Modify XML files with PowerShell (for manipulating AppV)

#===================================CHANGE OS VALUE===========================================
#
#   By Trentent Tye 2012-12-19
#
#   This script will find all the applications in TEST and PROD and query the user to
#   which application they want to change the OS VALUE in the OSD file.  You will be given
#   four options.  1 - Remove any OS VALUE from the file, 2 - Set an OS VALUE,
#    4 - Get current value (if exists)
#
#
#
#
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#

#=====================================================================================
#=====================================================================================

#setting up variables
$APPV_Packages_Path = "\\jeeves\appv_images"

#Which environment to change?
$caption = "Choose Action";
$message = "Modify OS VALUE for which type of application?";
$Prod = new-Object System.Management.Automation.Host.ChoiceDescription "&Prod","Prod";
$Test = new-Object System.Management.Automation.Host.ChoiceDescription "&Test","Test";
$choices = [System.Management.Automation.Host.ChoiceDescription[]]($Test,$Prod);
$answer = $host.ui.PromptForChoice($caption,$message,$choices,0)
 
switch ($answer){
    0 {"You entered Test"; $Env = "TEST"}
    1 {"You entered Prod"; $Env = "PROD"}
}

#=====================================================================================
#=====================================================================================

#get list of applications (osd files) and put into a dictionary and
#display the key-value combos for user to enter a number
#if the user does not enter a correct choice, show the screen again.
Clear-Host
$completedsuccessfully = $TRUE
do {
$list = dir $APPV_Packages_Path\$ENV -include *.osd -recurse | Select-Object -ExpandProperty Name  | sort
$n = 0

#create a dictionary and put all the OSD files into it and add a numerical value to each one
$dict = New-Object 'System.Collections.Generic.Dictionary[String,String]'

foreach ($i in $list) { 
$n++
$dict.Add("$n","$i")
}

#format the dictionary nicely...
$dict | ft -auto

$appChoice = read-host -Prompt "Please select an application"
$appName = $dict.Get_Item("$appChoice")
if ($?) {
   $completedsuccessfully = $TRUE
   } else {
   Clear-Host
   Write-Host "An invalid choice (" -nonewline; Write-Host "$appChoice" -f Red -nonewline; Write-Host ") was selected";
   $completedsuccessfully = $FALSE
   }
} until ($completedsuccessfully)
Write-Host "You selected '" -nonewline; Write-Host "$appName" -f Yellow -nonewline; Write-Host "'";

#=====================================================================================
#=====================================================================================
#Setup functions for the next section

function GetOSValue() {
    #get the path to the OSD file
    #Get OSD file as an XML
    $OSDFile = dir $APPV_Packages_Path\$ENV -include $appName -recurse
    [xml]$OSD = Get-Content "$OSDFile"
    Write-host "======================================================================"
    Write-host ""
    Write-host "Application: " -nonewline; write-host "$appName" -f Yellow;
    $OSD.SOFTPKG.IMPLEMENTATION.OS | fl | Out-String
    Write-host "======================================================================"
}

function RemoveOSValue() {
    #get the path to the OSD file
    #Get OSD file as an XML
    $OSDFile = dir $APPV_Packages_Path\$ENV -include $appName -recurse
    [xml]$OSD = Get-Content "$OSDFile"
    Write-host "======================================================================"
    Write-host ""
    Write-host "Application: " -nonewline; write-host "$appName" -f Yellow;
    Write-host "" ; write-host "Original value:"
    $OSD.SOFTPKG.IMPLEMENTATION.OS | fl
    Write-Host "Removing ALL OS Value(s)..."

    #select OS node from the XML file  
    #remove the node, continue until no more OS Values exist
    try {
        do {
            $node = $OSD.SelectSingleNode("//SOFTPKG/IMPLEMENTATION/OS")
            [Void]$node.ParentNode.RemoveChild($node)
        } until ( $? -eq $FALSE )
    } catch {
        write-host "Complete"
        write-host ""
    }



    #backup the original file
    $File = dir $APPV_Packages_Path\$ENV -include $appName -recurse
    $fileObj = get-item $File

    # Get the date
    $DateStamp = get-date -uformat "%Y-%m-%d@%H-%M-%S"

    #make our backup
    copy "$File" "$File-$DateStamp"

    # Display the new name
    "Backup filename: $File-$DateStamp"

    #save our file 
    $osd.Save($OSDfile)
    

    Write-host "======================================================================"
}

function SetOSValue() {
    #get the path to the OSD file
    #Get OSD file as an XML
    $OSDFile = dir $APPV_Packages_Path\$ENV -include $appName -recurse
    [xml]$OSD = Get-Content "$OSDFile"
    Write-host "======================================================================"
    Write-host ""
    Write-host "Application: " -nonewline; write-host "$appName" -f Yellow;
    write-host ""
    Write-Host "Setting OS Value..."
    #select OS node from the XML file  
    # Creation of a nod ans his text
    $xmlElt = $OSD.CreateElement("OS")
    # Creation of an attribute in the principal nod
    $xmlAtt = $OSD.CreateAttribute("VALUE")

    #ask which OS you'd like
    $caption = "Choose Action";
    $message = "Which OS do you want to deploy this app?";
    $2003 = new-Object System.Management.Automation.Host.ChoiceDescription "&3 - 2003 R2 x32","2003 R2 x32";
    $2008 = new-Object System.Management.Automation.Host.ChoiceDescription "&8 - 2008 R2 x64","2008 R2 x64";
    $choices = [System.Management.Automation.Host.ChoiceDescription[]]($2003,$2008);
    $answer = $host.ui.PromptForChoice($caption,$message,$choices,0)
 
    switch ($answer){
        0 {$xmlAtt.Value = "Win2003TS"}
        1 {$xmlAtt.Value = "Win2008R2TS64"}
    }

    
    # Appending the attribute to the element
    $xmlElt.Attributes.Append($xmlAtt)
    # Appending the new element to the proper location
    [void]$OSD.SOFTPKG.IMPLEMENTATION.AppendChild($xmlElt)


    $osd.Save($OSDfile)
    

    Write-host "======================================================================"
}


#=====================================================================================
#=====================================================================================

#What would they like to do to the file?
function action() {
$caption = "Choose Action";
$message = "Modify OS VALUE for which type of application?";
$1 = new-Object System.Management.Automation.Host.ChoiceDescription "&1 Remove OS VALUE","Remove OS VALUE";
$2 = new-Object System.Management.Automation.Host.ChoiceDescription "&2 Set an OS VALUE","Set an OS VALUE";
$3 = new-Object System.Management.Automation.Host.ChoiceDescription "&3","";
$4 = new-Object System.Management.Automation.Host.ChoiceDescription "&4 Get current OS VALUE","Get current OS VALUE";
$choices = [System.Management.Automation.Host.ChoiceDescription[]]($1,$2,$3,$4);
$answer = $host.ui.PromptForChoice($caption,$message,$choices,3)
 
switch ($answer){
    0 {RemoveOSValue;exit}
    1 {RemoveOSValue;SetOSValue;exit}
    2 {Write-Host "Incorrect Option, please try again"}
    3 {GetOSValue}
  }
}

#loop forever
$loop = 1
do {action} until ($loop = 0)