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

namespace Artilleries
{
    internal class SetArtilleriesGeneric<T>
        where T : class
    {
        private readonly List<T> _places;
        public int Count => _places.Count;
        private readonly int _maxCount;

        public SetArtilleriesGeneric(int count)
        {
            _maxCount = count;
            _places = new List<T>();
        }

        public int Insert(T artillery)
        {
            return Insert(artillery, 0);
        }

        public int Insert(T artillery, int position)
        {
            if (position < 0 || position >= Count || Count == _maxCount)
            {
                return -1;
            }

            _places.Insert(position, artillery);

            return position;
        }

        public T Remove(int position)
        {
            if (position < 0 || position >= Count)
            {
                return null;
            }

            var result = _places[position];

            _places.RemoveAt(position);
            return result;
        }

        public T this[int position]
        {
            get 
            {
                if (position < 0 || position >= Count)
                {
                    return null;
                }

                return _places[position];
            }
            set
            {
                if (position >= 0 && position < Count)
                {
                    Insert(value, position);
                }
            }
        }

        public IEnumerable<T> GetArtilleries()
        {
            foreach (var artillery in _places)
            {
                if (artillery != null)
                {
                    yield return artillery;
                }
                else
                {
                    yield break;
                }
            }
        }
    }
}