using DCFApixels.DragonECS.Internal;
using DCFApixels.DragonECS.Utils;
using System;
using System.Linq;
using System.Runtime.CompilerServices;

namespace DCFApixels.DragonECS
{
    public abstract partial class EcsWorld
    {
        private SparseArray<int> _poolIds = new SparseArray<int>();
        private SparseArray<int> _componentIds = new SparseArray<int>();
        private int _poolsCount;
        internal IEcsPoolImplementation[] _pools;
        private EcsNullPool _nullPool = EcsNullPool.instance;

        #region ComponentInfo
        public int GetComponentID<T>() => DeclareComponentType(EcsTypeCode.Get<T>());
        public int GetComponentID(Type type) => DeclareComponentType(EcsTypeCode.Get(type));
        public bool IsComponentTypeDeclared<T>() => _componentIds.Contains(EcsTypeCode.Get<T>());
        public bool IsComponentTypeDeclared(Type type) => _componentIds.Contains(EcsTypeCode.Get(type));
        public Type GetComponentType(int componentID) => _pools[componentID].ComponentType;
        #endregion

        #region Getters

#if UNITY_2020_3_OR_NEWER
        [UnityEngine.Scripting.Preserve]
#endif
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public TPool GetPool<TPool>() where TPool : IEcsPoolImplementation, new()
        {
            return Get<PoolCache<TPool>>().instance;
        }
#if UNITY_2020_3_OR_NEWER
        [UnityEngine.Scripting.Preserve]
#endif
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public TPool GetPoolUnchecked<TPool>() where TPool : IEcsPoolImplementation, new()
        {
            return UncheckedGet<PoolCache<TPool>>().instance;
        }
#if UNITY_2020_3_OR_NEWER
        [UnityEngine.Scripting.Preserve]
#endif
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static TPool GetPool<TPool>(int worldID) where TPool : IEcsPoolImplementation, new()
        {
            return Get<PoolCache<TPool>>(worldID).instance;
        }
#if UNITY_2020_3_OR_NEWER
        [UnityEngine.Scripting.Preserve]
#endif
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static TPool UncheckedGetPool<TPool>(int worldID) where TPool : IEcsPoolImplementation, new()
        {
            return UncheckedGet<PoolCache<TPool>>(worldID).instance;
        }
        #endregion

        #region Declare/Create
        private int DeclareComponentType(int typeCode)
        {
            if (!_componentIds.TryGetValue(typeCode, out int componentId))
            {
                componentId = _poolsCount++;
                _componentIds.Add(typeCode, componentId);
            }
            return componentId;
        }
        private TPool CreatePool<TPool>() where TPool : IEcsPoolImplementation, new()
        {
            int poolTypeCode = EcsTypeCode.Get<TPool>();
            if (_poolIds.Contains(poolTypeCode))
                throw new EcsFrameworkException("The pool has already been created.");

            Type componentType = typeof(TPool).GetInterfaces().First(o => o.IsGenericType && o.GetGenericTypeDefinition() == typeof(IEcsPoolImplementation<>)).GetGenericArguments()[0];
            int componentTypeCode = EcsTypeCode.Get(componentType);

            if (_componentIds.TryGetValue(componentTypeCode, out int componentID))
            {
                _poolIds[poolTypeCode] = componentID;
            }
            else
            {
                componentID = _poolsCount++;
                _poolIds[poolTypeCode] = componentID;
                _componentIds[componentTypeCode] = componentID;
            }

            if (_poolsCount >= _pools.Length)
            {
                int oldCapacity = _pools.Length;
                Array.Resize(ref _pools, _pools.Length << 1);
                ArrayUtility.Fill(_pools, _nullPool, oldCapacity, oldCapacity - _pools.Length);
            }

            if (_pools[componentID] == _nullPool)
            {
                var pool = new TPool();
                _pools[componentID] = pool;
                pool.OnInit(this, componentID);
            }
            return (TPool)_pools[componentID];
        }
        #endregion
    }
}