#requires -version 3.0

<#
.Synopsis
Re-import VM from XML config using existing drive locations.
.Description
This script will read the XML configuration file from a Hyper-V backup or saved
virtual machine configuration file and recreate the virtual machine in place 
using the existing VHD or VHDX files. It is assumed that everything remains in
place but that the virtual machine was removed from inventory and you want to
restore it in place, without resorting to restoring from a backup.
.Parameter Path
The path to the XML Hyper-V configuration file.
.Parameter vmPath
The alternate location for the virtual machine.
.Example
PS C:\> dir e:\backup\*.xml | c:\scripts\import-VMConfig.ps1
.Link
New-VM
Set-VM
Add-VMHardDiskDrive
Set-VMDvdDrive
Get-Content
.Notes
Last Updated: March 12, 2013
Author      : Jeffery Hicks (@JeffHicks)
version     : 1.0

  ****************************************************************
  * DO NOT USE IN A PRODUCTION ENVIRONMENT UNTIL YOU HAVE TESTED *
  * THOROUGHLY IN A LAB ENVIRONMENT. USE AT YOUR OWN RISK.  IF   *
  * YOU DO NOT UNDERSTAND WHAT THIS SCRIPT DOES OR HOW IT WORKS, *
  * DO NOT USE IT OUTSIDE OF A SECURE, TEST SETTING.             *
  ****************************************************************
#>

[cmdletbinding(SupportsShouldProcess)]


Param(
[Parameter(Position=0,Mandatory=$True,HelpMessage="Enter the path to the XML configuration file",
ValueFromPipeline,ValueFromPipelineByPropertyname)]
[ValidateScript({Test-Path $_})]
[alias("fullname")]
[string]$Path,
[ValidateScript({Test-Path $_})]
[string]$vmPath
)

Process {
Write-Verbose "Creating VM from $Path"

[xml]$vmconfig = Get-Content -Path $Path

$name = $vmconfig.configuration.properties.name.'#text'

Write-Host "Importing virtual machine $name from $path" -ForegroundColor Yellow
$processors = $vmconfig.configuration.settings.processors.count.'#text'
$memory = (Select-Xml -xml $vmconfig -XPath "//memory").node.Bank
if ($memory.dynamic_memory_enabled."#text" -eq "True") {
    $dynamicmemory = $True
}
else {
    $dynamicmemory = $False
}

#memory values need to be in bytes
$MemoryMaximumBytes = ($memory.limit."#text" -as [int]) * 1MB
$MemoryStartupBytes = ($memory.size."#text" -as [int]) * 1MB
$MemoryMinimumBytes = ($memory.reservation."#text" -as [int]) * 1MB

#get the name of the virtual switch
$switchname = (Select-Xml -xml $vmconfig -XPath "//AltSwitchName").node."#text"

#determine boot device
Switch ((Select-Xml -xml $vmconfig -XPath "//boot").node.device0."#text") {
"Floppy"    { $bootdevice = "floppy" }
"HardDrive" { $bootdevice = "IDE" }
"Optical"   { $bootdevice = "CD" }
"Network"   { $bootdevice = "LegacyNetworkAdapter" }
"Default"   { $bootdevice = "IDE" }
} #switch

#define a hash table of parameter values for New-VM
$newVMParams = @{
 Name = $name
 NoVHD = $True
 MemoryStartupBytes = $MemoryStartupBytes
 SwitchName = $switchname
 BootDevice = $bootdevice
 ErrorAction = "Stop"
}

#use the default path unless otherwise specified
if ($vmPath) {
    $newVMParams.Add("Path",$vmPath)
}

Write-Verbose "Creating new virtual machine"
Write-Verbose ($newVMParams | Out-String)

Try {
    #create the VM using the "old" values
    $vm = New-VM @newVMParams 
}
Catch {
    Write-Warning "Failed to recreate virtual machine $name"
    Write-Warning $_.Exception.Message
    #bail out
    Return
}

$notes = (Select-Xml -xml $vmconfig -XPath "//notes").node.'#text'

#Set-VM parameters to configure new VM with old values
$SetVMParams = @{
    ProcessorCount = $processors
    MemoryStartupBytes = $MemoryStartupBytes
}

If ($dynamicmemory) {
    $SetVMParams.Add("DynamicMemory",$True)
    $SetVMParams.Add("MemoryMinimumBytes",$MemoryMinimumBytes)
    $SetVMParams.Add("MemoryMaximumBytes", $MemoryMaximumBytes)
    
}
else {
    $setVMParams.Add("StaticMemory",$True)
}

if ($notes) {
 $SetVMParams.Add("Notes",$notes)
}

Write-Verbose "Setting VM values"
Write-Verbose ( $SetVMParams | out-string)
#set the values on the VM
$vm | Set-VM @SetVMParams -Passthru

<#
These items are not found in the xml file and
may have to be manually configured:

SmartPagingFilePath 
AutomaticStartAction
AutomaticStopAction
AutomaticStartDelay
SnapshotFileLocation
AllowUnverifiedPaths
#>

#Add drives to the virtual machine
$controllers = Select-Xml -xml $vmconfig -xpath "//*[starts-with(name(.),'controller')]"
#a regular expression pattern to pull the number from controllers
[regex]$rx="\d"

foreach ($controller in $controllers) {
  $node = $controller.Node
  Write-Verbose "Processing $($node.Name)"
  #Check for SCSI 
  if ($node.ParentNode.ChannelInstanceGuid) {
     $ControllerType = "SCSI"
  }
  else {
     $ControllerType = "IDE"
  }
  
  $drives = $node.ChildNodes | where {$_.pathname."#text"}
  if (-Not $drives) {
    Write-Verbose "No configured drives found"
  }

  foreach ($drive in $drives) {   
      #if drive type is ISO then set DVD Drive accordingly
      $driveType=$drive.type."#text"
      $VHDPath = $drive.pathname."#text"
      Write-Verbose $VHDPath
      $addDriveParam = @{
        ControllerNumber = $rx.Match($controller.node.name).value
        Path = $VHDPath
      }  
        if ($drive.pool_id."#text") {
          $ResourcePoolName = $drive.pool_id."#text"
          $addDriveParam.Add("ResourcePoolname",$ResourcePoolName)
        }
               
        if ($drivetype -eq 'ISO') {
            Write-Verbose "Setting DVD drive"
            Write-Verbose ($AddDriveParam | out-string)
            #Set-VMDvdDrive doesn't support Whatif so I have to add it
            if ($Pscmdlet.ShouldProcess($VHDPath)) {
                Set-VMDvdDrive -vmname $vm.name @addDriveParam
            }
        }
        else {
            $addDriveParam.add("ControllerType",$ControllerType)
            Write-Verbose "Adding hard disk drive"
            Write-Verbose ($AddDriveParam | out-string)
            $vm | Add-VMHardDiskDrive @AddDriveparam
        }
  } #foreach drive

} #foreach controller

Write-Verbose "Finished processing controllers"

} #process

#end of script