using DCFApixels.DragonECS.Relations.Internal;
using DCFApixels.DragonECS.Relations.Utils;
using System;

namespace DCFApixels.DragonECS
{
    public static class EcsWorldGraph
    {
        private static readonly SparseArray64<EcsArc> _matrix = new SparseArray64<EcsArc>(4);
        private static EcsArc[] _arcsMapping = new EcsArc[4];

        #region Register/Unregister
        private static EcsArc Register(EcsWorld startWorld, EcsWorld endWorld, EcsArcWorld arcWorld)
        {
            int startWorldID = startWorld.id;
            int endWorldID = endWorld.id;
            int arcWorldID = arcWorld.id;

            if(_arcsMapping.Length <= arcWorldID)
            {
                Array.Resize(ref _arcsMapping, arcWorldID + 4);
            }

#if DEBUG
            if (_matrix.Contains(startWorldID, endWorldID))
            {
                throw new EcsFrameworkException();
            }
#endif
            EcsArc arc = new EcsArc(startWorld, endWorld, arcWorld);
            _matrix[startWorldID, endWorldID] = arc;
            _arcsMapping[arcWorldID] = arc;
            return arc;
        }
        private static void Unregister(EcsWorld startWorld, EcsWorld endWorld)
        {
            int startWorldID = startWorld.id;
            int endWorldID = endWorld.id;
            EcsArc arc = _matrix[startWorldID, endWorldID];
            _arcsMapping[arc.ArcWorld.id] = null;
            _matrix.Remove(startWorldID, endWorldID);
        }
        #endregion

        #region Get/Has
//        private static EcsArc GetOrRigister(EcsWorld startWorld, EcsWorld otherWorld)
//        {
//#if DEBUG
//            if (!_matrix.Contains(startWorld.id, otherWorld.id))
//            {
//                return Register();
//            }
//#endif
//            return _matrix[startWorld.id, otherWorld.id];
//        }
        private static EcsArc Get(EcsWorld startWorld, EcsWorld otherWorld)
        {
#if DEBUG
            if (!_matrix.Contains(startWorld.id, otherWorld.id))
            {
                throw new EcsFrameworkException();
            }
#endif
            return _matrix[startWorld.id, otherWorld.id];
        }
        private static bool Has(EcsWorld startWorld, EcsWorld endWorld) => Has(startWorld.id, endWorld.id);
        private static bool Has(int startWorldID, int endWorldID) => _matrix.Contains(startWorldID, endWorldID);
        #endregion

        #region Extension
        public static bool IsRegistered(this EcsArcWorld self)
        {
            if (self == null)
            {
                Throw.ArgumentNull();
            }
            int id = self.id;
            return id < _arcsMapping.Length && _arcsMapping[self.id] != null;
        }
        public static EcsArc GetRegisteredArc(this EcsArcWorld self)
        {
            if (self == null)
            {
                Throw.ArgumentNull();
            }
            int id = self.id;
            if(id < _arcsMapping.Length && _arcsMapping[self.id] == null)
            {
                throw new Exception();
            }
            return _arcsMapping[self.id];
        }



        public static EcsArc SetLoopArcAuto(this EcsWorld self) => SetArcAuto(self, self);
        public static EcsArc SetArcAuto(this EcsWorld start, EcsWorld end)
        {
            if (start == null || end == null)
            {
                Throw.ArgumentNull();
            }
            return Register(start, end, new EcsArcWorld());
        }

        public static EcsArc SetLoopArc(this EcsWorld self, EcsArcWorld arc) => SetArc(self, self, arc);
        public static EcsArc SetArc(this EcsWorld start, EcsWorld end, EcsArcWorld arc)
        {
            if (start == null || end == null || arc == null)
            {
                Throw.ArgumentNull();
            }
            return Register(start, end, arc);
        }

        public static bool HasLoopArc(this EcsWorld self) => HasArc(self, self);
        public static bool HasArc(this EcsWorld start, EcsWorld end)
        {
            if (start == null || end == null)
            {
                Throw.ArgumentNull();
            }
            return Has(start, end);
        }

        public static EcsArc GetLoopArc(this EcsWorld self) => GetArc(self, self);
        public static EcsArc GetArc(this EcsWorld start, EcsWorld end)
        {
            if (start == null || end == null)
            {
                Throw.ArgumentNull();
            }
            return Get(start, end);
        }

        public static bool TryGetLoopArc(this EcsWorld self, out EcsArc arc) => TryGetArc(self, self, out arc);
        public static bool TryGetArc(this EcsWorld start, EcsWorld end, out EcsArc arc)
        {
            if (start == null || end == null)
            {
                Throw.ArgumentNull();
            }
            bool result = Has(start, end);
            arc = result ? Get(start, end) : null;
            return result;
        }

        public static void DestroyLoopArc(this EcsWorld self) => DestroyArcWith(self, self);
        public static void DestroyArcWith(this EcsWorld start, EcsWorld end)
        {
            if (start == null || end == null)
            {
                Throw.ArgumentNull();
            }
            Get(start, end).ArcWorld.Destroy();
            Unregister(start, end);
        }
        #endregion
    }
}