using DCFApixels.DragonECS;
using DCFApixels.DragonECS.Relations.Utils;
using System.Collections;
using System.Runtime.CompilerServices;

namespace DragonECS.DragonECS
{
    //Relation entity
    //Relation
    //Relation component
    public readonly struct Relations
    {
        public readonly RelationManager manager;
        public Relations(RelationManager manager)
        {
            this.manager = manager;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public ref readonly RelationTargets GetRelationTargets(int relationEntityID) => ref manager.GetRelationTargets(relationEntityID);
    }
    public class RelationManager : IEcsWorldEventListener, IEcsEntityEventListener
    {
        private EcsRelationWorld _relationWorld;

        private EcsWorld _world;
        private EcsWorld _otherWorld;

        private SparseArray64<int> _relationsMatrix = new SparseArray64<int>();

        public readonly Orientation Forward;
        public readonly Orientation Reverse;

        private RelationTargets[] _relationTargets;

        public EcsWorld World => _world;
        public EcsWorld RelationWorld => _relationWorld;
        public EcsWorld OtherWorld => _otherWorld;
        public bool IsSolo => _world == _otherWorld;

        internal RelationManager(EcsWorld world, EcsRelationWorld relationWorld, EcsWorld otherWorld)
        {
            _relationWorld = relationWorld;
            _world = world;
            _otherWorld = otherWorld;

            _relationTargets = new RelationTargets[relationWorld.Capacity];

            _relationWorld.AddListener(worldEventListener: this);
            _relationWorld.AddListener(entityEventListener: this);

            IdsBasket basket = new IdsBasket(256);
            IdsBasket otherBasket = new IdsBasket(256);

            Forward = new Orientation(this, relationWorld, basket, otherBasket);
            Reverse = new Orientation(this, relationWorld, otherBasket, basket);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public ref readonly RelationTargets GetRelationTargets(int relationEntityID)
        {
            return ref _relationTargets[relationEntityID];
        }

        #region Callbacks
        void IEcsWorldEventListener.OnWorldResize(int newSize)
        {
            Array.Resize(ref _relationTargets, newSize);
        }
        void IEcsWorldEventListener.OnReleaseDelEntityBuffer(ReadOnlySpan<int> buffer) { }
        void IEcsWorldEventListener.OnWorldDestroy() { }

        void IEcsEntityEventListener.OnNewEntity(int entityID) { }
        void IEcsEntityEventListener.OnDelEntity(int entityID)
        {
            ref RelationTargets rel = ref _relationTargets[entityID];
            if (_relationsMatrix.Contains(rel.entity, rel.otherEntity))
                Forward.DelRelation(rel.entity, rel.otherEntity);
        }
        #endregion

        #region Orientation
        public readonly struct Orientation
        {
            private readonly RelationManager _source;

            private readonly EcsWorld _relationWorld;

            private readonly IdsBasket _basket;
            private readonly IdsBasket _otherBasket;

            public Orientation(RelationManager source, EcsWorld relationWorld, IdsBasket basket, IdsBasket otherBasket)
            {
                _source = source;
                _relationWorld = relationWorld;
                _basket = basket;
                _otherBasket = otherBasket;
            }

            #region New/Del
            public int NewRelation(int entityID, int otherEntityID)
            {
                if (HasRelation(entityID, otherEntityID))
                    throw new EcsRelationException();
                int e = _relationWorld.NewEmptyEntity();
                _basket.AddToHead(entityID, otherEntityID);
                _otherBasket.AddToHead(otherEntityID, entityID);
                _source._relationTargets[e] = new RelationTargets(entityID, otherEntityID);
                return e;
            }
            public void DelRelation(int entityID, int otherEntityID)
            {
                if (!_source._relationsMatrix.TryGetValue(entityID, otherEntityID, out int e))
                    throw new EcsRelationException();
                _basket.DelHead(entityID);
                _otherBasket.Del(entityID);
                _relationWorld.DelEntity(e);
                _source._relationTargets[e] = RelationTargets.Empty;
            }
            #endregion

            #region Has
            public bool HasRelation(int entityID, int otherEntityID) => _source._relationsMatrix.Contains(entityID, otherEntityID);
            //public bool HasRelationWith(EcsSubject subject, int entityID, int otherEntityID)
            //{
            //    if (subject.World != _relationWorld)
            //        throw new ArgumentException();
            //    return _source._relationsMatrix.TryGetValue(entityID, otherEntityID, out int entity) && subject.IsMatches(entity);
            //}
            #endregion

            #region GetRelation
            public int GetRelation(int entityID, int otherEntityID)
            {
                if (!_source._relationsMatrix.TryGetValue(entityID, otherEntityID, out int e))
                    throw new EcsRelationException();
                return e;
            }
            public bool TryGetRelation(int entityID, int otherEntityID, out int entity)
            {
                return _source._relationsMatrix.TryGetValue(entityID, otherEntityID, out entity);
            }
            //public bool TryGetRelation(EcsSubject subject, int entityID, int otherEntityID, out int entity)
            //{
            //    return _source._relationsMatrix.TryGetValue(entityID, otherEntityID, out entity) && subject.IsMatches(entity);
            //}
            #endregion

            #region GetRelations
            public IdsLinkedList.Span GetRelations(int entityID)
            {
                return _basket.GetSpanFor(entityID);
            }
            //ReadOnlySpan<int> временная заглушка, потому тут будет спан из линкедлиста
            //public ReadOnlySpan<int> GetRelationsWith(EcsSubject subject, int entityID)
            //{
            //    if (subject.World != _relationWorld)
            //        throw new ArgumentException();
            //    throw new NotImplementedException();
            //}
            #endregion
        }

        public struct RelationsSpan
        {
            private readonly IdsBasket _basket;
            private readonly EcsSubject _subject;
        }
        #endregion
    }

    public static class WorldRelationExtensions
    {
        public static void SetRelationWith(this EcsWorld self, EcsWorld otherWorld)
        {
            WorldRelationsMatrix.Register(self, otherWorld, new EcsRelationWorld());
        }
        public static void SetRelationWith(this EcsWorld self, EcsWorld otherWorld, EcsRelationWorld relationWorld)
        {
            WorldRelationsMatrix.Register(self, otherWorld, relationWorld);
        }
        public static void DelRelationWith(this EcsWorld self, EcsWorld otherWorld)
        {
            WorldRelationsMatrix.Unregister(self, otherWorld);
        }
    }
}