namespace ProjectAirplaneWithRadar.CollectionGenericObjects
{
    /// <summary>
    /// Параметризованный набор объектов
    /// </summary>
    /// <typeparam name="T">Параметр: ограничение - ссылочный тип</typeparam>
    public class MassiveGenericObjects<T> : ICollectionGenericObjects<T>
        where T : class
    {
        /// <summary>
        /// Массив объектов, которые храним
        /// </summary>
        private T?[] _collection;

        public int Count => _collection.Length;

        public int MaxCount
        {
            get
            {
                return _collection.Length;
            }

            set
            {
                if (value > 0)
                {
                    if (_collection.Length > 0)
                    {
                        Array.Resize(ref _collection, value);
                    }
                    else
                    {
                        _collection = new T?[value];
                    }
                }
            }            
        }

        public CollectionType GetCollectionType => CollectionType.Massive;

        /// <summary>
        /// Конструктор
        /// </summary>
        public MassiveGenericObjects()
        {
            _collection = Array.Empty<T?>();
        }

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

        public int Insert(T obj)
        {
            for (int i = 0; i < Count; i++)
            {
                if (_collection[i] == null)
                {
                    _collection[i] = obj;
                    return i;
                }
            }
            return -1;
        }

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

            if (_collection[position] == null)
            {
                _collection[position] = obj;
                return position;
            }

            int temp = position + 1;
            while (temp < Count)
            {
                if (_collection[temp] == null)
                {
                    _collection[temp] = obj;
                    return temp;
                }
                temp++;
            }

            temp = position - 1;
            while (temp > 0)
            {
                if (_collection[temp] == null)
                {
                    _collection[temp] = obj;
                    return temp;
                }
                temp--;
            }

            return -1;
        }

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

            if (_collection[position] == null)
            {
                return null;
            }

            T? temp = _collection[position];
            _collection[position] = null;
            return temp;
        }

        public IEnumerable<T?> GetItems()
        {
            for (int i = 0; i < _collection.Length; ++i)
            {
                yield return _collection[i];
            }
        }
    }
}