param(
  [Parameter(Mandatory=$true)][string]$Directory,
  [Parameter(Mandatory=$true)][string]$Output
)

Add-Type -AssemblyName System.Runtime.WindowsRuntime
[Windows.Storage.StorageFile, Windows.Storage, ContentType=WindowsRuntime] | Out-Null
[Windows.Graphics.Imaging.BitmapDecoder, Windows.Graphics.Imaging, ContentType=WindowsRuntime] | Out-Null
[Windows.Media.Ocr.OcrEngine, Windows.Foundation, ContentType=WindowsRuntime] | Out-Null
[Windows.Globalization.Language, Windows.Globalization, ContentType=WindowsRuntime] | Out-Null

function Await-Result($AsyncOperation, [Type]$ResultType) {
  $method = [System.WindowsRuntimeSystemExtensions].GetMethods() |
    Where-Object { $_.Name -eq 'AsTask' -and $_.IsGenericMethod -and $_.GetParameters().Count -eq 1 } |
    Select-Object -First 1
  $task = $method.MakeGenericMethod($ResultType).Invoke($null, @($AsyncOperation))
  $task.Wait()
  return $task.Result
}

$engine = [Windows.Media.Ocr.OcrEngine]::TryCreateFromLanguage([Windows.Globalization.Language]::new('ar-SA'))
$rows = @()
foreach ($item in Get-ChildItem -LiteralPath $Directory -Filter '*.png' -File | Sort-Object Name) {
  try {
    $file = Await-Result ([Windows.Storage.StorageFile]::GetFileFromPathAsync($item.FullName)) ([Windows.Storage.StorageFile])
    $stream = Await-Result ($file.OpenAsync([Windows.Storage.FileAccessMode]::Read)) ([Windows.Storage.Streams.IRandomAccessStream])
    $decoder = Await-Result ([Windows.Graphics.Imaging.BitmapDecoder]::CreateAsync($stream)) ([Windows.Graphics.Imaging.BitmapDecoder])
    $bitmap = Await-Result ($decoder.GetSoftwareBitmapAsync()) ([Windows.Graphics.Imaging.SoftwareBitmap])
    $result = Await-Result ($engine.RecognizeAsync($bitmap)) ([Windows.Media.Ocr.OcrResult])
    $rows += [pscustomobject]@{file=$item.Name; text=(($result.Lines | ForEach-Object {$_.Text}) -join ' | ')}
    $stream.Dispose()
  } catch {
    $rows += [pscustomobject]@{file=$item.Name; text=''; error=$_.Exception.Message}
  }
}
$rows | ConvertTo-Json -Depth 3 | Set-Content -LiteralPath $Output -Encoding UTF8
Write-Output ("OCR rows: " + $rows.Count)