#requires -version 2.0
###################################################################################################
## A Template for Script Cmdlets which can _also_ be executed in the pipeline ....
##   by Joel Bennett, in hopes it will help...
## Version History
## v1.0 - First public release (after over 9 different versions in my various other functions)
## v1.2 - Show the use of Write-Output, and change "return" in the BEGIN to "Write-Output" to avoid
##      the pooling of the output from the process block when it's invoked as a function.
## v1.3 - Switched back to "break" instead of "return" so that if you pass via the pipeline AND via
##      the inputObject, only the inputObject gets process (this is how cmdlets behave).
##      - Cleaned up the comments, and removed the confusing alternate method and $args handling
##
## v2.0 - First Version as a Script Cmdlet. 
##      This is much easier with support for [ValueFromPipeline] and [ValueFromPipelineByName] 
##
###################################################################################################



Cmdlet Test-PipelineV2 -ConfirmImpact low -snapin Huddled.Tests
{
   Param (
      [Position(0)] [ConsoleColor] $Color,
      [Position(1)] [Mandatory] [ValueFromPipeline] [String[]] $InputObject
   )
   BEGIN {
      if ($CommandLineParameters.ContainsKey("InputObject")) {
         # Don't do anything here, because we're about to get re-invoked...
         $FromArgs = $true
      } else {
         # Normal "run-once" BEGIN processing
         $FromArgs = $false
         Write-Verbose "Begin $Color"
      }
   }
   PROCESS {
      # We no longer have to test for $_ or even to see if the [ValueFromPipeline] param is set
      # It *HAS* to be set, because it's a [Mandatory] parameter :)
      if ($FromArgs) {
         # Don't do anything here except re-invoke ourselves.
         Write-Output $InputObject | &($MyInvocation.InvocationName) $Color
      } else { 
         # Normal Pipeline-friendly per-item processing
         Write-Host "Process: $InputObject" -Fore $Color
         ## You should make a practice of explicitly calling Write-Output on things
         ## That's how you emit them into the pipeline instead of just printing them
         Write-Output $InputObject
      }
   }
   END {
      if ($FromArgs) {  
         # Don't do anything here ... it just confuses things
      } else {
         # Normal "run-once" END processing
         Write-Verbose "End $Color"
      }
   }
}
###################################################################################################
## Test Script:
##
## "a","b","c" | Test-PipelineV2 "Cyan" -verbose
## @("a","b","c") | Test-PipelineV2 "Cyan" -verbose
## Test-PipelineV2 "Cyan" @("a","b","c") -verbose 
## 
## "a","b","c" | Test-PipelineV2 "Cyan" -verbose | Test-PipelineV2 "Green" -verbose
## @("a","b","c") | Test-PipelineV2 "Cyan" -verbose | Test-PipelineV2 "Green" -verbose
## Test-PipelineV2 "Cyan" @("a","b","c") -verbose  | Test-PipelineV2 "Green" -verbose
## 
###################################################################################################
## Expected Output:
##
## [PS]> .\Test.ps1
## VERBOSE: Begin Cyan
## Process: a
## a
## Process: b
## b
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: Begin Cyan
## Process: a
## a
## Process: b
## b
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: Begin Cyan
## Process: a
## a
## Process: b
## b
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: Begin Cyan
## VERBOSE: Begin Green
## Process: a
## Process: a
## a
## Process: b
## Process: b
## b
## Process: c
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: End Green
## VERBOSE: Begin Cyan
## VERBOSE: Begin Green
## Process: a
## Process: a
## a
## Process: b
## Process: b
## b
## Process: c
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: End Green
## VERBOSE: Begin Green
## VERBOSE: Begin Cyan
## Process: a
## Process: a
## a
## Process: b
## Process: b
## b
## Process: c
## Process: c
## c
## VERBOSE: End Cyan
## VERBOSE: End Green