using AcDream.App.Rendering.Wb;
using AcDream.Core.Meshing;
using Xunit;

namespace AcDream.Core.Tests.Rendering.Wb;

/// <summary>
/// A.5 T21: lock in the depth-write attribution per translucency kind.
/// <para>
/// <c>WbDrawDispatcher.Draw</c> uses a two-pass structure:
/// <list type="bullet">
///   <item>Opaque pass — <c>DepthMask(true)</c>: writes depth so that
///     later transparent geometry sorts correctly against solid surfaces.</item>
///   <item>Transparent pass — <c>DepthMask(false)</c>: reads depth but
///     does NOT write it, so alpha-blended surfaces don't occlude each
///     other by Z-fighting.</item>
/// </list>
/// The partition that decides which pass a batch enters is
/// <see cref="WbDrawDispatcher.IsOpaquePublic"/>:
/// <c>Opaque</c> and <c>ClipMap</c> go to the opaque pass (depth write);
/// <c>AlphaBlend</c>, <c>Additive</c>, <c>InvAlpha</c> go to the
/// transparent pass (no depth write).
/// </para>
/// </summary>
public sealed class WbDispatcherDepthMaskTests
{
    [Theory]
    [InlineData(TranslucencyKind.Opaque,     true)]   // opaque pass — depth write
    [InlineData(TranslucencyKind.ClipMap,    true)]   // foliage — depth write (binary alpha / A2C)
    [InlineData(TranslucencyKind.AlphaBlend, false)]  // transparent — no depth write
    [InlineData(TranslucencyKind.Additive,   false)]
    [InlineData(TranslucencyKind.InvAlpha,   false)]
    public void IsOpaquePartition_ImpliesDepthWriteAttribution(
        TranslucencyKind kind, bool expectsDepthWrite)
    {
        bool isOpaque = WbDrawDispatcher.IsOpaquePublic(kind);
        Assert.Equal(expectsDepthWrite, isOpaque);
    }
}