using System.Collections.Generic;
using System.Linq;
using UnityEngine;

internal class Slot
{
    public GameObject slot;
    public Item item;
    public int amount;
    public int size;
}

public class Inventory : MonoBehaviour
{
    #region Data
    private GameObject _slotHolder;

    private int _slotAmount;
    private GameObject[] _slots;

    private bool _visible = false;

    private readonly List<Slot> _slotList = new List<Slot>();

    public GameObject inventory;
    #endregion

    #region Events
    private void Awake()
    {
        if (inventory == null)
        {
            Debug.LogError("No Inventory object assigned!");
            return;
        }

        _slotHolder = inventory.transform.Find("SlotHolder").gameObject;
        if (_slotHolder == null)
        {
            Debug.LogError("Inventory object does not contain a SlotHolder object");
            return;
        }

        _GrabInventorySlots();
    }
    #endregion

    #region API
    public bool IsVisible()
    {
        return _visible;
    }

    public void ToggleVisibility()
    {
        _visible = !_visible;
        inventory.SetActive(_visible);
    }

    public void AddItem(Item aItem, int aAmount = 1)
    {
        // Check if the item is stackable and the inventory contains this item already
        bool contains = _slotList.Any(x => x.item.id == aItem.id);
        if (contains)
        {
            var slots = _slotList.Where(x => x.item.id == aItem.id).ToArray();
            foreach (var slot in slots)
            {
                if ((slot.amount + aAmount) < slot.size)
                {
                    // Enough space, insert directly
                    slot.amount += aAmount;
                    return;
                }

                if ((slot.amount + aAmount) > slot.size)
                {
                    // Check if enough empty slots are free for remainder
                    int remainder = (slot.amount + aAmount) - slot.size;
                    if (remainder > slot.size)
                    {
                        // Need more than one slot
                    }
                    else
                    {
                        // Remainded should fit into one slot

                    }
                }
            }
        }
    }

    private Slot _GetFreeSlot()
    {
        foreach (Slot slot in _slotList)
        {
            if (slot.amount == 0)
            {
                return slot;
            }
        }

        return null;
    }

    private Slot _GetFreeSlotContainingItem(Item aItem)
    {
        foreach (Slot slot in _slotList)
        {
            if (slot.item.id == aItem.id)
            {
                if (slot.amount < slot.size)
                {
                    return slot;
                }
            }
        }

        return null;
    }

    private void _GrabInventorySlots()
    {
        _slotAmount = _slotHolder.transform.childCount;
        _slots = new GameObject[_slotAmount];

        for (int i = 0; i < _slotAmount; i++)
        {
            _slots[i] = _slotHolder.transform.GetChild(i).gameObject;
            Slot item = new Slot
            {
                slot = _slots[i],
                item = null,
                amount = 0,
                size = _slots[i].GetComponent<InventorySlot>().slotSize
            };

            _slotList.Add(item);
        }

        Debug.Log("Found " + _slotAmount + " inventory slots");
    }
    #endregion
}