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

public abstract class DraggablePanelController : PanelController<KeyValuePair<int, Item>>, DraggablePanelInterface
{
    [SerializeField] protected new List<ISlot> ChildBoxList = new List<ISlot>();

    protected static UIWarehouseManager _uiManager;

    protected new UIWarehouseManager UiManager
    {
        get
        {
            if (_uiManager == null) { return FetchUiManager() as UIWarehouseManager; }

            return null;
        }
    }


    public ISlot SetupDragAndDropToSlot(ISlot slot)
    {
        slot.OnBeginDragEvent += BeginDrag;
        slot.OnEndDragEvent += EndDrag;
        slot.OnDragEvent += Drag;
        slot.OnDropEvent += Drop;

        return slot;
    }

    public void BeginDrag(ItemSlot itemSlot)
    {
        if (itemSlot.Item != null)
        {
            DraggedSlotController.Instance.CreateDraggedSlot(itemSlot, _panelContent.transform.position);
        }
    }

    public void Drag(ItemSlot itemSlot)
    {
        DraggedSlotController.Instance.UpdatePosition(Input.mousePosition);
    }

    public virtual void EndDrag(ItemSlot itemSlot)
    {
        if (!DraggedSlotController.Instance.IsDragged()) // if there was nothing dragged - ignore event
            return;

        DraggedSlotController.Instance.RemoveDraggedSlot();

       
        // Rebuild/apply UiManager content (list of items) base on slots values after its updating
        for (int i = 0; i < ChildBoxList.Count; i++)
        {
            if (ChildBoxList[i].Item != null) 
            {
                UiManager.Add(new KeyValuePair<int, Item>(i, ChildBoxList[i].Item));
            }
            else 
            {
                UiManager.RemoveByPosition(i);
            }
        }
    }

    public virtual void Drop(ItemSlot dropItemSlot)
    {
        if (!DraggedSlotController.Instance.IsDragged()) // if there was nothing dragged - ignore event
            return;

        var draggedSlot = GetDraggedSlot();

        if (dropItemSlot.CanReceiveItem(draggedSlot.Item) && draggedSlot.CanReceiveItem(dropItemSlot.Item))
        {
            EquippableItem dragItem = draggedSlot.Item as EquippableItem;
            EquippableItem dropItem = dropItemSlot.Item as EquippableItem;

            // TODO insert child criterials

            //draggedSlot.Item = (EquippableItem)new Item("test", "test desc", 1, null, null);

            Item tmpDraggedItem = draggedSlot.Item == null ? null : new EquippableItem(draggedSlot.Item); // InventoryUIManager.Instance.DraggedSlot.Item;  // remember temporary currently dragged item
            UiManager.Add(new KeyValuePair<int, Item>(dropItemSlot.Number, tmpDraggedItem));

            // !!! remember item from dropped position to future operation !!!
            if (dropItem)
                DraggedSlotController.Instance.UpdateItem(new EquippableItem(dropItem));
            else
                DraggedSlotController.Instance.UpdateItem(null);
        }
    }

    public ISlot GetDraggedSlot()
    {
        return DraggedSlotController.Instance.DraggedSlot;
    }
}