# encoding: ascii
# api: powershell
# title: Get-Parameter
# description: Get-Parameter is used to obtain all of the parameters for a cmdlet.  It also returns info like aliases and whether a parameter is mandatory.
# version: 0.1
# author: halr9000
# license: CC0
# x-poshcode-id: 3658
# x-archived: 2016-03-21T07:13:38
# x-published: 2013-09-23T02:54:00
#
# Updated 9/24 to work as a standalone script instead of a function
# Usage:
# Get-Parameter <Cmdlet Name>
# Revisions:
# 0.8 (halr9000)
# Does not show common params by default, added switch to override
# Added Position property
# 0.81 (halr9000)
# Added Type property
# Added WhatIf and Confirm to list of common params
# 0.90 (halr9000)
# Added Type (cool!) and two Pipeline properties
# Added Full switch, if enabled you get it all, otherwise…
# Pruned default output so that it fits better into a narrow table.
# Special one time bonus offer: Now includes “gpm” helper function!  This is just a sample scenario which I find useful.
# 0.91 (oisin/x0n)
# Added alias resolving (included nested aliases)
# If command not found, no longer returns a single empty parameter definition
# 0.92 (halr9000)
# Tweaked output of types to handle some ugly nullable generics and SwitchParameter now says Boolean which is more descriptive
#
param ( 
  $Cmdlet,
  [switch]$ShowCommon, 
  [switch]$Full
)

$command = Get-Command $Cmdlet -ea silentlycontinue 

# resolve aliases (an alias can point to another alias)
while ($command.CommandType -eq "Alias") {
	$command = Get-Command ($command.definition)
}
if (-not $command) { return }

foreach ($paramset in $command.ParameterSets){
	$Output = @()
	foreach ($param in $paramset.Parameters) {
		if ( ! $ShowCommon ) {
			if ($param.aliases -match "vb|db|ea|wa|ev|wv|ov|ob|wi|cf") { continue }
		}
		$process = "" | Select-Object Name, Type, ParameterSet, Aliases, Position, IsMandatory,
		Pipeline, PipelineByPropertyName
		$process.Name = $param.Name
		if ( $param.ParameterType.Name -eq "SwitchParameter" ) {
			$process.Type = "Boolean"
		}
		else {
			switch -regex ( $param.ParameterType ) {
				"Nullable``1\[(.+)\]" { $process.Type = $matches[1].Split('.')[-1] + " (nullable)" ; break }
				default { $process.Type = $param.ParameterType.Name }
			}
		}
		if ( $paramset.name -eq "__AllParameterSets" ) { $process.ParameterSet = "Default" }
		else { $process.ParameterSet = $paramset.Name }
		$process.Aliases = $param.aliases
		if ( $param.Position -lt 0 ) { $process.Position = $null }
		else { $process.Position = $param.Position }
		$process.IsMandatory = $param.IsMandatory
		$process.Pipeline = $param.ValueFromPipeline
		$process.PipelineByPropertyName = $param.ValueFromPipelineByPropertyName
		$output += $process
	}
	if ( ! $Full ) { 
		$Output | ft name,type,IsMandatory,pipeline -GroupBy parameterset -AutoSize
	}
	else { Write-Output $Output }
}
