#Requires -version 2.0

#First Run issues
# -----------------------------------------------------------------------------
#Restricted - No scripts can be run. Windows PowerShell can be used only in interactive mode.
#AllSigned - Only scripts signed by a trusted publisher can be run.
#RemoteSigned - Downloaded scripts must be signed by a trusted publisher before they can be run.
#Unrestricted - No restrictions; all Windows PowerShell scripts can be run.
#
#Set-ExecutionPolicy Unrestricted
#Set-ExecutionPolicy “Unrestricted” -Scope CurrentUser -Confirm:$false
#
#$PSVersionTable.PSVersion get current version
# -----------------------------------------------------------------------------

#Reference Links
#https://msdn.microsoft.com/en-us/library/aa394394(v=vs.85).aspx
#https://books.google.ca/books?id=DD1jA3RgFEMC&pg=PA216&lpg=PA216&dq=Win32_Registry+currentSize&source=bl&ots=FOBI7NUgEQ&sig=zLw5f5i9VGpeHnie0Z05vuBDLco&hl=en&sa=X&ved=0ahUKEwjmyfrx1d3NAhVowYMKHUVtC2cQ6AEINTAE#v=onepage&q=Win32_Registry%20currentSize&f=false
# size in MB

# -----------------------------------------------------------------------------
# Script: get-RegistrySizeAge.ps1
# Version: 1.2017.05.03
# Author: Mark Pahulje
#    http://metadataconsulting.blogspot.com/
# Date: 08-Apr-2017
# Keywords: Registry, WMI, Size, Age
# Comments:
#
# "Those who forget to script are doomed to repeat their work."
#
#  ****************************************************************
#  * 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.             *
#  ****************************************************************
# -----------------------------------------------------------------------------

Function get-RegistrySizeAge {

<#
.SYNOPSIS
Get registry size, status, utilization and age
.DESCRIPTION
This command uses WMI to retrieve size and status information for the Windows registry. Sizes are provided in MB. This version has no provision for alternate credentials.
.PARAMETER Computername
The name of a computer to query. The default is the local host.
.EXAMPLE
PS C:\> get-RegistrySizeAge

Computername : SERENITY
Status       : OK
CurrentSize  : 185
MaximumSize  : 2048
FreeSize     : 1863
PercentFree  : 90.966796875
Created      : 1/28/2011 4:12:23 PM
Age          : 95.17:40:14.1730245

Return registry usage information for the local host.
.EXAMPLE
PS C:\> Get-Content Computers.txt | Get-Registry | Export-CSV c:\work\RegistryReport.csv
Retrieve registry usage information for all the computers in the text file, computers.txt. The results
are exported to a CSV file.
.NOTES
NAME        :  get-RegistrySizeAge
VERSION     :  1.2017.05.03
LAST UPDATED:  5/3/2017
AUTHOR      :  Mark Pahulje
.LINK
http://metadataconsulting.blogspot.ca/2016/07/windows-10-registry-size-number-of-keys-number-of-key-value-pairs.html
.LINK
Get-WMIObject
.INPUTS
String
.OUTPUTS
A custom object
#>

[cmdletbinding()]

Param (
[Parameter(Position=0,ValueFromPipeline=$True,ValueFromPipelineByPropertyName=$True)]
[ValidateNotNullorEmpty()]
[String[]]$Computername=$env:Computername
)

Begin {
    Write-Verbose "Starting $($myinvocation.mycommand)"
} #Begin


    #@{Name="Computername";Expression={$_.__SERVER}},
Process {

Write-Host "`r`nGet Registry Age and Size running on " (Get-WmiObject -class Win32_OperatingSystem).Caption -BackgroundColor Red

    Foreach ($computer in $computername) {
        Write-Verbose "Processing $computer"
        Try {
         #retrieve registry information via WMI
         $data=Get-WmiObject -Class Win32_Registry -ComputerName $computer -ErrorAction Stop

         #direct call to .NET library
         [datetime]$InstallDateMngmtDTC = [System.Management.ManagementDateTimeConverter]::ToDateTime(($data).InstallDate)

         Add-Member -InputObject $data -MemberType NoteProperty -Name InstallDateMngmtDTC -Value $InstallDateMngmtDTC

         #Format the results and write an object to the pipeline
         #All members here https://msdn.microsoft.com/en-us/library/aa394394(v=vs.85).aspx

         $data | Select-Object -Property @{Name="Registry Name";Expression={$_.Name}},
         @{Name="Registry Status";Expression={$_.Status}},
         #@{Name="Registry Description";Expression={$_.Description}},
         #@{Name="Registry Caption";Expression={$_.Caption}},
         @{Name="Current Size";Expression={"{0:N0} Mb" -f ($_.CurrentSize)}},
         @{Name="Free Size";Expression={"{0:N0} Mb" -f ($_.MaximumSize - $_.CurrentSize)}},
         @{Name="Maximum Size";Expression={"{0:N0} Mb" -f ($_.MaximumSize)}},
         @{Name="Percent Used";Expression={"{0:N1} %" -f ( $_.CurrentSize/$_.MaximumSize*100 )}},
         @{Name="Percent Free";Expression={"{0:N1} %" -f ( (1 - ($_.CurrentSize/$_.MaximumSize))*100 )}},
         @{Name="Created";Expression={$_.ConvertToDateTime($_.InstallDate)}},
         @{Name="Age";Expression={(Get-Date) - ( $_.ConvertToDateTime($_.InstallDate)) }},
         @{Name="Age Formatted";Expression={"{1:N0} years, {2:N0} months, {3:N0} days & {0:hh} hours, {0:mm} mins, {0:ss} secs, {0:fff}  msecs" -f (  ((Get-Date) - ($_.InstallDateMngmtDTC)), [Math]::Truncate( (((Get-Date) - ($_.InstallDateMngmtDTC)).Days/365.2425) ), [Math]::Truncate( ((((Get-Date) - ($_.InstallDateMngmtDTC)).Days%365.2425)/30.436875)),  ((((Get-Date) - ($_.InstallDateMngmtDTC)).Days%30.436875))   ) }}

        } #try

        Catch {
            Write-Warning "Failed to retrieve registry information from $($Computer.ToUpper())"
            Write-Warning $_.Exception.Message
        }#Catch

    }#foreach $computer
} #Process

End {
    Write-Verbose "Ending $($myinvocation.mycommand)"
} #End

} #end function

get-RegistrySizeAge