<#
.SYNOPSIS
    Create folders with randomized content
.DESCRIPTION
    This script generates n random folders each limited to a size y in MB which are then filled randomly with files included in the filter
.NOTES
    Author: Jan-Hendrik Peters / www.janhendrikpeters.de
    Date:   2015-05-14
.PARAMETER SourcePath
    The source path of the files to be copied
.PARAMETER NumberOfFolders
    The number of folders to be created
.PARAMETER MaxFolderSizeInMB
    The maximum folder size in Megabyte
.PARAMETER OutputPath
    The target parent path within which the folders should be created
.PARAMETER FileFilter
    The file filter as required by the Get-ChildItem cmdlet
.PARAMETER WhatIf
    Use to test the copy action before
#>
param
(
    [Parameter(Mandatory=$true)]
    [ValidateScript({Test-Path $_ -PathType 'Container'})] 
    [string]$SourcePath = "Z:\Musik",
    [Parameter(Mandatory=$true)]
    [int]$NumberOfFolders = 6,
    [Parameter(Mandatory=$true)]
    [int]$MaxFolderSizeInMB = 650,
    [Parameter(Mandatory=$true)]
    [string]$OutputPath = "D:\GT_Music",
    [Parameter(Mandatory=$true)]
    [string]$FileFilter = "*.mp3",
    [switch]$WhatIf
)

[hashtable]$Files = @{}
[hashtable]$UsedRandoms = @{}

$Count = 0
Get-ChildItem -Path $SourcePath -Filter $FileFilter -Recurse | foreach{
$Files.Add($Count, $_)
$Count ++
}

if($Files.Count -eq 0)
{
    Write-Warning "No suitable files ($FileFilter) found in $SourcePath! Hint: Include wildcards (*) in your filter."
    exit 1
}

function Get-SuperRandom
{
param
($Minimum,$Maximum)
$Maximum = $Maximum + 1
$IsRandom = $false

if($UsedRandoms.Count -ge $Maximum)
{
    throw "Out of random numbers"
}

while(!$IsRandom)
{
    $Random = Get-Random -Minimum $Minimum -Maximum $Maximum
    if($UsedRandoms.ContainsKey($Random))
    {
        $IsRandom = $false
    }
    else
    {
        $IsRandom = $true
        $UsedRandoms.Add($Random, $true)
        Write-Output $Random
    }
}

}

if(!(Test-Path $OutputPath))
{
    try
    {
        $null = New-Item -ItemType Directory -Path $OutputPath -WhatIf:$WhatIf -ErrorAction Stop
    }
    catch
    {
        Write-Warning "Error creating output path $OutputPath. Exiting."
        exit 2
    }
}

foreach($CD in 1..$NumberOfFolders)
{
    $TargetPath = Join-Path $OutputPath $CD
    if(!(Test-Path $TargetPath))
    {
        try
        {
            $null = New-Item -ItemType Directory -Path $TargetPath -WhatIf:$WhatIf -ErrorAction Stop
        }
        catch
        {
            Write-Warning "Error creating output path $TargetPath. Exiting."
            exit 2
        }
    }
    $TotalSize = 0
    while($TotalSize -le $MaxFolderSizeInMB)
    {        
        try
        {
            $Rnd = Get-SuperRandom -Minimum 0 -Maximum $Files.Count
        }
        catch
        {
            $TotalSize = $MaxFolderSizeInMB + 12345
            continue
        }

        Write-Progress -Activity "Filling up CD $CD" -Status "Copying $($Files[$Rnd].Name)" -Id 666 -PercentComplete ($TotalSize/$MaxFolderSizeInMB*100)

        Copy-Item -Path ($Files[$Rnd].FullName) -Destination $TargetPath -ErrorAction SilentlyContinue -WhatIf:$WhatIf
        $TotalSize = $TotalSize + ([math]::Round($Files[$Rnd].Length / 1024 /1024))
    }
}