using UnityEngine;

namespace Entity
{
    /// <summary>
    /// 表示背包中的一个槽位，存储特定类型的物品及其数量。
    /// </summary>
    public class InventorySlot
    {
        public Item.ItemResource Item { get; private set; } // 槽位中的物品资源
        public int Quantity { get; private set; } // 槽位中物品的数量

        /// <summary>
        /// 创建一个新的背包槽位。
        /// </summary>
        /// <param name="item">槽位中的物品资源。</param>
        /// <param name="quantity">初始数量。</param>
        public InventorySlot(Item.ItemResource item, int quantity)
        {
            if (item == null)
            {
                Debug.LogError("InventorySlot cannot be initialized with a null ItemResource.");
                return;
            }

            Item = item;
            Quantity = Mathf.Max(0, quantity); // 确保数量不为负
            // 确保初始数量不超过最大堆叠
            if (Quantity > Item.MaxStack)
            {
                Debug.LogWarning(
                    $"Initial quantity {Quantity} for {Item.Name} exceeds MaxStack {Item.MaxStack}. Clamping to MaxStack.");
                Quantity = Item.MaxStack;
            }
        }

        /// <summary>
        /// 向槽位中添加指定数量的物品。
        /// </summary>
        /// <param name="amount">要添加的数量。</param>
        /// <returns>实际添加的数量。</returns>
        public int AddQuantity(int amount)
        {
            if (Item == null || amount <= 0) return 0;

            var spaceLeft = Item.MaxStack - Quantity;
            if (spaceLeft <= 0) return 0; // 槽位已满

            var added = Mathf.Min(amount, spaceLeft);
            Quantity += added;
            return added;
        }

        /// <summary>
        /// 从槽位中移除指定数量的物品。
        /// </summary>
        /// <param name="amount">要移除的数量。</param>
        /// <returns>实际移除的数量。</returns>
        public int RemoveQuantity(int amount)
        {
            if (Item == null || amount <= 0) return 0;

            var removed = Mathf.Min(amount, Quantity);
            Quantity -= removed;
            return removed;
        }

        /// <summary>
        /// 获取槽位是否为空。
        /// </summary>
        public bool IsEmpty => Quantity <= 0;

        /// <summary>
        /// 获取槽位是否已满。
        /// </summary>
        public bool IsFull => Item != null && Quantity >= Item.MaxStack;
    }
}