Add MoveWindowToMonitorIndexTransform (#975)

Adds a transform to make it easier to move a window to a monitor with a specific index (#974).

src/Whim.Tests/Store/MapSector/Transforms/MoveWindowToMonitorIndexTransformTests.cs

@@ -0,0 +1,53 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace Whim.Tests;
+
+[SuppressMessage("Reliability", "CA2000:Dispose objects before losing scope")]
+public class MoveWindowToMonitorIndexTransformTests
+{
+	[Theory, AutoSubstituteData<StoreCustomization>]
+	internal void NoMonitorAtIndex(IContext ctx, MutableRootSector rootSector)
+	{
+		// Given there is no monitor at the index
+		IWindow window = CreateWindow((HWND)10);
+		IMonitor originalMonitor = CreateMonitor((HMONITOR)10);
+		IMonitor newMonitor = CreateMonitor((HMONITOR)11);
+
+		PopulateThreeWayMap(ctx, rootSector, originalMonitor, CreateWorkspace(ctx), window);
+		PopulateMonitorWorkspaceMap(ctx, rootSector, newMonitor, CreateWorkspace(ctx));
+
+		MoveWindowToMonitorIndexTransform sut = new(2, window.Handle);
+
+		// When
+		var result = ctx.Store.Dispatch(sut);
+
+		// Then
+		Assert.False(result.IsSuccessful);
+	}
+
+	[Theory, AutoSubstituteData<StoreCustomization>]
+	internal void Success(IContext ctx, MutableRootSector rootSector)
+	{
+		// Given there is a three way map
+		IWindow window = CreateWindow((HWND)10);
+
+		IMonitor originalMonitor = CreateMonitor((HMONITOR)10);
+		IMonitor newMonitor = CreateMonitor((HMONITOR)11);
+
+		Workspace originalWorkspace = CreateWorkspace(ctx);
+		Workspace newWorkspace = CreateWorkspace(ctx);
+
+		PopulateThreeWayMap(ctx, rootSector, originalMonitor, originalWorkspace, window);
+		PopulateMonitorWorkspaceMap(ctx, rootSector, newMonitor, newWorkspace);
+
+		MoveWindowToMonitorIndexTransform sut = new(1, window.Handle);
+
+		// When
+		var result = ctx.Store.Dispatch(sut);
+
+		// Then
+		Assert.True(result.IsSuccessful);
+		Assert.Equal(newWorkspace.Id, rootSector.MapSector.WindowWorkspaceMap[window.Handle]);
+		Assert.Equal(newWorkspace.Id, rootSector.MapSector.MonitorWorkspaceMap[newMonitor.Handle]);
+	}
+}

src/Whim.Tests/Store/MonitorSector/MonitorPickersTests.cs

@@ -92,6 +92,7 @@ internal void PickLastWhimActiveMonitor(IContext ctx, MutableRootSector root)
 		Assert.Equal((HMONITOR)2, result.Handle);
 	}
 
+	#region PickAdjacentMonitor
 	[InlineAutoSubstituteData<StoreCustomization>(true)]
 	[InlineAutoSubstituteData<StoreCustomization>(false)]
 	[Theory]
@@ -132,6 +133,40 @@ MutableRootSector root
 		// Then
 		Assert.Equal(root.MonitorSector.Monitors[endIdx].Handle, result.Value.Handle);
 	}
+	#endregion
+
+	#region PickMonitorByIndex
+	[Theory]
+	[InlineAutoSubstituteData<StoreCustomization>(-1)]
+	[InlineAutoSubstituteData<StoreCustomization>(4)]
+	internal void PickMonitorByIndex_MonitorIndexOutOfRange(int index, IContext ctx, MutableRootSector root)
+	{
+		// Given
+		PopulateMonitors(root);
+
+		// When
+		Result<IMonitor> result = ctx.Store.Pick(Pickers.PickMonitorByIndex(index));
+
+		// Then
+		Assert.False(result.IsSuccessful);
+	}
+
+	[Theory]
+	[InlineAutoSubstituteData<StoreCustomization>(0)]
+	[InlineAutoSubstituteData<StoreCustomization>(3)]
+	internal void PickMonitorByIndex_Success(int index, IContext ctx, MutableRootSector root)
+	{
+		// Given
+		PopulateMonitors(root);
+
+		// When
+		Result<IMonitor> result = ctx.Store.Pick(Pickers.PickMonitorByIndex(index));
+
+		// Then
+		Assert.True(result.IsSuccessful);
+		Assert.Equal(root.MonitorSector.Monitors[index].Handle, result.Value.Handle);
+	}
+	#endregion
 }
 
 public class GetMonitorAtPointPickerTests

src/Whim/Store/MapSector/Transforms/MoveWindowToMonitorIndexTransform.cs

@@ -0,0 +1,25 @@
+namespace Whim;
+
+/// <summary>
+/// Move the window with <paramref name="WindowHandle"/> to the monitor at <paramref name="MonitorIndex"/>.
+/// </summary>
+/// <param name="MonitorIndex">
+/// The 0-based index of the monitor to move the window to.
+/// </param>
+/// <param name="WindowHandle">
+/// The handle of the window to move. If not provided, this will default to the focused/active window.
+/// </param>
+public record MoveWindowToMonitorIndexTransform(int MonitorIndex, HWND WindowHandle = default) : Transform
+{
+	internal override Result<Unit> Execute(IContext ctx, IInternalContext internalCtx, MutableRootSector rootSector)
+	{
+		// Get the monitor at index.
+		Result<IMonitor> monitorResult = ctx.Store.Pick(PickMonitorByIndex(MonitorIndex));
+		if (!monitorResult.TryGet(out IMonitor monitor))
+		{
+			return Result.FromException<Unit>(monitorResult.Error!);
+		}
+
+		return ctx.Store.Dispatch(new MoveWindowToMonitorTransform(monitor.Handle, WindowHandle));
+	}
+}

src/Whim/Store/MonitorSector/IMonitorSector.cs

@@ -6,7 +6,12 @@ namespace Whim;
 public interface IMonitorSector
 {
 	/// <summary>
-	/// All the monitors currently tracked by Whim.
+	/// All the monitors currently tracked by Whim. The monitors are ordered by their x-coordinate
+	/// and then by their y-coordinate.
+	///
+	/// Your primary monitor will have the top-left coordinate be (0, 0).
+	/// Accordingly, monitors to the left of the primary monitor will have negative x-coordinates,
+	/// and monitors above the primary monitor will have negative y-coordinates.
 	/// </summary>
 	ImmutableArray<IMonitor> Monitors { get; }
 

src/Whim/Store/MonitorSector/MonitorPickers.cs

@@ -94,6 +94,25 @@ public static PurePicker<Result<IMonitor>> PickAdjacentMonitor(
 			return Result.FromValue(monitors[(monitorIdx + delta).Mod(monitors.Length)]);
 		};
 
+	/// <summary>
+	/// Get the monitor at the given index.
+	/// </summary>
+	/// <param name="index">
+	/// The 0-based index of the monitor to get.
+	/// </param>
+	/// <returns></returns>
+	public static PurePicker<Result<IMonitor>> PickMonitorByIndex(int index) =>
+		(rootSector) =>
+		{
+			ImmutableArray<IMonitor> monitors = rootSector.MonitorSector.Monitors;
+			if (index < 0 || index >= monitors.Length)
+			{
+				return Result.FromException<IMonitor>(StoreExceptions.InvalidMonitorIndex(index));
+			}
+
+			return Result.FromValue(monitors[index]);
+		};
+
 	/// <summary>
 	/// Get the monitor at the point <paramref name="point"/>
 	/// </summary>

src/Whim/Store/StoreExceptions.cs

@@ -26,4 +26,7 @@ public static Exception NoWorkspaceFoundForWindow(HWND windowHandle) =>
 		new WhimException($"No workspace found for window {windowHandle}.");
 
 	public static Exception NoValidWindow() => new WhimException("No valid window found.");
+
+	public static Exception InvalidMonitorIndex(int monitorIndex) =>
+		new WhimException($"No monitor found at index {monitorIndex}.");
 }