using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.Collections
{
    /// <summary>
    /// Part of a collection. This contains a direct reference to origin collection,
    /// so all change to origin collection will be reflected in this object.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class ReferencedSlicedCollection<T> : ICollection<T>
    {
        private ICollection<T> _collection;
        private int _begin;
        private int _length;

        internal ReferencedSlicedCollection()
        {
            _collection = Array.Empty<T>();
            _begin = 0;
            _length = 0;
        }

        public ReferencedSlicedCollection(ICollection<T> collection, int begin, int length)
        {
            ArgumentNullException.ThrowIfNull(collection);
            ArgumentOutOfRangeException.ThrowIfLessThan(begin, 0);
            ArgumentOutOfRangeException.ThrowIfLessThan(length, 0);
            ArgumentOutOfRangeException.ThrowIfLessThan(begin + length, collection.Count);
            _collection = collection;
            _begin = begin;
            _length = length;
        }   

        public int Count => _length;

        public bool IsReadOnly => true;

        void ICollection<T>.Add(T item)
        {
            throw new NotSupportedException();
        }

        public void Clear()
        {
            throw new NotImplementedException();
        }

        public bool Contains(T item)
        {
            throw new NotImplementedException();
        }

        public void CopyTo(T[] array, int arrayIndex)
        {
            throw new NotImplementedException();
        }

        public IEnumerator<T> GetEnumerator()
        {
            throw new NotImplementedException();
        }

        public bool Remove(T item)
        {
            throw new NotImplementedException();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            throw new NotImplementedException();
        }
    }
}