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

namespace AcDream.App.Tests.Rendering;

/// <summary>
/// T1 (fused BR-2/3) partition contract — retail draw order: static world
/// first, every server-spawned DYNAMIC in the frame's single LAST pass.
/// <list type="bullet">
///   <item>ALL ServerGuid != 0 entities land in <c>Dynamics</c> regardless of
///   cell (indoor, outdoor, unresolved, even non-visible cells — retail never
///   drops a live entity for visibility-set reasons; culling is the
///   viewcone's job, T3).</item>
///   <item><c>ByCell</c> carries only dat-baked indoor statics of VISIBLE
///   cells (drawn with their cell).</item>
///   <item><c>OutdoorStatic</c> carries shells/scenery (the world pass).</item>
/// </list>
/// </summary>
public class InteriorEntityPartitionTests
{
    private const uint CellA = 0xA9B40170;
    private const uint CellB = 0xA9B40171;
    private const uint HiddenCell = 0xA9B40199;
    private const uint OutdoorCell = 0xA9B40020;

    private static WorldEntity Ent(uint id, uint serverGuid, uint? parentCell) => new()
    {
        Id = id,
        ServerGuid = serverGuid,
        SourceGfxObjOrSetupId = 0x01000001,
        Position = Vector3.Zero,
        Rotation = Quaternion.Identity,
        MeshRefs = new[] { new MeshRef(0x01000001, Matrix4x4.Identity) },
        ParentCellId = parentCell,
    };

    private static IEnumerable<(uint, Vector3, Vector3, IReadOnlyList<WorldEntity>,
        IReadOnlyDictionary<uint, WorldEntity>?)> OneLb(uint lbId, params WorldEntity[] ents)
        => new[] { (lbId, Vector3.Zero, Vector3.Zero, (IReadOnlyList<WorldEntity>)ents,
                    (IReadOnlyDictionary<uint, WorldEntity>?)null) };

    [Fact]
    public void AllServerSpawned_GoToDynamics_StaticsSplitByCellAndOutdoor()
    {
        var unresolvedLive = Ent(1, serverGuid: 0x5000000A, parentCell: null);
        var liveNpcInCell = Ent(2, serverGuid: 0x80001234, parentCell: CellA);
        var staticA = Ent(3, serverGuid: 0, parentCell: CellA);
        var staticB = Ent(4, serverGuid: 0, parentCell: CellB);
        var scenery = Ent(5, serverGuid: 0, parentCell: null);
        var liveOutdoor = Ent(6, serverGuid: 0x80005678, parentCell: OutdoorCell);

        var visible = new HashSet<uint> { CellA, CellB };
        var result = InteriorEntityPartition.Partition(
            visible, OneLb(0xA9B4FFFF, unresolvedLive, liveNpcInCell, staticA, staticB, scenery, liveOutdoor));

        // Every server-spawned entity is a dynamic — drawn in the last pass.
        Assert.Equal(3, result.Dynamics.Count);
        Assert.Contains(unresolvedLive, result.Dynamics);
        Assert.Contains(liveNpcInCell, result.Dynamics);
        Assert.Contains(liveOutdoor, result.Dynamics);

        // Indoor statics ride with their (visible) cell.
        Assert.Single(result.ByCell[CellA]);
        Assert.Contains(staticA, result.ByCell[CellA]);
        Assert.Single(result.ByCell[CellB]);
        Assert.Contains(staticB, result.ByCell[CellB]);

        // Outdoor statics (shells/scenery) ride with the world pass.
        Assert.Single(result.OutdoorStatic);
        Assert.Contains(scenery, result.OutdoorStatic);
    }

    [Fact]
    public void HiddenCell_DropsStatics_ButNeverDynamics()
    {
        var staticHidden = Ent(3, serverGuid: 0, parentCell: HiddenCell);
        var liveHidden = Ent(4, serverGuid: 0x80001234, parentCell: HiddenCell);
        var visible = new HashSet<uint> { CellA };

        var result = InteriorEntityPartition.Partition(
            visible, OneLb(0xA9B4FFFF, staticHidden, liveHidden));

        // A static in a non-flooded cell is not drawn this frame…
        Assert.False(result.ByCell.ContainsKey(HiddenCell));
        Assert.Empty(result.OutdoorStatic);

        // …but a LIVE entity is never dropped by the visibility set (the old
        // contract dropped it — the audit's livedynamic-invisible divergence).
        Assert.Single(result.Dynamics);
        Assert.Contains(liveHidden, result.Dynamics);
    }

    [Fact]
    public void EntityWithNoMeshRefs_IsSkipped()
    {
        var noMesh = new WorldEntity
        {
            Id = 9, ServerGuid = 0, SourceGfxObjOrSetupId = 0x01000001,
            Position = Vector3.Zero, Rotation = Quaternion.Identity,
            MeshRefs = System.Array.Empty<MeshRef>(), ParentCellId = CellA,
        };
        var result = InteriorEntityPartition.Partition(
            new HashSet<uint> { CellA }, OneLb(0xA9B4FFFF, noMesh));

        Assert.False(result.ByCell.ContainsKey(CellA));
        Assert.Empty(result.Dynamics);
        Assert.Empty(result.OutdoorStatic);
    }
}