Terminal.Gui/Tests/UnitTestsParallelizable/ViewBase/Draw/ViewDrawTextAndLineCanvasTests.cs

using System.Text;
using UnitTests;
using Xunit.Abstractions;

namespace ViewBaseTests.Drawing;

public class ViewDrawTextAndLineCanvasTests () : FakeDriverBase
{
    #region DrawText Tests

    [Fact]
    public void DrawText_EmptyText_DoesNotThrow ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = ""
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        var exception = Record.Exception (() => view.Draw ());

        Assert.Null (exception);
    }

    [Fact]
    public void DrawText_NullText_DoesNotThrow ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = null!
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        var exception = Record.Exception (() => view.Draw ());

        Assert.Null (exception);
    }

    [Fact]
    public void DrawText_DrawsTextToDriver ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 1,
            Y = 1,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = "Test"
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        view.Draw ();

        // Text should appear at the content location
        Point screenPos = view.ContentToScreen (Point.Empty);

        Assert.Equal ("T", driver.Contents! [screenPos.Y, screenPos.X].Grapheme);
        Assert.Equal ("e", driver.Contents [screenPos.Y, screenPos.X + 1].Grapheme);
        Assert.Equal ("s", driver.Contents [screenPos.Y, screenPos.X + 2].Grapheme);
        Assert.Equal ("t", driver.Contents [screenPos.Y, screenPos.X + 3].Grapheme);
    }

    [Fact]
    public void DrawText_WithFocus_UsesFocusAttribute ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = "Test",
            CanFocus = true
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();
        view.SetFocus ();

        view.Draw ();

        // Text should use focus attribute
        Point screenPos = view.ContentToScreen (Point.Empty);
        Attribute expectedAttr = view.GetAttributeForRole (VisualRole.Focus);

        Assert.Equal (expectedAttr, driver.Contents! [screenPos.Y, screenPos.X].Attribute);
    }

    [Fact]
    public void DrawText_WithoutFocus_UsesNormalAttribute ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = "Test",
            CanFocus = true
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        view.Draw ();

        // Text should use normal attribute
        Point screenPos = view.ContentToScreen (Point.Empty);
        Attribute expectedAttr = view.GetAttributeForRole (VisualRole.Normal);

        Assert.Equal (expectedAttr, driver.Contents! [screenPos.Y, screenPos.X].Attribute);
    }

    [Fact]
    public void DrawText_SetsSubViewNeedsDraw ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = "Test"
        };
        var child = new View { X = 0, Y = 0, Width = 10, Height = 10 };
        view.Add (child);
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        // Clear SubViewNeedsDraw
        view.Draw ();
        Assert.False (view.SubViewNeedsDraw);

        // Call DrawText directly which should set SubViewNeedsDraw
        view.DrawText ();

        // SubViews need to be redrawn since text was drawn over them
        Assert.True (view.SubViewNeedsDraw);
    }

    [Fact]
    public void DrawingText_Event_Raised ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        bool eventRaised = false;

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            Text = "Test"
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        view.DrawingText += (s, e) => eventRaised = true;

        view.Draw ();

        Assert.True (eventRaised);
    }

    #endregion

    #region LineCanvas Tests

    [Fact]
    public void LineCanvas_InitiallyEmpty ()
    {
        var view = new View ();

        Assert.NotNull (view.LineCanvas);
        Assert.Equal (Rectangle.Empty, view.LineCanvas.Bounds);
    }

    [Fact]
    public void RenderLineCanvas_DrawsLines ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        // Add a line to the canvas
        Point screenPos = new Point (15, 15);
        view.LineCanvas.AddLine (screenPos, 5, Orientation.Horizontal, LineStyle.Single);

        view.RenderLineCanvas ();

        // Verify the line was drawn (check for horizontal line character)
        for (int i = 0; i < 5; i++)
        {
            Assert.NotEqual (" ", driver.Contents! [screenPos.Y, screenPos.X + i].Grapheme);
        }
    }

    [Fact]
    public void RenderLineCanvas_ClearsAfterRendering ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        // Add a line to the canvas
        view.LineCanvas.AddLine (new Point (15, 15), 5, Orientation.Horizontal, LineStyle.Single);

        Assert.NotEqual (Rectangle.Empty, view.LineCanvas.Bounds);

        view.RenderLineCanvas ();

        // LineCanvas should be cleared after rendering
        Assert.Equal (Rectangle.Empty, view.LineCanvas.Bounds);
    }

    [Fact]
    public void RenderLineCanvas_WithSuperViewRendersLineCanvas_DoesNotClear ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new View
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            SuperViewRendersLineCanvas = true
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        // Add a line to the canvas
        view.LineCanvas.AddLine (new Point (15, 15), 5, Orientation.Horizontal, LineStyle.Single);

        Rectangle boundsBefore = view.LineCanvas.Bounds;

        view.RenderLineCanvas ();

        // LineCanvas should NOT be cleared when SuperViewRendersLineCanvas is true
        Assert.Equal (boundsBefore, view.LineCanvas.Bounds);
    }

    [Fact]
    public void SuperViewRendersLineCanvas_MergesWithParentCanvas ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var parent = new View
        {
            X = 10,
            Y = 10,
            Width = 50,
            Height = 50,
            Driver = driver
        };
        var child = new View
        {
            X = 5,
            Y = 5,
            Width = 30,
            Height = 30,
            SuperViewRendersLineCanvas = true
        };
        parent.Add (child);
        parent.BeginInit ();
        parent.EndInit ();
        parent.LayoutSubViews ();

        // Add a line to child's canvas
        child.LineCanvas.AddLine (new Point (20, 20), 5, Orientation.Horizontal, LineStyle.Single);

        Assert.NotEqual (Rectangle.Empty, child.LineCanvas.Bounds);
        Assert.Equal (Rectangle.Empty, parent.LineCanvas.Bounds);

        parent.Draw ();

        // Child's canvas should have been merged into parent's
        // and child's canvas should be cleared
        Assert.Equal (Rectangle.Empty, child.LineCanvas.Bounds);
    }

    [Fact]
    public void OnRenderingLineCanvas_CanPreventRendering ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var view = new TestView
        {
            X = 10,
            Y = 10,
            Width = 20,
            Height = 20,
            Driver = driver,
            PreventRenderLineCanvas = true
        };
        view.BeginInit ();
        view.EndInit ();
        view.LayoutSubViews ();

        // Add a line to the canvas
        Point screenPos = new Point (15, 15);
        view.LineCanvas.AddLine (screenPos, 5, Orientation.Horizontal, LineStyle.Single);

        view.Draw ();

        // When OnRenderingLineCanvas returns true, RenderLineCanvas is not called
        // So the LineCanvas should still have lines (not cleared)
        // BUT because SuperViewRendersLineCanvas is false (default), the LineCanvas
        // gets cleared during the draw cycle anyway. We need to check that the
        // line was NOT actually rendered to the driver.
        bool lineRendered = true;
        for (int i = 0; i < 5; i++)
        {
            if (driver.Contents! [screenPos.Y, screenPos.X + i].Grapheme == " ")
            {
                lineRendered = false;
                break;
            }
        }

        Assert.False (lineRendered);
    }

    #endregion

    #region SuperViewRendersLineCanvas Tests

    [Fact]
    public void SuperViewRendersLineCanvas_DefaultFalse ()
    {
        var view = new View ();

        Assert.False (view.SuperViewRendersLineCanvas);
    }

    [Fact]
    public void SuperViewRendersLineCanvas_CanBeSet ()
    {
        var view = new View { SuperViewRendersLineCanvas = true };

        Assert.True (view.SuperViewRendersLineCanvas);
    }

    [Fact]
    public void Draw_WithSuperViewRendersLineCanvas_SetsNeedsDraw ()
    {
        IDriver driver = CreateFakeDriver (80, 25);
        driver.Clip = new Region (driver.Screen);

        var parent = new View
        {
            X = 10,
            Y = 10,
            Width = 50,
            Height = 50,
            Driver = driver
        };
        var child = new View
        {
            X = 5,
            Y = 5,
            Width = 30,
            Height = 30,
            SuperViewRendersLineCanvas = true
        };
        parent.Add (child);
        parent.BeginInit ();
        parent.EndInit ();
        parent.LayoutSubViews ();

        // Draw once to clear NeedsDraw
        parent.Draw ();
        Assert.False (child.NeedsDraw);

        // Draw again - child with SuperViewRendersLineCanvas should be redrawn
        parent.Draw ();

        // The child should have been set to NeedsDraw during DrawSubViews
        // This is verified by the fact that it was drawn (we can't check NeedsDraw after Draw)
    }

    #endregion

    #region Helper Test View

    private class TestView : View
    {
        public bool PreventRenderLineCanvas { get; set; }

        protected override bool OnRenderingLineCanvas ()
        {
            return PreventRenderLineCanvas || base.OnRenderingLineCanvas ();
        }
    }

    #endregion
}