#requires -version 2.0

#Jeffery Hicks
#Twitter: @JeffHicks
#http://jdhitsolutions.com/blog
#To learn more about PowerShell check out :
#  Windows PowerShell 2.0: TFM


#  ****************************************************************
#  * 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 Export-Function { 
 

<#
.Synopsis
Export a PowerShell function to a file.
.Description
Get a Windows PowerShell function and export it to a file. You can export functions
individually, each to its own file, or you can export them to the same file using
-Append. By default the filename will be a PowerShell script file with the same 
name as the function, but you can specify an alternate name. See examples.
.Parameter Name
The name of the function to export.
.Parameter Path
The folder for the exported function. 
.Parameter Filename
The filename for the exported function. The default is the function name.
.Parameter Append
Write each function to the same file.
.Example
PS C:\> Export-Function "MyFunction"

This will export the MyFunction function to a script file called MyFunction.ps1.
.Example
PS C:\> dir function:*ISE* | Export-Function -path c:\export -filename ISEFunctions.psm1 -append

Get all functions with ISE in the name and export them to a module file C:\export\ISEFunctions.psm1
.Inputs
Strings for function names
.Outputs
None
.Link
About_Functions
Function (provider)
Get-Command

.Notes
VERSION: 1.1

This function supports cmdlet binding so you can use -Verbose and -Whatif.
#>

[cmdletbinding(SupportsShouldProcess=$True)]

Param(
[Parameter(Position=0,Mandatory=$true,ValueFromPipeline=$True,
HelpMessage="Enter the name of a current function to export")]
[ValidateNotNullorEmpty()]
[string]$name,

[Parameter(Position=1,HelpMessage="Enter the folder to store the file.")]
[ValidateScript({Test-path $_})]
[string]$path="C:\scripts",

[Parameter(Position=2,
HelpMessage="Enter the name of the file to create. The default is the function name.")]
[ValidateNotNullorEmpty()]
[string]$filename="$name.ps1",

[switch]$append
)
begin {

        Write-Verbose "Starting $($myinvocation.mycommand)"
        #initialize a counter
        $i=0
    
}
process {

        #verify function exists
        try {
            $myfunction=Get-Command -Name $name -ErrorAction "Stop"
        }
        catch {
            Write-Warning "Failed to find function $name"
            Return
        }
        
        #function found so continue
        if ($myFunction) {
                        
            #strip out illegal filename characters from function name
            [regex]$r="[:/\\]"
        
            if ($r.matches($filename)[0]) {
                Write-Verbose "Removing illegal filename characters from $filename"
                $r.matches($filename) | foreach {
                 $filename=$filename.replace($_.value,"")
                }
            } #if $r.matches
            
            $filepath=Join-Path -Path $path -ChildPath $filename
           
#this command needs to be left justifie so the final result is nicely
#formatted
$output=@(
"{0} {1} {2} 
 {3} 
{4} #end function

###############################################################################

" -f $myFunction.CommandType,$myFunction.name,"{",$myFunction.definition,"}")
            
          if ($pscmdlet.ShouldProcess($name)) {
            #increment the counter by 1
            $i++
            if ($append) {
                write-Verbose "Exporting and appending to $filepath"
            $output | Out-File -FilePath $filepath -Append
            }
            else {
                Write-Verbose "Exporting $name to $filepath"
                $output | Out-File -FilePath $filepath
            }
           } #if shouldprocess
        } #if $myFunction
        
    
}
end {

        Write-Verbose "Ending $($myinvocation.mycommand)"
        Write-Host "Exported $i functions" -ForegroundColor Green
    
}
 
} #end function