cirnogodot/Scripts/UI/ItemsMenu.cs

using Godot;
using System;
using Cirno.Scripts;
using Godot.Collections;

public partial class ItemsMenu : ItemList
{
    private InventoryManager _inventoryManager;
    private Dictionary<long, string> _itemsDic = new();
    
    public override void _Ready()
    {
        CallDeferred(MethodName.DeferredInitialize);
        this.Hide();
    }

    public override void _Process(double delta)
    {
        if (Input.IsActionJustPressed("inventory"))
        {
            if (!Visible)
            {
                ShowInventory();
            }
            else
            {
                HideInventory();
            }
        }
    }

    private void DeferredInitialize()
    {
        _inventoryManager = GameManager.Instance.GetInventoryManager();
        
        ItemSelected += OnItemSelected;
        Clear();
        
        ItemActivated += OnItemSelected;
    }

    private void OnItemSelected(long index)
    {
        var item = _itemsDic[index];
        GD.Print("Item: " + item);

        _inventoryManager.UseItem(item);
        
        HideInventory();
    }

    public void HideInventory()
    {
        this.Hide();
        Clear();
        _itemsDic.Clear();
    }

    public void ShowInventory()
    {
        this.Show();
        foreach (var item in _inventoryManager.Items)
        {
            if (item.Count <= 0) continue;
            
            var index = this.AddItem($"{item.Item.ItemName} x{item.Count}", item.Item.InventorySprite,
                item.Item.Selectable);
            
            this.SetItemTooltip(index, item.Item.ItemDescription);
            
            _itemsDic.Add(index, item.Item.ItemKey);
            
        }
    }
}