using NUnit.Framework;
using FluentAssertions;

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

namespace Tests
{
    public class ComponentTests
    {
        struct MockComponent : IComponent
        {
            public string myString;
            public int myInt;
        }

        struct EntityMessage : IMessage
        {
            public Entity entity;
        }

        static IEnumerable<(Guid, MockComponent)> gottenMockComponentIDPairs = Enumerable.Empty<(Guid, MockComponent)>();
        static (Guid, MockComponent) gottenMockComponentIDPair;

        [Receives(typeof(EntityMessage))]
        [Reads(typeof(MockComponent))]
        class GetMockComponentEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var entityMessage in ReadMessages<EntityMessage>())
                {
                    gottenMockComponentIDPair = GetComponent<MockComponent>(entityMessage.entity);
                }
            }
        }

        struct AddComponentTestMessage : IMessage
        {
            public Entity entity;
            public MockComponent mockComponent;
        }

        [Receives(typeof(AddComponentTestMessage))]
        [Reads(typeof(MockComponent))]
        class AddComponentTestEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var addComponentTestMessage in ReadMessages<AddComponentTestMessage>())
                {
                    Assert.IsTrue(HasComponent<MockComponent>(addComponentTestMessage.entity));
                    Assert.That(GetComponent<MockComponent>(addComponentTestMessage.entity).Item2, Is.EqualTo(addComponentTestMessage.mockComponent));
                }
            }
        }

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

            var entity = worldBuilder.CreateEntity();

            MockComponent mockComponent;
            mockComponent.myInt = 3;
            mockComponent.myString = "hello";

            worldBuilder.AddComponent(entity, mockComponent);

            AddComponentTestMessage addComponentTestMessage;
            addComponentTestMessage.entity = entity;
            addComponentTestMessage.mockComponent = mockComponent;
            worldBuilder.SendMessage(addComponentTestMessage);

            var world = worldBuilder.Build();

            world.Update(0.01);
        }

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

            MockComponent mockComponent;
            mockComponent.myInt = 3;
            mockComponent.myString = "hello";

            var entity = worldBuilder.CreateEntity();
            worldBuilder.AddComponent(entity, mockComponent);
            worldBuilder.AddComponent(entity, mockComponent);

            Assert.Throws<MultipleComponentOfSameTypeException>(() => worldBuilder.Build());
        }

        [Reads(typeof(MockComponent))]
        [Writes(typeof(MockComponent))]
        class MultipleAddEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var (mockComponentID, mockComponent) in ReadComponents<MockComponent>())
                {
                    var entity = GetEntityByComponentID(mockComponentID);

                    SetComponent(entity, new MockComponent());
                }
            }
        }

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

            var entity = worldBuilder.CreateEntity();
            worldBuilder.AddComponent(entity, new MockComponent());

            var world = worldBuilder.Build();

            Assert.Throws<MultipleComponentOfSameTypeException>(() => world.Update(0.01));
        }

        [Reads(typeof(MockComponent))]
        [Writes(typeof(MockComponent))]
        class AddAndRemoveComponentEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var (mockComponentID, mockComponent) in ReadComponents<MockComponent>())
                {
                    var entity = GetEntityByComponentID(mockComponentID);
                    SetComponent(entity, mockComponent);
                    RemoveComponent(mockComponentID);
                }
            }
        }

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

            var entity = worldBuilder.CreateEntity();
            worldBuilder.AddComponent(entity, new MockComponent());

            var world = worldBuilder.Build();

            Assert.DoesNotThrow(() => world.Update(0.01));
        }

        struct AddMockComponentMessage : IMessage
        {
            public Entity entity;
            public MockComponent mockComponent;
        }

        [Sends(typeof(AddMockComponentMessage))]
        class EmitMockComponentMessageEngine : Engine
        {
            private Entity entity;

            public EmitMockComponentMessageEngine(Entity entity)
            {
                this.entity = entity;
            }

            public override void Update(double dt)
            {
                MockComponent mockComponent;
                mockComponent.myInt = 10;
                mockComponent.myString = "four";

                AddMockComponentMessage addMockComponentMessage;
                addMockComponentMessage.entity = entity;
                addMockComponentMessage.mockComponent = mockComponent;
                SendMessage(addMockComponentMessage);
            }
        }

        [WritesPending(typeof(MockComponent))]
        [Receives(typeof(AddMockComponentMessage))]
        [Writes(typeof(MockComponent))]
        class AddMockComponentEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var message in ReadMessages<AddMockComponentMessage>())
                {
                    SetComponent(message.entity, message.mockComponent);
                }
            }
        }

        [ReadsPending(typeof(MockComponent))]
        class HasMockComponentEngine : Engine
        {
            private Entity entity;

            public HasMockComponentEngine(Entity entity)
            {
                this.entity = entity;
            }

            public override void Update(double dt)
            {
                Assert.IsTrue(HasComponent<MockComponent>(entity));
            }
        }

        [Test]
        public void AddComponentAndReadSameFrame()
        {
            var worldBuilder = new WorldBuilder();
            var entity = worldBuilder.CreateEntity();

            worldBuilder.AddEngine(new EmitMockComponentMessageEngine(entity));
            worldBuilder.AddEngine(new AddMockComponentEngine());
            worldBuilder.AddEngine(new HasMockComponentEngine(entity));

            var world = worldBuilder.Build();

            world.Update(0.01);
        }

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

            var entity = worldBuilder.CreateEntity();

            MockComponent mockComponent;
            mockComponent.myInt = 3;
            mockComponent.myString = "hello";

            var componentID = worldBuilder.AddComponent<MockComponent>(entity, mockComponent);

            EntityMessage entityMessage;
            entityMessage.entity = entity;
            worldBuilder.SendMessage(entityMessage);

            var world = worldBuilder.Build();

            world.Update(0.01);

            Assert.AreEqual((componentID, mockComponent), gottenMockComponentIDPair);
        }

        struct HasComponentTestMessage : IMessage
        {
            public Entity entity;
        }

        [Receives(typeof(HasComponentTestMessage))]
        [Reads(typeof(MockComponent))]
        class HasComponentTestEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var hasComponentTestEngine in ReadMessages<HasComponentTestMessage>())
                {
                    Assert.IsTrue(HasComponent<MockComponent>(hasComponentTestEngine.entity));
                }
            }
        }

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

            var entity = worldBuilder.CreateEntity();

            MockComponent mockComponent;
            mockComponent.myInt = 3;
            mockComponent.myString = "hello";

            worldBuilder.AddComponent(entity, mockComponent);

            HasComponentTestMessage hasComponentTestMessage;
            hasComponentTestMessage.entity = entity;
            worldBuilder.SendMessage(hasComponentTestMessage);

            var world = worldBuilder.Build();

            world.Update(0.01);
        }

        struct RemoveComponentTestMessage : IMessage
        {
            public Entity entity;
            public Guid componentID;
        }

        [Receives(typeof(RemoveComponentTestMessage))]
        class RemoveComponentTestEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var removeComponentMessage in ReadMessages<RemoveComponentTestMessage>())
                {
                    RemoveComponent(removeComponentMessage.componentID);
                }
            }
        }

        [Receives(typeof(RemoveComponentTestMessage))]
        [Sends(typeof(CheckHasMockComponentMessage))]
        class DoRemoveCheckEngine : Engine
        {
            private Entity entity;

            public DoRemoveCheckEngine(Entity entity)
            {
                this.entity = entity;
            }

            public override void Update(double dt)
            {
                if (SomeMessage<RemoveComponentTestMessage>())
                {
                    CheckHasMockComponentMessage checkHasMockComponentMessage;
                    checkHasMockComponentMessage.entity = entity;
                    checkHasMockComponentMessage.shouldHaveComponent = true;
                    SendMessage(checkHasMockComponentMessage);
                }
                else
                {
                    CheckHasMockComponentMessage checkHasMockComponentMessage;
                    checkHasMockComponentMessage.entity = entity;
                    checkHasMockComponentMessage.shouldHaveComponent = false;
                    SendMessage(checkHasMockComponentMessage);
                }
            }
        }

        [Receives(typeof(CheckHasMockComponentMessage))]
        [Reads(typeof(MockComponent))]
        class CheckHasMockComponentEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var checkHasMockComponentMessage in ReadMessages<CheckHasMockComponentMessage>())
                {
                    Assert.IsTrue(HasComponent<MockComponent>(checkHasMockComponentMessage.entity));
                }
            }
        }

        [Test]
        public void RemoveComponent()
        {
            var worldBuilder = new WorldBuilder();
            var entity = worldBuilder.CreateEntity();

            worldBuilder.AddEngine(new RemoveComponentTestEngine());
            worldBuilder.AddEngine(new CheckHasMockComponentEngine());
            worldBuilder.AddEngine(new DoRemoveCheckEngine(entity));

            MockComponent mockComponent;
            mockComponent.myInt = 3;
            mockComponent.myString = "hello";

            var componentID = worldBuilder.AddComponent(entity, mockComponent);

            RemoveComponentTestMessage removeComponentMessage;
            removeComponentMessage.entity = entity;
            removeComponentMessage.componentID = componentID;
            worldBuilder.SendMessage(removeComponentMessage);

            var world = worldBuilder.Build();

            world.Update(0.01f);
        }

        struct CheckHasMockComponentMessage : IMessage
        {
            public Entity entity;
            public bool shouldHaveComponent;
        }

        [Receives(typeof(CheckHasMockComponentMessage))]
        [ReadsPending(typeof(MockComponent))]
        class CheckHasPendingMockComponentEngine : Engine
        {
            public override void Update(double dt)
            {
                foreach (var checkHasMockComponentMessage in ReadMessages<CheckHasMockComponentMessage>())
                {
                    Assert.IsTrue(HasComponent<MockComponent>(checkHasMockComponentMessage.entity));
                }
            }
        }
    }
}