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

namespace Sailboat
{
    class SetBoatsGeneric<T> where T : class
    {
        private readonly List<T> _places;

        public int Count => _places.Count;

        private readonly int _maxCount;
        private int BusyPlaces = 0;

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

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

        public int Insert(T boat, int position)
        {
            if (position < 0 || position >= _maxCount || BusyPlaces == _maxCount)
            {
                return -1;
            }
            BusyPlaces++;
            _places.Insert(position, boat);
            return position;
        }

        public T Remove(int position)
        {
            if (position < 0 || position >= _maxCount)
            {
                return null;
            }
            BusyPlaces--;
            T boat = _places[position];
            _places.RemoveAt(position);
            return boat;
        }

        public T this[int position]
        {
            get
            {
                if (position < 0 || position >= _maxCount) return null;
                return _places[position];
            }
            set
            {
                Insert(value, position);
            }

        }

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