using System.Numerics;
using AcDream.App.UI;

namespace AcDream.App.Tests.UI;

public class UiRootInputTests
{
    [Fact]
    public void UiNineSlicePanel_IsNotAnchorManaged_SoUserMoveResizeSticks()
    {
        // Regression: the per-frame anchor pass must NOT reset a window's rect,
        // or move/resize get undone every frame. Windows are user-positioned.
        var panel = new UiNineSlicePanel(_ => ((uint)1, 32, 32));
        Assert.Equal(AnchorEdges.None, panel.Anchors);
    }

    private sealed class CoordRecorder : UiElement
    {
        public (int x, int y)? Down, Move;
        public CoordRecorder() { CapturesPointerDrag = true; }
        public override bool OnEvent(in UiEvent e)
        {
            if (e.Type == UiEventType.MouseDown) { Down = (e.Data1, e.Data2); return true; }
            if (e.Type == UiEventType.MouseMove) { Move = (e.Data1, e.Data2); return true; }
            return false;
        }
    }

    [Fact]
    public void MouseDown_And_MouseMove_DeliverSameTargetLocalFrame_ForNestedChild()
    {
        // Regression (adversarial review): a nested child must receive target-LOCAL
        // coords on MouseDown AND MouseMove for the same physical point — otherwise
        // drag-select anchors ~(child offset) px off from where you click. Before the
        // fix MouseDown used HitTestTopDown's window-relative coords (50,40) while
        // MouseMove used target-local (42,32).
        var root = new UiRoot { Width = 800, Height = 600 };
        var panel = new UiPanel { Left = 50, Top = 60, Width = 200, Height = 100 };
        var child = new CoordRecorder { Left = 8, Top = 8, Width = 150, Height = 80 };
        panel.AddChild(child);
        root.AddChild(panel);

        // child ScreenPosition = (58,68). Click screen (100,100) -> local (42,32).
        root.OnMouseDown(UiMouseButton.Left, 100, 100);
        Assert.Equal((42, 32), child.Down);

        // drag to (120,110) -> local (62,42); MUST share the MouseDown frame.
        root.OnMouseMove(120, 110);
        Assert.Equal((62, 42), child.Move);
    }

    [Fact]
    public void ApplyAnchor_None_IsNoOp()
    {
        var e = new UiPanel { Left = 50, Top = 60, Width = 100, Height = 40, Anchors = AnchorEdges.None };
        e.ApplyAnchor(800, 600);
        Assert.Equal(50f, e.Left);
        Assert.Equal(60f, e.Top);
        Assert.Equal(100f, e.Width);
        Assert.Equal(40f, e.Height);
    }

    [Fact]
    public void WantsMouse_TrueOverWidget_FalseOverEmptySpace()
    {
        var root = new UiRoot { Width = 800, Height = 600 };
        var panel = new UiPanel { Left = 10, Top = 10, Width = 100, Height = 50 };
        root.AddChild(panel);

        root.OnMouseMove(50, 30);    // inside the panel
        Assert.True(root.WantsMouse);

        root.OnMouseMove(500, 400);  // empty space
        Assert.False(root.WantsMouse);
    }

    [Fact]
    public void WindowDrag_RepositionsDraggablePanel_StopsOnRelease()
    {
        var root = new UiRoot { Width = 800, Height = 600 };
        var panel = new UiPanel { Left = 10, Top = 10, Width = 100, Height = 50, Draggable = true };
        root.AddChild(panel);

        root.OnMouseDown(UiMouseButton.Left, 20, 20); // grab at (10,10) into the panel
        root.OnMouseMove(120, 90);                     // drag
        Assert.Equal(110f, panel.Left);                // 120 - 10
        Assert.Equal(80f, panel.Top);                  // 90 - 10

        root.OnMouseUp(UiMouseButton.Left, 120, 90);
        root.OnMouseMove(300, 300);                    // released — must not move
        Assert.Equal(110f, panel.Left);
        Assert.Equal(80f, panel.Top);
    }

    [Fact]
    public void NonDraggablePanel_DoesNotMoveOnDrag()
    {
        var root = new UiRoot { Width = 800, Height = 600 };
        var panel = new UiPanel { Left = 10, Top = 10, Width = 100, Height = 50 }; // Draggable defaults false
        root.AddChild(panel);

        root.OnMouseDown(UiMouseButton.Left, 20, 20);
        root.OnMouseMove(120, 90);
        Assert.Equal(10f, panel.Left);
        Assert.Equal(10f, panel.Top);
    }

    [Fact]
    public void CapturesPointerDragChild_DoesNotMoveDraggableAncestor_OnInteriorDrag()
    {
        // A child that captures pointer drags (text selection) must NOT move its
        // draggable ancestor window when the user drags inside it.
        var root = new UiRoot { Width = 800, Height = 600 };
        var window = new UiPanel { Left = 10, Top = 10, Width = 200, Height = 100, Draggable = true };
        var child = new UiPanel { Left = 20, Top = 20, Width = 120, Height = 60, CapturesPointerDrag = true };
        window.AddChild(child);
        root.AddChild(window);

        // Press deep inside the child, then drag.
        root.OnMouseDown(UiMouseButton.Left, 60, 60);
        root.OnMouseMove(160, 160);

        // Window stays put; the captured child receives the drag itself.
        Assert.Equal(10f, window.Left);
        Assert.Equal(10f, window.Top);
        Assert.Same(child, root.Captured);

        root.OnMouseUp(UiMouseButton.Left, 160, 160);
        Assert.Equal(10f, window.Left);
        Assert.Equal(10f, window.Top);
    }

    [Fact]
    public void CapturesPointerDragChild_StillAllowsEdgeResizeOfResizableWindow()
    {
        // Edge resize must still win even when a CapturesPointerDrag child covers
        // the frame: a resizable chat window can be resized from its border.
        var root = new UiRoot { Width = 800, Height = 600 };
        var window = new UiPanel { Left = 100, Top = 100, Width = 200, Height = 100,
            Draggable = true, Resizable = true, MinWidth = 40, MinHeight = 40 };
        // Child fills the whole window (anchored) and captures interior drags.
        var child = new UiPanel { Left = 0, Top = 0, Width = 200, Height = 100,
            CapturesPointerDrag = true,
            Anchors = AnchorEdges.Left | AnchorEdges.Top | AnchorEdges.Right | AnchorEdges.Bottom };
        window.AddChild(child);
        root.AddChild(window);

        // Grab within ResizeGrip(5) of the right edge (x=298 of right edge x=300) → resize.
        root.OnMouseDown(UiMouseButton.Left, 298, 150);
        root.OnMouseMove(338, 150);
        Assert.Equal(240f, window.Width);
        Assert.Equal(100f, window.Left);
        root.OnMouseUp(UiMouseButton.Left, 338, 150);
    }

    [Fact]
    public void ResizeRect_RightBottom_GrowsSizeOnly()
    {
        var (x, y, w, h) = UiRoot.ResizeRect(10, 20, 100, 50,
            ResizeEdges.Right | ResizeEdges.Bottom, dx: 30, dy: 15, minW: 40, minH: 40);
        Assert.Equal(10f, x); Assert.Equal(20f, y);
        Assert.Equal(130f, w); Assert.Equal(65f, h);
    }

    [Fact]
    public void ResizeRect_LeftTop_MovesOriginAndClampsToMin()
    {
        // Drag left edge right by 80 on a 100-wide / min-40 window: width clamps to 40,
        // origin shifts so the RIGHT edge (110) stays put → x = 70.
        var (x, _, w, _) = UiRoot.ResizeRect(10, 20, 100, 50,
            ResizeEdges.Left, dx: 80, dy: 0, minW: 40, minH: 40);
        Assert.Equal(40f, w);
        Assert.Equal(70f, x);
    }

    [Fact]
    public void HitEdges_DetectsCornerAndInteriorNone()
    {
        var panel = new UiPanel { Left = 100, Top = 100, Width = 200, Height = 100 };
        // bottom-right corner (300,200)
        Assert.Equal(ResizeEdges.Right | ResizeEdges.Bottom, UiRoot.HitEdges(panel, 300, 200, 5));
        // deep interior → no edges
        Assert.Equal(ResizeEdges.None, UiRoot.HitEdges(panel, 200, 150, 5));
    }

    [Fact]
    public void EdgeDrag_ResizesPanel_InteriorDragMoves()
    {
        var root = new UiRoot { Width = 800, Height = 600 };
        var panel = new UiPanel { Left = 100, Top = 100, Width = 200, Height = 100,
            Draggable = true, Resizable = true, MinWidth = 40, MinHeight = 40 };
        root.AddChild(panel);

        // grab just inside the right edge (x=298, within ResizeGrip=5 of x=300) and drag right → wider, same origin
        root.OnMouseDown(UiMouseButton.Left, 298, 150);
        root.OnMouseMove(338, 150);
        Assert.Equal(240f, panel.Width);
        Assert.Equal(100f, panel.Left);
        root.OnMouseUp(UiMouseButton.Left, 338, 150);

        // grab the interior and drag → moves
        root.OnMouseDown(UiMouseButton.Left, 200, 150);
        root.OnMouseMove(220, 170);
        Assert.Equal(120f, panel.Left);
        Assert.Equal(120f, panel.Top);
        root.OnMouseUp(UiMouseButton.Left, 220, 170);
    }

    [Fact]
    public void HitEdges_RespectsResizeAxisLock()
    {
        var panel = new UiPanel { Left = 100, Top = 100, Width = 200, Height = 100, ResizeY = false };
        // right edge still detected (X allowed)
        Assert.True((UiRoot.HitEdges(panel, 300, 150, 5) & ResizeEdges.Right) != 0);
        // bottom edge masked out (Y locked)
        Assert.True((UiRoot.HitEdges(panel, 200, 200, 5) & ResizeEdges.Bottom) == 0);
    }

    [Fact]
    public void ComputeAnchoredRect_LeftRight_StretchesWidth()
    {
        // bar at x=8,w=200 in a 220-wide parent (right margin 12). Parent grows to 300.
        var (x, _, w, _) = UiElement.ComputeAnchoredRect(
            AnchorEdges.Left | AnchorEdges.Right | AnchorEdges.Top,
            mL: 8, mT: 24, mR: 12, mB: 58, w0: 200, h0: 14, parentW: 300, parentH: 96);
        Assert.Equal(8f, x);
        Assert.Equal(280f, w);   // 300 - 12 - 8
    }

    [Fact]
    public void ComputeAnchoredRect_LeftTopOnly_KeepsFixedSizeAndOrigin()
    {
        var (x, y, w, h) = UiElement.ComputeAnchoredRect(
            AnchorEdges.Left | AnchorEdges.Top,
            mL: 8, mT: 24, mR: 12, mB: 58, w0: 200, h0: 14, parentW: 300, parentH: 96);
        Assert.Equal(8f, x); Assert.Equal(24f, y);
        Assert.Equal(200f, w); Assert.Equal(14f, h);
    }
}