[CmdletBinding()]
Param(
    [Parameter(Mandatory = $True, Position = 1)]
    [string]$sourcePath,
    [Parameter(Mandatory = $True, Position = 2)]
    [string]$targetPath,
    [Parameter(Mandatory = $True, Position = 3)]
    [string]$password
)

$enginePath = "C:\Program Files (x86)\PDFtk\bin\pdftk.exe"

function EncryptFiles($path = $pwd, [string[]]$exclude)
{
    foreach ($item in Get-ChildItem $path)
    {
        if ($exclude | Where {$item -like $_})
        {
            continue
        }
        if (Test-Path $item.FullName -PathType Container)
        {
            $target = $item.FullName.Replace($sourcePath, $targetPath)
            if (!(Test-Path $target))
            {
                New-Item -ItemType directory -Path $target | Out-Null
            }
            EncryptFiles $item.FullName $exclude
        }
        else
        {
            if ($item.Extension.Equals(".pdf"))
            {
                $oldItem = $item.FullName
                $newItem = $oldItem.Replace("$sourcePath", "$targetPath")
                & "$enginePath" $oldItem output $newItem owner_pw $password 2>&1 | Out-Null
                if ($LASTEXITCODE -eq 1)
                {
                    Write-Host "An error occured while processing file: $item" -ForegroundColor Red
                    $error
                }
                else
                {
                    Write-Host "Successfully secured file: $item" -ForegroundColor Green
                }
            }
        }
    }
}

Write-Host "PDF encryption script" -ForegroundColor Green

if (!(Test-Path -Path $enginePath))
{
    Write-Host "Error: pdftk engine not installed" -ForegroundColor Red
    return
}

if (-not $sourcePath)
{
    Write-Host "Error: please provide source directory" -ForegroundColor Red
    return
}
if (!(Test-Path $sourcePath))
{
    Write-Host "Error: source directory does not exist"
    return
}
$sourcePath = (Get-Item -Path $sourcePath).FullName


if (-not $targetPath)
{
    Write-Host "Error: please provide target directory" -ForegroundColor Red
    return
}
if (-not $sourcePath.EndsWith("\"))
{
    $sourcePath = $sourcePath + "\";
}
if (-not $targetPath.EndsWith("\"))
{
    $targetPath = $targetPath + "\";
}

EncryptFiles $sourcePath
Write-Host "All done" -ForegroundColor Green