using NUnit.Framework;
using FluentAssertions;

using Encompass;
using Encompass.Engines;
using Encompass.Exceptions;
using System;
using System.Collections.Generic;

namespace Tests
{
    class DetectorTest
    {
        class NoComponentTypesDetector : Detector
        {
            public override void Detect(Entity entity, double dt) { }
        }

        [Test]
        public void DetectorWithNoComponentTypes()
        {
            var worldBuilder = new WorldBuilder();

            Action addEngine = () => worldBuilder.AddEngine(new NoComponentTypesDetector());
            addEngine.Should().Throw<DetectorWithoutComponentTypesException>();
        }

        struct AComponent : IComponent { }
        struct BComponent : IComponent { }
        struct CComponent : IComponent { }

        static List<Entity> trackedEntities = new List<Entity>();

        [Detects(typeof(AComponent), typeof(BComponent))]
        class TestDetector : Detector
        {
            public override void Detect(Entity entity, double dt)
            {
                trackedEntities.Add(entity);
            }
        }

        [Test]
        public void CheckAndTrackEntities()
        {
            var worldBuilder = new WorldBuilder();
            var detector = worldBuilder.AddEngine(new TestDetector());

            var entityToTrack = worldBuilder.CreateEntity();
            entityToTrack.AddComponent(new AComponent());
            entityToTrack.AddComponent(new BComponent());

            var entityNotToTrack = worldBuilder.CreateEntity();
            entityNotToTrack.AddComponent(new AComponent());
            entityNotToTrack.AddComponent(new CComponent());

            var entityWithDeactivatedComponents = worldBuilder.CreateEntity();
            var aComponent = entityWithDeactivatedComponents.AddComponent(new AComponent());
            entityWithDeactivatedComponents.AddComponent(new BComponent());
            entityWithDeactivatedComponents.DeactivateComponent(aComponent);

            var entityWithOneDeactivatedComponent = worldBuilder.CreateEntity();
            var inactiveComponent = entityWithOneDeactivatedComponent.AddComponent(new AComponent());
            entityWithOneDeactivatedComponent.AddComponent(new AComponent());
            entityWithOneDeactivatedComponent.AddComponent(new BComponent());
            entityWithOneDeactivatedComponent.DeactivateComponent(inactiveComponent);

            var world = worldBuilder.Build();
            world.Update(0.01);

            trackedEntities.Should().Contain(entityToTrack);
            trackedEntities.Should().NotContain(entityNotToTrack);
            trackedEntities.Should().NotContain(entityWithDeactivatedComponents);
            trackedEntities.Should().Contain(entityWithOneDeactivatedComponent);
        }

        [Test]
        public void EntityUntrackedWhenComponentRemoved()
        {
            var worldBuilder = new WorldBuilder();
            worldBuilder.AddEngine(new TestDetector());

            var entityToUntrack = worldBuilder.CreateEntity();
            entityToUntrack.AddComponent(new AComponent());
            var bComponent = entityToUntrack.AddComponent(new BComponent());

            var world = worldBuilder.Build();

            // have to update twice because we are updating from outside the world
            entityToUntrack.RemoveComponent(bComponent);
            world.Update(0.01);

            trackedEntities.Clear();
            world.Update(0.01);

            trackedEntities.Should().NotContain(entityToUntrack);
        }

        [Test]
        public void DetectCalledPerTrackedEntityOnWorldUpdat()
        {
            var worldBuilder = new WorldBuilder();
            worldBuilder.AddEngine(new TestDetector());

            var entityOne = worldBuilder.CreateEntity();
            entityOne.AddComponent(new AComponent());
            entityOne.AddComponent(new BComponent());

            var entityTwo = worldBuilder.CreateEntity();
            entityTwo.AddComponent(new AComponent());
            entityTwo.AddComponent(new BComponent());

            trackedEntities.Clear();

            var world = worldBuilder.Build();

            world.Update(0.01);

            trackedEntities.Should().Contain(entityOne);
            trackedEntities.Should().Contain(entityTwo);
        }
    }
}