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

namespace Chernobyl.Mathematics.Collision
{
    /// <summary>
    /// A base class test fixture that tests the <see cref="ICollidable"/>
    /// type.
    /// </summary>
    public abstract class CollidableTests
    {
        [Test, Description("Ensures the ICollidable.OnCollisionStarted event " +
            "is invoked when the ICollidable.HandleCollisionStarted(ICollidable) " + 
            "method has been invoked.")]
        public virtual void CollisionStartedandEnded()
        {
            Circle circle = new Circle(40.5f);

            ICollidable collidable = CreateCollidable();
            collidable.OnCollisionStarted += (sender, e) =>
                Assert.Pass("ICollidable.OnCollisionStarted event has been invoked, test passes");

            collidable.HandleCollisionStarted(circle);

            Assert.Fail("ICollidable.OnCollisionStarted event was NOT invoked.");
        }

        [Test, Description("Ensures the ICollidable.OnCollisionEnded event " +
            "is invoked when the ICollidable.HandleCollisionEnded(ICollidable) " +
            "method has been invoked.")]
        public virtual void CollisionEnded()
        {
            Circle circle = new Circle(40.5f);

            ICollidable collidable = CreateCollidable();
            collidable.OnCollisionEnded += (sender, e) =>
                Assert.Pass("ICollidable.OnCollisionEnded event has been invoked, test passes");

            collidable.HandleCollisionStarted(circle);
            collidable.HandleCollisionEnded(circle);

            Assert.Fail("ICollidable.OnCollisionEnded event was NOT invoked.");
        }

        /// <summary>
        /// Should create an <see cref="ICollidable"/> that can be collided 
        /// against for testing purposes. This method should always create a new
        ///  <see cref="ICollidable"/> and never reuse the same instance.
        /// </summary>
        /// <returns>The new <see cref="ICollidable"/> to test with.</returns>
        protected abstract ICollidable CreateCollidable();
    }
}