// Copyright (c) Wojciech Figat. All rights reserved.

#if FLAX_TESTS
using System;
using FlaxEngine.Utilities;
using NUnit.Framework;

namespace FlaxEngine.Tests
{
    /// <summary>
    /// Tests for <see cref="Transform"/>.
    /// </summary>
    [TestFixture]
    public class TestTransform
    {
        /// <summary>
        /// Test transformation matrix calculation.
        /// </summary>
        [Test]
        public void TestWorldMatrix()
        {
            Transform t1 = new Transform(new Vector3(10, 1, 10), Quaternion.Euler(45, 0, -15), new Float3(1.5f, 0.5f, 0.1f));

            Matrix a1 = t1.GetWorld();

            Matrix a2;
            {
                Matrix m1, m2;
                Matrix.Scaling(ref t1.Scale, out a2);
                Matrix.RotationQuaternion(ref t1.Orientation, out m2);
                Matrix.Multiply(ref a2, ref m2, out m1);
                Float3 translation = t1.Translation;
                Matrix.Translation(ref translation, out m2);
                Matrix.Multiply(ref m1, ref m2, out a2);
            }

            Matrix a3;
            t1.GetWorld(out a3);

            Assert.AreEqual(a1, a2);
            Assert.AreEqual(a1, a3);
        }

        /// <summary>
        /// Tests the local space to world space conversion.
        /// </summary>
        [Test]
        public void TestLocalToWorld()
        {
            Transform t1 = new Transform(new Vector3(10, 1, 10), Quaternion.Euler(45, 0, -15), new Float3(1.5f, 0.5f, 0.1f));
            Transform t2 = new Transform(new Vector3(0, 20, 0), Quaternion.Euler(0, 0, 15), new Float3(1.0f, 2.0f, 1.0f));

            Transform a1 = t1.LocalToWorld(t2);
            Vector3 a2 = t1.LocalToWorld(t2.Translation);

            Vector3 a3;
            {
                Vector3 result;
                Matrix scale, rotation, scaleRotation;
                Matrix.Scaling(ref t1.Scale, out scale);
                Matrix.RotationQuaternion(ref t1.Orientation, out rotation);
                Matrix.Multiply(ref scale, ref rotation, out scaleRotation);
                Vector3.Transform(ref t2.Translation, ref scaleRotation, out result);
                a3 = result + t1.Translation;
            }

            var a4T = new Vector3[1];
            t1.LocalToWorld(new Vector3[1] { t2.Translation }, a4T);
            Vector3 a4 = a4T[0];

            Assert.IsTrue(Vector3.NearEqual(a1.Translation, a2));
            Assert.IsTrue(Vector3.NearEqual(a2, a3));
            Assert.IsTrue(Vector3.NearEqual(a2, a4));
        }

        /// <summary>
        /// Tests the world space to local space conversion.
        /// </summary>
        [Test]
        public void TestWorldToLocal()
        {
            Transform t1 = new Transform(new Vector3(10, 1, 10), Quaternion.Euler(45, 0, -15), new Float3(1.5f, 0.5f, 0.1f));
            Transform t2 = new Transform(new Vector3(0, 20, 0), Quaternion.Euler(0, 0, 15), new Float3(1.0f, 2.0f, 1.0f));

            Transform a1 = t1.WorldToLocal(t2);
            Float3 a2 = t1.WorldToLocal(t2.Translation);

            Float3 a3;
            {
                Matrix scale, rotation, scaleRotation;
                Matrix.Scaling(ref t1.Scale, out scale);
                Matrix.RotationQuaternion(ref t1.Orientation, out rotation);
                Matrix.Multiply(ref scale, ref rotation, out scaleRotation);
                Matrix.Invert(ref scaleRotation, out scale);
                a3 = t2.Translation - t1.Translation;
                Float3.Transform(ref a3, ref scale, out a3);
            }

            var a4T = new Vector3[1];
            t1.WorldToLocal(new Vector3[1] { t2.Translation }, a4T);
            Float3 a4 = a4T[0];

            Assert.IsTrue(Float3.NearEqual((Float3)a1.Translation, a2));
            Assert.IsTrue(Float3.NearEqual(a2, a3, 0.0001f));
            Assert.IsTrue(Float3.NearEqual(a2, a4));
        }

        /// <summary>
        /// Test conversions between transform local/world space
        /// </summary>
        [Test]
        public void TestWorldAndLocalSpace()
        {
            Transform trans = new Transform(new Vector3(1, 2, 3));

            Assert.IsTrue(Float3.NearEqual(new Float3(1, 2, 3), (Float3)trans.LocalToWorld(new Float3(0, 0, 0))));
            Assert.IsTrue(Float3.NearEqual(new Float3(4, 4, 4), (Float3)trans.LocalToWorld(new Float3(3, 2, 1))));
            Assert.IsTrue(Float3.NearEqual(new Float3(-1, -2, -3), (Float3)trans.WorldToLocal(new Float3(0, 0, 0))));
            Assert.IsTrue(Float3.NearEqual(new Float3(0, 0, 0), (Float3)trans.WorldToLocal(new Float3(1, 2, 3))));

            trans = new Transform(Vector3.Zero, Quaternion.Euler(0, 90, 0));
            Assert.IsTrue(Float3.NearEqual(new Float3(0, 2, -1), (Float3)trans.LocalToWorld(new Float3(1, 2, 0))));

            trans.Translation = new Vector3(1, 0, 0);
            trans.Orientation = Quaternion.RotationX((float)Math.PI * 0.5f);
            trans.Scale = new Vector3(2, 2, 2);
            Assert.IsTrue(Float3.NearEqual(new Float3(1, 0, 2), (Float3)trans.LocalToWorld(new Float3(0, 1, 0))));

            Transform t1 = trans.LocalToWorld(Transform.Identity);
            Assert.IsTrue(Float3.NearEqual(new Float3(1.0f, 0, 0), (Float3)t1.Translation));
            Assert.IsTrue(Quaternion.NearEqual(Quaternion.RotationX((float)Math.PI * 0.5f), t1.Orientation));
            Assert.IsTrue(Float3.NearEqual(new Float3(2.0f, 2.0f, 2.0f), t1.Scale));

            Transform t2 = trans.WorldToLocal(Transform.Identity);
            Assert.IsTrue(Float3.NearEqual(new Float3(-0.5f, 0, 0), (Float3)t2.Translation));
            Assert.IsTrue(Quaternion.NearEqual(Quaternion.RotationX((float)Math.PI * -0.5f), t2.Orientation));
            Assert.IsTrue(Float3.NearEqual(new Float3(0.5f, 0.5f, 0.5f), t2.Scale));

            var rand = new Random(10);
            for (int i = 0; i < 10; i++)
            {
                Transform a = new Transform(rand.NextVector3(), Quaternion.Euler(i * 10, 0, i), rand.NextVector3() * 10.0f);
                Transform b = new Transform(rand.NextVector3(), Quaternion.Euler(i, 1, 22), rand.NextVector3() * 0.3f);

                Transform ab = a.LocalToWorld(b);
                Transform ba = a.WorldToLocal(ab);

                Assert.IsTrue(Transform.NearEqual(ref b, ref ba, 0.00001f), $"Got: {b} but expected {ba}");
            }
        }

        /// <summary>
        /// Test conversions between transform local/world space
        /// </summary>
        [Test]
        public void TestAddSubtract()
        {
            var rand = new Random(10);
            for (int i = 0; i < 10; i++)
            {
                Transform a = new Transform(rand.NextVector3(), Quaternion.Euler(i * 10, 0, i), rand.NextVector3() * 10.0f);
                Transform b = new Transform(rand.NextVector3(), Quaternion.Euler(i, 1, 22), rand.NextVector3() * 0.3f);

                Transform ab = a + b;
                Transform newA = ab - b;
                Assert.IsTrue(Transform.NearEqual(ref a, ref newA, 0.00001f), $"Got: {newA} but expected {a}");

                Transform ba = b + a;
                Transform newB = ba - a;
                Assert.IsTrue(Transform.NearEqual(ref b, ref newB, 0.00001f), $"Got: {newB} but expected {b}");
            }
        }
    }
}
#endif