused')]
        [System.String]
        $State = 'NoChange',

        [Parameter()]
        [ValidateSet('NoChange', 'Auto', 'Automatic', 'Manual', 'Disabled')]
        [System.String]
        $StartMode = 'NoChange',

        [Parameter()]
        [TimeSpan]
        $WaitTime = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [System.String]
        $LoggingStage,

        [Parameter()]
        [Switch]
        $ThrowOnFailure
    )

    $service = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue

    if (-not $service)
    {
        if ($LoggingStage)
        {
            Write-SkippedEvent -Source $Server -Stage $LoggingStage -Reason @{
                $ServiceName = 'NotFound'
            }
        }

        if ($ThrowOnFailure)
        {
            throw "Service $ServiceName not found on $Server."
        }
        return
    }

    # Check and change the StartMode if necessary
    if ($StartMode -eq 'Auto')
    {
        $StartMode = 'Automatic'
    }

    if (($StartMode -ne 'NoChange') -and ($service.StartMode -ne $StartMode))
    {
        Set-Service -Name $ServiceName -StartupType $StartMode

        if ($StartMode -eq 'Disabled')
        {
            $State = 'Stopped'
        }
    }

    # Determine if the start/stop/restart action is needed
    if ($State -eq 'NoChange' -or $service.State -eq $State)
    {
        return
    }

    if ($LoggingStage)
    {
        $logEntry = New-LogEntry -Source $Server -Stage $LoggingStage
        Write-EventOfEntry -Event Start -Entry $logEntry
    }

    switch ($State)
    {
        'Stopped'
        {
            Stop-Service -Name $ServiceName | Out-Null
        }

        'Running'
        {
            if ($service.State -eq 'Paused')
            {
                Resume-Service -Name $ServiceName | Out-Null
            }
            else
            {
                Start-Service -Name $ServiceName | Out-Null
            }
        }

        'Paused'
        {
            if ($service.State -eq 'Running')
            {
                Suspend-Service -Name $ServiceName | Out-Null
            }
            else
            {
                # service is stopped, start it up first
                Start-Service -Name $ServiceName | Out-Null

                if ($WaitTime -eq [TimeSpan]::Zero)
                {
                    $startupWaitTime = New-TimeSpan -Minutes 5
                }
                else
                {
                    $startupWaitTime = $WaitTime
                }

                Wait-ServiceState `
                    -ServiceName $ServiceName `
                    -Server $Server `
                    -State 'Running' `
                    -WaitTime $startupWaitTime `
                    -ThrowOnFailure:$ThrowOnFailure

                # pause now
                Suspend-Service -Name $ServiceName | Out-Null
            }
        }
    }

    if ($WaitTime -gt [TimeSpan]::Zero)
    {
        Wait-ServiceState `
            -ServiceName $ServiceName `
            -Server $Server `
            -State $State `
            -WaitTime $WaitTime `
            -ThrowOnFailure:$ThrowOnFailure
    }

    if ($LoggingStage)
    {
        Write-EventOfEntry -Event Completed -Entry $logEntry -reason @{
            'MaxWaitMinutes' = $WaitTime.TotalMinutes
        }
    }
}

# .DESCRIPTION
# Create a log entry object to be used in logging with various events and reasons
#
# .PARAMETER Source
# Name of the computer that originates this logging
#
# .PARAMETER Stage
# Logging stage
#
# .PARAMETER Id
# Id of this log entry
#
# .PARAMETER Count
# Value for the count column, meaning of this count varies with id and stage
#
# .RETURN
# Log Entry object which can be use Write-EventOfEntry & Write-SkippedEvent
function New-LogEntry
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Source,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Stage,

        [Parameter()]
        [System.String]
        $Id,

        [Parameter()]
        [int]
        $Count = -1
    )

    $logProps = @{
        Source  = $Source
        Stage   = $Stage
        Id      = $Id
        Count   = $Count
        Created = Get-Date
    }

    return New-Object PsObject -Property $logProps
}

# .DESCRIPTION
# Add a log entry of certain event to the current log file
#
# .PARAMETER Event
# Event to be logged. For Completed event, the duration is automatically
# computed from the time LogEntry was created
#
# .PARAMETER Entry
# Log Entry, created by New-LogEntry
#
# .PARAMETER Reason
# Reason of this event
function Write-EventOfEntry
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Event,

        [Parameter(Mandatory = $true)]
        [System.Object]
        $Entry,

        [Parameter()]
        [System.Collections.Hashtable]
        $Reason
    )

    if ($Event -eq 'Completed')
    {
        $duration = (Get-Date) - $Entry.Created
    }

    if ($Reason)
    {
        $Reason.GetEnumerator() |
            Sort-Object Key |
            ForEach-Object {
                if ($ReasonStr)
                {
                    $ReasonStr += '; '
                }

                $ReasonStr += '{0}={1}' -f $_.Name, $_.Value
            }
    }

    $msg = [System.String]::Format('{0},{1},{2},{3},{4},{5:g},{6},{7},{8}', `
        (Get-Date), `
            $Entry.Source, `
            $Entry.Stage, `
            $Event, `
            $Entry.Id, `
            $duration, `
        $(
            if ($Entry.Count -ne -1)
            {
                $Entry.Count
            }
            else
            {
                ''
            }), `
            $ReasonStr, `
            $Script:ExchangeVersion)

    Write-Verbose -Message $msg

    if (-not $Script:LogFileName)
    {
        return
    }

    $maxTries = 3
    while ($maxTries -gt 0)
    {
        try
        {
            Add-Content -Path $Script:LogFileName -Value $msg -ErrorAction Stop
            return
        }
        catch [IO.DriveNotFoundException]
        {
            # we stop logging if log causes exception
            $Script:LogFileName = $null
            Write-Verbose -Message $_.Exception.Message
            return
        }
        catch
        {
            # we may have other MM workflow accessing the log file
            # delay 1 sec and try again
            Start-Sleep -Seconds 1
            $maxTries--
        }
    }
}

# .DESCRIPTION
# Log a Skipped event to the current log file
#
# .PARAMETER Source
# Name of the computer that originates this logging
#
# .PARAMETER Stage
# Logging stage
#
# .PARAMETER Id
# Id of this log entry
#
# .PARAMETER Count
# Value for the count column, meaning of this count varies with id and stage
#
# .PARAMETER Reason
# Reason of this event

function Write-SkippedEvent
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Source,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Stage,

        [Parameter()]
        [System.String]
        $Id,

        [Parameter()]
        [int]
        $Count,

        [Parameter()]
        [System.Collections.Hashtable]
        $Reason
    )

    $entry = New-LogEntry -Source $Source -Stage $Stage -Id $Id -Count $Count
    Write-EventOfEntry -Event Skipped -Entry $entry -Reason $Reason
}

# .DESCRIPTION
# Log an Info event to the current log file
#
# .PARAMETER Source
# Name of the computer that originates this logging
#
# .PARAMETER Stage
# Logging stage
#
# .PARAMETER Id
# Id of this log entry
#
# .PARAMETER Count
# Value for the count column, meaning of this count varies with id and stage
#
# .PARAMETER Reason
# Reason of this event

function Write-InfoEvent
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Source,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Stage,

        [Parameter()]
        [System.String]
        $Id,

        [Parameter()]
        [int]
        $Count,

        [Parameter()]
        [System.Collections.Hashtable]
        $Reason
    )

    $entry = New-LogEntry -Source $Source -Stage $Stage -Id $Id -Count $Count
    Write-EventOfEntry -Event Info -Entry $entry -Reason $Reason
}

# .DESCRIPTION
# Used by Wait-EmptyEntriesCompletion.
# Takes a hash table by the entry's id. Remove any entry that's not found in ActiveEntries.
#
# .PARAMETER ActiveEntries
# Array of active entries
#
# .PARAMETER DetailLogging
# Whether to log progress of each entry.
#
# .PARAMETER Tracker
# Tracking hash table to be updated
#
# .RETURN
# returns True if at least an entry removed. Otherwise returns False.
function Remove-CompletedEntriesFromHashtable
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseDeclaredVarsMoreThanAssignments", "")]
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Collections.Hashtable]
        $Tracker,

        [Parameter()]
        [Object[]]
        $ActiveEntries = @(),

        [Parameter()]
        [Switch]
        $DetailLogging
    )

    $progressMade = $false

    $activeIds = $ActiveEntries | ForEach-Object { $_.Id }
    $completedKeys = $tracker.Keys | Where-Object { $activeIds -notcontains $_ }
    $completedKeys | ForEach-Object {
        # update entry
        $entry = $Tracker[$_]
        $entry.LogEntry.Count = 0

        if ($DetailLogging)
        {
            Write-EventOfEntry -Event Completed -Entry $entry.LogEntry
        }

        # remove completed entry from tracking
        $Tracker.Remove($_)
        $progressMade = $true
    }

    return $progressMade
}

# .DESCRIPTION
# Used by Wait-EmptyEntriesCompletion.
# Takes a hash table by the entry's id. Adds/Updates any entry that's found in ActiveEntries.
#
# .PARAMETER Tracker
# Tracking hash table to be updated
#
# .PARAMETER Source
# Name of server, for logging purpose, which GetEntries Scriptblock is retrieving data from
#
# .PARAMETER Stage
# Name of the Stage of the overall BeginMM process, for logging purpose
#
# .PARAMETER DetailLogging
# Whether to log progress of each entry.
#
# .PARAMETER ActiveEntries
# Array of active entries
#
# .RETURN
# Returns True if at least an entry is updated or created. Otherwise returns False.
function Update-EntriesTracker
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [System.Collections.Hashtable]
        $Tracker,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Source,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Stage,

        [Parameter()]
        [Switch]
        $DetailLogging,

        [Parameter()]
        [Object[]] $ActiveEntries = @()
    )

    $progressMade = $false

    # Update the tracker hash table; Create new entries as needed
    $ActiveEntries | ForEach-Object {
        if (-not $tracker.ContainsKey($_.Id))
        {
            $logEntry = New-LogEntry -Source $Source -Stage $Stage -Id $_.Id -Count $_.Count

            $trackEnty = New-Object PsObject -Property @{
                LogEntry    = $logEntry
                LastUpdated = Get-Date
            }

            $tracker.Add($_.Id, $trackEnty)

            if ($DetailLogging)
            {
                Write-EventOfEntry -Event Start -Entry $logEntry
            }

            $progressMade = $true
        }
        else
        {
            $trackingEntry = $tracker[$_.Id]
            $drainRateProp = $_.PsObject.Properties.Match('DrainRate')
            if ((($drainRateProp.count -gt 0) -and ($_.DrainRate -gt 0)) -or `
                (($drainRateProp.count -eq 0) -and ($trackingEntry.LogEntry.Count -ne $_.Count)))
            {
                $trackingEntry.LogEntry.Count = $_.Count
                $trackingEntry.LastUpdated = Get-Date
                $progressMade = $true
            }
        }
    }

    return $progressMade
}

# .DESCRIPTION
# Implements a generic wait function for entries returned by a scriptblock to go
# to zero or abort when time allow exceed or no progress was made.
# Each entry is tracked individually.
#
# .PARAMETER GetEntries
# ScriptBlock to be called every PollingFrequency interval with GetScriptArgs arguments
# to retrieve an array of entries with count
#
# .PARAMETER Stage
# Name of the Stage of the overall BeginMM process, for logging purpose
#
# .PARAMETER DetailLogging
# Whether to log progress of each entry.
#
# .PARAMETER GetEntriesAgrs
# Parameters for the GetEntries script block
#
# .PARAMETER Source
# Name of server, for logging purpose, which GetEntries Scriptblock is retrieving data from
#
# .PARAMETER PollingFrequency
# Frequency of polling queues for status
#
# .PARAMETER Timeout
# Timeout not to exceed
#
# .PARAMETER NoProgressTimeout
# Timeout for when no progress is made
#
# .PARAMETER ThrowOnTimeout
# Whether to throw error on timeout
#
# .RETURN
# Returns the remaining count of messages in the queues. When the wait ends with overall timeout
# or no progress timeout, this function returns a non-zero value.
function Wait-EmptyEntriesCompletion
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ScriptBlock]
        $GetEntries,

        [Parameter(Mandatory = $true)]
        [System.String]
        $Stage,

        [Parameter()]
        [Switch]
        $DetailLogging,

        [Parameter()]
        [object[]]
        $GetEntriesArgs = @(),

        [Parameter()]
        [System.String]
        $Source = $env:COMPUTERNAME,

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    $tracker = @{ }
    $endTime = (Get-Date) + $Timeout
    $summaryLog = $null
    $firstTime = $true

    while ($true)
    {
        $activeEntries = Invoke-Command -ScriptBlock $GetEntries -ArgumentList $GetEntriesArgs | Where-Object { $_.Count -gt 0 }

        if ($firstTime)
        {
            if ($DetailLogging -and -not $ActiveEntries)
            {
                Write-SkippedEvent -Source $Source -Stage $Stage -Reason @{
                    Reason = 'Not needed'
                }
            }
            else
            {
                $startCount = 0
                $startCount += $activeEntries | Measure-Object -Sum -Property Count | ForEach-Object { $_.Sum }

                $summaryLog = New-LogEntry -Source $Source -Stage $Stage -Count $startCount
                Write-EventOfEntry -Event Start -Entry $summaryLog
            }

            $firstTime = $false
        }

        $foundCompleted = Remove-CompletedEntriesFromHashtable `
            -Tracker $tracker `
            -ActiveEntries $activeEntries `
            -DetailLogging:$DetailLogging

        if (-not $activeEntries)
        {
            break;
        }

        $foundUpdate = Update-EntriesTracker `
            -Tracker $tracker `
            -ActiveEntries $activeEntries `
            -Source $Source `
            -Stage $Stage `
            -DetailLogging:$DetailLogging

        if ((Get-Date) -gt $endTime)
        {
            Write-Verbose -Message "$Source - $Stage Time-out occurred. Wait aborted!"
            $Reason = $Script:AllotedTimeExceeded
            break;
        }
        elseif ($foundCompleted -or $foundUpdate)
        {
            $remaningCount = $activeEntries | Measure-Object -Sum -Property Count | ForEach-Object { $_.Sum }
            Write-Verbose -Message "$Source - $Stage Progress made. $remaningCount items remain."
        }
        else
        {
            # checking if it's been too long since progress was made
            $recentEntries = $tracker.Values | Where-Object { ((Get-Date) - $_.LastUpdated) -lt $NoProgressTimeout }
            if (-not $recentEntries)
            {
                Write-Verbose -Message "$Source - $Stage NoProgressTimeout occurred. Wait aborted!"
                $Reason = $Script:NoProgressTimeout
                break;
            }
        }

        Start-Sleep -Seconds $PollingFrequency.Seconds
    }

    $remainingCount = 0
    $remainingCount += $activeEntries | Measure-Object -Sum -Property Count | ForEach-Object { $_.Sum }

    if ($DetailLogging)
    {
        $tracker.Values | ForEach-Object {
            Write-EventOfEntry -Event Completed -Entry $_.LogEntry -Reason @{
                Reason = $reason
            }
        }
    }
    else
    {
        $summaryLog.Count = $remainingCount

        if ($reason)
        {
            Write-EventOfEntry -Event Completed -Entry $summaryLog -Reason @{
                Reason = $reason
            }
        }
        else
        {
            Write-EventOfEntry -Event Completed -Entry $summaryLog
        }
    }

    if ($ThrowOnTimeout)
    {
        throw New-Object System.TimeoutException 'Time-out reached.'
    }

    return $remainingCount
}

# .SYNOPSIS
# Waits for the draining of Remote SMTP Relay queues, MapiDelivery queues and Submission queue.
#
# .DESCRIPTION
# Monitors and waits for all messages to be drained before returning. Will throw
# TimeoutException if time-out is reached or if no progress is made in NoProgressTimeout.
#
# .PARAMETER Server
# Target server for the operation.
#
# .PARAMETER QueueTypes
# Array of DeliveryTypes defined in:
# http://technet.microsoft.com/en-us/library/bb125022(v=exchg.150).aspx#NextHopSolutionKey.
# If null specified, all queue types are included in the wait. This function implicitly
# includes Submission queue and excludes Poison queue.
#
# .PARAMETER ActiveMsgOnly
# Whether to wait for active messages or all messages.
#
# .PARAMETER Stage
# Whether the wait is for the natural draining or the redirection
#
# .PARAMETER PollingFrequency
# Frequency of polling queues for status
#
# .PARAMETER Timeout
# Timeout not to exceed
#
# .PARAMETER NoProgressTimeout
# Timeout for when no progress is made
#
# .PARAMETER ThrowOnTimeout
# Whether to throw error on timeout
#
# .RETURN
# Returns the remaining count of messages in the queues. When the wait ends with overall timeout or no progress timeout,
# this function returns a non-zero value.
function Wait-EmptyQueuesCompletion
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Server,

        [Parameter()]
        [System.String[]]
        $QueueTypes = $null,

        [Parameter()]
        [bool]
        $ActiveMsgOnly = $false,

        [Parameter()]
        [System.String]
        $Stage = 'QueueDrain',

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    $getQueueEntries = `
    {
        param
        (
            [Parameter(Mandatory = $true)]
            [System.String]
            $Server = $null,

            [Parameter(Mandatory = $true)]
            [System.String[]]
            $QueueTypes,

            [Parameter(Mandatory = $true)]
            [bool]
            $ActiveMsgOnly
        )

        $filter = "{MessageCount -gt 0 -and DeliveryType -ne 'ShadowRedundancy' -and NextHopDomain -ne 'Poison Message'}"
        $queues = get-queue -server $Server -ErrorAction SilentlyContinue -filter $filter |
            Where-Object { $null -eq $QueueTypes -or $QueueTypes -contains $_.DeliveryType }

        $entries = $queues | ForEach-Object {
            if ($ActiveMsgOnly)
            {
                $count = $_.MessageCountsPerPriority | Measure-Object -Sum | ForEach-Object { $_.Sum }
            }
            else
            {
                $count = $_.MessageCount
            }

            $queueInfo = `
            @{
                Id        = $_.Identity
                Count     = $count
                DrainRate = $_.OutgoingRate
            }
            New-Object PsObject -Property $queueInfo
        }

        return $entries
    }

    Write-Verbose -Message "$Server - Start waiting for $Stage..."

    $remaining = Wait-EmptyEntriesCompletion `
        -GetEntries $getQueueEntries `
        -GetEntriesArgs $Server, $queueTypes, $ActiveMsgOnly `
        -Source $Server `
        -Stage $Stage `
        -DetailLogging:$false `
        -PollingFrequency $PollingFrequency `
        -TimeOut $TimeOut `
        -NoProgressTimeout $NoProgressTimeout `
        -ThrowOnTimeout:$ThrowOnTimeout

    Write-Verbose -Message "$Server - Wait for $Stage ended with $remaining items remain."

    return $remaining
}

# .DESCRIPTION
# returns the pending discard events from a specified server
#
# .PARAMETER Server
# Target server for the operation.
#
# .PARAMETER Detail
# If detail is specified, Discard Ids are included in the discard information returned.
#
# .RETURN
# Returns array of discard events count of each shadow server. When -Detail present,
# DiscardIDs of each shadow server are also returned.
function Get-DiscardInfo
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Server,

        [Parameter()]
        [switch]
        $Detail
    )

    if ($Detail)
    {
        $argument = 'verbose'
    }
    else
    {
        $argument = 'basic'
    }

    $shadowInfo = [xml] (Get-ExchangeDiagnosticInfo -Server $Server -Process edgetransport -Component ShadowRedundancy -argument $argument)

    $discardInfo = $shadowInfo.Diagnostics.Components.ShadowRedundancy.ShadowServerCollection.ShadowServer |
        Where-Object { $_.ShadowServerInfo.discardEventsCount -gt 0 } |
        ForEach-Object {
            $infoProps = @{
                Id         = [System.Text.Encoding]::ASCII.GetString([System.Convert]::FromBase64String($_.Context))
                Count      = $_.ShadowServerInfo.discardEventsCount
                DiscardIds = @()
            }

            if ($Detail)
            {
                $infoProps.DiscardIds = $_.ShadowServerInfo.discardEventMessageId
            }

            New-Object psobject -Property $infoProps
        }

    return $discardInfo
}

# .SYNOPSIS
# Waits for discard events to be consumed by shadow servers
#
# .DESCRIPTION
# Monitors and waits for all discard events to be consumed by shadow servers before returned.
# Will throw TimeoutException if timeout is reached or if no progress is made in NoProgressTimeout.
#
# .PARAMETER Server
# Target server for the operation.
#
# .PARAMETER ActiveServers
# Array of active servers whose discard events are waiting to be drained
#
# .PARAMETER PollingFrequency
# Frequency of polling queues for status
#
# .PARAMETER Timeout
# Timeout not to exceed
#
# .PARAMETER NoProgressTimeout
# Timeout for when no progress is made
#
# .PARAMETER ThrowOnTimeout
# Whether to throw error on timeout
#
# .RETURN
# Returns the remaining count of discard events. When the wait ends with timeout exceeded or no progress
# this functions returns a non-zero value.
function Wait-EmptyDiscardsCompletion
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Server,

        [Parameter(Mandatory = $true)]
        [System.String[]]
        $ActiveServers,

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    Write-Verbose -Message "$Server - Start waiting for ShadowDiscardDrain..."

    # log the undrainable entries
    $discardInfo = Get-DiscardInfo -server $Server
    $discardInfo |
        Where-Object { $ActiveServers -notcontains $_.Id.Split('.')[0] } |
        ForEach-Object {
            Write-SkippedEvent -Source $Server -Stage ShadowDiscardDrain -Id $_.Id -Count $_.Count -Reason @{
                Reason = $Script:ServerInMM
            }
        }

    # wait for discard events to be drained
    $getDiscardInfo = `
    {
        param
        (
            [Parameter(Mandatory = $true)]
            [System.String]
            $Server = $null,

            [Parameter(Mandatory = $true)]
            [System.String[]]
            $ActiveServers = $null
        )

        $discardInfo = Get-DiscardInfo -server $Server
        $discardInfo | Where-Object { $ActiveServers -contains $_.Id.Split('.')[0] }
    }

    $remaining = Wait-EmptyEntriesCompletion `
        -GetEntries $getDiscardInfo `
        -GetEntriesArgs $Server, $ActiveServers `
        -Source $Server `
        -Stage ShadowDiscardDrain `
        -PollingFrequency $PollingFrequency `
        -TimeOut $TimeOut `
        -NoProgressTimeout $NoProgressTimeout `
        -ThrowOnTimeout:$ThrowOnTimeout

    Write-Verbose -Message "$Server - ShadowDiscardDrain ended with $remaining items remain."

    return $remaining
}

<#
    .SYNOPSIS
        Waits for the event log StartScanForMessages (id = 17008) to be logged to Windows Event Log
        This tells that the bootscanner had completed counting for the outstanding items and
        start boot-scanning messages
 
    .PARAMETER ServerFqdn
        Fqdn of the server
 
    .PARAMETER PollingFrequency
        Frequency of polling for event
 
    .PARAMETER Timeout
        Timeout not to exceed
 
    .PARAMETER NoProgressTimeout
        Timeout for when no progress is made
 
    .PARAMETER ThrowOnTimeout
        Whether to throw error on timeout
#>
function Wait-BootLoaderCountCheck
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $ServerFqdn,

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    $waitBootScanningEvent =
    {
        param
        (
            [Parameter(Mandatory = $true)]
            [System.String]
            $fqdn = $null,

            [Parameter(Mandatory = $true)]
            [DateTime]
            $StartTime = $null
        )

        $bootScanningEvent = @{
            LogName      = 'Application'
            ProviderName = 'MsExchangeTransport'
            Id           = 17008
            StartTime    = $StartTime
        }

        $event = Get-WinEvent -ComputerName $ServerFqdn -FilterHashtable $bootScanningEvent -ErrorAction SilentlyContinue

        if ($event)
        {
            # return null to complete the wait
            return $null
        }
        else
        {
            $bootScanningEvent = `
            @{
                Id    = 'TransportQueueDatabase'
                Count = 1
            }
            New-Object PsObject -Property $bootScanningEvent
        }
    }

    $server = $ServerFqdn.split('.')[0]
    $xml = [xml] (Get-ExchangeDiagnosticInfo -Process 'EdgeTransport' -server $server -erroraction SilentlyContinue)
    if ($xml)
    {
        $processStartTime = [DateTime] ($xml.Diagnostics.ProcessInfo.StartTime)
        Wait-EmptyEntriesCompletion `
            -GetEntries $waitBootScanningEvent `
            -GetEntriesArgs $ServerFqdn, $processStartTime `
            -Source $server `
            -Stage BootLoaderCountCheck `
            -PollingFrequency $PollingFrequency `
            -TimeOut $Timeout `
            -NoProgressTimeout $NoProgressTimeout `
            -ThrowOnTimeout:$ThrowOnTimeout
    }
}

# .DESCRIPTION
# Waits for the 'BootLoader Outstanding Items' perfcounter to go down to 0
#
# .PARAMETER ServerFqdn
# Fqdn of the server
#
# .PARAMETER PollingFrequency
# Frequency of polling for event
#
# .PARAMETER Timeout
# Timeout not to exceed
#
# .PARAMETER NoProgressTimeout
# Timeout for when no progress is made
#
# .PARAMETER ThrowOnTimeout
# Whether to throw error on timeout
#
# .RETURN
# none
function Wait-BootLoaderSubmitCheck
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $ServerFqdn,

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    $getOutstandingItems =
    {
        param
        (
            [Parameter(Mandatory = $true)]
            [System.String]
            $fqdn = $null
        )

        $counter = Get-Counter `
            -Counter '\MSExchangeTransport Database(other*)\BootLoader Outstanding Items' `
            -ComputerName $fqdn `
            -ErrorAction SilentlyContinue
        try
        {
            $counterInfo = `
            @{
                Id    = 'BootLoaderOutstandingItems'
                Count = $counter.CounterSamples[0].RawValue
            }
        }
        catch
        {
            $counterInfo = `
            @{
                Id    = 'BootLoaderOutstandingItems'
                Count = 1
            }
        }

        return New-Object PsObject -Property $counterInfo
    }

    $server = $ServerFqdn.split('.')[0]
    $remaining = Wait-EmptyEntriesCompletion `
        -GetEntries $getOutstandingItems `
        -GetEntriesArgs $ServerFqdn `
        -Source $server `
        -Stage BootLoaderSubmitCheck `
        -PollingFrequency $PollingFrequency `
        -TimeOut $Timeout `
        -NoProgressTimeout $NoProgressTimeout `
        -ThrowOnTimeout:$ThrowOnTimeout

    return $remaining
}

<#
    .SYNOPSIS
        If the process has been running for more than 30 mins, then this function returns immediately.
        Otherwise, wait for the bootscanner to complete up to 30 minutes or the specified timeout, whichever
        less.
 
    .PARAMETER Server
        Target server for the operation.
 
    .PARAMETER MaxBootLoaderProcessTimeout
        Max time for the BootLoader to completely bootscanning all the unprocessed messages.
 
    .PARAMETER PollingFrequency
        Frequency of polling queues for status
 
    .PARAMETER Timeout
        Timeout not to exceed
 
    .PARAMETER NoProgressTimeout
        Timeout for when no progress is made
 
    .PARAMETER ThrowOnTimeout
        Whether to throw error on timeout
#>
function Wait-BootLoaderReady
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $Server,

        [Parameter()]
        [TimeSpan]
        $MaxBootLoaderProcessTimeout = (New-TimeSpan -Minutes 30),

        [Parameter()]
        [TimeSpan]
        $PollingFrequency = (New-TimeSpan -Seconds 10),

        [Parameter()]
        [TimeSpan]
        $Timeout = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [TimeSpan]
        $NoProgressTimeout = (New-TimeSpan -Minutes 1),

        [Parameter()]
        [Switch]
        $ThrowOnTimeout
    )

    Write-Verbose -Message "$Server - Waiting for BootLoader to be ready..."

    $exchangeServer = Get-ExchangeServer $Server
    if (-not $exchangeServer)
    {
        Write-Warning -Message 'Could not get the exchange server. Skip waiting for BootLoader.'
        return 0
    }

    $retry = 5
    while ($true)
    {
        try
        {
            $xml = [xml] (Get-ExchangeDiagnosticInfo -Process 'EdgeTransport' -server $Server -erroraction SilentlyContinue)
            $processLifeTime = [TimeSpan] ($xml.Diagnostics.ProcessInfo.LifeTime)
            $processStartTime = [DateTime] ($xml.Diagnostics.ProcessInfo.StartTime)
            break
        }
        catch
        {
            if ($retry -gt 0)
            {
                Write-Verbose -Message "$Server - Can not read the process lifetime. Sleep 20 to retry..."
                Start-Sleep 20
                $retry--
            }
            else
            {
                break
            }
        }
    }


    if (-not $processLifeTime -or -not $processStartTime)
    {
        # EdgeTransport isn't running or Server isn't a HubTransport, nothing to wait here
        Write-SkippedEvent -Source $Server -Stage BootLoaderCountCheck -Reason @{
            Reason = 'EdgeTransportUnreachable'
        }
        Write-SkippedEvent -Source $Server -Stage BootLoaderSubmitCheck -Reason @{
            Reason = 'EdgeTransportUnreachable'
        }

        Write-Warning -Message "$Server - EdgeTransport is not running or server $server is unreachable. Skipping waiting for BootLoader."
        return 0
    }

    if ($processLifeTime -gt $MaxBootLoaderProcessTimeout)
    {
        Write-SkippedEvent -Source $Server -Stage BootLoaderCountCheck -Reason @{
            ProcessLifeTime = $processLifeTime
        }
        Write-SkippedEvent -Source $Server -Stage BootLoaderSubmitCheck -Reason @{
            ProcessLifeTime = $processLifeTime
        }

        Write-Verbose -Message "$Server - EdgeTransport has been running for $processLifeTime. BootLoader is ready"
        return 0
    }
    elseif ($MaxBootLoaderProcessTimeout - $processLifeTime -gt $Timeout)
    {
        $waitTime = $Timeout
    }
    else
    {
        $waitTime = $MaxBootLoaderProcessTimeout - $processLifeTime
    }

    $msg = "$Server EdgeTransport has been running for $processLifeTime! Let's give BootLoader $waitTime to complete."
    Write-Verbose -Message $msg

    $stopWatch = [System.Diagnostics.Stopwatch]::StartNew()

    Wait-BootLoaderCountCheck `
        -ServerFqdn ($exchangeServer.fqdn) `
        -PollingFrequency $PollingFrequency `
        -TimeOut $waitTime `
        -NoProgressTimeout $waitTime `
        -ThrowOnTimeout:$ThrowOnTimeout

    $stopWatch.Stop()
    $elapsed = $stopWatch.Elapsed
    $waitTime = $waitTime - $elapsed

    Wait-BootLoaderSubmitCheck `
        -ServerFqdn ($exchangeServer.fqdn) `
        -PollingFrequency $PollingFrequency `
        -TimeOut $waitTime `
        -NoProgressTimeout $NoProgressTimeout `
        -ThrowOnTimeout:$ThrowOnTimeout

    Write-Verbose -Message "$Server - BootLoader ended with $remaining items remain"
    return $remaining
}

# .DESCRIPTION
# Put the MsExchangeTransport/EdgeTransport on the specified server to Draining
# mode WITHOUT changing the server component state. This is done by pausing the service.
#
# .PARAMETER Server
# Server to drain the active messages from
#
# .PARAMETER TransportService
# Optional MsExchangeTransport service object.
function Clear-ActiveMessage
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Server,

        [Parameter()]
        [System.Object]
        $TransportService
    )

    Wait-BootLoaderReady -Server $Server

    if (-not $TransportService)
    {
        $exServer = Get-ExchangeServer $Server
        Write-Verbose -Message "$Server - Pausing the MsExchangeTransport service to stop accepting new traffic"
        $TransportService = Get-Service -ComputerName $exServer.Fqdn -Name MSExchangeTransport -errorAction silentlyContinue
    }

    if ($TransportService)
    {
        $TransportService.Pause() | Out-Null
    }

    $queueTypes = @('SmtpDeliveryToMailbox', 'SmtpRelayToRemoteAdSite', 'SmtpRelayToDag', 'SmtpRelayToServers', 'Undefined')
    Wait-EmptyQueuesCompletion -Server $server -QueueTypes $queueTypes -ActiveMsgOnly $true -Stage QueueDrain -Timeout 00:01:30
}

# .DESCRIPTION
# Redirecting messages from the specified server to all other servers in its dag
#
# .PARAMETER server
# Server whose messages are being redirecting
#
# .PARAMETER ExcludeLocalSite
# Whether to redirect messages to servers at the same site
#
# .PARAMETER LogIfRemain
# Whether to write to window event log if there remaining message that can not be redirected
#
# .RETURN
# Returns active servers in the dag
#
function Send-MessagesToNewServer
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Server,

        [Parameter()]
        [switch]
        $ExcludeLocalSite,

        [Parameter()]
        [switch]
        $LogIfRemain,

        [Parameter()]
        [System.String[]]
        $MessageRedirectExclusions
    )

    # get domain name of the server
    $fqdn = Get-ExchangeServer $Server | ForEach-Object { $_.Fqdn }
    $domainIndex = $fqdn.Indexof('.')
    $domain = $fqdn.SubString($domainIndex)

    $serversInDag = Get-ServersInDag -server $Server -ExcludeLocalSite:$ExcludeLocalSite -AdditionalExclusions $MessageRedirectExclusions
    if (-not $serversInDag -or $serversInDag.count -eq 0)
    {
        Write-Warning -Message "$Server - Could not find servers in the DAG to redirect messages to that do not meeting exclusion criteria. Skipping redirect."
        return $null
    }

    $serversInDag = Get-ActiveServer $serversInDag
    $hubFqdns = $serversInDag | Where-Object { $_ -ne $Server } | ForEach-Object { $_ + $domain }

    $verboseMessage = "$Server - Redirecting messages to " + [System.String]::Join(', ', $hubFqdns)
    Write-Verbose -Message $verboseMessage

    Redirect-Message -Target $hubFqdns -Server $Server -Confirm:$false -ErrorAction SilentlyContinue

    $timeOut = (New-TimeSpan -Minutes 8)
    $remaining = Wait-EmptyQueuesCompletion -Server $Server -Stage Redirect -Timeout $timeOut

    if ($remaining -and $LogIfRemain)
    {
        $message = "Transport service is going to Maintenance with $messageCount messages in its queues."
        Log-WindowsEvent -EventId $Script:UnredirectedMessageEventId -Message $message
    }

    return $serversInDag
}

# .DESCRIPTION
# Forcing heartbeats from other shadow servers in the dag to the primary
# Wait for all discard events to be drained by its shadow servers
#
# .PARAMETER primary
# Primary server
#
# .PARAMETER shadowServers
# Array of shadow servers
#
# .PARAMETER LogIfRemain
# Whether to log a windows event log if there is remains discard event that can't be drained.
#
# .RETURN
# none
#
function Clear-DiscardEvent
{
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $Primary,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [System.String[]]
        $ShadowServers,

        [Parameter()]
        [switch]
        $LogIfRemain
    )

    $filter = "{DeliveryType -eq 'ShadowRedundancy' -and NextHopDomain -like '$Primary*'}"
    $ShadowServers | ForEach-Object {
        Write-Verbose -Message "$Primary - Forcing heart-beat on server $_"
        Retry-Queue -server $_ -Filter $filter -ErrorAction SilentlyContinue
    }

    Write-Verbose -Message "$Primary - Waiting for the heartbeats to complete processing"
    $remaining = Wait-EmptyDiscardsCompletion -Server $Primary -ActiveServers $ShadowServers -NoProgressTimeout (New-TimeSpan -Minutes 2)

    if ($remaining -and $LogIfRemain)
    {
        $message = "Transport service is going to Maintenance with $remaining unacknowledged discard events."
        Log-WindowsEvent -EventId $Script:UndrainedDiscardEventEventId -Message $message
    }
}

function Unblock-SubmissionQueue
{
    Write-Verbose -Message 'Getting handles for Transport worker process and service'
    $TransportWorkerProcess = (Get-Process EdgeTransport)
    $TransportServiceProcess = (Get-Process MSExchangeTransport)
    $TransportService = (Get-Service MSExchangeTransport)

    ## Create the dump
    Write-Output 'Sending trouble signal (204) to Transport Service'
    try
    {
        $TransportService.ExecuteCommand(204)
    }
    ## This could fail and its ok.
    catch
    {
        Write-Verbose -Message ('Sending trouble signal (204) to Transport Service issued an error:' + $Error[0].ToString())
    }

    Write-Verbose -Message 'Waiting 90s for the worker process to exit(Watson dump being created)'
    if ($TransportWorkerProcess.WaitForExit(90000))
    {
        Write-Output 'Worker process exited'
    }
    else
    {
        Write-Warning -Message "Worker process hasn't exited."
    }

    ##Stop transport, one way or another
    Write-Output 'Stopping Transport.'
    try
    {
        $TransportService.Stop()
    }
    ## This could timeout and it's ok.
    catch
    {
        Write-Verbose -Message ('Stopping Transport issued an error:' + $Error[0].ToString())
    }

    Write-Verbose -Message 'Waiting for Transport to stop completely'
    while (-not $TransportServiceProcess.WaitForExit(30000))
    {
        if (-not $TransportWorkerProcess.HasExited)
        {
            Write-Warning -Message "Transport worker process didn't stop yet. Killing the process"
            $TransportWorkerProcess.Kill()
        }
        else
        {
            Write-Warning -Message 'Transport service didnt stop yet. Killing the process'
            $TransportServiceProcess.Kill()
        }
    }
    $TransportService.WaitForStatus('Stopped') ## If it never stops the workflow will timeout and we should wake some people up.
    Write-Output 'Transport is stopped.'

    ## Starting transport will cause the dependencies to start.
    Write-Output 'Starting Transport'
    try
    {
        $TransportService.Start()
    }
    ## This could timeout and its ok.
    catch
    {
        Write-Verbose -Message ('Starting Transport issued an error:' + $Error[0].ToString())
    }

    $TransportService.WaitForStatus('Running') ## If it never starts the workflow will timeout and we should wake some people up.

    Write-Output 'Transport restarted.'
}

# .DESCRIPTION
# Sets specified component to state requested.
#
# .PARAMETER $State
# Requested state for the component.
#
# .PARAMETER $Component
# Component to set.
#
# .PARAMETER $Requester
# Requester who set the state.
#
# .PARAMETER Server
# The server to change the component state
#
function Set-ComponentState
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter(Mandatory = $true)]
        [ValidateSet('Active', 'Inactive')]
        [System.String]
        $State,

        [Parameter()]
        [System.String]
        $Component = 'HubTransport',

        [Parameter()]
        [System.String]
        $Requester = 'Maintenance',

        [Parameter()]
        [System.String]
        $Server = $env:COMPUTERNAME
    )

    Write-Verbose -Message "Setting $Component state to $State"
    Set-ServerComponentState `
        -Identity $Server `
        -Component $Component `
        -Requester $Requester `
        -State $State `
        -ErrorAction SilentlyContinue
}

# .DESCRIPTION
# Gets state of the specified component of an exchange server
#
# .PARAMETER $Server
# Server to retrieve component state of
#
# .PARAMETER $Component
# Component to get.
#
function Get-ComponentState
{
    param
    (
        [Parameter()]
        [System.String]
        $Server = $env:COMPUTERNAME,

        [Parameter()]
        [System.String]
        $Component = 'HubTransport'
    )

    Write-Verbose -Message "Getting $Component state of $Server"
    $serverComponentState = Get-ServerComponentState `
        -Identity $Server `
        -Component $Component `
        -ErrorAction SilentlyContinue
    Write-Verbose -Message "ServerComponentState of $Component is '$($serverComponentState.State)'"

    return $serverComponentState
}

# .DESCRIPTION
# Wait for the state of a service to change to the specified state
#
# .PARAMETER $ServiceName
# Name of the service to wait for
#
# .PARAMETER $Server
# Server where the service is running on
#
# .PARAMETER $State
# State to wait for
#
# .PARAMETER $WaitTime
# Maximum wait time for the service to change its state
#
# .PARAMETER $ThrowOnFailure
# Whether to throw on failures
#
# .RETURN
# None
function Wait-ServiceState
{
    param
    (
        [Parameter(Mandatory = $true)]
        [System.String]
        $ServiceName,

        [Parameter(Mandatory = $true)]
        [ValidateSet('Stopped', 'Running', 'Paused')]
        [System.String]
        $State,

        [Parameter()]
        [System.String]
        $Server = $env:COMPUTERNAME,

        [Parameter()]
        [TimeSpan]
        $WaitTime = (New-TimeSpan -Minutes 5),

        [Parameter()]
        [Switch]
        $ThrowOnFailure
    )

    $service = Get-Service -ComputerName $Server -ServiceName $ServiceName

    if (-not $service)
    {
        if ($ThrowOnFailure)
        {
            throw "Service $ServiceName not found on $Server."
        }
        return
    }

    try
    {
        $service.WaitForStatus($State, $WaitTime) | Out-Null
    }
    catch
    {
        if ($ThrowOnFailure)
        {
            throw $_
        }
    }
}

# .DESCRIPTION
# Function to stop a service by killing the underlying process
#
# .PARAMETER $ServiceName
# Name of the service to stop
#
# .PARAMETER $StartMode
# Service startup mode to set after killing the service, default to 'Auto'
function Stop-ServiceForcefully
{
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    param
    (
        [Parameter()]
        [ValidateNotNullOrEmpty()]
        [System.String]
        $ServiceName = $(throw 'ServiceName required.'),

        [Parameter()]
        [ValidateSet('Auto', 'Manual', 'Disabled')]
        [System.String]
        $StartMode = 'Auto'
    )

    Write-Verbose -Message "Stopping $ServiceName Service"
    Set-ServiceState -ServiceName $ServiceName -StartMode Disabled -WaitTime ([TimeSpan]::Zero)
    # Wait in case it needs time to take effect
    Wait-Event -Timeout 5

    $processFullPath = (Get-CimInstance -query "SELECT PathName FROM Win32_Service WHERE Name = '$ServiceName'").PathName.Replace('"', '')
    $processName = (Split-Path $processFullPath -Leaf).Replace('.exe', '')

    $process = Get-Process -Name $processName -ErrorAction SilentlyContinue
    if ($null -ne $process)
    {
        Stop-Process $process -Force
        # we wait so that the next statement that sets the startup type back to automatic does not
        # take effect while the process is still being killed and cause SCM to start the service back up
        Wait-Event -Timeout 5
    }
    else
    {
        Write-Verbose -Message 'The service process was not running'
    }

    Set-ServiceState -ServiceName $ServiceName -StartMode $StartMode -WaitTime ([TimeSpan]::Zero)
}
#endregion

Export-ModuleMember -Function Start-TransportMaintenance
Export-ModuleMember -Function Stop-TransportMaintenance
Export-ModuleMember -Function Wait-BootLoaderReady