using NightclubArcadia.Player.Math;
using NUnit.Framework;
using UnityEngine;

namespace NightclubArcadia.Locomotion.Math.Tests
{
    public class MotionInputMathTests
    {
        [Test]
        public void WorldToCameraRelativeInput_ZeroVelocity_ReturnsZero()
        {
            var result = MotionInputMath.WorldToCameraRelativeInput(Vector3.zero, 2f, 0f);
            Assert.AreEqual(Vector2.zero, result);
        }

        [Test]
        public void WorldToCameraRelativeInput_YawZero_PreservesForward()
        {
            var world = new Vector3(0f, 0f, 2f);
            var result = MotionInputMath.WorldToCameraRelativeInput(world, 2f, 0f);
            Assert.AreEqual(new Vector2(0f, 1f), result);
        }

        [Test]
        public void WorldToCameraRelativeInput_Yaw90_RotatesCorrectly()
        {
            // Camera yawed +90 degrees faces +X. World velocity is +Z, which from
            // that camera is to the LEFT, so the camera-relative x is -1, not +1.
            // The conversion applies Quaternion.Euler(0, -cameraYaw, 0), and Unity's
            // Y rotation is clockwise viewed from above, so forward maps to -right.
            // WorldToCameraRelativeInput_RoundTripsThroughAtan2 pins the same
            // convention: it only reconstructs the world direction because the yaw
            // is subtracted here and added back there.
            var world = new Vector3(0f, 0f, 2f);
            var result = MotionInputMath.WorldToCameraRelativeInput(world, 2f, 90f);
            Assert.That(result.x, Is.EqualTo(-1f).Within(0.001f));
            Assert.That(result.y, Is.EqualTo(0f).Within(0.001f));
        }

        [Test]
        public void WorldToCameraRelativeInput_ClampFractionToOne()
        {
            var world = new Vector3(0f, 0f, 10f);
            var result = MotionInputMath.WorldToCameraRelativeInput(world, 2f, 0f);
            Assert.That(result.magnitude, Is.EqualTo(1f).Within(0.001f));
        }

        [Test]
        public void WorldToCameraRelativeInput_RoundTripsThroughAtan2()
        {
            var world = new Vector3(1f, 0f, 2f).normalized;
            var cameraYaw = 15f;
            var input = MotionInputMath.WorldToCameraRelativeInput(world, 1f, cameraYaw);
            var targetRotation = Mathf.Atan2(input.x, input.y) * Mathf.Rad2Deg + cameraYaw;
            var reconstructed = Quaternion.Euler(0f, targetRotation, 0f) * Vector3.forward;
            var flatWorld = new Vector3(world.x, 0f, world.z).normalized;

            Assert.That(Vector3.Dot(reconstructed, flatWorld), Is.EqualTo(1f).Within(0.001f));
        }

        [Test]
        public void ScreenDeltaToWorldPan_UsesCameraBasis()
        {
            var right = Vector3.right;
            var forward = Vector3.forward;
            var delta = new Vector2(10f, 0f);
            var result = MotionInputMath.ScreenDeltaToWorldPan(delta, right, forward, 0.02f);

            // Compared per component with a tolerance rather than Assert.AreEqual:
            // Vector3.Equals is exact, and -10f * 0.02f lands one ulp away from the
            // -0.2f literal, so an exact comparison fails on a correct result.
            Assert.That(result.x, Is.EqualTo(-0.2f).Within(0.0001f));
            Assert.That(result.y, Is.EqualTo(0f).Within(0.0001f));
            Assert.That(result.z, Is.EqualTo(0f).Within(0.0001f));
        }
    }
}