namespace BeiBao
{
    /// <summary>
    /// 定义物品类
    /// 每个物品有名称、ID、最大堆叠数量和当前数量。
    /// </summary>
    public class Item
    {
        private string _itemName;
        private int _itemID;
        private int _maxStack;
        private int _quantity;

        /// <summary>
        /// 名字
        /// </summary>
        public string ItemName => _itemName;

        /// <summary>
        /// ID
        /// </summary>
        public int ItemID => _itemID;

        /// <summary>
        /// 最大堆叠数量
        /// </summary>
        public int MaxStack => _maxStack;

        /// <summary>
        /// 当前数量
        /// </summary>
        public int Quantity => _quantity;

        public Item(string itemName, int itemID, int maxStack)
        {
            _itemName = itemName;
            _itemID = itemID;
            _maxStack = maxStack;
            _quantity = 0;
        }

        // 尝试增加数量，返回剩余未能堆叠的数量
        public int AddQuantity(int quantity)
        {
            int remaining = quantity;
            if (Quantity + remaining > MaxStack)
            {
                remaining = (Quantity + quantity) - MaxStack;
                _quantity = MaxStack;
            }
            else
            {
                _quantity += remaining;
                remaining = 0;
            }

            return remaining;
        }

        /// <summary>
        /// 仅作为检查，并不发生实际的数据改变
        /// </summary>
        /// <param name="quantity"></param>
        /// <returns></returns>
        public int CheckAddQuantity(int quantity)
        {
            int remaining = quantity;
            return Quantity + remaining > MaxStack ? remaining = (Quantity + quantity) - MaxStack : 0;
        }

        // 尝试移除数量，返回是否成功
        public bool RemoveQuantity(int quantity)
        {
            if (Quantity >= quantity)
            {
                _quantity -= quantity;
                return true;
            }

            return false;
        }

        /// <summary>
        /// 仅作为检查，并不发生实际的数据改变
        /// </summary>
        /// <param name="quantity"></param>
        /// <returns></returns>
        public int CheckRemoveQuantity(int quantity)
        {
            int tmp = quantity - _quantity;
            return tmp <= 0 ? 0 : tmp;
        }
    }
}