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

namespace AcDream.Core.Tests.Physics.Motion;

/// <summary>
/// R3-W1 — action FIFO discipline + <c>ApplyMotion</c>/<c>RemoveMotion</c>
/// field effects on <see cref="RawMotionState"/> (closes J2). Oracle:
/// docs/research/named-retail/acclient_2013_pseudo_c.txt — verbatim bodies
/// quoted in RawMotionState.cs doc comments:
/// <c>RawMotionState::AddAction</c> (0x0051e840), <c>RemoveAction</c>
/// (0x0051e8a0), <c>ApplyMotion</c> (0x0051eb60), <c>RemoveMotion</c>
/// (0x0051e6e0).
/// </summary>
public sealed class RawMotionStateActionFifoTests
{
    // ── AddAction / RemoveAction / GetNumActions FIFO discipline ──────────

    [Fact]
    public void AddAction_AppendsInOrder()
    {
        var raw = new RawMotionState();
        raw.AddAction(0x1000004Bu, 1.0f, 1, autonomous: false);
        raw.AddAction(0x10000050u, 1.5f, 2, autonomous: true);

        Assert.Equal(2, raw.Actions.Count);
        Assert.Equal((ushort)0x004Bu, raw.Actions[0].Command); // widened to ushort on wire, verified below
        Assert.Equal((ushort)0x0050u, raw.Actions[1].Command);
    }

    [Fact]
    public void RemoveAction_PopsHeadFirst_FifoOrder()
    {
        var raw = new RawMotionState();
        raw.AddAction(0x1000004Bu, 1.0f, 1, autonomous: false);
        raw.AddAction(0x10000050u, 1.5f, 2, autonomous: true);

        uint first = raw.RemoveAction();
        uint second = raw.RemoveAction();

        Assert.Equal(0x004Bu, first);  // head popped first (FIFO)
        Assert.Equal(0x0050u, second);
        Assert.Empty(raw.Actions);
    }

    [Fact]
    public void RemoveAction_Empty_ReturnsZero()
    {
        var raw = new RawMotionState();
        Assert.Equal(0u, raw.RemoveAction());
    }

    [Fact]
    public void AddAction_StoresSpeedStampAutonomous()
    {
        var raw = new RawMotionState();
        raw.AddAction(0x1000004Bu, speed: 2.5f, actionStamp: 0x7FFFu, autonomous: true);

        var a = raw.Actions[0];
        Assert.Equal(2.5f, a.Speed);
        Assert.Equal((ushort)0x7FFFu, a.Stamp);
        Assert.True(a.Autonomous);
    }

    // ── ApplyMotion field effects (0x0051eb60) ─────────────────────────────

    [Fact]
    public void ApplyMotion_TurnRight_SetsTurnCommandAndSpeed_HonorsSetHoldKeyBit()
    {
        var raw = new RawMotionState();
        var p = new MovementParameters { Speed = 1.5f, SetHoldKey = true };

        raw.ApplyMotion(0x6500000du, p); // TurnRight

        Assert.Equal(0x6500000du, raw.TurnCommand);
        Assert.Equal(1.5f, raw.TurnSpeed);
        Assert.Equal(HoldKey.Invalid, raw.TurnHoldKey); // SetHoldKey bit set -> Invalid
    }

    [Fact]
    public void ApplyMotion_TurnRight_SetHoldKeyClear_UsesHoldKeyToApply()
    {
        var raw = new RawMotionState();
        var p = new MovementParameters { Speed = 1.5f, SetHoldKey = false, HoldKeyToApply = HoldKey.Run };

        raw.ApplyMotion(0x6500000du, p);

        Assert.Equal(HoldKey.Run, raw.TurnHoldKey);
    }

    [Fact]
    public void ApplyMotion_SideStepRight_SetsSidestepCommandAndSpeed()
    {
        var raw = new RawMotionState();
        var p = new MovementParameters { Speed = 1.248f, SetHoldKey = true };

        raw.ApplyMotion(0x6500000fu, p); // SideStepRight

        Assert.Equal(0x6500000fu, raw.SidestepCommand);
        Assert.Equal(1.248f, raw.SidestepSpeed);
        Assert.Equal(HoldKey.Invalid, raw.SidestepHoldKey);
    }

    [Fact]
    public void ApplyMotion_ForwardClassMotion_SetsForwardCommandAndSpeed()
    {
        // WalkForward = 0x45000005 has bit 0x40000000 set (forward-class)
        // and is NOT 0x44000007 (RunForward) -> the write branch fires.
        var raw = new RawMotionState();
        var p = new MovementParameters { Speed = 1.0f, SetHoldKey = true };

        raw.ApplyMotion(0x45000005u, p);

        Assert.Equal(0x45000005u, raw.ForwardCommand);
        Assert.Equal(1.0f, raw.ForwardSpeed);
        Assert.Equal(HoldKey.Invalid, raw.ForwardHoldKey);
    }

    [Fact]
    public void ApplyMotion_RunForwardExactId_ForwardClassButExcluded_NoWrite()
    {
        // Verbatim retail quirk (0x0051eb60): arg2 == 0x44000007 (RunForward)
        // with the forward-class bit (0x40000000) set falls through BOTH
        // inner branches — no field write occurs. Port verbatim, not fixed.
        var raw = new RawMotionState();
        var before = raw.ForwardCommand;
        var p = new MovementParameters { Speed = 3.0f };

        raw.ApplyMotion(0x44000007u, p);

        Assert.Equal(before, raw.ForwardCommand); // untouched
        Assert.Equal(1.0f, raw.ForwardSpeed);      // untouched (still ctor default)
    }

    [Fact]
    public void ApplyMotion_StyleClassMotion_SetsCurrentStyleAndResetsForwardToReady()
    {
        // High bit set (>= 0x80000000) and current_style differs -> style branch.
        var raw = new RawMotionState { ForwardCommand = 0x45000005u };
        var p = new MovementParameters();

        raw.ApplyMotion(0x80000042u, p);

        Assert.Equal(0x41000003u, raw.ForwardCommand); // reset to Ready
        Assert.Equal(0x80000042u, raw.CurrentStyle);
    }

    [Fact]
    public void ApplyMotion_StyleClassMotion_SameAsCurrentStyle_NoOp()
    {
        var raw = new RawMotionState { CurrentStyle = 0x80000042u, ForwardCommand = 0x45000005u };
        var p = new MovementParameters();

        raw.ApplyMotion(0x80000042u, p);

        // current_style already equals arg2 -> the style branch's condition
        // (current_style != arg2) is false, so forward_command is untouched.
        Assert.Equal(0x45000005u, raw.ForwardCommand);
        Assert.Equal(0x80000042u, raw.CurrentStyle);
    }

    [Fact]
    public void ApplyMotion_ActionClassMotion_AddsAction()
    {
        // Outside turn/sidestep range, bit 0x40000000 clear, arg2 >= 0
        // (not style-class), bit 0x10000000 set -> AddAction.
        var raw = new RawMotionState();
        var p = new MovementParameters { Speed = 1.0f, ActionStamp = 42u, Autonomous = true };

        raw.ApplyMotion(0x1000004Bu, p); // Jumpup action id

        Assert.Single(raw.Actions);
        var a = raw.Actions[0];
        Assert.Equal((ushort)0x004Bu, a.Command);
        Assert.Equal(1.0f, a.Speed);
        Assert.Equal((ushort)42u, a.Stamp);
        Assert.True(a.Autonomous);
    }

    // ── RemoveMotion field effects (0x0051e6e0) ────────────────────────────

    [Fact]
    public void RemoveMotion_TurnRange_ClearsTurnCommand()
    {
        var raw = new RawMotionState { TurnCommand = 0x6500000du };
        raw.RemoveMotion(0x6500000du);
        Assert.Equal(0u, raw.TurnCommand);
    }

    [Fact]
    public void RemoveMotion_TurnLeftRange_ClearsTurnCommand()
    {
        var raw = new RawMotionState { TurnCommand = 0x6500000eu };
        raw.RemoveMotion(0x6500000eu);
        Assert.Equal(0u, raw.TurnCommand);
    }

    [Fact]
    public void RemoveMotion_SidestepRange_ClearsSidestepCommand()
    {
        var raw = new RawMotionState { SidestepCommand = 0x6500000fu };
        raw.RemoveMotion(0x6500000fu);
        Assert.Equal(0u, raw.SidestepCommand);
    }

    [Fact]
    public void RemoveMotion_ForwardClassMotion_MatchingCommand_ResetsToReady()
    {
        var raw = new RawMotionState { ForwardCommand = 0x45000005u, ForwardSpeed = 3.0f };
        raw.RemoveMotion(0x45000005u);

        Assert.Equal(0x41000003u, raw.ForwardCommand);
        Assert.Equal(1f, raw.ForwardSpeed);
    }

    [Fact]
    public void RemoveMotion_ForwardClassMotion_NonMatchingCommand_NoOp()
    {
        var raw = new RawMotionState { ForwardCommand = 0x45000005u, ForwardSpeed = 3.0f };
        raw.RemoveMotion(0x44000007u); // different forward-class id

        Assert.Equal(0x45000005u, raw.ForwardCommand); // untouched
        Assert.Equal(3.0f, raw.ForwardSpeed);
    }

    [Fact]
    public void RemoveMotion_StyleClassMotion_MatchingCurrentStyle_ResetsToNonCombat()
    {
        var raw = new RawMotionState { CurrentStyle = 0x80000042u };
        raw.RemoveMotion(0x80000042u);

        Assert.Equal(0x8000003du, raw.CurrentStyle); // reset to NonCombat
    }

    [Fact]
    public void RemoveMotion_StyleClassMotion_NonMatchingCurrentStyle_NoOp()
    {
        var raw = new RawMotionState { CurrentStyle = 0x80000042u };
        raw.RemoveMotion(0x80000099u); // different style id

        Assert.Equal(0x80000042u, raw.CurrentStyle); // untouched
    }
}