###############################################################
#
# Scriptname:  PRTGCustomCitrixDGAvailableVDIs.ps1
#
# Autor:       Urs Heeb
# Date:        13.09.2022
#
# Version:     2022.09.01 / 13.09.22 / Urs Heeb
#                  Create script based on other custom PRTG scripts
#              2022.09.02 / 14.09.22 / Urs Heeb
#                  Create the output and calculation of percent
#                  Check all delivery groups and set the array
#              2022.09.03 / 15.09.22 / Urs Heeb
#                  Create the output and the final notification $RetString
#              2022.10.01 / 03.10.22 / Urs Heeb
#                  Modify the output for test delivery groups (no Alarm)
#                  
#
# Description: Script does following:
#              Connects to a Citrix controller
#              Gets the information of all delivery groups
#              Calculates the available VDIs 
#
# Requirements:
#              PRTG variables are needed while configuration
#              %host %windowsdomain %windowsuser %windowspassword
#              PRTG service user needs read permission on Citrix controller
#
###############################################################

###
# Get parameter from PRTG
param (
[string]$server,
[string]$domain,
[string]$username,
[string]$password
)

# For troubleshooting
<#
$server="controller.domain.pit"
$username="username"
$password="password"
#>

# Prepare credentials
$credentials = New-Object System.Management.Automation.PSCredential (($domain+'\'+$username), (ConvertTo-SecureString $password -AsPlainText -Force))

###
# Prepare an array and get the information from a Citrix controller by an Invoke-Command
# Citrix PS commands are only available on those servers
$Data = $null
$Data=@()

$Data += Invoke-Command -Computername $server -credential $credentials -ScriptBlock {

    # Load Citrix PS Snapin
    add-pssnapin citrix*

    # Get delivery groups with the needed information
    $DeliveryGroups=Get-BrokerDesktopGroup | Select-Object -Property Name, TotalDesktops, DesktopsAvailable, InMaintenanceMode

    # Set the array for later work
    $DG=@()
    ForEach ($group in $DeliveryGroups){
       $DG += [PSCustomObject]@{Name=$group.Name;Total=$group.TotalDesktops;Available=$group.DesktopsAvailable;Maintenance=$group.InMaintenanceMode} 
    }

    # Return data to PRTG probe
    return $DG
}

###
# Prepare the data and the PRTG XML output

# Reset some variables and define standard values
$returnState=$null
$returnState=@()
$returnStateOK = 0
$returnStateWarning = 1
$returnStateCritical = 2

# Start preparing XML output
$retXml = "<prtg>`n"

# Get data for each delivery group from the array created on the Citrix Controller
ForEach ($Dataset in $Data){
    $AlertString = "ALERT - low VDI capacity"
    $AlertLimit = 10
    $WarningString = "Warning - VDI capacity reachs the end"
    $WarningLimit = 20
    # Prepare variables based on the array data
    $DGName = $Dataset.Name
    $DGTotal = $Dataset.Total
    $DGAvailable = $Dataset.Available
    # Calculate the percentage of the available VDIs
    $DGPercent = "{0:N0}" -f (100/$DGTotal*$DGAvailable)
    $DGMaintenance = $Dataset.Maintenance

    # Determine if a delivery group is a test group
    # Test DGs will never go into alarm state
    # Test DGs in maintenance will have a percentage value of 100 to avoid an alarm
    If ($DGName -like "*test*"){
        $AlertString = $null
        $AlertLimit = $null
        $WarningString = "Warning - Test VDI capacity reachs the end"
        If ([Int64]$DGPercent -ge 20) {
            $RetState = $returnStateOK
            $returnState += [PSCustomObject]@{Name=$DGName;State=[Int64]$RetState} 
        }
        ElseIf ($DGMaintenance){
            $RetState=$returnStateWarning
            $DGPercent=100
        }
        Else {
            $RetState = $returnStateWarning
            $returnState += [PSCustomObject]@{Name=$DGName;State=[Int64]$RetState} 
        }
    }
    # Determine if a delivery group is in maintenance
    # DGs in maintenance goes into warning state, but doesn't affect the whole sensor
    # DGs in maintenance will not be stated based on her usage
    # DGs in maintenance will have a percentage value of 100 to avoid an alarm
    ElseIf ($DGMaintenance){
        $RetState=$returnStateWarning
        $DGPercent=100
    }
    # Determine return state if delivery group is not in maintenance
    # The values depend on the size of the delivery group
    Else {
        If ([Int64]$DGPercent -lt 10){
            $RetState = $returnStateCritical
            $AlertString = "ALERT - low VDI capacity"
            $returnState += [PSCustomObject]@{Name=$DGName;State=[Int64]$RetState} 
        }
        ElseIf ([Int64]$DGPercent -ge 20) {
            $RetState = $returnStateOK
#            $WarningString = "Warning - VDI capacity reachs the end"
            $returnState += [PSCustomObject]@{Name=$DGName;State=[Int64]$RetState} 
        }
        Else {
            $RetState = $returnStateWarning
            $returnState += [PSCustomObject]@{Name=$DGName;State=[Int64]$RetState} 
        }
    }

    #$retXml += "  <result>`n"
    #$retXml += "    <channel>$DGName State</channel>`n"
    #$retXml += "    <value>$RetState</value>`n"
    #$retXml += "  </result>`n"
    $retXml += "  <result>`n"
    $retXml += "    <channel>$DGName Free %</channel>`n"
    $retXml += "    <value>$DGPercent</value>`n"
    $retXml += "    <unit>Percent</unit>`n"
    $retXml += "    <limitMode>1</limitMode>`n"
    $retXml += "    <limitMinError>$AlertLimit</limitMinError>`n"
    $retXml += "    <limitErrorMsg>$AlertString</limitErrorMsg>`n"
    $retXml += "    <limitMinWarning>$WarningLimit</limitMinWarning>`n"
    $retXml += "    <limitWarningMsg>$WarningString</limitWarningMsg>`n"
    $retXml += "  </result>`n"
    $retXml += "  <result>`n"
    $retXml += "    <channel>$DGName Free VDIs</channel>`n"
    $retXml += "    <value>$DGAvailable</value>`n"
    $retXml += "    <unit>Count</unit>`n"
    $retXml += "  </result>`n"
}

# Determine return string depends on the several states
If ($returnState.State -contains 2) {
    $RetString = "ALERT - low VDI capacity"    
}
ElseIf ($returnState.State -contains 1) {
    $RetString = "Warning - VDI capacity reachs the end"    
}
Else {
    $RetString = "OK"    
}

$retXml += "  <text>$RetString</text>`n"
$retXml += "</prtg>`n"

###
# Return info to PRTG
write-host $retXml