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

namespace Chernobyl.Mathematics.Collision
{
    [TestFixture, Description("A TestFixture that tests the " +
        "CollisionMediator<TCollidable> class.")]
    public class CollisionMediatorTests
    {
        [Test, Description("Ensures the CollisionMediator(IExtendedCollidable<TCollidable>) " +
            "constructor throws an ArgumentNullException if the parameter passed to it is null.")]
        public void ConstructorArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(() => new CollisionMediator<Rectangle>(null));
        }

        [Test, Description("A test that ensures that OnCollisionStarted and " +
            "OnCollisionEnded events are not sent to the IExtendedCollidable<TCollidable> " +
            "that is used for the CollisionMediator<TCollidable>'s implementation")]
        public void CollidableImplementorDoesNotInvokeEvents()
        {
            Rectangle collidableImplementor = new Rectangle(0, 0, 100, 100);
            CollisionMediator<Rectangle> collisionMediator = new CollisionMediator<Rectangle>(collidableImplementor);

            collidableImplementor.OnCollisionStarted += (sender, e) => Assert.Fail("The implementing collidable should not have had its OnCollisionStarted event invoked.");
            collidableImplementor.OnCollisionEnded += (sender, e) => Assert.Fail("The implementing collidable should not have had its OnCollisionEnded event invoked.");

            Point2D collider = new Point2D(50, 50);
            collisionMediator.HandleCollisionStarted(collider);
            collisionMediator.HandleCollisionEnded(collider);

            Assert.Pass("The implementing collidable did not have its OnCollisionStarted event invoked.");
        }

        [Test, Description("A test that ensures that the OnCollisionStarted " +
            "event is properly invoked on the CollisionMediator<Rectangle> " +
            "when the IExtendedCollidable<TCollidable> used for that " +
            "CollisionMediator<Rectangle>'s implementation  has it's " +
            "OnCollisionStarted event invoked.")]
        public void CollidableMediatorPassesImplementorsOnCollisionStartedEventForward()
        {
            Rectangle collidableImplementor = new Rectangle(0, 0, 100, 100);
            CollisionMediator<Rectangle> collisionMediator = new CollisionMediator<Rectangle>(collidableImplementor);

            collisionMediator.OnCollisionStarted += (sender, e) => Assert.Pass("The CollisionMediator<Rectangle> had its OnCollisionStarted event invoked.");

            Point2D collider = new Point2D(50, 50);
            collidableImplementor.HandleCollisionStarted(collider);

            Assert.Fail("The CollisionMediator<Rectangle> did not have its OnCollisionStarted event invoked.");
        }

        [Test, Description("A test that ensures that the OnCollisionEnded " +
            "event is properly invoked on the CollisionMediator<Rectangle> " +
            "when the IExtendedCollidable<TCollidable> used for that " +
            "CollisionMediator<Rectangle>'s implementation  has it's " +
            "OnCollisionEnded event invoked.")]
        public void CollidableMediatorPassesImplementorsOnCollisionEndedEventForward()
        {
            Rectangle collidableImplementor = new Rectangle(0, 0, 100, 100);
            CollisionMediator<Rectangle> collisionMediator = new CollisionMediator<Rectangle>(collidableImplementor);

            collisionMediator.OnCollisionEnded += (sender, e) => Assert.Pass("The CollisionMediator<Rectangle> had its OnCollisionEnded event invoked.");

            Point2D collider = new Point2D(50, 50);
            collidableImplementor.HandleCollisionEnded(collider);

            Assert.Fail("The CollisionMediator<Rectangle> did not have its OnCollisionEnded event invoked.");
        }

        [TestFixture, Description("Tests the IShape and ITransform portion " +
            "of the CollisionMediator<TCollidable>.")]
        public class CollisionMediatorShapeTests : RectangleTests.RectangleShapeTests
        {
            protected override IShape CreateShape()
            {
                return new CollisionMediator<Rectangle>((Rectangle)base.CreateShape());
            }
        }

        [TestFixture, Description("Tests the IExtendedCollidable<Rectangle> " +
            "portion of the Rectangle.")]
        public class CollisionMediatorExtendedCollidableTests : RectangleTests.RectangleExtendedCollidableTests
        {
            protected override IExtendedCollidable<Rectangle> CreateExtendedCollidable()
            {
                return new CollisionMediator<Rectangle>(base.CreateExtendedCollidable());
            }
        }
    }
}