Console: Add --listdevices option

NAPS2.Internals/Threading/AsyncProducers.cs

@@ -3,6 +3,11 @@ namespace NAPS2.Util;
 
 public static class AsyncProducers
 {
+    public static async IAsyncEnumerable<T> Empty<T>()
+    {
+        yield break;
+    }
+
     public static IAsyncEnumerable<T> RunProducer<T>(ItemProducer<T> producer) where T : class
     {
         return RunProducer(new AsyncItemProducer<T>(produce =>

NAPS2.Lib.Tests/Automation/CommandLineIntegrationTests.cs

@@ -1048,6 +1048,25 @@ await _automationHelper.RunCommand(
         AssertRecoveryCleanedUp();
     }
 
+    [Fact]
+    public async Task ListDevices()
+    {
+        var (_, scanDriverFactoryMock) = CreateDriverMocks();
+
+        var outputWriter = new StringWriter();
+        await _automationHelper.WithContainerBuilder(container =>
+        {
+            container.RegisterInstance(new ConsoleOutput(outputWriter));
+        }).RunCommand(
+            new AutomatedScanningOptions
+            {
+                ListDevices = true
+            }, scanDriverFactoryMock);
+
+        Assert.Equal("test_name1\r\ntest_name2\r\n", outputWriter.ToString());
+        AssertRecoveryCleanedUp();
+    }
+
     private static (IScanDriver, IScanDriverFactory) CreateDriverMocks()
     {
         var scanDriverMock = Substitute.For<IScanDriver>();

NAPS2.Lib/Automation/AutomatedScanning.cs

@@ -97,6 +97,12 @@ public async Task Execute()
                 }
             }
 
+            if (_options.ListDevices)
+            {
+                await ListDevices();
+                return;
+            }
+
             if (!PreCheckOverwriteFile())
             {
                 return;
@@ -217,6 +223,21 @@ private async Task InstallComponents()
         await downloadController.StartDownloadsAsync();
     }
 
+    private async Task ListDevices()
+    {
+        if (!GetProfile(out var profile))
+        {
+            profile = new ScanProfile();
+        }
+        await SetProfileOverrides(profile);
+        var cts = new CancellationTokenSource();
+        Console.CancelKeyPress += (_, _) => cts.Cancel();
+        await foreach (var device in _scanPerformer.GetDevices(profile, cts.Token))
+        {
+            _output.Writer.WriteLine(device.Name);
+        }
+    }
+
     private void ReorderScannedImages()
     {
         var sep = _options.SplitPatchT ? SaveSeparator.PatchT
@@ -439,7 +460,7 @@ public bool ValidateOptions()
     {
         // Most validation is done by the CommandLineParser library, but some constraints that can't be represented by that API need to be checked here
         if (_options.OutputPath == null && _options.EmailFileName == null && _options.Install == null &&
-            !_options.AutoSave)
+            !_options.AutoSave && !_options.ListDevices)
         {
             _errorOutput.DisplayError(ConsoleResources.OutputOrEmailRequired);
             return false;
@@ -450,6 +471,15 @@ public bool ValidateOptions()
             return false;
         }
 
+        if (_options.Driver != null)
+        {
+            if (ScanPerformer.ParseDriver(_options.Driver) == Driver.Default)
+            {
+                _errorOutput.DisplayError(ConsoleResources.InvalidDriver);
+                return false;
+            }
+        }
+
         if (_options.PageSize != null)
         {
             var pageSize = PageSize.Parse(_options.PageSize);
@@ -744,33 +774,11 @@ private bool GetProfile(out ScanProfile profile)
 
     private async Task<bool> SetProfileOverrides(ScanProfile profile)
     {
-        var driver = Driver.Default;
         if (!string.IsNullOrEmpty(_options.Driver))
         {
-            driver = ScanPerformer.ParseDriver(_options.Driver);
+            var driver = ScanPerformer.ParseDriver(_options.Driver);
             profile.DriverName = driver.ToString().ToLowerInvariant();
         }
-        if (!string.IsNullOrEmpty(_options.Device))
-        {
-            var scanController = new ScanController(_scanningContext, _scanBridgeFactory);
-            var cts = new CancellationTokenSource();
-            bool foundDevice = false;
-            await foreach (var device in scanController.GetDevices(driver, cts.Token))
-            {
-                if (device.Name.ContainsInvariantIgnoreCase(_options.Device!))
-                {
-                    cts.Cancel();
-                    profile.Device = new ScanProfileDevice(device.ID, device.Name);
-                    foundDevice = true;
-                    break;
-                }
-            }
-            if (!foundDevice)
-            {
-                _errorOutput.DisplayError(SdkResources.DeviceNotFound);
-                return false;
-            }
-        }
         if (_options.Source != null)
         {
             profile.PaperSource = _options.Source.Value;
@@ -802,6 +810,28 @@ private async Task<bool> SetProfileOverrides(ScanProfile profile)
         {
             profile.RotateDegrees = _options.RotateDegrees.Value;
         }
+
+        if (!string.IsNullOrEmpty(_options.Device))
+        {
+            var cts = new CancellationTokenSource();
+            bool foundDevice = false;
+            await foreach (var device in _scanPerformer.GetDevices(profile, cts.Token))
+            {
+                if (device.Name.ContainsInvariantIgnoreCase(_options.Device!))
+                {
+                    cts.Cancel();
+                    profile.Device = new ScanProfileDevice(device.ID, device.Name);
+                    foundDevice = true;
+                    break;
+                }
+            }
+            if (!foundDevice)
+            {
+                _errorOutput.DisplayError(SdkResources.DeviceNotFound);
+                return false;
+            }
+        }
+
         return true;
     }
 

NAPS2.Lib/Automation/AutomatedScanningOptions.cs

@@ -66,6 +66,9 @@ public class AutomatedScanningOptions
     [Option("device", HelpText = "Scanning device name (can be inexact).")]
     public string? Device { get; set; }
 
+    [Option("listdevices", HelpText = "Instead of scanning, list available devices.")]
+    public bool ListDevices { get; set; }
+
     #endregion
 
     #region Scan Options

NAPS2.Lib/Lang/ConsoleResources/ConsoleResources.resx

@@ -257,4 +257,7 @@ Use the "--importpassword" option.</value>
   <data name="InvalidDpi" xml:space="preserve">
     <value>The DPI option was not valid (must be 100/150/200/300/400/600/800/1200/2400/4800).</value>
   </data>
+  <data name="InvalidDriver" xml:space="preserve">
+    <value>The driver option was not valid (must be wia/twain/escl/sane/apple).</value>
+  </data>
 </root>

NAPS2.Lib/Scan/IScanPerformer.cs

@@ -10,5 +10,7 @@ public interface IScanPerformer
 {
     Task<ScanDevice?> PromptForDevice(ScanProfile scanProfile, IntPtr dialogParent = default);
 
+    IAsyncEnumerable<ScanDevice> GetDevices(ScanProfile scanProfile, CancellationToken cancelToken = default);
+
     IAsyncEnumerable<ProcessedImage> PerformScan(ScanProfile scanProfile, ScanParams scanParams, IntPtr dialogParent = default, CancellationToken cancelToken = default);
 }

NAPS2.Lib/Scan/ScanPerformer.cs

@@ -68,6 +68,21 @@ public ScanPerformer(IDevicePrompt devicePrompt, Naps2Config config, OperationPr
         }
     }
 
+    public IAsyncEnumerable<ScanDevice> GetDevices(ScanProfile scanProfile, CancellationToken cancelToken = default)
+    {
+        try
+        {
+            var options = BuildOptions(scanProfile, new ScanParams(), IntPtr.Zero);
+            var controller = CreateScanController(new ScanParams());
+            return controller.GetDevices(options, cancelToken);
+        }
+        catch (Exception error)
+        {
+            HandleError(error);
+            return AsyncProducers.Empty<ScanDevice>();
+        }
+    }
+
     public async IAsyncEnumerable<ProcessedImage> PerformScan(ScanProfile scanProfile, ScanParams scanParams,
         IntPtr dialogParent = default, [EnumeratorCancellation] CancellationToken cancelToken = default)
     {
@@ -81,9 +96,7 @@ public async IAsyncEnumerable<ProcessedImage> PerformScan(ScanProfile scanProfil
             yield break;
         }
 
-        var localPostProcessor = new LocalPostProcessor(_scanningContext, ConfigureOcrController(scanParams));
-        var controller = new ScanController(_scanningContext, localPostProcessor, _scanOptionsValidator,
-            _scanBridgeFactory);
+        var controller = CreateScanController(scanParams);
         var op = new ScanOperation(options);
 
         controller.PageStart += (sender, args) => op.NextPage(args.PageNumber);
@@ -135,6 +148,14 @@ public async IAsyncEnumerable<ProcessedImage> PerformScan(ScanProfile scanProfil
         }
     }
 
+    private ScanController CreateScanController(ScanParams scanParams)
+    {
+        var localPostProcessor = new LocalPostProcessor(_scanningContext, ConfigureOcrController(scanParams));
+        var controller = new ScanController(_scanningContext, localPostProcessor, _scanOptionsValidator,
+            _scanBridgeFactory);
+        return controller;
+    }
+
     private OcrController ConfigureOcrController(ScanParams scanParams)
     {
         OcrController ocrController = new OcrController(_scanningContext);