using System.Numerics;
using AcDream.App.Input;
using AcDream.App.Physics;
using AcDream.Core.Physics;
using AcDream.Core.Physics.Motion;
using DatReaderWriter.Types;
using DatEnvCell = DatReaderWriter.DBObjs.EnvCell;

namespace AcDream.App.Tests.Input;

public sealed class PlayerMovementPlacementTransactionTests
{
    private const uint PlayerGuid = 0x5000_0001u;
    private const uint TargetGuid = 0x7000_0001u;
    private const uint PriorCell = 0x0101_0101u;
    private const uint DestinationCell = 0x0101_0102u;

    /// <summary>
    /// C5a (2026-08-05) re-point: <c>PlayerMovementController.CommitPreparedPosition</c>
    /// is deleted (zero production callers — production placement now arms
    /// the login-entry leash via <c>ArmConstraintLeashAtCommittedPlacement</c>,
    /// called from <c>RuntimeLocalPlayerPhysicsPublicationState.ArmFirstEntryConstraintLeash</c>
    /// AFTER <c>RuntimeSetPositionState.TryApplyDormantLocalActivationFinalCommit</c>
    /// has already published the shared current cell — see that method's
    /// doc comment). Architecture-review correction (A5, 2026-08-05): the two
    /// deleted invariants did NOT relocate symmetrically.
    /// <b>Render-root publish DID move</b> — it happens inside
    /// <c>RuntimeSetPositionState.TryApplyDormantLocalActivationFinalCommit</c>
    /// itself, via <c>_physics.Engine.UpdatePlayerCurrCell(result.CellId)</c>
    /// (<c>RuntimeSetPositionState.cs:2774</c>).
    /// <b>Sticky-target release did NOT move anywhere</b> — <c>grep -rn
    /// "UnStick" src/AcDream.Runtime/</c> returns zero call sites on this
    /// path; the only local-player <c>UnStick</c> left is
    /// <c>PlayerMovementController.SetPositionCore</c>'s
    /// <c>if (publishSharedState) PositionManager?.UnStick();</c>, and
    /// <c>PreparePositionForCommit</c> passes <c>publishSharedState: false</c>.
    /// The unstick-at-first-entry-commit behaviour <c>CommitPreparedPosition</c>
    /// used to perform is simply gone — it was dead code (the method had zero
    /// production callers before this slice deleted it), so nothing regresses
    /// today, but no layer pins the invariant "first-entry commit releases any
    /// sticky target" any more. That is disposition 3.6's one real coverage
    /// loss (see the C5a commit message).
    /// This App-layer fixture (a bare <see cref="PlayerMovementController"/> +
    /// <see cref="EntityPhysicsHost"/> pair, no Runtime activation pipeline)
    /// cannot drive the Runtime final-commit transaction without
    /// disproportionate fixture growth — recorded here as the explicit C5a
    /// scope decision rather than silently dropped.
    /// What THIS test still proves, unchanged: <see cref="PlayerMovementController.PreparePositionForCommit"/>
    /// defers the render-root publish exactly as before (<c>controller.CellId</c>
    /// updates immediately; <c>physics.DataCache.CellGraph.CurrCell</c> and
    /// the sticky target stay untouched), and the surviving production
    /// commit-arm, <see cref="PlayerMovementController.ArmConstraintLeashAtCommittedPlacement"/>,
    /// arms the constraint leash without independently touching either —
    /// neither the render-root publish (a DIFFERENT layer's job now) nor the
    /// sticky release (nobody's job any more).
    /// </summary>
    [Fact]
    public void PreparedPosition_DefersRenderRootPublish_CommitArmsLeashOnly()
    {
        PhysicsEngine physics = PhysicsWithCells(PriorCell, DestinationCell);
        physics.UpdatePlayerCurrCell(PriorCell);
        var controller = new PlayerMovementController(physics);
        var hosts = new Dictionary<uint, IPhysicsObjHost>();
        IPhysicsObjHost? Resolve(uint id) => hosts.GetValueOrDefault(id);
        EntityPhysicsHost player = Host(PlayerGuid, Resolve);
        EntityPhysicsHost target = Host(TargetGuid, Resolve);
        hosts.Add(PlayerGuid, player);
        hosts.Add(TargetGuid, target);
        controller.PositionManager = player.PositionManager;
        player.PositionManager.StickTo(TargetGuid, 0.5f, 1.8f);

        controller.PreparePositionForCommit(
            new Vector3(2f, 3f, 4f),
            DestinationCell,
            new Vector3(2f, 3f, 4f));

        Assert.Equal(DestinationCell, controller.CellId);
        Assert.Equal(PriorCell, physics.DataCache!.CellGraph.CurrCell!.Id);
        Assert.Equal(TargetGuid, player.PositionManager.GetStickyObjectId());
        Assert.False(player.PositionManager.IsFullyConstrained());
        Assert.Null(player.PositionManager.Constraint);

        controller.ArmConstraintLeashAtCommittedPlacement();

        // The leash is armed...
        Assert.NotNull(player.PositionManager.Constraint);
        Assert.True(player.PositionManager.Constraint!.IsConstrained);
        // ...but the surviving App-layer commit does NOT publish the render
        // root or release the sticky target — those now happen inside the
        // Runtime dormant-activation final commit, before this method runs.
        Assert.Equal(PriorCell, physics.DataCache.CellGraph.CurrCell!.Id);
        Assert.Equal(TargetGuid, player.PositionManager.GetStickyObjectId());
    }

    private static PhysicsEngine PhysicsWithCells(params uint[] cellIds)
    {
        var physics = new PhysicsEngine { DataCache = new PhysicsDataCache() };
        foreach (uint cellId in cellIds)
        {
            var cellStruct = new CellStruct
            {
                VertexArray = new VertexArray
                {
                    Vertices = new Dictionary<ushort, SWVertex>(),
                },
                Polygons = new Dictionary<ushort, Polygon>(),
                CellBSP = new CellBSPTree
                {
                    Root = new CellBSPNode
                    {
                        Type = DatReaderWriter.Enums.BSPNodeType.Leaf,
                    },
                },
            };
            var envCell = new DatEnvCell
            {
                CellPortals = [],
                VisibleCells = [],
            };
            physics.DataCache.CacheCellStruct(
                cellId,
                envCell,
                cellStruct,
                Matrix4x4.Identity);
        }
        return physics;
    }

    private static EntityPhysicsHost Host(
        uint guid,
        Func<uint, IPhysicsObjHost?> resolve) =>
        new(
            guid,
            getPosition: () => new AcDream.Core.Physics.Position(
                PriorCell,
                Vector3.Zero,
                Quaternion.Identity),
            getVelocity: () => Vector3.Zero,
            getRadius: () => 0.5f,
            inContact: () => true,
            minterpMaxSpeed: () => 1f,
            curTime: () => 0d,
            physicsTimerTime: () => 0d,
            getObjectA: resolve,
            handleUpdateTarget: _ => { },
            interruptCurrentMovement: () => { });
}