using System.Numerics;
using AcDream.App.Rendering;
using AcDream.App.Rendering.Gpu;
using AcDream.App.Tests.Rendering.Gpu;
using AcDream.App.UI;
using AcDream.App.UI.Layout;
namespace AcDream.App.Tests.UI.Layout;

public class UiDatElementTests
{
    private sealed class NullGpuFrameSource : ICurrentGpuFrameSource
    {
        public IGpuFrame? CurrentFrame => null;
    }

    private static (TextRenderer renderer, UiRenderContext ctx) BuildRenderContext()
    {
        var device = new RecordingGpuDevice();
        var renderer = new TextRenderer(device, new NullGpuFrameSource(), "unused");
        renderer.Begin(new Vector2(1920f, 1080f));
        var ctx = new UiRenderContext(renderer, new Vector2(1920f, 1080f));
        return (renderer, ctx);
    }

    /// <summary>
    /// Retail's blit is copy-or-tile only (Graphic::Draw @0x00693b20 — no
    /// stretch mode exists), so an element grown past its media's native size
    /// tiles: u1 = Width/tw. Whole-screen stretching is NOT this layer's job —
    /// it happens uniformly at UiRoot.FixedCanvasSize / TextRenderer.CanvasScale
    /// (register AD-98), covered by the test below.
    /// </summary>
    [Fact]
    public void OwnBackground_TilesUvPastOne_WhenRectExceedsNativeSize()
    {
        var info = new ElementInfo { Width = 1920, Height = 1080 };
        info.StateMedia[""] = (0x06007576u, 1);
        var e = new UiDatElement(info, _ => (7u, 800, 600))
        {
            Left = 0,
            Top = 0,
            Width = 1920,
            Height = 1080,
        };

        (TextRenderer renderer, UiRenderContext ctx) = BuildRenderContext();
        e.DrawSelfAndChildren(ctx);

        var (texture, verts) = Assert.Single(renderer.DebugSpriteSegmentVerts);
        Assert.Equal(7u, texture);
        // Vertex layout: x,y,u,v,r,g,b,a, 6 verts/quad. TextRenderer.AppendQuad emits
        // vertex index 1 as (x+w, y+h, u1, v1) — the (u1,v1) far corner.
        float uMax = verts[1 * 8 + 2];
        float vMax = verts[1 * 8 + 3];
        Assert.Equal(1920f / 800f, uMax, 3);
        Assert.Equal(1080f / 600f, vMax, 3);
    }

    /// <summary>
    /// AD-98 whole-canvas stretch: with the renderer's CanvasScale set (the
    /// char-select 800×600 canvas on a 1920×1080 window), an element drawn at
    /// authored size emits a quad scaled by exactly (2.4, 1.8) in GEOMETRY while
    /// its UVs stay authored (0..1 here) — one stretched image, no tiling, the
    /// same math retail's present-time frame stretch produces.
    /// </summary>
    [Fact]
    public void CanvasScale_StretchesQuadGeometry_LeavesUvsAuthored()
    {
        var info = new ElementInfo { Width = 800, Height = 600 };
        info.StateMedia[""] = (0x06007576u, 1);
        var e = new UiDatElement(info, _ => (7u, 800, 600))
        {
            Left = 0,
            Top = 0,
            Width = 800,
            Height = 600,
        };

        (TextRenderer renderer, UiRenderContext ctx) = BuildRenderContext();
        renderer.CanvasScale = new Vector2(1920f / 800f, 1080f / 600f);
        try
        {
            e.DrawSelfAndChildren(ctx);
        }
        finally
        {
            renderer.CanvasScale = Vector2.One;
        }

        var (_, verts) = Assert.Single(renderer.DebugSpriteSegmentVerts);
        // Far corner (vertex 1): geometry scaled to the window, UVs authored.
        Assert.Equal(1920f, verts[1 * 8 + 0], 3);
        Assert.Equal(1080f, verts[1 * 8 + 1], 3);
        Assert.Equal(1f, verts[1 * 8 + 2], 3);
        Assert.Equal(1f, verts[1 * 8 + 3], 3);
    }

    [Fact]
    public void ActiveMedia_PrefersNamedStateOverDirect()
    {
        var info = new ElementInfo();
        info.StateMedia[""] = (0x06000001, 1);          // DirectState (DrawMode Normal=1)
        info.StateMedia["ShowDetail"] = (0x06000002, 3); // named (Alphablend=3)
        var e = new UiDatElement(info, _ => (0, 0, 0)) { ActiveState = "ShowDetail" };
        Assert.Equal(0x06000002u, e.ActiveMedia().File);
        Assert.Equal(3, e.ActiveMedia().DrawMode);
        e.ActiveState = "";
        Assert.Equal(0x06000001u, e.ActiveMedia().File);
        Assert.Equal(1, e.ActiveMedia().DrawMode);
    }

    [Fact]
    public void ActiveMedia_NoMedia_ReturnsZero()
    {
        var e = new UiDatElement(new ElementInfo(), _ => (0, 0, 0));
        Assert.Equal(0u, e.ActiveMedia().File);
        Assert.Equal(0, e.ActiveMedia().DrawMode);
    }

    [Fact]
    public void ActiveMedia_MissingNamedState_FallsBackToDirect()
    {
        var info = new ElementInfo();
        info.StateMedia[""] = (0x06000005, 1);
        var e = new UiDatElement(info, _ => (0, 0, 0)) { ActiveState = "NoSuchState" };
        Assert.Equal(0x06000005u, e.ActiveMedia().File);
    }

    // ── G1 tests: DefaultStateName + "Normal" implicit default ───────────────

    /// <summary>
    /// Task G1 change 5: when an element has no DefaultStateName but does have a "Normal"
    /// state sprite, the ctor should default ActiveState to "Normal" so the element
    /// renders its normal-state sprite without requiring explicit state assignment.
    /// </summary>
    [Fact]
    public void UiDatElement_DefaultsActiveStateToNormal_WhenNormalPresent()
    {
        var info = new ElementInfo();
        info.StateMedia["Normal"] = (0x0000AAAAu, 1);
        info.StateMedia["Hover"]  = (0x0000BBBBu, 1);

        var e = new UiDatElement(info, _ => (0, 0, 0));

        // Should have defaulted to "Normal" state.
        Assert.Equal(0x0000AAAAu, e.ActiveMedia().File);
    }

    /// <summary>
    /// Task G1 change 5: when DefaultStateName is set (e.g. "Minimized"),
    /// it takes priority over the "Normal" implicit default.
    /// </summary>
    [Fact]
    public void UiDatElement_DefaultsActiveStateToDefaultStateName_WhenSet()
    {
        var info = new ElementInfo { DefaultStateName = "Minimized" };
        info.StateMedia["Minimized"] = (0x0000BBBBu, 1);
        info.StateMedia["Maximized"] = (0x0000CCCCu, 1);
        info.StateMedia["Normal"]    = (0x0000DDDDu, 1);

        var e = new UiDatElement(info, _ => (0, 0, 0));

        // DefaultStateName "Minimized" wins over "Normal" implicit default.
        Assert.Equal(0x0000BBBBu, e.ActiveMedia().File);
    }

    /// <summary>
    /// Task G1 change 5: elements with only a DirectState sprite and no "Normal" state
    /// should still default to "" (DirectState) — no regression for chrome/grip elements.
    /// </summary>
    [Fact]
    public void UiDatElement_NoDefaultStateName_NoNormal_DefaultsToDirectState()
    {
        var info = new ElementInfo();
        info.StateMedia[""] = (0x06007777u, 1);  // DirectState only (e.g. vitals chrome corner)

        var e = new UiDatElement(info, _ => (0, 0, 0));

        // No DefaultStateName, no "Normal" state → ActiveState stays "" (DirectState).
        Assert.Equal(0x06007777u, e.ActiveMedia().File);
    }

    [Fact]
    public void NumericStateBridge_SetsNamedStateWithoutChangingGeometry()
    {
        var info = new ElementInfo { X = 4, Y = 5, Width = 30, Height = 40 };
        info.States[RetailUiStateIds.ShowDetail] = new UiStateInfo
        {
            Id = RetailUiStateIds.ShowDetail,
            Name = "ShowDetail",
            Image = new UiImageMedia(0x06000009u, 3),
        };
        info.StateMedia["ShowDetail"] = (0x06000009u, 3);
        var element = new UiDatElement(info, _ => (0u, 0, 0))
        {
            Left = info.X,
            Top = info.Y,
            Width = info.Width,
            Height = info.Height,
        };

        Assert.True(element.TrySetRetailState(RetailUiStateIds.ShowDetail));

        Assert.Equal(RetailUiStateIds.ShowDetail, element.ActiveRetailStateId);
        Assert.Equal((0x06000009u, 3), element.ActiveMedia());
        Assert.Equal((4f, 5f, 30f, 40f),
            (element.Left, element.Top, element.Width, element.Height));
    }

    [Fact]
    public void NumericStateBridge_MissingStatePreservesCurrentState()
    {
        var info = new ElementInfo { DefaultStateName = "Normal" };
        info.StateMedia["Normal"] = (0x06000001u, 1);
        var element = new UiDatElement(info, _ => (0u, 0, 0));

        Assert.False(element.TrySetRetailState(RetailUiStateIds.ShowDetail));
        Assert.Equal("Normal", element.ActiveState);
    }
}