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

namespace AcDream.Core.Tests.Physics.Motion;

// ─────────────────────────────────────────────────────────────────────────────
// #174 pin (2026-07-05): the RemoveLinkAnimations seam must be retail
// CPhysicsObj::RemoveLinkAnimations 0x0050fe20 — a TAILCALL to
// CPartArray::HandleEnterWorld 0x00517d70 → MotionTableManager::
// HandleEnterWorld 0x0051bdd0: CSequence::remove_all_link_animations PLUS a
// full pending_animations drain (`while (head) AnimationDone(0)`), each pop
// relaying MotionDone → CMotionInterp pops its pending_motions node in
// lockstep.
//
// The pre-fix binding was the bare sequence strip: every LeaveGround (jump)
// removed the link animations that queued MotionTableManager nodes were
// counting down on, orphaning them (NumAnims > 0, animations gone). Both
// queues then dammed permanently — MotionsPending() never drained at rest —
// and BeginTurnToHeading/BeginMoveForward (retail 0x00529b90 motions_pending
// gate) starved every armed moveto: ACE's walk-to-door mt-6 armed but the
// body never walked; the close-range Use turn never completed so the
// deferred action was silently eaten. Live evidence: launch-174-autowalk.log
// (last player pending=False at the first MovementJump press; old jump
// motions still completing at rest minutes later).
// ─────────────────────────────────────────────────────────────────────────────
public class Issue174LinkStripDrainTests
{
    private readonly ITestOutputHelper _out;
    public Issue174LinkStripDrainTests(ITestOutputHelper output) => _out = output;

    /// <summary>
    /// The jam repro: queue motions (link + cycle nodes land in BOTH the
    /// interp's pending_motions and the manager's pending_animations), then
    /// fire the LeaveGround-side seam. With the retail HandleEnterWorld
    /// binding both queues drain to empty; the pre-fix bare-strip binding
    /// left both non-empty forever.
    /// </summary>
    [Fact]
    public void RemoveLinkAnimationsSeam_DrainsBothQueues()
    {
        var h = new RemoteChaseHarness(_out);

        // Drive a motion burst — walk, run, stop — the shape a player's
        // pre-jump input produces. Each successful dispatch pairs an interp
        // node with a manager node.
        var p = new MovementParameters();
        h.Interp.DoMotion(MotionCommand.WalkForward, p);
        h.Interp.set_hold_run(true, interrupt: false);
        h.Interp.StopMotion(MotionCommand.WalkForward, p);

        Assert.True(h.Interp.MotionsPending(),
            "precondition: the burst must leave pending interp nodes");
        Assert.NotEmpty(h.Seq.Manager.PendingAnimations);

        // The LeaveGround seam (retail CMotionInterp::LeaveGround 0x00528b00
        // fires CPhysicsObj::RemoveLinkAnimations).
        h.Interp.RemoveLinkAnimations!.Invoke();

        Assert.False(h.Interp.MotionsPending(),
            "HandleEnterWorld's drain must pop every pending interp node " +
            "(retail: each AnimationDone(0) relays MotionDone)");
        Assert.Empty(h.Seq.Manager.PendingAnimations);
    }

    /// <summary>
    /// The post-jump livability pin: after the seam fires mid-activity, a
    /// NEW moveto-style dispatch must be able to queue and complete — the
    /// #174 symptom was that BeginTurnToHeading's motions_pending gate never
    /// re-opened after a jump, permanently starving armed movetos.
    /// </summary>
    [Fact]
    public void AfterSeamDrain_NewMotionsQueueAndComplete()
    {
        var h = new RemoteChaseHarness(_out);
        var p = new MovementParameters();

        // Pre-jump activity, then the jump's LeaveGround strip+drain.
        h.Interp.DoMotion(MotionCommand.WalkForward, p);
        h.Interp.RemoveLinkAnimations!.Invoke();
        Assert.False(h.Interp.MotionsPending());

        // A fresh dispatch (the armed moveto's turn) queues...
        h.Interp.DoMotion(MotionCommand.TurnRight, p);
        Assert.True(h.Interp.MotionsPending());

        // ...and the normal completion path (the manager's queue feeding
        // MotionDone) drains it — the gate re-opens.
        while (h.Seq.Manager.PendingAnimations.GetEnumerator() is var e && e.MoveNext())
            h.Seq.Manager.AnimationDone(success: true);

        h.Seq.Manager.CheckForCompletedMotions();
        Assert.False(h.Interp.MotionsPending(),
            "the normal AnimationDone → MotionDone chain must drain the new node");
    }
}