using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System;
using static SimpleInventorySystem.GridUI;

namespace SimpleInventorySystem
{
    public class SlotUI : MonoBehaviour, IDropHandler
    {
        public int width;
        public int height;
        public bool useImageAsSlotHolder;
        public Image image;
        public GridUI grid;
        public GridUI.Cell cell;
        public ItemUI itemUI;
        [HideInInspector] public GroupSlotUI groupSlot;
        private AppendUI appendUI;

        internal ItemUI GetItemUI()
        {
            return itemUI;
        }

        public float imageScale = 1f;
        public List<ItemTags> AllowedItemTags;

        public void OnDrop(PointerEventData eventData)
        {
            //
            //("OnDrop");
            if (eventData.pointerDrag != null && AllowedDraggable(eventData.pointerDrag))
            {
                DropOntoSlot(eventData.pointerDrag);
            }
        }

        public bool AllowedDraggable(GameObject gameObject)
        {
            return gameObject.GetComponent<ItemUI>() != null;
        }

        public bool DropOntoSlot(GameObject item)
        {
            ItemUI itemDrop = item.GetComponent<ItemUI>();
            List<Cell> occupiedCells = new List<Cell>();
            
            bool dropCheck = grid.CanMoveInCells(itemDrop, this, occupiedCells);

            ItemTags itemTag = itemDrop.ItemTag;

            bool allowed = AllowedItemTags == null || AllowedItemTags.Count == 0 || AllowedItemTags.Contains(ItemTags.Any) || AllowedItemTags.Contains(itemTag);

            Debug.Log("GridUI: DropOntoSlot(): " + gameObject.name + ": " + "dropCheck: " + dropCheck);
            Debug.Log("GridUI: DropOntoSlot(): " + gameObject.name + ": " + "allowed: " + allowed);

            if (dropCheck && allowed)
            {
                Debug.Log("SlotUI: " + occupiedCells.Count);
                itemDrop.SetSlots(occupiedCells);

                Transform parent = transform;
                if (useImageAsSlotHolder && image != null)
                {
                    parent = image.gameObject.transform;
                }
                item.GetComponent<Transform>().SetParent(parent);
                item.GetComponent<RectTransform>().anchoredPosition = GetComponent<RectTransform>().anchoredPosition;
                //item.GetComponent<RectTransform>().pivot = new Vector2(0, 1);
                itemDrop.SetImageScale(imageScale);
                itemDrop.SetSlot(this);
                this.itemUI = itemDrop;
                grid.HideSlotsOfItem(itemDrop);
                HideImage();

                if(groupSlot != null)
                {
                    groupSlot.OnItemDropped();
                }
                if (appendUI != null)
                {
                    appendUI.AppendUIToTransform();
                }
                return true;
            }
            else if (itemDrop.previousSlot != this)
            {
                Debug.LogWarning("SlotUI: Failed to drop. dropCheck: " + dropCheck + ", allowed: " + allowed);
                // return item to previous parent
                itemDrop.ReturnToSlot();
                return false;
                //Debug.Log("Resetting parent");
            }
            else
            {
                Debug.LogWarning("SlotUI: Failed to drop. dropCheck: " + dropCheck + ", allowed: " + allowed);
                Debug.LogError("SlotUI: Something wrong has happened.");
                return false;
            }
        }

        void Awake()
        {
            if(image == null)
            {
                Image[] images = GetComponentsInChildren<Image>(); // This will retrieve the first instance of an image in the FIRST child with the component
                //Debug.Log(images.Length);
                if(images.Length > 0)
                {
                    if(images[0].transform == transform)
                    {
                        if(images.Length > 1)
                        {
                            image = images[1];
                        }
                    }
                    else
                    {
                        image = images[0];
                    }
                }
            }

            if(grid == null)
                grid = GetComponentInParent<GridUI>();

            if(TryGetComponent(out AppendUI aui))
            {
                appendUI = aui;
            }
        }

        public void RemoveDragDropItem()
        {
            ShowImage();

            if (cell != null)
            {
                cell.inUse = false;
            }

            if(groupSlot != null)
            {
                groupSlot.OnItemRemoved();
            }

            if (appendUI != null)
            {
                appendUI.RemoveUIFromTransform();
            }
        }

        public bool IsSingleCellSlot()
        {
            return width == 1 && height == 1;
        }

        // Start is called before the first frame update
        void Start()
        {

        }

        // Update is called once per frame
        void Update()
        {

        }

        internal void HideImage()
        {
            if(image != null)
            {
                image.color = new Color(image.color.r, image.color.g, image.color.b, 0);
            }
        }
        internal void ShowImage()
        {
            if (image != null)
            {
                image.color = new Color(image.color.r, image.color.g, image.color.b, 1);
            }
        }
    }
}