using System;
using System.Runtime.CompilerServices;
using PkmnLibSharp.FFI;

[assembly: InternalsVisibleTo("PkmnLibRSharp")]
namespace PkmnLibSharp.Utils
{
    public abstract class ExternPointer<TCache> : BasePointer<TCache>
        where TCache : class
    {
        private bool _isOwner;
        private bool _isInvalidated;
        private bool _isDisposed;
        
        protected ExternPointer()
        {
            
        }

        protected ExternPointer(IntPtr ptr, bool isOwner)
        {
            InitializePointer(ptr, isOwner);
        }
        
        protected ExternPointer(IdentifiablePointer ptr, bool isOwner) : base(ptr)
        {
            _isOwner = isOwner;
        }


        protected void InitializePointer(IntPtr ptr, bool isOwner)
        {
            InitializePointer(ptr);
            _isOwner = isOwner;
        }
        
        protected void InitializePointer(IdentifiablePointer ptr, bool isOwner)
        {
            InitializePointer(ptr);
            _isOwner = isOwner;
        }

        internal override IntPtr Ptr
        {
            get
            {
                if (_isInvalidated)
                {
                    throw new Exception("Pointer was used after invalidate");
                }
                return base.Ptr;
            }
        }

        private IntPtr TakeOwnership()
        {
            if (!_isOwner)
            {
                throw new Exception("Tried to take ownership of a non-owned object");
            }
            _isOwner = false;
            return Ptr;
        }
        
        internal IntPtr TakeOwnershipAndInvalidate()
        {
            var ptr = TakeOwnership();
            Invalidate();
            return ptr;
        }

        internal void Invalidate()
        {
            _isInvalidated = true;
            CacheHandler.RemoveCache(Identifier);
            InvalidateChildren();
        }

        public virtual void InvalidateChildren(){}
        
        public override void Dispose()
        {
            if (_isDisposed)
                return;
            if (_isOwner)
            {
                InvalidateChildren();
                if (!_isInvalidated)
                    Destructor();
                _isOwner = false;
                CacheHandler.RemoveCache(Identifier);
            }
            _isDisposed = true;
            _isInvalidated = true;
            GC.SuppressFinalize(this);
        }

        public override bool Equals(object obj)
        {
            if (obj is ExternPointer<TCache> other)
            {
                return Identifier == other.Identifier;
            }
            return false;
        }

        protected bool Equals(ExternPointer<TCache> other)
        {
            if (Identifier != 0)
            {
                return Identifier == other.Identifier;
            }
            return Ptr == other.Ptr;
        }

        public override int GetHashCode()
        {
            if (Identifier != 0)
                return (int)Identifier;
            return (int)Ptr;
        }

        public static bool operator ==(ExternPointer<TCache>? left, ExternPointer<TCache>? right)
        {
            return Equals(left, right);
        }

        public static bool operator !=(ExternPointer<TCache>? left, ExternPointer<TCache>? right)
        {
            return !Equals(left, right);
        }
    }
}