#requires -version 2.0

# Jeffery Hicks
# http://jdhitsolutions.com/blog
# follow on Twitter: http://twitter.com/JeffHicks
#
# 
# "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-Parameter {

<#
.Synopsis
    Retrieve command parameter information.
.Description
    Using Get-Command, this function will return information about parameters 
    for any loaded cmdlet or function. The common parameters like Verbose and
    ErrorAction are omitted. Get-Parameter returns a custom object with the most
    useful information an administrator might need to know. Here is an example:
    
    Position          : 0
    Name              : Name
    Type              : System.String[]
    Aliases           : {ServiceName}
    ValueFromPipeline : True
    Mandatory         : False
    ParameterSet      : Default

.Parameter Command
    The name of a cmdlet or function. The parameter has an alias of Name.
.Example
    PS C:\> get-parameter get-service

    Return parameter information for get-service
.Example
PS C:\Scripts> get-parameter mkdir | select Name,type 
Found 6 specific parameters for mkdir

Name                        Type
----                        ----
Path                        System.String[]
Name                        System.String
Value                       System.Object
Force                       System.Management.Automation.SwitchParameter
Credential                  System.Management.Automation.PSCredential
UseTransaction              System.Management.Automation.SwitchParameter
.Example
PS C:\Scripts> get-parameter get-wmiobject | sort parameterset | format-table -GroupBy ParameterSet -Property Name,Alias,Position,Type -autosize
Found 18 non-common parameters for get-wmiobject


   ParameterSet: __AllParameterSets

Name          Alias Position Type
----          ----- -------- ----
ThrottleLimit                System.Int32
Amended                      System.Management.Automation.SwitchParameter
AsJob                        System.Management.Automation.SwitchParameter


   ParameterSet: class

Name          Alias Position Type
----          ----- -------- ----
Locale                       System.String
Impersonation                System.Management.ImpersonationLevel


   ParameterSet: list

Name         Alias Position Type
----         ----- -------- ----
Namespace                   System.String
ComputerName                System.String[]
Authority                   System.String
List                        System.Management.Automation.SwitchParameter
Recurse                     System.Management.Automation.SwitchParameter


   ParameterSet: query

Name                Alias Position Type
----                ----- -------- ----
Filter                             System.String
Property                  1        System.String[]
Class                     0        System.String
EnableAllPrivileges                System.Management.Automation.SwitchParameter
DirectRead                         System.Management.Automation.SwitchParameter


   ParameterSet: WQLQuery

Name           Alias Position Type
----           ----- -------- ----
Query                         System.String
Credential                    System.Management.Automation.PSCredential
Authentication                System.Management.AuthenticationLevel

.Inputs
    [string]
.Outputs
    custom object
.Link
    http://jdhitsolutions.com/blog/2010/07/get-parameter
.Link
    Get-Command
    
.Notes
 NAME:      Get-Parameter
 VERSION:   1.2
 AUTHOR:    Jeffery Hicks
 LASTEDIT:  July 20, 2010
 
 Learn more with a copy of Windows PowerShell 2.0: TFM (SAPIEN Press 2010)
 #>

Param(
[Parameter(Position=0,Mandatory=$True,
ValueFromPipeline=$True,ValueFromPipelineByPropertyName=$True,
HelpMessage="Enter a cmdlet name")]
[ValidateNotNullorEmpty()]
[Alias("name")]
[string]$command
)

Process {
    #define the set of common parameters to exclude
    $common=@("Verbose",
    "Debug",
    "ErrorAction",
    "ErrorVariable",
    "WarningAction",
    "WarningVariable",
    "OutVariable",
    "OutBuffer",
    "WhatIf",
    "Confirm")

    Try {
        $data=(Get-Command -Name $command -errorAction "Stop").parameters
    }
    Catch {
        Write-Warning "Failed to find command $command"
    }
    #keep going if parameters were found
    if ($data.count -gt 0) {
        #$data is a hash table
        $params=$data.keys | where {$common -notcontains $_} 
        $count=($params | measure-object).count
        #only keep going if non-common parameters were found
        write-host "Found $count non-common parameters for $command" `
        -ForegroundColor Green
        
        if ($count -gt 0) {
            #get information from each parameter
            
            $params | foreach {
                $name=$_
                $type=$data.item($name).ParameterType
                $aliases=$data.item($name).Aliases
                $attributes=$data.item($name).Attributes
                if ($attributes[0].position -ge 0) {
                    $position=$attributes[0].position
                  }
                else {
                    $position=$null
                }
                #write a custom object to the pipeline    
                New-Object -TypeName PSObject -Property @{
                    Name=$name
                    Aliases=$aliases
                    Mandatory=$attributes[0].mandatory
                    Position=$position
                    ValueFromPipeline=$attributes[0].ValueFromPipeline
                    Type=$type
                    ParameterSet=$attributes[0].ParameterSetName
                } 
            } #foreach
        } #if $count
     } #if $data
     else {
        Write-Host "$command has no defined parameters" -ForegroundColor Red
     }
 } #process
} #end function

#uncomment if you also want to define the alias
#Set-Alias -Name gpa -Value Get-Parameter