using AcDream.Core.Physics;
using AcDream.Core.Physics.Motion;
using Xunit;

namespace AcDream.Core.Tests.Physics;

/// <summary>
/// R4-V5 door-swing fix (2026-07-03, register TS-40): CMotionInterp's
/// dispatch tails strip link animations for DETACHED objects only (retail
/// <c>if (physics_obj->cell == 0) RemoveLinkAnimations</c>, raw @305627).
/// The old proxy (<c>CellPosition.ObjCellId == 0</c>) was seeded only by
/// the local player's SnapToCell, so every REMOTE body read "detached" and
/// every dispatched transition link (door open/close swings, remote
/// walk↔run links) was stripped the same tick it was appended — the pose
/// snapped straight to the new cycle. These pin the corrected
/// <see cref="PhysicsBody.InWorld"/> guard polarity.
/// </summary>
public class InWorldLinkGuardTests
{
    [Fact]
    public void InWorldBody_DispatchKeepsTransitionLinks()
    {
        var body = new PhysicsBody
        {
            InWorld = true,
            TransientState = TransientStateFlags.Contact
                           | TransientStateFlags.OnWalkable
                           | TransientStateFlags.Active,
        };
        var interp = new MotionInterpreter(body);
        int strips = 0;
        interp.RemoveLinkAnimations = () => strips++;

        interp.DoInterpretedMotion(MotionCommand.WalkForward, new MovementParameters());

        Assert.Equal(0, strips);
    }

    [Fact]
    public void DetachedBody_DispatchStripsLinks_RetailGuard()
    {
        var body = new PhysicsBody
        {
            // InWorld left false — retail's pre-enter_world detached state.
            TransientState = TransientStateFlags.Contact
                           | TransientStateFlags.OnWalkable
                           | TransientStateFlags.Active,
        };
        var interp = new MotionInterpreter(body);
        int strips = 0;
        interp.RemoveLinkAnimations = () => strips++;

        interp.DoInterpretedMotion(MotionCommand.WalkForward, new MovementParameters());

        Assert.Equal(1, strips);
    }

    [Fact]
    public void RemoteShapedBody_StopCompletely_KeepsLinksToo()
    {
        // The other two guard sites (StopCompletely / StopInterpretedMotion)
        // share the same InWorld polarity.
        var body = new PhysicsBody
        {
            InWorld = true,
            TransientState = TransientStateFlags.Contact
                           | TransientStateFlags.OnWalkable
                           | TransientStateFlags.Active,
        };
        var interp = new MotionInterpreter(body);
        int strips = 0;
        interp.RemoveLinkAnimations = () => strips++;

        interp.StopCompletely();

        Assert.Equal(0, strips);
    }
}