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

namespace AcDream.Core.Tests.Physics;

// ─────────────────────────────────────────────────────────────────────────────
// MotionInterpreterJumpFamilyTests — R3-W3 (closes J5, J6, J7-interp-side,
// J16-epsilons). Pins per docs/research/2026-07-02-r3-motioninterp/W0-pins.md
// (A1, A2, A5, A6, A10) and r3-motioninterp-decomp.md §3a-3h.
//
// Source addresses tested:
//   FUN_00527a50 (0x00527a50)  jump_charge_is_allowed  @304935
//   FUN_005281c0 (0x005281c0)  charge_jump              @305448
//   FUN_00527aa0 (0x00527aa0)  get_jump_v_z             @304953
//   FUN_005280c0 (0x005280c0)  get_leave_ground_velocity @305404
//   FUN_005282b0 (0x005282b0)  jump_is_allowed          (full chain)
//   FUN_00528780 (0x00528780)  jump                     @305792
// ─────────────────────────────────────────────────────────────────────────────

/// <summary>Fake WeenieObject for jump-family test isolation.</summary>
file sealed class FakeWeenie : IWeenieObject
{
    public float RunRate = 1.0f;
    public float JumpVz = 10.0f;
    public bool CanJumpResult = true;
    public bool InqRunRateResult = true;
    public bool InqJumpVelocityResult = true;

    /// <summary>Controls the JumpStaminaCost virtual (vtable +0x44 per the
    /// raw 305549-305556 shape): true = affordable (pass), false = 0x47.</summary>
    public bool JumpStaminaCostResult = true;
    public int JumpStaminaCostCalls;

    public bool InqJumpVelocity(float extent, out float vz)
    {
        vz = JumpVz * extent;
        return InqJumpVelocityResult;
    }

    public bool InqRunRate(out float rate)
    {
        rate = RunRate;
        return InqRunRateResult;
    }

    public bool CanJump(float extent) => CanJumpResult;

    public bool JumpStaminaCost(float extent, out int cost)
    {
        JumpStaminaCostCalls++;
        cost = 0;
        return JumpStaminaCostResult;
    }
}

public sealed class MotionInterpreterJumpFamilyTests
{
    // ── helpers ───────────────────────────────────────────────────────────────

    private static PhysicsBody MakeGrounded()
    {
        var body = new PhysicsBody
        {
            State = PhysicsStateFlags.Gravity | PhysicsStateFlags.ReportCollisions,
        };
        body.TransientState = TransientStateFlags.Contact
                            | TransientStateFlags.OnWalkable
                            | TransientStateFlags.Active;
        return body;
    }

    private static PhysicsBody MakeAirborne()
    {
        var body = new PhysicsBody
        {
            State = PhysicsStateFlags.Gravity | PhysicsStateFlags.ReportCollisions,
        };
        body.TransientState = TransientStateFlags.Active;
        return body;
    }

    private static MotionInterpreter MakeInterp(PhysicsBody? body = null, IWeenieObject? weenie = null)
    {
        body ??= MakeGrounded();
        return new MotionInterpreter(body, weenie);
    }

    // =========================================================================
    // jump_charge_is_allowed — 0x00527a50 @304935
    //
    // Raw (r3-motioninterp-decomp.md §3b):
    //   weenie_obj = this->weenie_obj;
    //   if (weenie_obj != 0 && weenie_obj->vtable->CanJump(this->jump_extent) == 0)
    //       return 0x49;
    //   forward_command = this->interpreted_state.forward_command;
    //   if (forward_command != 0x40000008
    //       && (forward_command <= 0x41000011 || forward_command > 0x41000014))
    //       return 0;
    //   return 0x48;
    // =========================================================================

    [Fact]
    public void JumpChargeIsAllowed_NoWeenie_ReadyForward_ReturnsNone()
    {
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = MotionCommand.Ready;

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_WeenieCanJumpFalse_ReturnsCantJumpLoadedDown()
    {
        var weenie = new FakeWeenie { CanJumpResult = false };
        var interp = MakeInterp(weenie: weenie);
        interp.InterpretedState.ForwardCommand = MotionCommand.Ready;

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.CantJumpLoadedDown, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_Fallen_ReturnsYouCantJumpFromThisPosition()
    {
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = MotionCommand.Fallen; // 0x40000008

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
    }

    [Theory]
    [InlineData(MotionCommand.Crouch)]   // 0x41000012
    [InlineData(MotionCommand.Sitting)]  // 0x41000013
    [InlineData(MotionCommand.Sleeping)] // 0x41000014
    public void JumpChargeIsAllowed_CrouchSitSleepRange_ReturnsYouCantJumpFromThisPosition(uint forward)
    {
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = forward;

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_CrouchLowerBoundExact_Passes()
    {
        // forward_command <= 0x41000011 passes (the gate is a strict
        // inequality on the LOWER bound: forward_command > 0x41000011 is
        // required to even consider the block). 0x41000011 == CrouchLowerBound
        // itself must PASS (not blocked) — verbatim boundary.
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = MotionCommand.CrouchLowerBound; // 0x41000011

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_SleepUpperBoundExact_Blocked()
    {
        // forward_command > 0x41000014 passes; == 0x41000014 (Sleeping) is
        // still inside the blocked range (already covered above), but this
        // pins the boundary explicitly: 0x41000015 (one past Sleeping) must
        // PASS.
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = MotionCommand.CrouchUpperExclusive; // 0x41000015

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_Falling_Passes()
    {
        // Falling (0x40000015) is NOT Fallen (0x40000008) — must pass this
        // gate (though jump_is_allowed's separate ground check blocks
        // mid-air jumps by a different mechanism — A1 adjudication).
        var interp = MakeInterp();
        interp.InterpretedState.ForwardCommand = MotionCommand.Falling;

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpChargeIsAllowed_CanJumpCheckedBeforePostureCheck()
    {
        // Raw order: CanJump gate FIRST, forward_command gate SECOND. A
        // weenie that refuses CanJump returns 0x49 even in a posture that
        // would otherwise pass.
        var weenie = new FakeWeenie { CanJumpResult = false };
        var interp = MakeInterp(weenie: weenie);
        interp.InterpretedState.ForwardCommand = MotionCommand.Falling; // would pass posture gate

        var result = interp.JumpChargeIsAllowed(0.5f);

        Assert.Equal(WeenieError.CantJumpLoadedDown, result);
    }

    // =========================================================================
    // charge_jump — 0x005281c0 @305448 (closes J6)
    //
    // Raw (r3-motioninterp-decomp.md §3e):
    //   weenie_obj = this->weenie_obj;
    //   if (weenie_obj != 0 && weenie_obj->vtable->CanJump(this->jump_extent) == 0)
    //       return 0x49;
    //   forward_command = this->interpreted_state.forward_command;
    //   if (forward_command == 0x40000008
    //       || (forward_command > 0x41000011 && forward_command <= 0x41000014))
    //       return 0x48;
    //   transient_state = physics_obj->transient_state;
    //   if ((transient_state & 1) != 0 && (transient_state & 2) != 0
    //       && forward_command == 0x41000003
    //       && interpreted_state.sidestep_command == 0
    //       && interpreted_state.turn_command == 0)
    //       standing_longjump = 1;
    //   return 0;
    // =========================================================================

    [Fact]
    public void ChargeJump_GroundedIdle_ArmsStandingLongJump()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;
        // Default interpreted state: ForwardCommand=Ready, SideStep=0, Turn=0.

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.None, result);
        Assert.True(interp.StandingLongJump, "grounded + idle must arm StandingLongJump");
    }

    [Fact]
    public void ChargeJump_GroundedButMoving_DoesNotArmStandingLongJump()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;
        interp.InterpretedState.ForwardCommand = MotionCommand.RunForward;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.None, result);
        Assert.False(interp.StandingLongJump, "must not arm while moving forward");
    }

    [Fact]
    public void ChargeJump_GroundedIdleButSidestepping_DoesNotArmStandingLongJump()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;
        interp.InterpretedState.ForwardCommand = MotionCommand.Ready;
        interp.InterpretedState.SideStepCommand = MotionCommand.SideStepRight;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.None, result);
        Assert.False(interp.StandingLongJump, "must not arm while sidestepping");
    }

    [Fact]
    public void ChargeJump_GroundedIdleButTurning_DoesNotArmStandingLongJump()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;
        interp.InterpretedState.ForwardCommand = MotionCommand.Ready;
        interp.InterpretedState.TurnCommand = MotionCommand.TurnRight;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.None, result);
        Assert.False(interp.StandingLongJump, "must not arm while turning");
    }

    [Fact]
    public void ChargeJump_Airborne_DoesNotArmStandingLongJump()
    {
        var body = MakeAirborne();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.None, result);
        Assert.False(interp.StandingLongJump, "must not arm while airborne (no Contact+OnWalkable)");
    }

    [Fact]
    public void ChargeJump_WeenieBlocksCanJump_ReturnsCantJumpLoadedDown_NoArm()
    {
        var weenie = new FakeWeenie { CanJumpResult = false };
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);
        interp.StandingLongJump = false;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.CantJumpLoadedDown, result);
        Assert.False(interp.StandingLongJump);
    }

    [Fact]
    public void ChargeJump_Fallen_ReturnsYouCantJumpFromThisPosition_NoArm()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.InterpretedState.ForwardCommand = MotionCommand.Fallen;
        interp.StandingLongJump = false;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
        Assert.False(interp.StandingLongJump);
    }

    [Fact]
    public void ChargeJump_CrouchRange_ReturnsYouCantJumpFromThisPosition_NoArm()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.InterpretedState.ForwardCommand = MotionCommand.Sitting;
        interp.StandingLongJump = false;

        var result = interp.ChargeJump();

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
        Assert.False(interp.StandingLongJump);
    }

    // ── J6 regression pin: contact_allows_move no longer arms StandingLongJump ──

    [Fact]
    public void ContactAllowsMove_GroundedAndIdle_DoesNotArmStandingLongJump()
    {
        // J6: the S2a-flagged misattribution is DELETED. Only ChargeJump
        // arms StandingLongJump now — contact_allows_move must have no side
        // effect on this flag at all, in either direction.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = false;

        interp.contact_allows_move(MotionCommand.WalkForward);

        Assert.False(interp.StandingLongJump,
            "contact_allows_move must never arm StandingLongJump (J6 — moved to ChargeJump exclusively)");
    }

    [Fact]
    public void ContactAllowsMove_GroundedAndIdle_DoesNotClearPreArmedStandingLongJump()
    {
        // contact_allows_move must not touch the flag at all — verify it
        // doesn't clear a flag armed by a prior ChargeJump call either.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = true;

        interp.contact_allows_move(MotionCommand.WalkForward);

        Assert.True(interp.StandingLongJump,
            "contact_allows_move must not clear an externally-armed StandingLongJump flag");
    }

    // =========================================================================
    // get_jump_v_z — 0x00527aa0 @304953 (A5; closes J16-epsilons)
    // Epsilon: 0.000199999995f (NOT the old 0.001 JumpExtentEpsilon).
    // =========================================================================

    [Fact]
    public void GetJumpVZ_EpsilonIsRetailLiteral()
    {
        Assert.Equal(0.000199999995f, MotionInterpreter.JumpVzEpsilon);
    }

    [Fact]
    public void GetJumpVZ_JustBelowEpsilon_ReturnsZero()
    {
        var weenie = new FakeWeenie { JumpVz = 10.0f };
        var interp = MakeInterp(weenie: weenie);
        interp.JumpExtent = 0.0001f; // < 0.000199999995f

        Assert.Equal(0f, interp.GetJumpVZ(), precision: 6);
    }

    [Fact]
    public void GetJumpVZ_JustAboveEpsilon_DelegatesToWeenie()
    {
        var weenie = new FakeWeenie { JumpVz = 10.0f };
        var interp = MakeInterp(weenie: weenie);
        interp.JumpExtent = 0.0003f; // > 0.000199999995f

        float vz = interp.GetJumpVZ();

        // Not the zero-fallback: delegates to InqJumpVelocity(extent, ...).
        Assert.Equal(weenie.JumpVz * 0.0003f, vz, precision: 4);
    }

    [Fact]
    public void GetJumpVZ_ExactlyOldWrongEpsilon_0_001_IsAboveRetailEpsilon_NotZero()
    {
        // Regression pin: the OLD (wrong) epsilon was 0.001. At extent =
        // 0.0005 the old code would have returned 0 (0.0005 < 0.001), but
        // retail's epsilon (0.0002) means 0.0005 must NOT hit the zero path.
        var weenie = new FakeWeenie { JumpVz = 10.0f };
        var interp = MakeInterp(weenie: weenie);
        interp.JumpExtent = 0.0005f;

        float vz = interp.GetJumpVZ();

        Assert.NotEqual(0f, vz);
        Assert.Equal(weenie.JumpVz * 0.0005f, vz, precision: 4);
    }

    [Fact]
    public void GetJumpVZ_NoWeenie_ReturnsDefault()
    {
        var interp = MakeInterp();
        interp.JumpExtent = 0.5f;

        Assert.Equal(MotionInterpreter.DefaultJumpVz, interp.GetJumpVZ(), precision: 4);
    }

    [Fact]
    public void GetJumpVZ_ExtentClampsAtMax1()
    {
        var weenie = new FakeWeenie { JumpVz = 10.0f };
        var interp = MakeInterp(weenie: weenie);
        interp.JumpExtent = 5.0f; // over-clamped

        float vz = interp.GetJumpVZ();

        Assert.Equal(10.0f, vz, precision: 4);
    }

    [Fact]
    public void GetJumpVZ_WeenieRefusesInqJumpVelocity_ReturnsZero()
    {
        var weenie = new FakeWeenie { InqJumpVelocityResult = false };
        var interp = MakeInterp(weenie: weenie);
        interp.JumpExtent = 0.5f;

        Assert.Equal(0f, interp.GetJumpVZ(), precision: 5);
    }

    // =========================================================================
    // get_leave_ground_velocity — 0x005280c0 @305404 (A6; closes J16-epsilons)
    // =========================================================================

    [Fact]
    public void GetLeaveGroundVelocity_WalkingForward_HasPositiveYAndZ()
    {
        var weenie = new FakeWeenie { JumpVz = 10.0f };
        var body = MakeGrounded();
        var interp = new MotionInterpreter(body, weenie)
        {
            JumpExtent = 1.0f,
        };
        interp.InterpretedState.ForwardCommand = MotionCommand.WalkForward;
        interp.InterpretedState.ForwardSpeed = 1.0f;

        var vel = interp.GetLeaveGroundVelocity();

        Assert.True(vel.Y > 0f, "Y velocity should be positive when walking forward");
        Assert.True(vel.Z > 0f, "Z (jump) velocity should be positive");
    }

    [Fact]
    public void GetLeaveGroundVelocity_TrulyZero_FallsBackToWorldVelocityGlobalToLocal()
    {
        // A6: fallback fires ONLY when |x| AND |y| AND |z| are ALL <
        // epsilon. When it fires, ALL THREE components (including the
        // just-computed jump v_z) are overwritten with
        // globaltolocal(m_velocityVector) — the existing
        // Quaternion.Inverse(Orientation) transform IS global->local; keep.
        var body = MakeGrounded();
        body.Velocity = new Vector3(2.0f, 3.0f, 0f); // nonzero WORLD velocity (momentum)
        body.Orientation = Quaternion.Identity;       // identity: local == global for this pin
        var interp = new MotionInterpreter(body)
        {
            JumpExtent = 0f, // below epsilon -> get_jump_v_z returns 0
        };
        // Default interpreted state = Ready (no walk/run/sidestep command) -> XY also 0.

        var vel = interp.GetLeaveGroundVelocity();

        // Fallback must have fired: velocity now reflects body.Velocity
        // (global->local via inverse-identity == identity here), NOT the
        // all-zero get_state_velocity()/get_jump_v_z() composition.
        Assert.Equal(2.0f, vel.X, precision: 4);
        Assert.Equal(3.0f, vel.Y, precision: 4);
        Assert.Equal(0.0f, vel.Z, precision: 4);
    }

    [Fact]
    public void GetLeaveGroundVelocity_TrulyZero_NoWorldVelocity_StaysZero()
    {
        var body = MakeGrounded();
        body.Velocity = Vector3.Zero;
        var interp = new MotionInterpreter(body)
        {
            JumpExtent = 0f,
        };

        var vel = interp.GetLeaveGroundVelocity();

        Assert.Equal(0f, vel.X, precision: 5);
        Assert.Equal(0f, vel.Y, precision: 5);
        Assert.Equal(0f, vel.Z, precision: 5);
    }

    [Fact]
    public void GetLeaveGroundVelocity_NonzeroXOnly_DoesNotTriggerFallback()
    {
        // A6: the fallback requires ALL THREE axes below epsilon. A
        // sidestep-only launch (nonzero X, zero Y, zero jump Z) must NOT
        // trigger the momentum fallback — it should keep the computed X.
        var body = MakeGrounded();
        body.Velocity = new Vector3(99f, 99f, 99f); // if fallback wrongly fired, this would show
        var interp = new MotionInterpreter(body)
        {
            JumpExtent = 0f, // jump v_z stays 0
        };
        interp.InterpretedState.SideStepCommand = MotionCommand.SideStepRight;
        interp.InterpretedState.SideStepSpeed = 1.0f;

        var vel = interp.GetLeaveGroundVelocity();

        // X must be the sidestep-derived value, not 99 (fallback did not fire).
        Assert.NotEqual(99f, vel.X);
        Assert.True(vel.X > 0f, "sidestep should have produced nonzero X from get_state_velocity");
    }

    [Fact]
    public void GetLeaveGroundVelocity_EpsilonBoundary_JustBelow_TriggersFallback()
    {
        var body = MakeGrounded();
        body.Velocity = new Vector3(5f, 0f, 0f);
        body.Orientation = Quaternion.Identity;
        var interp = new MotionInterpreter(body)
        {
            JumpExtent = 0.0001f, // < 0.000199999995f -> get_jump_v_z() == 0
        };
        // Default interpreted state -> XY == 0 too. All three axes are
        // exactly at the "essentially zero" edge -> fallback fires.

        var vel = interp.GetLeaveGroundVelocity();

        Assert.Equal(5f, vel.X, precision: 4);
    }

    // =========================================================================
    // jump_is_allowed — 0x005282b0 (A2, A10; closes J5)
    //
    // Raw entry shape (r3-motioninterp-decomp.md §3h):
    //   if (physics_obj != 0) {
    //     if (weenie != 0) eax_2 = weenie->IsCreature();
    //     if (weenie != 0 && eax_2 == 0)                 // non-creature weenie
    //         goto shared_gate;
    //     if (physics_obj == 0 || (state bit 0x400) == 0) // gravity-state off
    //         goto shared_gate;
    //     if (Contact && OnWalkable)                      // grounded
    //         goto shared_gate;
    //   }
    //   return 0x24;
    //
    // shared_gate:
    //   if (IsFullyConstrained) return 0x47;
    //   head = pending_motions.head_;
    //   if (head != 0) eax_6 = head.jump_error_code;
    //   if (head == 0 || eax_6 == 0) {
    //       eax_6 = jump_charge_is_allowed();
    //       if (eax_6 == 0) {
    //           eax_7 = motion_allows_jump(interpreted_state.forward_command);
    //           if (eax_7 != 0) return eax_7;
    //           if (weenie_obj_1 == 0) return eax_7;      // == 0 here
    //           eax_6 = 0x47;
    //           if (weenie_obj_1->JumpStaminaCost(extent, &cost) != 0)
    //               return eax_7;                          // == 0 (success)
    //           // JumpStaminaCost returned 0 (false) -> falls through, eax_6 stays 0x47
    //       }
    //   }
    //   return eax_6;
    // =========================================================================

    [Fact]
    public void JumpIsAllowed_NullPhysicsObj_ReturnsNotGrounded()
    {
        var interp = new MotionInterpreter();

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.NotGrounded, result);
    }

    [Fact]
    public void JumpIsAllowed_CreatureWeenie_Airborne_GravityState_ReturnsNotGrounded()
    {
        var body = MakeAirborne();
        var interp = MakeInterp(body);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.NotGrounded, result);
    }

    [Fact]
    public void JumpIsAllowed_CreatureWeenie_Grounded_ReturnsNone()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);

        var result = interp.jump_is_allowed(0.5f, out int cost);

        Assert.Equal(WeenieError.None, result);
        Assert.Equal(0, cost);
    }

    [Fact]
    public void JumpIsAllowed_NonCreatureWeenie_Airborne_SkipsGroundGate_ReturnsNone()
    {
        // weenie present && !IsCreature() -> skip the ground check entirely,
        // go straight to the shared gate. Airborne here must NOT block.
        var weenie = new FakeWeenie();
        var body = MakeAirborne();
        var interp = MakeInterp(body, weenie);
        // Non-creature: use an explicit fake that overrides IsCreature.
        var nonCreature = new NonCreatureFakeWeenie();
        interp.WeenieObj = nonCreature;

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpIsAllowed_NoWeenie_GravityStateOff_SkipsGroundGate_ReturnsNone()
    {
        // "no weenie" -> weenie_obj == 0 branch is fine either way (the
        // `weenie != 0 && eax_2 == 0` non-creature-skip only applies when a
        // weenie exists); but the SEPARATE gravity-state-off skip
        // (state bit 0x400 clear) also reaches the shared gate regardless
        // of weenie presence. Pin: no gravity flag -> shared gate, not
        // blocked outright.
        var body = new PhysicsBody
        {
            State = PhysicsStateFlags.None, // gravity flag clear
            TransientState = TransientStateFlags.None,
        };
        var interp = MakeInterp(body);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpIsAllowed_IsFullyConstrained_ReturnsGeneralMovementFailure()
    {
        var body = MakeGrounded();
        body.IsFullyConstrained = true;
        var interp = MakeInterp(body);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.GeneralMovementFailure, result); // 0x47
    }

    [Fact]
    public void JumpIsAllowed_IsFullyConstrained_BeatsPendingHeadPeek()
    {
        // A2 ordering: IsFullyConstrained is checked BEFORE the pending-head
        // peek. Even if the head carries a DIFFERENT nonzero error, the
        // IsFullyConstrained code (0x47) must win.
        var body = MakeGrounded();
        body.IsFullyConstrained = true;
        var interp = MakeInterp(body);
        interp.AddToQueue(0, MotionCommand.WalkForward, (uint)WeenieError.CantJumpLoadedDown);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.GeneralMovementFailure, result);
    }

    [Fact]
    public void JumpIsAllowed_PendingHeadNonzeroError_ShortCircuitsChain()
    {
        // A2: the peek fires WHENEVER the queue is non-empty (no Count>1
        // gate). A nonzero head.JumpErrorCode is returned VERBATIM, and the
        // charge/motion/stamina chain is skipped entirely (proven via the
        // weenie's CanJump/JumpStaminaCost never being consulted for THIS
        // code path — CanJump would return CantJumpLoadedDown some other
        // way, so instead assert JumpStaminaCost, which only the fallthrough
        // chain calls, is never invoked).
        var weenie = new FakeWeenie();
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);
        interp.AddToQueue(0, MotionCommand.WalkForward, (uint)WeenieError.YouCantJumpFromThisPosition);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
        Assert.Equal(0, weenie.JumpStaminaCostCalls);
    }

    [Fact]
    public void JumpIsAllowed_PendingHeadZeroError_FallsThroughToChain()
    {
        // A2: head exists but JumpErrorCode == 0 -> chain still runs.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.AddToQueue(0, MotionCommand.WalkForward, jumpErrorCode: 0);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpIsAllowed_EmptyQueue_FallsThroughToChain()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        // No AddToQueue call -> head is null -> chain runs normally.

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.None, result);
    }

    [Fact]
    public void JumpIsAllowed_ChargeBlocked_Fallen_ReturnsYouCantJumpFromThisPosition()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.InterpretedState.ForwardCommand = MotionCommand.Fallen;

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
    }

    [Fact]
    public void JumpIsAllowed_ChargeBlocked_WeenieCanJumpFalse_ReturnsCantJumpLoadedDown()
    {
        var weenie = new FakeWeenie { CanJumpResult = false };
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.CantJumpLoadedDown, result);
    }

    [Fact]
    public void JumpIsAllowed_MotionAllowsJumpBlocks_ReturnsYouCantJumpFromThisPosition()
    {
        // jump_charge_is_allowed passes (Ready forward command), but the
        // SEPARATE motion_allows_jump(forward_command) check blocks — use a
        // forward command in the [0x4000001e, 0x40000039] blocklist band
        // that jump_charge_is_allowed does NOT gate on (only Fallen/Crouch
        // range does), so this pins the double-check shape.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.InterpretedState.ForwardCommand = 0x40000020u; // inside [0x4000001e, 0x40000039]

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.YouCantJumpFromThisPosition, result);
    }

    [Fact]
    public void JumpIsAllowed_NoWeenie_PassesChain_ReturnsNone()
    {
        // motion_allows_jump passes and weenie_obj == null -> return eax_7
        // (== 0) directly, skipping the JumpStaminaCost consult entirely.
        var body = MakeGrounded();
        var interp = MakeInterp(body); // no weenie

        var result = interp.jump_is_allowed(0.5f, out int cost);

        Assert.Equal(WeenieError.None, result);
        Assert.Equal(0, cost);
    }

    [Fact]
    public void JumpIsAllowed_WeenieJumpStaminaCostRefuses_ReturnsGeneralMovementFailure()
    {
        var weenie = new FakeWeenie { JumpStaminaCostResult = false };
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.GeneralMovementFailure, result); // 0x47
        Assert.Equal(1, weenie.JumpStaminaCostCalls);
    }

    [Fact]
    public void JumpIsAllowed_WeenieJumpStaminaCostAffords_ReturnsNone()
    {
        var weenie = new FakeWeenie { JumpStaminaCostResult = true };
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);

        var result = interp.jump_is_allowed(0.5f, out _);

        Assert.Equal(WeenieError.None, result);
        Assert.Equal(1, weenie.JumpStaminaCostCalls);
    }

    /// <summary>Fake weenie whose IsCreature() returns false, for the
    /// non-creature ground-gate-skip pin.</summary>
    private sealed class NonCreatureFakeWeenie : IWeenieObject
    {
        public bool InqJumpVelocity(float extent, out float vz) { vz = 10f; return true; }
        public bool InqRunRate(out float rate) { rate = 1f; return true; }
        public bool CanJump(float extent) => true;
        public bool IsCreature() => false;
    }

    // =========================================================================
    // jump — 0x00528780 @305792 (closes J7-interp-side)
    // =========================================================================

    [Fact]
    public void Jump_Grounded_SetsJumpExtentAndLeavesWalkable()
    {
        var body = MakeGrounded();
        var interp = MakeInterp(body);

        var result = interp.jump(0.5f);

        Assert.Equal(WeenieError.None, result);
        Assert.Equal(0.5f, interp.JumpExtent, precision: 5);
        Assert.False(body.OnWalkable, "Body should no longer be on walkable after jump");
    }

    [Fact]
    public void Jump_Airborne_ReturnsNotGrounded()
    {
        var body = MakeAirborne();
        var interp = MakeInterp(body);

        var result = interp.jump(0.5f);

        Assert.Equal(WeenieError.NotGrounded, result);
    }

    [Fact]
    public void Jump_WeenieBlocksJump_ClearsStandingLongJump()
    {
        var weenie = new FakeWeenie { CanJumpResult = false };
        var body = MakeGrounded();
        var interp = MakeInterp(body, weenie);
        interp.StandingLongJump = true;

        var result = interp.jump(0.5f);

        Assert.Equal(WeenieError.CantJumpLoadedDown, result);
        Assert.False(interp.StandingLongJump, "a failed jump attempt cancels any pending StandingLongJump");
    }

    [Fact]
    public void Jump_NullPhysicsObj_ReturnsNoPhysicsObject()
    {
        var interp = new MotionInterpreter();

        var result = interp.jump(0.5f);

        Assert.Equal(WeenieError.NoPhysicsObject, result);
    }

    [Fact]
    public void Jump_Success_DoesNotClearStandingLongJump()
    {
        // Only the FAILURE path clears StandingLongJump (raw 305800:
        // `this->standing_longjump = 0;` sits inside the `if (result != 0)`
        // branch only). A successful jump leaves whatever value the flag
        // already had.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        interp.StandingLongJump = true;

        var result = interp.jump(0.5f);

        Assert.Equal(WeenieError.None, result);
        Assert.True(interp.StandingLongJump, "success path must not touch StandingLongJump");
    }

    [Fact]
    public void Jump_CallsInterruptCurrentMovementSeam()
    {
        // J7 / "Adjacent findings": jump() ALWAYS calls
        // interrupt_current_movement first (raw @305800), regardless of
        // outcome. Register no-op seam until R4's cancel_moveto exists.
        var body = MakeGrounded();
        var interp = MakeInterp(body);
        bool called = false;
        interp.InterruptCurrentMovement = () => called = true;

        interp.jump(0.5f);

        Assert.True(called, "jump() must invoke the InterruptCurrentMovement seam");
    }

    [Fact]
    public void Jump_CallsInterruptCurrentMovementSeam_EvenOnFailure()
    {
        var body = MakeAirborne();
        var interp = MakeInterp(body);
        bool called = false;
        interp.InterruptCurrentMovement = () => called = true;

        interp.jump(0.5f);

        Assert.True(called, "jump() calls interrupt_current_movement before jump_is_allowed, unconditionally");
    }

    // =========================================================================
    // IWeenieObject.IsThePlayer — default false; PlayerWeenie true (for W4's
    // A3 dispatch gate; no consumer yet in W3).
    // =========================================================================

    [Fact]
    public void IWeenieObject_IsThePlayer_DefaultsFalse()
    {
        // Default interface members are only reachable through the
        // interface type, not the concrete implementer — call via
        // IWeenieObject to exercise the DIM (not a compile error site).
        IWeenieObject weenie = new FakeWeenie();

        Assert.False(weenie.IsThePlayer());
    }

    [Fact]
    public void PlayerWeenie_IsThePlayer_ReturnsTrue()
    {
        var weenie = new PlayerWeenie();

        Assert.True(weenie.IsThePlayer());
    }
}