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

namespace AcDream.Core.Tests.Physics.Motion;

/// <summary>
/// R5-V5 — <see cref="MovementManager"/> facade conformance (retail struct
/// acclient.h /* 3463 */; methods 0x00524000-0x00524790, decomp extract
/// <c>docs/research/2026-07-03-r5-managers/r5-movementmanager-decomp.md</c>).
/// The facade is pure relay/ownership — these tests pin the retail call
/// shapes: which child each method touches, the lazy MakeMoveToManager
/// create, the PerformMovement type dispatch, and null-tolerance before the
/// moveto manager exists. Behavior of the children themselves is covered by
/// the MotionInterpreter / MoveToManager suites (UNMODIFIED by R5-V5).
/// </summary>
public sealed class MovementManagerTests
{
    /// <summary>Non-creature weenie: silences the MotionInterpreter's
    /// HitGround/LeaveGround creature gates (retail IsCreature vtable
    /// +0x2c) so a test can isolate the facade's MOVETO relay leg.</summary>
    private sealed class NonCreatureWeenie : IWeenieObject
    {
        public bool InqJumpVelocity(float extent, out float vz) { vz = 0f; return false; }
        public bool InqRunRate(out float rate) { rate = 1f; return false; }
        public bool CanJump(float extent) => false;
        bool IWeenieObject.IsCreature() => false;
    }

    /// <summary>Facade over the shared MoveToManagerHarness: the harness's
    /// REAL MotionInterpreter is the minterp child; the harness's REAL
    /// seam-scripted MoveToManager arrives via <see cref="MovementManager.MoveToFactory"/>
    /// (the acdream stand-in for retail's physics_obj/weenie_obj
    /// backpointers that MakeMoveToManager constructs from).</summary>
    private static (MovementManager Mm, MoveToManagerHarness H, int[] FactoryCalls) MakeFacade()
    {
        var h = new MoveToManagerHarness();
        var factoryCalls = new int[1];
        var mm = new MovementManager(h.Interp)
        {
            MoveToFactory = () => { factoryCalls[0]++; return h.Manager; },
        };
        return (mm, h, factoryCalls);
    }

    // ── MakeMoveToManager — 0x00524000 ──────────────────────────────────────

    [Fact]
    public void MakeMoveToManager_CreatesViaFactory_ExactlyOnce()
    {
        var (mm, h, calls) = MakeFacade();
        Assert.Null(mm.MoveTo);

        mm.MakeMoveToManager();
        Assert.Same(h.Manager, mm.MoveTo);
        Assert.Equal(1, calls[0]);

        // Retail: no-op if already present.
        mm.MakeMoveToManager();
        Assert.Same(h.Manager, mm.MoveTo);
        Assert.Equal(1, calls[0]);
    }

    [Fact]
    public void MakeMoveToManager_WithoutFactory_IsANoOp()
    {
        var mm = new MovementManager(new MotionInterpreter());
        mm.MakeMoveToManager();
        Assert.Null(mm.MoveTo);
    }

    // ── PerformMovement — 0x005240d0 (the type-1..9 two-way dispatch) ───────

    [Fact]
    public void PerformMovement_InterpTypes_RouteToMinterp_NotMoveTo()
    {
        var (mm, h, calls) = MakeFacade();

        var result = mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.InterpretedCommand,
            Motion = MotionCommand.WalkForward,
            Speed = 1f,
            ModifyInterpretedState = true,
        });

        Assert.Equal(WeenieError.None, result);
        Assert.Equal(MotionCommand.WalkForward, h.Interp.InterpretedState.ForwardCommand);
        // Types 1-5 never touch the moveto side (jump table 0x0052415c).
        Assert.Equal(0, calls[0]);
        Assert.Null(mm.MoveTo);
    }

    [Fact]
    public void PerformMovement_MoveToTypes_LazyCreate_AndRouteToMoveTo()
    {
        var (mm, h, calls) = MakeFacade();

        var result = mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });

        // Retail cases 5-8 (types 6-9): MakeMoveToManager first, delegate,
        // and the MoveToManager path's return is NOT propagated (@0052414f
        // `return 0`) — the facade reports None regardless.
        Assert.Equal(WeenieError.None, result);
        Assert.Equal(1, calls[0]);
        Assert.Equal(MovementType.MoveToPosition, h.Manager.MovementTypeState);
    }

    [Fact]
    public void PerformMovement_InvalidAndOutOfRangeTypes_Fail0x47()
    {
        var (mm, _, calls) = MakeFacade();

        // Retail head: (type - 1) > 8 → 0x47. Type 0 underflows unsigned →
        // always > 8; anything above 9 fails the same check.
        Assert.Equal(WeenieError.GeneralMovementFailure,
            mm.PerformMovement(new MovementStruct { Type = MovementType.Invalid }));
        Assert.Equal(WeenieError.GeneralMovementFailure,
            mm.PerformMovement(new MovementStruct { Type = (MovementType)10 }));
        Assert.Equal(0, calls[0]);
    }

    [Fact]
    public void PerformMovement_MoveToType_WithoutFactory_Fails0x47()
    {
        // acdream-only guard for the unreachable-in-production ordering
        // (a type-6..9 event before the bind sites set MoveToFactory):
        // retail would MoveToManager::Create here; without a factory the
        // facade reports the same 0x47 the range check uses.
        var mm = new MovementManager(new MotionInterpreter());
        Assert.Equal(WeenieError.GeneralMovementFailure,
            mm.PerformMovement(new MovementStruct { Type = MovementType.TurnToHeading }));
    }

    // ── UseTime — 0x005242f0 (moveto only; never lazy-creates) ──────────────

    [Fact]
    public void UseTime_BeforeMoveToExists_IsANoOp_AndDoesNotCreate()
    {
        var (mm, _, calls) = MakeFacade();
        mm.UseTime();
        Assert.Equal(0, calls[0]);
        Assert.Null(mm.MoveTo);
    }

    [Fact]
    public void UseTime_RelaysToMoveTo()
    {
        // The MoveToManagerUseTimeGateTests arrival shape, driven through
        // the facade: grounded, facing the target, arrived — one UseTime
        // completes the move.
        var (mm, h, _) = MakeFacade();
        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 90f;

        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters { DistanceToObject = 0.6f, UseSpheres = false },
        });
        h.DrainPendingMotions();

        h.WorldPosition = new Position(1u, new Vector3(19.7f, 0f, 0f), Quaternion.Identity);
        h.Advance(2.0);
        mm.UseTime();

        Assert.Equal(MovementType.Invalid, h.Manager.MovementTypeState);
    }

    // ── HitGround — 0x00524300 (minterp FIRST, then moveto) ────────────────

    [Fact]
    public void HitGround_RelaysToMinterp_AndToleratesNullMoveTo()
    {
        var (mm, h, _) = MakeFacade();
        h.Body.State |= PhysicsStateFlags.Gravity; // CMotionInterp::HitGround gates on state & 0x400
        bool minterpHit = false;
        h.Interp.RemoveLinkAnimations = () => minterpHit = true;

        mm.HitGround(); // MoveTo still null — retail's if-present guard
        Assert.True(minterpHit);
    }

    [Fact]
    public void HitGround_RelaysMinterpFirst_ThenMoveTo()
    {
        var (mm, h, _) = MakeFacade();
        h.Body.State |= PhysicsStateFlags.Gravity;
        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 90f;
        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });
        h.DrainPendingMotions();

        // Order pin: the FIRST RemoveLinkAnimations firing belongs to the
        // minterp leg (CMotionInterp::HitGround invokes it before any
        // dispatch), at which point the moveto leg's BeginNextNode
        // re-dispatch has NOT happened yet — the pending queue is still
        // drained. Later firings (the moveto dispatch's own TS-40
        // detached-strip at the DoInterpretedMotion tail runs AFTER its
        // enqueue) must not overwrite the recording — ??= keeps the first.
        bool? queueEmptyAtMinterpLeg = null;
        h.Interp.RemoveLinkAnimations =
            () => queueEmptyAtMinterpLeg ??= !h.Interp.MotionsPending();

        mm.HitGround();

        Assert.True(queueEmptyAtMinterpLeg);          // minterp leg ran first
        Assert.True(h.Interp.MotionsPending());       // a re-dispatch landed after it
    }

    [Fact]
    public void HitGround_ReachesMoveTo_WhenMinterpLegIsGated()
    {
        // Isolate the MOVETO leg: a non-creature weenie makes
        // CMotionInterp::HitGround a retail no-op (IsCreature gate), so any
        // re-dispatched pending motion can only come from
        // MoveToManager::HitGround → BeginNextNode.
        var (mm, h, _) = MakeFacade();
        h.Interp.WeenieObj = new NonCreatureWeenie();
        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 90f;
        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });
        h.DrainPendingMotions();

        mm.HitGround();

        Assert.True(h.Interp.MotionsPending());
    }

    // ── HandleExitWorld — 0x00524350 (minterp ONLY) ─────────────────────────

    [Fact]
    public void HandleExitWorld_DrainsMinterp_AndDoesNotTouchMoveTo()
    {
        var (mm, h, _) = MakeFacade();
        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        h.Heading = 90f;
        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });
        Assert.True(h.Interp.MotionsPending()); // the arm's dispatch is queued

        mm.HandleExitWorld();

        Assert.False(h.Interp.MotionsPending());
        // Retail HandleExitWorld does NOT touch moveto_manager — the armed
        // move survives (its teardown is CancelMoveTo / exit-world at the
        // CPhysicsObj layer, not here).
        Assert.Equal(MovementType.MoveToPosition, h.Manager.MovementTypeState);
    }

    // ── CancelMoveTo — 0x005241b0 / IsMovingTo — 0x00524260 ────────────────

    [Fact]
    public void CancelMoveTo_NullTolerant_AndRelaysToMoveTo()
    {
        var (mm, h, _) = MakeFacade();
        mm.CancelMoveTo(WeenieError.ActionCancelled); // no moveto yet — no throw

        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToPosition,
            Pos = new Position(1u, new Vector3(20f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });
        Assert.True(mm.IsMovingTo());

        mm.CancelMoveTo(WeenieError.ActionCancelled);

        Assert.Equal(MovementType.Invalid, h.Manager.MovementTypeState);
        Assert.False(mm.IsMovingTo());
        Assert.True(h.StopCompletelyCalls > 0);
    }

    [Fact]
    public void IsMovingTo_FalseBeforeMoveToExists()
    {
        var (mm, _, _) = MakeFacade();
        Assert.False(mm.IsMovingTo());
    }

    // ── HandleUpdateTarget — 0x00524790 (→ moveto) ──────────────────────────

    [Fact]
    public void HandleUpdateTarget_NullTolerant_AndFeedsMoveToDeferredStart()
    {
        var (mm, h, _) = MakeFacade();
        var info = new TargetInfo
        {
            ObjectId = 0x5000AAAAu,
            Status = TargetStatus.Ok,
            TargetPosition = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity),
            InterpolatedPosition = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity),
        };
        mm.HandleUpdateTarget(info); // no moveto yet — no throw

        // The V2 "uninitialized type-6 stall": MoveToObject defers its node
        // build to the FIRST HandleUpdateTarget delivery.
        h.ContactValue = true;
        h.WorldPosition = new Position(1u, Vector3.Zero, Quaternion.Identity);
        mm.PerformMovement(new MovementStruct
        {
            Type = MovementType.MoveToObject,
            ObjectId = 0x5000AAAAu,
            TopLevelId = 0x5000AAAAu,
            Pos = new Position(1u, new Vector3(10f, 0f, 0f), Quaternion.Identity),
            Params = new MovementParameters(),
        });
        Assert.False(h.Manager.Initialized);

        mm.HandleUpdateTarget(info);

        Assert.True(h.Manager.Initialized);
    }
}