using System;
using System.Collections.Generic;
using System.Text;
using UnityEngine;

[Serializable]
public class InventorySlot
{
    public ItemData item;
    public int amount;

    public InventorySlot(ItemData item, int amount)
    {
        this.item = item;
        this.amount = Mathf.Max(0, amount);
    }
}

public class Inventory : MonoBehaviour
{
    [SerializeField] private List<InventorySlot> slots = new List<InventorySlot>();

    public event Action OnInventoryChanged;

    public IReadOnlyList<InventorySlot> Slots => slots;

    public bool HasItem(ItemData item, int amount)
    {
        if (item == null)
            return true;

        return GetAmount(item) >= Mathf.Max(1, amount);
    }

    public int GetAmount(ItemData item)
    {
        if (item == null)
            return 0;

        InventorySlot slot = FindSlot(item);
        return slot != null ? Mathf.Max(0, slot.amount) : 0;
    }

    public bool AddItem(ItemData item, int amount)
    {
        if (item == null || amount <= 0)
            return false;

        InventorySlot slot = FindSlot(item);
        int maxStack = Mathf.Max(1, item.maxStack);

        if (slot == null)
        {
            slots.Add(new InventorySlot(item, Mathf.Min(amount, maxStack)));
            RaiseChanged();
            return true;
        }

        int newAmount = Mathf.Clamp(slot.amount + amount, 0, maxStack);
        if (newAmount == slot.amount)
            return false;

        slot.amount = newAmount;
        RaiseChanged();
        return true;
    }

    public bool RemoveItem(ItemData item, int amount)
    {
        if (item == null || amount <= 0)
            return false;

        InventorySlot slot = FindSlot(item);
        if (slot == null || slot.amount < amount)
            return false;

        slot.amount -= amount;
        if (slot.amount <= 0)
            slots.Remove(slot);

        RaiseChanged();
        return true;
    }

    public string GetDebugText()
    {
        if (slots.Count == 0)
            return "Инвентарь: пусто";

        StringBuilder builder = new StringBuilder("Инвентарь: ");
        bool first = true;

        foreach (InventorySlot slot in slots)
        {
            if (slot == null || slot.item == null || slot.amount <= 0)
                continue;

            if (!first)
                builder.Append(", ");

            builder.Append(slot.item.itemName);
            builder.Append(" x");
            builder.Append(slot.amount);
            first = false;
        }

        return first ? "Инвентарь: пусто" : builder.ToString();
    }

    private InventorySlot FindSlot(ItemData item)
    {
        return slots.Find(slot => slot != null && slot.item == item);
    }

    private void RaiseChanged()
    {
        OnInventoryChanged?.Invoke();
    }
}