using System;
using Chernobyl.Mathematics.Geometry;
using NUnit.Framework;

namespace Chernobyl.Mathematics.Movement
{
    [TestFixture, Description("Test for the CagedTransform2D type.")]
    public class CagedTransform2DTests
    {
        [Test, Description("A test that ensures the CagedTransform2D constructor " +
            "throws an ArgumentNullException when it is given a null Rectangle.")]
        public void ConstructorArgumentNullException()
        {
            // ReSharper disable ObjectCreationAsStatement
            Assert.Throws<ArgumentNullException>(() => new CagedTransform2D(null));
            // ReSharper restore ObjectCreationAsStatement
        }

        [Test, Description("A test that ensures the CagedTransform2D does not " +
            "try to move itself when it is inside its cage.")]
        public void InsideCageTest()
        {
            Rectangle cage = new Rectangle(5, 5);
            CagedTransform2D transform = new CagedTransform2D(cage);
            transform.Translate(1, 2);

            Assert.True(cage.Encloses((Point2D)transform.Position.Xy),
                        "The transform is not within the cage, when it should be.");
        }

        [Test, Description("A test that ensures the CagedTransform2D moves " +
            "itself back inside its cage when it is moved out of it.")]
        public void OutsideCageTest()
        {
            Rectangle cage = new Rectangle(5, 5);
            CagedTransform2D transform = new CagedTransform2D(cage);
            transform.Translate(6, 7);

            Assert.True(cage.Encloses((Point2D)transform.Position.Xy),
                        "The transform is not within the cage, when it should be.");
        }

        [Test, Description("A test that ensures a parented CagedTransform2D does " +
            "not try to move itself when it is inside its cage.")]
        public void ParentedInsideCageTest()
        {
            Rectangle cage = new Rectangle(5, 5);
            MatrixTransform parent = new MatrixTransform();
            CagedTransform2D transform = new CagedTransform2D(cage);
            Transform.MakeParentChild(parent, transform);
            parent.Translate(1, 2);

            Assert.True(cage.Encloses((Point2D)transform.Position.Xy),
                        "The transform is not within the cage, when it should be.");
        }

        [Test, Description("A test that ensures a parented CagedTransform2D moves " +
            "itself back inside its cage when it is moved out of it.")]
        public void ParentedOutsideCageTest()
        {
            Rectangle cage = new Rectangle(5, 5);
            MatrixTransform parent = new MatrixTransform();
            CagedTransform2D transform = new CagedTransform2D(cage);
            Transform.MakeParentChild(parent, transform);
            parent.Translate(6, 7);

            Assert.True(cage.Encloses((Point2D)transform.Position.Xy),
                        "The transform is not within the cage, when it should be.");
        }

        [Test, Description("A test that ensures CagedTransform2D moves " +
            "itself back inside its cage when the cage itself is moved.")]
        public void CageMovesTest()
        {
            Rectangle cage = new Rectangle(5, 5);
            CagedTransform2D transform = new CagedTransform2D(cage);
            cage.Translate(6, 7);

            Assert.True(cage.Encloses((Point2D)transform.Position.Xy),
                        "The transform is not within the cage, when it should be.");
        }

        // TODO: tests needed:
        // ArgumentOutOfRangeException if BorderDistance is set to 0.
        // ArgumentOutOfRangeException if BorderDistance is set to less than 0.
        // Ensure BorderDistance is defaulted to the proper value after construction.
        // Ensure BorderDistance is used properly.
        // What happens if given a Rectangle with an area of 0? Need to add a test for this case.
    }
}