#nullable enable
using System;
using Godot;
using System.Collections.Generic;

namespace Babushka.scripts.CSharp.Common.Inventory;

public partial class InventoryInstance : Node
{
    private List<InventorySlot> _slots = new();
    public IReadOnlyList<InventorySlot> Slots => _slots;

    [Signal]
    public delegate void SlotAmountChangedEventHandler();
    [Signal]
    public delegate void InventoryContentsChangedEventHandler();

    [Export]
    public int SlotAmount
    {
        get => _slots.Count;
        set
        {
            if (value < _slots.Count)
            {
                _slots.RemoveRange(value, _slots.Count - value);
            }
            else if (value > _slots.Count)
            {
                for (var i = _slots.Count; i < value; i++)
                {
                    _slots.Add(new InventorySlot());
                }
            }
            EmitSignal(SignalName.SlotAmountChanged);
        }
    }
    
    public InventoryActionResult AddItem(ItemInstance newItem, int inventorySlot = -1)
    {
        if (inventorySlot < 0)
        {
            inventorySlot = _slots.FindIndex(slot => slot.IsEmpty());
        }
        
        if (inventorySlot < 0 || !_slots[inventorySlot].IsEmpty())
        {
            return InventoryActionResult.DestinationFull;
        }
        
        if (inventorySlot >= _slots.Count)
        {
            return InventoryActionResult.DestinationDoesNotExists;
        }
        
        _slots[inventorySlot].itemInstance = newItem;
        EmitSignal(SignalName.InventoryContentsChanged);
        return InventoryActionResult.Success;
    }
    
    public InventoryActionResult RemoveItem(int inventorySlot, out ItemInstance? itemInstance )
    {
        if (inventorySlot < 0 || inventorySlot >= _slots.Count)
        {
            itemInstance = null;
            return InventoryActionResult.SourceDoesNotExists;
        }
        
        if (_slots[inventorySlot].IsEmpty())
        {
            itemInstance = null;
            return InventoryActionResult.SourceIsEmpty;
        }
        
        itemInstance = _slots[inventorySlot].itemInstance;
        _slots[inventorySlot].itemInstance = null;
        EmitSignal(SignalName.InventoryContentsChanged);
        return InventoryActionResult.Success;
    }
    
    public InventoryActionResult RemoveItem(int inventorySlot)
    {
        return RemoveItem(inventorySlot, out _);
    }
}