using NUnit.Framework;
using ProjectM.Simulation;
using Unity.Mathematics;

namespace ProjectM.Tests
{
    public class AnimParamMathTests
    {
        const float Eps = 1e-3f;
        static readonly float2 Fwd = new float2(0f, 1f); // facing world +Z
        const float Max = 5f;

        [Test] public void ZeroVelocity_AllZero()
        {
            var r = AnimParamMath.LocomotionParams(float3.zero, Fwd, Max);
            Assert.AreEqual(0f, r.x, Eps); Assert.AreEqual(0f, r.y, Eps); Assert.AreEqual(0f, r.z, Eps);
        }

        [Test] public void FullForward_MoveZ1_Speed1()
        {
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, Max), Fwd, Max);
            Assert.AreEqual(0f, r.x, Eps); Assert.AreEqual(1f, r.y, Eps); Assert.AreEqual(1f, r.z, Eps);
        }

        [Test] public void FullBackward_MoveZNeg1()
        {
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, -Max), Fwd, Max);
            Assert.AreEqual(0f, r.x, Eps); Assert.AreEqual(-1f, r.y, Eps); Assert.AreEqual(1f, r.z, Eps);
        }

        [Test] public void StrafeRight_MoveX1()
        {
            // facing +Z -> right = (+X). world velocity +X -> MoveX = +1.
            var r = AnimParamMath.LocomotionParams(new float3(Max, 0f, 0f), Fwd, Max);
            Assert.AreEqual(1f, r.x, Eps); Assert.AreEqual(0f, r.y, Eps); Assert.AreEqual(1f, r.z, Eps);
        }

        [Test] public void StrafeLeft_MoveXNeg1()
        {
            var r = AnimParamMath.LocomotionParams(new float3(-Max, 0f, 0f), Fwd, Max);
            Assert.AreEqual(-1f, r.x, Eps);
        }

        [Test] public void HalfForward_HalfSpeed()
        {
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, Max * 0.5f), Fwd, Max);
            Assert.AreEqual(0.5f, r.y, Eps); Assert.AreEqual(0.5f, r.z, Eps);
        }

        [Test] public void OverMax_SpeedClampsTo1()
        {
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, Max * 3f), Fwd, Max);
            Assert.AreEqual(1f, r.z, Eps); Assert.AreEqual(1f, r.y, Eps);
        }

        [Test] public void RotatedFacing_ProjectsIntoFrame()
        {
            // facing world +X; velocity world +X should read as forward (MoveZ+), not strafe.
            var r = AnimParamMath.LocomotionParams(new float3(Max, 0f, 0f), new float2(1f, 0f), Max);
            Assert.AreEqual(0f, r.x, Eps); Assert.AreEqual(1f, r.y, Eps);
        }

        [Test] public void DegenerateFacing_DefaultsToWorldForward()
        {
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, Max), float2.zero, Max);
            Assert.AreEqual(1f, r.y, Eps); // treated as facing +Z
        }

        [Test] public void ZeroMaxSpeed_NoNaN_NoDivByZero()
        {
            // guard: safeMax = max(maxSpeed, 1e-4) -> finite output even with maxSpeed 0.
            var r = AnimParamMath.LocomotionParams(new float3(0f, 0f, 1f), Fwd, 0f);
            Assert.IsFalse(float.IsNaN(r.x) || float.IsNaN(r.y) || float.IsNaN(r.z));
            Assert.AreEqual(1f, r.z, Eps); // clamps to 1
        }
    }
}