#requires -version 2.0

<#
 -----------------------------------------------------------------------------
 Script: HashCSVFunctions.txt
 Version: 0.9
 Author: Jeffery Hicks
    http://jdhitsolutions.com/blog
    http://twitter.com/JeffHicks
    http://www.ScriptingGeek.com
 Date: 2/2/2012
 Keywords: Hashtable, CSV, Export, Import
 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 Export-HashtoCSV {

<#
.Synopsis
Export a hashtable to a CSV file
.Description
This function will export a hash table to a CSV file. The function
will add a new column, Type, which will be the .NET type of each
value. This information is used with Import-CSVtoHash to properly
reconstitute the hash table.

.Parameter Path
The file name and path to the CSV file.

.Parameter Hashtable
The hash table object to export.

.Example
PS C:\> $myhash | Export-HashtoCSV MyHash.csv
PS C:\> get-contnet .\Myhash.csv
#TYPE Selected.System.Collections.DictionaryEntry
"Key","Value","Type"
"name","jeff","String"
"pi","3.14","Double"
"date","2/2/2012 8:53:58 AM","DateTime"
"size","3","Int32"

.Link
Import-CSVtoHash
Export-CSV

.Inputs
Hashtable
.Outputs
None

#>

[cmdletbinding(SupportsShouldProcess=$True)]

Param (
[Parameter(Position=0,Mandatory=$True,HelpMessage="Enter a filename and path for the CSV file")]
[ValidateNotNullorEmpty()]
[string]$Path,
[Parameter(Position=1,Mandatory=$True,HelpMessage="Enter a hashtable",
ValueFromPipeline=$True)]
[ValidateNotNullorEmpty()]
[hashtable]$Hashtable

)

Begin {
    Write-Verbose "Starting hashtable export"
    Write-Verbose "Exporting to $path"
}

Process {
    <#
      Add a column for the data type of each hash table entry.
      This can be used on import to properly reconstitute the
      hash table
    #>
    $hash.GetEnumerator() | 
    Select Key,Value,@{Name="Type";Expression={$_.value.gettype().name}} | 
    Export-Csv -Path $Path

}

End {
    Write-Verbose "Ending hashtable export"
}

} #end function

Function Import-CSVtoHash {

<#
.Synopsis
Import a CSV file and create a hash table
.Description
This function will import a CSV file of hash table data and recreate
the hash table object. Ideally the CSV file will have been created
with the Export-HashtoCSV function, bu you can import any CSV provided
it has Key and Value headings. If you include a Type heading, then the
values will be cast to that type.

"Key","Value","Type"
"name","jeff","String"
"pi","3.14","Double"
"date","2/2/2012 8:53:58 AM","DateTime"
"size","3","Int32"

.Parameter Path
The file name and path to the CSV file.

.Example
PS C:\> $h=Import-CSVtoHash MyHash.csv
PS C:\> $h
Name                           Value
----                           -----
name                           jeff
pi                             3.14
date                           2/2/2012 8:53:58 AM
size                           3

.Link
Export-HashtoCSV
Import-CSV

.Inputs
String
.Outputs
Hashtable

#>

[cmdletbinding()]

Param (
[Parameter(Position=0,Mandatory=$True,HelpMessage="Enter a filename and path for the CSV file")]
[ValidateNotNullorEmpty()]
[ValidateScript({Test-Path -Path $_})]
[string]$Path
)

Write-Verbose "Importing data from $Path"

Import-Csv -Path $path | ForEach-Object -begin {
     #define an empty hash table
     $hash=@{}
    } -process {
       <#
       if there is a type column, then add the entry as that type
       otherwise we'll treat it as a string
       #>
       if ($_.Type) {
         
         $type=[type]"$($_.type)"
       }
       else {
         $type=[type]"string"
       }
       Write-Verbose "Adding $($_.key)"
       Write-Verbose "Setting type to $type"
       
       $hash.Add($_.Key,($($_.Value) -as $type))

    } -end {
      #write hash to the pipeline
      Write-Output $hash
    }

write-verbose "Import complete"

} #end function