using System.Collections.Generic;
using System.Numerics;
using AcDream.App.Rendering;
using Xunit;

namespace AcDream.App.Tests.Rendering;

public class ClipFrameAssemblerTests
{
    private static ViewPolygon Square(float cx, float cy, float half) => new(new[]
    {
        new Vector2(cx - half, cy - half),
        new Vector2(cx + half, cy - half),
        new Vector2(cx + half, cy + half),
        new Vector2(cx - half, cy + half),
    });

    private static CellView ViewOf(params ViewPolygon[] polys)
    {
        var view = new CellView();
        foreach (var p in polys)
            view.Add(p);
        return view;
    }

    [Fact]
    public void TwoVisibleCells_PlusOutsideView_ProducesCorrectSlotMapAndCounts()
    {
        const uint cellA = 0xA9B40100;
        const uint cellB = 0xA9B40101;

        var pv = new PortalVisibilityFrame();
        pv.CellViews[cellA] = ViewOf(Square(-0.3f, 0f, 0.3f));
        pv.CellViews[cellB] = ViewOf(Square(0.3f, 0f, 0.2f));
        pv.OrderedVisibleCells.Add(cellA);
        pv.OrderedVisibleCells.Add(cellB);
        pv.OutsideView.Add(Square(0f, 0.5f, 0.25f));

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.Equal(4, asm.Frame.SlotCount); // slot 0 + two cells + one outside slice
        Assert.Contains(cellA, asm.CellIdToSlot.Keys);
        Assert.Contains(cellB, asm.CellIdToSlot.Keys);
        Assert.NotEqual(0, asm.CellIdToSlot[cellA]);
        Assert.NotEqual(0, asm.CellIdToSlot[cellB]);
        Assert.NotEqual(asm.CellIdToSlot[cellA], asm.CellIdToSlot[cellB]);
        Assert.Equal(4, asm.PerCellPlaneCounts[cellA]);
        Assert.Equal(4, asm.PerCellPlaneCounts[cellB]);

        Assert.True(asm.OutdoorVisible);
        Assert.NotEqual(0, asm.OutdoorSlot);
        Assert.Single(asm.OutsideViewSlices);
        Assert.Equal(asm.OutdoorSlot, asm.OutsideViewSlices[0].Slot);
        Assert.Equal(TerrainClipMode.Planes, asm.TerrainMode);
        Assert.Equal(4, asm.OutsidePlaneCount);
        Assert.Equal(0, asm.ScissorFallbacks);
    }

    [Fact]
    public void NothingVisibleCell_IsExcludedFromSlotMap_AndNotAppended()
    {
        const uint cellA = 0xA9B40100;
        const uint cellB = 0xA9B40101;

        var pv = new PortalVisibilityFrame();
        pv.CellViews[cellA] = ViewOf(Square(0f, 0f, 0.3f));
        pv.CellViews[cellB] = new CellView();
        pv.OrderedVisibleCells.Add(cellA);
        pv.OrderedVisibleCells.Add(cellB);

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.Equal(2, asm.Frame.SlotCount);
        Assert.Contains(cellA, asm.CellIdToSlot.Keys);
        Assert.DoesNotContain(cellB, asm.CellIdToSlot.Keys);
        Assert.False(asm.OutdoorVisible);
        Assert.Empty(asm.OutsideViewSlices);
        Assert.Equal(TerrainClipMode.Skip, asm.TerrainMode);
        Assert.Equal(0, asm.OutsidePlaneCount);
    }

    [Fact]
    public void OutsideViewMultiPolygon_PreservesRetailSlices()
    {
        const uint cellA = 0xA9B40100;

        var pv = new PortalVisibilityFrame();
        pv.CellViews[cellA] = ViewOf(Square(0f, 0f, 0.3f));
        pv.OrderedVisibleCells.Add(cellA);
        pv.OutsideView.Add(Square(-0.5f, 0f, 0.1f));
        pv.OutsideView.Add(Square(0.5f, 0f, 0.1f));

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.True(asm.OutdoorVisible);
        Assert.NotEqual(0, asm.OutdoorSlot);
        Assert.Equal(2, asm.OutsideViewSlices.Length);
        Assert.NotEqual(asm.OutsideViewSlices[0].Slot, asm.OutsideViewSlices[1].Slot);
        Assert.Equal(TerrainClipMode.Planes, asm.TerrainMode);
        Assert.Equal(4, asm.OutsidePlaneCount);
        Assert.Equal(0, asm.ScissorFallbacks);
        Assert.Equal(4, asm.Frame.SlotCount); // slot 0 + cell + two outside slices
        Assert.Equal(Vector4.Zero, asm.TerrainScissorNdcAabb);
    }

    [Fact]
    public void CellMultiPolygonView_PreservesRetailViewSlices()
    {
        const uint cellA = 0xA9B40100;

        var pv = new PortalVisibilityFrame();
        pv.CellViews[cellA] = ViewOf(
            Square(-0.4f, 0f, 0.1f),
            Square(0.4f, 0f, 0.1f));
        pv.OrderedVisibleCells.Add(cellA);
        pv.OutsideView.Add(Square(0f, 0f, 0.3f));

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.True(asm.CellIdToSlot[cellA] > 0);
        Assert.Equal(2, asm.CellIdToViewSlots[cellA].Length);
        Assert.Equal(2, asm.CellIdToViewSlices[cellA].Length);
        Assert.NotEqual(asm.CellIdToViewSlots[cellA][0], asm.CellIdToViewSlots[cellA][1]);
        Assert.Equal(4, asm.PerCellPlaneCounts[cellA]);
        Assert.Single(asm.OutsideViewSlices);
        Assert.Equal(4, asm.Frame.SlotCount); // slot 0 + two cell slices + outside slice
        Assert.Equal(0, asm.ScissorFallbacks);
        Assert.Equal(TerrainClipMode.Planes, asm.TerrainMode);
    }

    [Fact]
    public void Assemble_OutsideViewWithExitPortal_HasOutsideViewTrue_AabbMatchesBounds()
    {
        var pv = new PortalVisibilityFrame();
        pv.OutsideView.Add(Square(-0.3f, 0.2f, 0.25f));

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.True(asm.HasOutsideView);
        Assert.Equal(TerrainClipMode.Planes, asm.TerrainMode);
        Assert.Single(asm.OutsideViewSlices);

        var expected = new Vector4(
            pv.OutsideView.MinX, pv.OutsideView.MinY,
            pv.OutsideView.MaxX, pv.OutsideView.MaxY);
        Assert.Equal(expected, asm.OutsideViewNdcAabb);
    }

    [Fact]
    public void Assemble_OutsideViewMultiPolygon_PreservesSlicesAndUnionAabb()
    {
        var pv = new PortalVisibilityFrame();
        pv.OutsideView.Add(Square(-0.6f, 0f, 0.15f));
        pv.OutsideView.Add(Square(0.6f, 0f, 0.15f));

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.True(asm.HasOutsideView);
        Assert.Equal(TerrainClipMode.Planes, asm.TerrainMode);
        Assert.Equal(2, asm.OutsideViewSlices.Length);

        var expected = new Vector4(
            pv.OutsideView.MinX, pv.OutsideView.MinY,
            pv.OutsideView.MaxX, pv.OutsideView.MaxY);
        Assert.Equal(expected, asm.OutsideViewNdcAabb);
        Assert.Equal(Vector4.Zero, asm.TerrainScissorNdcAabb);
    }

    [Fact]
    public void Assemble_EmptyOutsideView_HasOutsideViewFalse_AabbZero()
    {
        const uint cellA = 0xA9B40100;
        var pv = new PortalVisibilityFrame();
        pv.CellViews[cellA] = ViewOf(Square(0f, 0f, 0.3f));
        pv.OrderedVisibleCells.Add(cellA);

        var asm = ClipFrameAssembler.Assemble(ClipFrame.NoClip(), pv);

        Assert.False(asm.HasOutsideView);
        Assert.Equal(TerrainClipMode.Skip, asm.TerrainMode);
        Assert.Equal(Vector4.Zero, asm.OutsideViewNdcAabb);
    }

    [Fact]
    public void Reset_ReusesFrame_NoSlotLeakAcrossAssemblies()
    {
        var frame = ClipFrame.NoClip();

        var pv1 = new PortalVisibilityFrame();
        pv1.CellViews[0xA9B40100] = ViewOf(Square(-0.3f, 0f, 0.2f));
        pv1.CellViews[0xA9B40101] = ViewOf(Square(0.3f, 0f, 0.2f));
        pv1.OrderedVisibleCells.Add(0xA9B40100);
        pv1.OrderedVisibleCells.Add(0xA9B40101);
        pv1.OutsideView.Add(Square(0f, 0.4f, 0.2f));
        var asm1 = ClipFrameAssembler.Assemble(frame, pv1);
        Assert.Equal(4, asm1.Frame.SlotCount);

        var pv2 = new PortalVisibilityFrame();
        pv2.CellViews[0xA9B40200] = ViewOf(Square(0f, 0f, 0.25f));
        pv2.OrderedVisibleCells.Add(0xA9B40200);
        var asm2 = ClipFrameAssembler.Assemble(frame, pv2);

        Assert.Equal(2, asm2.Frame.SlotCount);
        Assert.Contains(0xA9B40200, asm2.CellIdToSlot.Keys);
        Assert.DoesNotContain(0xA9B40100, asm2.CellIdToSlot.Keys);
        Assert.False(asm2.OutdoorVisible);
        Assert.Equal(TerrainClipMode.Skip, asm2.TerrainMode);
    }
}