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

namespace AcDream.App.Tests.Rendering;

/// <summary>
/// The OUTDOOR render root (R-A2, 2026-06-08): a portal-less <see cref="LoadedCell"/> whose only job is
/// to root the render outdoors so the flood seeds OutsideView FULL-SCREEN (terrain draws). Buildings are
/// flooded SEPARATELY per-building (<see cref="PortalVisibilityBuilder.ConstructViewBuilding"/>), so the
/// node carries NO reverse portals — the pre-R-A2 reverse-portal unified flood (which oscillated at the
/// doorway) is gone. Its tests moved here; the old <c>UnifiedFloodTests</c> was retired.
/// </summary>
public class OutdoorCellNodeTests
{
    [Fact]
    public void Build_ReturnsPortallessOutdoorRoot()
    {
        uint outdoorId = 0xA9B40031;
        var node = OutdoorCellNode.Build(outdoorId);

        Assert.Equal(outdoorId, node.CellId);
        Assert.True(node.IsOutdoorNode);  // the flag PortalVisibilityBuilder keys the full-screen OutsideView on
        Assert.True(node.SeenOutside);
        Assert.Equal(Matrix4x4.Identity, node.WorldTransform);
        Assert.Empty(node.Portals);       // R-A2: no reverse portals into buildings (buildings flood per-building)
    }

    [Fact]
    public void Build_OutdoorRoot_SeedsFullScreenOutsideView_OnlyNodeVisible()
    {
        // The load-bearing outdoor-terrain behavior: rooting at the IsOutdoorNode node seeds OutsideView
        // with the FULL-SCREEN NDC quad, so ClipFrameAssembler yields TerrainMode != Skip and
        // DrawLandscapeThroughOutsideView draws terrain/sky/scenery everywhere. The portal-less node
        // resolves to exactly {node} — no interior cells flooded from the root (those come per-building).
        var node = OutdoorCellNode.Build(0xA9B40031);

        var eye = new Vector3(0, -3, 1);
        var view = Matrix4x4.CreateLookAt(eye, new Vector3(0, 5, 1), Vector3.UnitZ);
        var proj = Matrix4x4.CreatePerspectiveFieldOfView(MathF.PI / 3f, 16f / 9f, 1f, 5000f);

        var frame = PortalVisibilityBuilder.Build(node, eye, _ => null, view * proj);

        Assert.Equal(new[] { 0xA9B40031u }, frame.OrderedVisibleCells); // only the node
        Assert.False(frame.OutsideView.IsEmpty);
        Assert.Equal(-1f, frame.OutsideView.MinX, 3);
        Assert.Equal(-1f, frame.OutsideView.MinY, 3);
        Assert.Equal(1f, frame.OutsideView.MaxX, 3);
        Assert.Equal(1f, frame.OutsideView.MaxY, 3);
    }
}