Shutting down and draining sessions on AWS machines in RDS farm

<#
.SYNOPSIS
Function for writing the log
#>
Function Write-Log
{
  Param(
      [int]$level
  ,   [string]$Message
  ,   [ValidateSet("Info", "Warning", "Error")][string]$severity = 'Info'
  ,   [string]$logname = $rdslog
  ,   [string]$color = "white"
  )
  $time = get-date
  Add-Content $logname -value ("{0} - [{1}] {2}" -f $time, $severity, $Message)
  if ($interactive) {
      switch ($severity)
      {
          'Error' {$color = 'Red'}
          'Warning' {$color = 'Yellow'}
      }
      if ($level -le $VerboseLogging)
      {
          if ($color -match "Red|Yellow")
          {
              Write-Host ("{0} - [{1}] {2}" -f $time, $severity, $Message)
              -ForegroundColor $color -BackgroundColor Black
              if ($severity -eq 'Error') {

                  throw $Message
              }
          }
          else
          {
              Write-Host ("{0} - [{1}] {2}" -f $time, $severity, $Message) -ForegroundColor $color
          }
      }
  }
  else
  {
      switch ($severity)
      {
          'Info' {Write-Verbose -Message $Message}
          'Warning' {Write-Warning -Message $Message}
          'Error' {
              throw $Message
          }
      }
  }
}

<#
.SYNOPSIS
Function for writing the usage log
#>
Function Write-UsageLog
{
  Param(
      [string]$collectionName,
      [int]$corecount,
      [int]$vmcount,
      [string]$logfilename=$rdsusagelog
  )
  $time=get-date
  Add-Content $logfilename -value ("{0}, {1}, {2}, {3}" -f $time, $collectionName,
  $corecount, $vmcount)
}

Function Get-InstancesInCollection{
<#
.SYNOPSIS
Gets instances in collection
.DESCRIPTION
Get instances to be used in start/stop processing
.EXAMPLE
$getInstancesInCollection = Get-InstancesInCollection

The code for the instance state, as a 16-bit unsigned integer. The high byte is an
opaque internal value and should be ignored. The low byte is set based on the state represented.
The valid values are 0 (pending), 16 (running), 32 (shutting-down), 48 (terminated),
64 (stopping), and 80 (stopped).
#>
  begin {
      Import-Module -Name RemoteDesktop

      $ConnectionBrokerFQDN = "rdcb.example.lan"
      $Collections=Get-RDSessionCollection -ConnectionBroker $ConnectionBrokerFQDN
      -ErrorAction Continue
      Set-DefaultAWSRegion eu-central-1
      $RDHosts = Get-RDSessionHost -CollectionName Collection1 -ConnectionBroker
      $ConnectionBrokerFQDN -ErrorAction Continue
      $CollectionUserSessions=Get-RDUserSession -ConnectionBroker $ConnectionBrokerFQDN
      -CollectionName $collection.CollectionName -ErrorAction Continue
      $CollectionTS = Get-RDUserSession -ConnectionBroker $ConnectionBrokerFQDN -CollectionName
      Collection1 -ErrorAction Continue
      $CollectionTSSortUnique = $CollectionTS | Group-Object HostServer
  }
  process{
      write-verbose "Getting instances"
      $awsCollection = @()
      foreach($cols in $CollectionTS) {
          $aws = New-Object -TypeName PSObject
          $instance = Get-EC2Instance -Filter @( @{name='tag:Name'; values=$cols.HostServer};
              @{name='instance-state-code'; values = 16} )
          | Select-Object -ExpandProperty instances
          $aws | Add-Member -Type NoteProperty
          -Name InstanceId -Value $instance.instanceId
          $aws | Add-Member -Type NoteProperty
          -Name HostServer -Value $cols.HostServer
          $aws | Add-Member -Type NoteProperty
          -Name UserName -Value $cols.UserName
          $awsCollection += $aws
      }
      return $awsCollection
  }
}
Function Get-EmptyInstancesInCollection{
<#
.SYNOPSIS
Gets empty instances in collection
.DESCRIPTION
Get empty instances to be used in start/stop processing
.EXAMPLE
$getEmpty = Get-EmptyInstancesInCollection
#>


  begin {
      Import-Module -Name RemoteDesktop
      $ConnectionBrokerFQDN = "rdcb.example.lan"
      $Collections=Get-RDSessionCollection -ConnectionBroker $ConnectionBrokerFQDN
      -ErrorAction Continue
      Set-DefaultAWSRegion eu-central-1
      $RDHosts = Get-RDSessionHost -CollectionName Collection1 -ConnectionBroker
      $ConnectionBrokerFQDN -ErrorAction Continue
      $CollectionUserSessions=Get-RDUserSession -ConnectionBroker $ConnectionBrokerFQDN
      -CollectionName $collection.CollectionName -ErrorAction Continue
      $CollectionTS = Get-RDUserSession -ConnectionBroker $ConnectionBrokerFQDN -CollectionName
      Collection1 -ErrorAction Continue
      $CollectionTSSortUnique = $CollectionTS | Group-Object HostServer
  }
  process{
      $emptyCollection = @()
      $RDHGroup = $RDHosts | Group-Object -Property SessionHost
      $CollectionTSGroup = $CollectionTS | Group-Object -Property HostServer
      $CompareItems = Compare-Object $RDHGroup $CollectionTSGroup -IncludeEqual
      $SelectInstancesWithUsers = Get-InstancesInCollection | Select-Object HostServer
      foreach($ci in $CompareItems){
          if(($ci | Select-Object -ExpandProperty SideIndicator) -eq "<="){
              $realVal = $ci | Select-Object -ExpandProperty InputObject | Select-Object Name
              $emptycoll = New-Object -TypeName PSObject
              $emptycoll | Add-Member -Type NoteProperty
              -Name HostServer -Value $realVal[0].Name

              $emptyCollection += $emptycoll
          }

      }
      return $emptyCollection
  }
}


<#
.SYNOPSIS
Function for creating variable from XML
#>
Function Set-ScriptVariable ($Name,$Value)
{
  Invoke-Expression ("$Script:" + $Name + " = "" + $Value + """)
}


<#
.SYNOPSIS
Function for schedulaing start-stop of EC2 instances and setting RD Hosts
in drain mode according to number of users.
#>
Function SuperSizeMe{

  begin {
      Import-Module -Name RemoteDesktop
      $getEmpty = Get-EmptyInstancesInCollection
      #$CurrentPath=Split-Path $script:MyInvocation.MyCommand.Path
      $CurrentPath ="."
      #XMl Configuration File Path
      $XMLPath = "$CurrentPath\schedule.xml"

      #Log path
      $rdslog="$CurrentPath\RDSScale.log"

      #usage log path
      $rdsusagelog="$CurrentPath\RDSUsage.log"


      ###### Verify XML file ######
      If (Test-Path $XMLPath) {
          write-verbose "Found $XMLPath"
          write-verbose "Validating file..."
          try {
              $Variable = [XML] (Get-Content $XMLPath)
          }
          catch {
              $Validate = $false
              Write-Error "$XMLPath is invalid. Check XML syntax - Unable to proceed"
              Write-Log 3 "$XMLPath is invalid. Check XML syntax - Unable to proceed" "Error"
              exit 1
          }
      }
      Else {
          $Validate = $false
          write-error "Missing $XMLPath - Unable to proceed"
          Write-Log 3 "Missing $XMLPath - Unable to proceed" "Error"
          exit 1
      }

      ##### Load XML Configuration values as variables #########
      Write-Verbose "loading values from Config.xml"
      $Variable=[XML] (Get-Content "$XMLPath")
      $Variable.RDSScale.RDSScaleSettings | ForEach-Object {$_.Variable} | Where-Object
      {$_.Name -ne $null} | ForEach-Object {Set-ScriptVariable -Name $_.Name -Value $_.Value}
  }


  process{
      #Construct Begin time and End time for the Peak period
      $CurrentDateTime=Get-Date
      $BeginPeakDateTime=[DateTime]::Parse($CurrentDateTime.ToShortDateString()+' '+$BeginPeakTime)
      $EndPeakDateTime=[DateTime]::Parse($CurrentDateTime.ToShortDateString()+' '+$EndPeakTime)

      #get the available collections in the RDS
      try{
          $Collections=Get-RDSessionCollection -ConnectionBroker $ConnectionBrokerFQDN -ErrorAction Continue
      }
      catch
      {
          Write-Log 1 "Failed to retrieve RDS collections: $($_.exception.message)" "Error"
          Exit 1
      }
      #check the number of running session hosts
      $collectiongroup = ($CollectionUserSessions) |Group HostServer| Sort-Object count
      $numberOfRunningHost=$collectiongroup.Length

      if($CurrentDateTime -gt $BeginPeakDateTime -and $CurrentDateTime -lt $EndPeakDateTime){
          echo "Peak time baby!"
          if($numberOfRunningHost -lt $MaximumNumberOfInstances){
          try{
              foreach($cols in $CollectionTS) {
                  $instance = Get-EC2Instance -Filter @( @{name='tag:Name'; values=$cols.HostServer};
                          @{name='instance-state-code'; values = 80} )
                      | Select-Object -ExpandProperty instances

                  Start-EC2Instance -InstanceId $instance.InstanceId
              }
          } catch{
                  write-log 1 "Failed to start EC2 instance $($_.exception.message)" "Error"
                  Exit 1
              }
          }
      }
      if($CurrentDateTime -lt $BeginPeakDateTime -and $CurrentDateTime -gt $EndPeakDateTime ){
          #Stop some instances

          foreach($ge in $getEmpty){
              $instance = Get-EC2Instance -Filter @( @{name='tag:Name'; values=$ge.HostServer};
                      @{name='instance-state-code'; values = 16} )
                  | Select-Object -ExpandProperty instances
              try{
                  Stop-EC2Instance -Instance $instance.InstanceId
              }
              catch {
                  write-log $($_.exception.message)
              }
          }
          echo "Before peak time"
          if($numberOfRunningHost -ge $MaximumNumberOfInstances -and $numberOfRunningHost
          -gt $MinimumNumberOfInstances){
              $sortToKill = Get-InstancesInCollection | Group-Object HostServer | Sort-Object count
              echo $sortToKill[0]
                  try{
                  Set-RDSessionHost -SessionHost $sortToKill[0].Name -NewConnectionAllowed
                  NotUntilReboot -ConnectionBroker $ConnectionBrokerFQDN -ErrorAction Continue
              }
              catch{
                  write-log 1 "Failed to set drain mode on session host: $($sortToKill[0].Name)
                  with error: $($_.exception.message)" "Error"
                  Exit 1
              }
          }
      }
  }
}