using AcDream.Core.Meshing;
using DatReaderWriter.Enums;

namespace AcDream.Core.Tests.Meshing;

/// <summary>
/// #426 (2026-08-23, the Holtburg windmill axle 0x010010CE): pins the two
/// predicates that replaced the buggy <c>isSolid = NoPos || Base1Solid</c>
/// extraction rule and the "retail never draws untextured subsets" #119
/// misconception. See RetailUntexturedSurfacePolicy.cs for the full retail
/// citations (D3DPolyRender::DrawMesh / DrawBuilding / DrawEnvCell).
/// </summary>
public sealed class RetailUntexturedSurfacePolicyTests
{
    [Theory]
    [InlineData(SurfaceType.Base1Solid, true)] // solid-colour — untextured
    [InlineData((SurfaceType)0, true)] // neither bit set — untextured
    [InlineData(SurfaceType.Base1Image, false)] // BASE1_IMAGE (0x2) — textured
    [InlineData(SurfaceType.Base1ClipMap, false)] // BASE1_CLIPMAP (0x4) — textured
    [InlineData(SurfaceType.Base1Image | SurfaceType.Base1Solid, false)] // both bits — retail's literal (type & 6) != 0 still calls this textured
    [InlineData(SurfaceType.Base1Image | SurfaceType.Additive, false)] // unrelated flags alongside a textured bit stay textured
    public void IsUntextured_MatchesRetailBitmask(SurfaceType type, bool expected)
    {
        Assert.Equal(expected, RetailUntexturedSurfacePolicy.IsUntextured(type));
    }

    [Theory]
    // (isBuildingShell, isUntextured) -> draws
    [InlineData(false, true, true)] // ordinary object, solid subset — retail draws it (#426's own bug)
    [InlineData(true, true, false)] // building shell, solid subset — retail's DrawBuilding skips it
    [InlineData(false, false, true)] // ordinary object, textured subset — always drawn
    [InlineData(true, false, true)] // building shell, textured subset — the shell gate only touches untextured subsets
    public void Draws_MatchesRetailBuildingShellGate(
        bool isBuildingShell,
        bool isUntextured,
        bool expectedDraws)
    {
        Assert.Equal(
            expectedDraws,
            RetailUntexturedSubsetPolicy.Draws(isBuildingShell, isUntextured));
    }
}