<#
	hvvmbase.ps1
	Written by Eric Siron
	(c) Altaro Software 2017

	Version 1.0.2 May 24, 2017

	Intended for use with the NSClient++ module from http://nsclient.org
	Provides reusable functions for other check scripts.
#>
if(-not $HVVMBaseIncluded)
{
	$HVVMBaseIncluded = $true

	$UtilityBase = Join-Path -Path $PSScriptRoot -ChildPath 'anutilitybase.ps1'
	if(-not (Test-Path -Path $UtilityBase))
	{
		Write-Host ('Required file {0} not found' -f $UtilityBase)
		exit 3
	}
	. $UtilityBase

	function Get-ANVMBaseVersion
	{
		New-Object System.Version(1, 0, 2, 0)
	}

	function Get-ANVMsAll
	{
		param(
			[Parameter()][String]$ComputerName = $env:COMPUTERNAME
		)
		Get-WmiObject -Namespace root\virtualization\v2 -Class Msvm_ComputerSystem -ComputerName $ComputerName
	}

	function Get-ANVMWmiObjectFromComputer
	{
		param(
			[Parameter(Position=1)][String]$ComputerName,
			[Parameter(ParameterSetName='By Name', Position=2)][String]$VMName,
			[Parameter(ParameterSetName='By ID')][String]$VMID
		)
		if($VMName)
		{
			$Filter = 'ElementName="{0}"' -f $VMName
		}
		elseif($VMID)
		{
			$Filter = 'Name="{0}"' -f $VMID
		}
		else
		{
			return
		}
		$GWMIParams = @{Namespace = 'root\virtualization\v2'; Class = 'Msvm_ComputerSystem'; Filter = $Filter; ErrorAction = ([System.Management.Automation.ActionPreference]::SilentlyContinue) }
		if($ComputerName -and $ComputerName -ne $env:COMPUTERNAME)
		{
			$GWMIParams.Add('ComputerName', $ComputerName)
		}
		Get-WmiObject @GWMIParams # -ComputerName $ComputerName -Namespace 'root\virtualization\v2' -Class 'Msvm_ComputerSystem' -Filter $Filter -ErrorAction SilentlyContinue
	}

	# will find ANY VM on the local host and any HA VM in the same cluster. will NOT find non-HA VMs on other nodes
	# if multiple VMs have the same name, will return whichever one that it wants to. I'm not sure how it decides. #sorrynotsorry
	function Get-ANVMWmiObject
	{
		param(
			[Parameter(Position=1)][String]$VMName
		)

		if(-not $VMName)
		{
			Write-Host 'No virtual machine name was supplied'
			Exit 2
		}

		# look locally first
		$VM = Get-ANVMWmiObjectFromComputer -ComputerName '.' -VMName $VMName
		if((-not $VM) -band (ANIsClustered))
		{
			$VMsOnOtherHosts = Get-WmiObject -Namespace root\MSCluster -Class MSCluster_Resource -Property OwnerNode, Id -Filter ('Type="Virtual Machine" AND NOT OwnerNode="{0}"' -f $env:COMPUTERNAME)
			$ClusterKey = $null

			try
			{
				$ClusterKey = [Microsoft.Win32.RegistryKey]::OpenBaseKey([Microsoft.Win32.RegistryHive]::LocalMachine, [Microsoft.Win32.RegistryView]::Default)
			}
			catch [System.Security.SecurityException], [System.UnauthorizedAccessException]
			{
				Write-Host ('NSClient++ user "{0}" cannot access the registry on "{1}"' -f $env:USERNAME, $OtherHostVM.OwnerNode, $env:COMPUTERNAME)
				Exit 2
			}
			catch
			{
				Write-Host ('Could not open registry on "{0}": {1}' -f $env:COMPUTERNAME, $_)
				Exit 2
			}

			foreach($OtherHostVM in $VMsOnOtherHosts)
			{
				try
				{
					$Subkey = $ClusterKey.OpenSubKey(('Cluster\Resources\{0}\Parameters' -f $OtherHostVM.Id), $false)
					$VMId = $Subkey.GetValue('VmID')
				}
				catch
				{
					Write-Host ('Could not open a cluster parameters key on "{0}": {1}' -f $env:COMPUTERNAME, $_)
					Exit 2
				}
				$Subkey.Close()
				$VM = Get-ANVMWmiObjectFromComputer -ComputerName $OtherHostVM.OwnerNode -VMID $VMId
				if($VM -ne $null -and $VM.ElementName -eq $VMName)
				{
					break
				}
				else
				{
					$VM = $null
				}
			}
		}
		if(-not $VM)
		{
			Write-Host ('Virtual machine "{0}" could not be found!' -f $VMName)
			Exit 2
		}
		$VM
	}

	function Get-ANVMIsClustered
	{
		param([Parameter(Position=1)][System.Management.ManagementObject]$VM)
		$IsClustered = $false
		$VMHostData = $VM.GetRelated('Msvm_VirtualSystemSettingData').GetRelated('Msvm_KvpExchangeComponentSettingData').HostOnlyItems
		foreach ($XMLKVPItem in $VMHostData)
		{
			$KVPKey = ([XML]$XMLKVPItem).SelectSingleNode('/INSTANCE/PROPERTY[@NAME=''Name'']/VALUE/child::text()').Value
			if($KVPKey -eq 'VirtualMachineIsClustered')
			{
				$KVPValue = ([XML]$XMLKVPItem).SelectSingleNode('/INSTANCE/PROPERTY[@NAME=''Data'']/VALUE/child::text()').Value
				$IsClustered = $KVPValue -eq 'TRUE'
			}
		}
		$IsClustered
	}
}