using UnityEngine;
using System.Collections.Generic;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class Inventory : MonoBehaviour
{
    [Header("10 Inventory Slots")]
    public Item[] slots = new Item[10];

    public int currentSlot = 0;

    [SerializeField] private Transform handSlot;
    private GameObject currentSpawnedItem;

    void Awake()
    {
        Debug.Log("Inventory initialized on: " + gameObject.name);

        var existing = FindObjectsOfType<Inventory>();
        if (existing.Length > 1)
        {
            Debug.LogWarning("Multiple Inventory instances found, destroying duplicate.");
            Destroy(gameObject);
            return;
        }

        DontDestroyOnLoad(gameObject);
    }



    void Update()
    {        // handle selecting slots with number keys using new unity input system
        for (int i = 0; i < 10; i++)
        {
            if (Input.GetKeyDown( "" + i ) )
            {
                // convert to int
                currentSlot = int.Parse("" + i);
                // map 1 to 0, 2 to 1, etc till 9 then 0 to 9
                currentSlot = (currentSlot - 1 + slots.Length) % slots.Length;
                EquipSlot(currentSlot);
                // Debug.Log("Selected slot: " + currentSlot);
                var ui = FindObjectOfType<InventoryUI>();
                if (ui != null)
                {
                    ui.RefreshUI();
                }
            }
       
        }
        float scroll = Input.GetAxis("Mouse ScrollWheel");
        if (scroll > 0f)
        {
            SelectPreviousSlot();
        }
        else if (scroll < 0f)
        {
            SelectNextSlot();
        }

    }

    public void AddItem(Item newItem)
    {
        for (int i = 0; i < slots.Length; i++)
        {
            if (slots[i] == null)
            {
                slots[i] = newItem;
                break;
            }
        }
    }

    public bool HasItem(string itemName)
    {
        foreach (var item in slots)
        {
            if (item != null && item.itemName == itemName)
            {
                return true;
            }
        }
        return false;
    }


    private void SelectNextSlot()
    {
        currentSlot = (currentSlot + 1) % slots.Length;
        EquipSlot(currentSlot);

        var ui = FindObjectOfType<InventoryUI>();
        if (ui != null)
        {
            ui.RefreshUI();
        }
    }

    private void SelectPreviousSlot()
    {
        currentSlot = (currentSlot - 1 + slots.Length) % slots.Length;
        EquipSlot(currentSlot);

        var ui = FindObjectOfType<InventoryUI>();
        if (ui != null)
        {
            ui.RefreshUI();
        }
    }

    public void EquipSlot(int slotIndex)
    {
        if (currentSpawnedItem != null)
        {
            Destroy(currentSpawnedItem);
        }

        Item itemInSlot = slots[slotIndex];
        GameObject prefab = itemInSlot != null ? itemInSlot.GetPrefab() : null;

        if (prefab != null && handSlot != null)
        {
            currentSpawnedItem = Instantiate(prefab, handSlot.position, handSlot.rotation, handSlot);
            currentSpawnedItem.transform.localPosition = Vector3.zero;
            currentSpawnedItem.transform.localRotation = Quaternion.identity;
        }
        else
        {
            currentSpawnedItem = null;
        }
    }
}