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, IPointerEnterHandler, IPointerExitHandler
    {
        [Header("Slot Attributes")]
        public int width;
        public int height;
        public Image image;
        public bool useImageAsSlotHolder;
        public bool EquipSlot;
        public bool FitItemImageInSlotImage = false;
        [Header("Slot-to-Item Compatibility")]
        public bool IgnoreItemSize;
        public List<ItemTags> AllowedItemTags;
        public List<ItemTags> DisallowedItemTags;
        public List<SlotUI> HasSlotsBelongingToItem;

        // Hidden In Inspector
        [HideInInspector] public Stack<ItemUI> stackedItems = new Stack<ItemUI>(); // WARNING: Stack can give some odd troubles with the raycast, consider revision or consideration.
        [HideInInspector] public LimitStackSlot limitStackSlot;
        [HideInInspector] public LimitStackSlotManager limitStackSlotManager;
        [HideInInspector] public bool DroppedOnFrame;
        [HideInInspector] public List<SlotUI> LinkedSlots = new List<SlotUI>();
        [HideInInspector] public List<GroupSlotUI> groupSlots;
        [HideInInspector] public GridUI grid;
        [HideInInspector] public GridUI.Cell cell;
        [HideInInspector] public bool CellInUse;
        [HideInInspector] public float imageScale = 1f; // TODO: See if this is still necessary
        [HideInInspector] public bool StackItemsOnSlot; // TODO: Figure out if this should be kept hidden

        // private variables
        [SerializeField]
        private ItemUI itemUI
        {
            get
            {
                if (stackedItems.Count == 0)
                {
                    return null;
                }
                Debug.Log("Peek: " + stackedItems.Peek().gameObject.name);
                return stackedItems.Peek();
            }
        }
        private AppendUI appendUI;
        private LinkedSlotUI linkedSlotUI;
        private bool droppedStackOntoEmptySlot;
        private RenderItemUIProperty renderProp;
        private SlotUI BelongsToItemInSlot;

        // public variables
        public bool PointerIsHoveredOver { get { return InventorySystem.IsMouseOverUI(gameObject); } }

        public ItemUI GetItemUI()
        {
            return itemUI;
        }

        /*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 IsLinkedSlot()
        {
            return linkedSlotUI != null;
        }

        public bool DropOntoSlot(GameObject item, bool dropStack = true)
        {
            ItemUI itemDrop = item.GetComponent<ItemUI>();
            ItemTags itemTag = itemDrop.ItemTag;

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

            if (!allowed || disallowed)
            {
                return false;
            }

            if (itemDrop.Stackable && StackItemsOnSlot)
            {
                Debug.LogWarning("Item stacks are incompattible with slot stacking.");
                return false;
            }

            if (limitStackSlot != null && limitStackSlot.HasReachedLimit())
            {
                return false;
            }

            if (IsLinkedSlot())
            {
                /*GameObject newItemDrop = Instantiate(item);
                itemDrop = newItemDrop.GetComponent<ItemUI>();
                itemDrop.IsLinkedSlotClone = true;*/
            }

            List<Cell> occupiedCells = new List<Cell>();

            /// STACKING
            /// This section concerns item stacks, not slot stacking
            if (!itemDrop.IsLinkedSlotClone && ((HasStack() && itemUI != null /*&& itemUI.itemPrefab == itemDrop.itemPrefab*/) || !dropStack))
            {
                Debug.Log("Handling Stack");
                int maxStackDrop = 1;
                if (dropStack)
                {
                    maxStackDrop = itemDrop.Count;
                    if (maxStackDrop > itemUI.StackLimit - itemUI.Count)
                    {
                        maxStackDrop = itemDrop.Count - itemUI.Count;
                    }
                }

                if (itemUI != null)
                {
                    if (itemUI.AddToStack(maxStackDrop))
                    {
                        Debug.Log("Add to stack");
                        itemDrop.RemoveFromStack(maxStackDrop);

                        if (appendUI != null && appendUI.StackAppend)
                        {
                            appendUI.AppendUIToTransform(itemDrop);
                        }

                        return true;
                    }
                }
                else
                {
                    Debug.Log("Stack handling");
                    GameObject GO = Instantiate(item, transform, false);
                    GO.transform.localPosition = new Vector3(0, 0, 0);
                    ItemUI oldItemDrop = itemDrop;
                    itemDrop = GO.GetComponent<ItemUI>();
                    if (itemDrop.AddToStack(maxStackDrop))
                    {
                        oldItemDrop.RemoveFromStack(maxStackDrop);
                    }
                    else
                    {
                        return false;
                    }
                }
            }

            bool dropCheck = (grid != null && grid.CanMoveInCells(itemDrop, this, occupiedCells)) || 
                (grid == null && !cell.inUse && (IgnoreItemSize || (cell.slot.width >= itemDrop.SizeAfterOrientation().Width && !cell.inUse && cell.slot.height >= itemDrop.SizeAfterOrientation().Height)));

            Debug.Log("DropCheck" + (grid == null
                && !cell.inUse && (IgnoreItemSize || (cell.slot.width >= itemDrop.SizeAfterOrientation().Width && !cell.inUse && cell.slot.height >= itemDrop.SizeAfterOrientation().Height))));

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

            if (dropCheck)
            {
                if ((occupiedCells != null && occupiedCells.Count > 1) || StackItemsOnSlot)
                {
                    //Debug.Log("SlotUI: " + occupiedCells.Count);
                    itemDrop.SetSlots(occupiedCells);
                }
                else
                {
                    Debug.Log("In Use");
                    cell.inUse = true;
                    CellInUse = cell.inUse;
                }

                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);
                if(FitItemImageInSlotImage)
                    itemDrop.FitImageInSlot(image.GetComponent<RectTransform>().sizeDelta);
                itemDrop.SetSlot(this);

                stackedItems.Push(itemDrop);

                Debug.Log("SlotUI:Drop:" + itemUI + ", " + itemDrop);

                itemUI.DropItemOntoSlot();

                if (itemUI.Stackable)
                {
                    droppedStackOntoEmptySlot = true;
                }

                if (!IsLinkedSlot())
                {
                    foreach (SlotUI ls in LinkedSlots)
                    {
                        if (ls == this)
                        {
                            Debug.LogWarning("No self-referencing for this array ;)");
                            continue;
                        }
                        //ls.DropOntoSlot(item);
                    }
                }

                if (grid != null)
                {
                    grid.HideSlotsOfItem(itemDrop);
                }

                if (!useImageAsSlotHolder)
                {
                    HideImage();
                }

                foreach (GroupSlotUI groupSlot in groupSlots)
                {

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

                if (appendUI != null)
                {
                    Debug.Log("Test");
                    appendUI.AppendUIToTransform(itemUI);
                }
                if (limitStackSlotManager != null)
                {
                    limitStackSlotManager.SetStackSlotLimit(itemUI);
                }

                if (limitStackSlot != null)
                {
                    limitStackSlot.Increment();
                }

                if (BelongsToItemInSlot != null && BelongsToItemInSlot.GetItemUI() != null)
                {
                    BelongsToItemInSlot.GetItemUI().AddToContainedItems(itemUI);
                }

                if (HasSlotsBelongingToItem != null)
                {
                    foreach (ItemUI i in itemUI.ContainedItems)
                    {
                        foreach(SlotUI s in HasSlotsBelongingToItem)
                        {
                            if (s.AllowedItemTags.Contains(i.ItemTag))
                            {
                                s.AddContainedItemToSlot(i);
                                break;
                            }
                        }
                    }
                }

                SetRenderItemUIPropertyValue();

                return true;
            }
            else if (itemDrop.previousSlot != this)
            {
                // TODO: See why this is outputting at beginning, probably from test objects in Loot
                //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>();

            // Check again
            if (grid == null)
            {
                cell = new Cell(0, 0, this, true);
            }

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

            if (TryGetComponent(out LinkedSlotUI lui))
            {
                linkedSlotUI = lui;
            }

            if (TryGetComponent(out RenderItemUIProperty rp))
            {
                renderProp = GetComponent<RenderItemUIProperty>();
                SetRenderItemUIPropertyValue();
            }

            if (TryGetComponent(out LimitStackSlot lss))
            {
                limitStackSlot = lss;
            }

            if (TryGetComponent(out LimitStackSlotManager lssm))
            {
                limitStackSlotManager = lssm;
            }
        }
        private void SetRenderItemUIPropertyValue()
        {
            if (renderProp != null)
            {
                renderProp.value = stackedItems.Count.ToString();
            }
        }

        public void AddContainedItemToSlot(ItemUI item)
        {
            HideImage();

            if (limitStackSlot != null)
            {
                limitStackSlot.Increment();
            }

            stackedItems.Push(item);
            item.transform.SetParent(transform, false);
            item.gameObject.SetActive(true);
            /*
                        foreach(ItemUI item in )
                        {
                            itemUI.transform.SetParent(itemUI.ParentContainer.transform, false);
                            itemUI.gameObject.SetActive(false);
                            stackedItems.Pop();
                        }*/
            SetRenderItemUIPropertyValue();
        }
        public void RemoveContainedItemsFromSlot()
        {
            ShowImage();

            while (stackedItems.Count > 0)
            {

                if (limitStackSlot != null)
                {
                    limitStackSlot.Decrement();
                }

                if (itemUI.ParentContainer == null)
                {
                    Debug.LogWarning("This should not be null");
                }
                if (itemUI.ParentContainer != null)
                    itemUI.transform.SetParent(itemUI.ParentContainer.transform, false);
                itemUI.gameObject.SetActive(false);
                
                ItemUI oldItem = stackedItems.Pop();
                oldItem.SetSlot(this);
            }

            SetRenderItemUIPropertyValue();
        }

        public void RemoveDragDropItem()
        {

            if (BelongsToItemInSlot != null && BelongsToItemInSlot.GetItemUI() != null)
            {
                BelongsToItemInSlot.GetItemUI().RemoveFromContainedItems(itemUI);
            }

            if (HasSlotsBelongingToItem != null)
            {
                foreach (SlotUI s in HasSlotsBelongingToItem)
                {
                    s.RemoveContainedItemsFromSlot();
                }
            }

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

            if (limitStackSlot != null)
            {
                limitStackSlot.Decrement();
            }

            if (limitStackSlotManager != null)
            {
                limitStackSlotManager.UnsetStackSlotLimit();
            }

            foreach (SlotUI linked in LinkedSlots)
            {
                linked.RemoveDragDropItem();
            }

            stackedItems.Pop();

            foreach (GroupSlotUI groupSlot in groupSlots)
            {
                groupSlot.OnItemRemoved();
            }

            UnsetCell();

            SetRenderItemUIPropertyValue();
        }

        public void UnsetCell()
        {
            if(itemUI == null)
            {
                ShowImage();

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

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

        public bool HasStack()
        {
            return itemUI != null && itemUI.Stackable;
        }
        public bool IsStacking()
        {
            return StackItemsOnSlot;
        }

        // Start is called before the first frame update
        void Start()
        {
            if (HasSlotsBelongingToItem.Count > 0)
            {
                foreach (SlotUI s in HasSlotsBelongingToItem)
                {
                    s.BelongsToItemInSlot = this;
                }
            }
            else
            {
                HasSlotsBelongingToItem = null;
            }
        }

        // Update is called once per frame
        void Update()
        {
            if (InventorySystem.instance.PressedDropItemKey(false) || InventorySystem.instance.PressedEquipItemKey(false))
            {
                return;
            }

            if (PointerIsHoveredOver)
            {
                ItemUI droppedItem = InventorySystem.instance.DraggedItem;
                if (droppedItem != null && !droppedItem.PickedUpOnFrame)
                {
                    if (Input.GetMouseButtonDown(0))
                    {
                        DroppedOnFrame = true;
                        bool callback = DropOntoSlot(droppedItem.gameObject, true);

                        if (callback && droppedItem.Stackable)
                        {
                            if (droppedItem.Count <= 0)
                            {
                                Destroy(droppedItem.gameObject);
                            }
                            else if (itemUI.Count < droppedItem.Count && !droppedStackOntoEmptySlot)
                            {
                                InventorySystem.instance.DraggedItem = droppedItem;
                                droppedStackOntoEmptySlot = false;
                            }
                        }
                    }
                    else if (Input.GetMouseButtonDown(1) && droppedItem.Stackable)
                    {
                        DroppedOnFrame = true;
                        Debug.Log("Right Click");
                        if (DropOntoSlot(droppedItem.gameObject, false))
                        {
                            if (droppedItem.Count <= 0)
                            {
                                Destroy(droppedItem.gameObject);
                            }
                            else
                            {
                                InventorySystem.instance.DraggedItem = droppedItem;
                                droppedItem.transform.SetParent(InventorySystem.instance.inventoryUI.transform);
                                droppedStackOntoEmptySlot = false;
                            }
                        }
                    }
                }
            }

            // TODO: make sure the key combo works as expected
            if (Input.GetMouseButtonUp(0))
            {
                DroppedOnFrame = false;
            }
        }

        public void SetCell(Cell cell)
        {
            this.cell = cell;
        }

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

        public void OnPointerClick(PointerEventData eventData)
        {
        }

        public void OnPointerDown(PointerEventData eventData)
        {
            if(InventorySystem.instance.PressedDropItemKey(false) || InventorySystem.instance.PressedEquipItemKey(false))
            {
                return;
            }

            ItemUI droppedItem = InventorySystem.instance.DraggedItem;
            if (droppedItem != null && !droppedItem.PickedUpOnFrame)
            {
                DropOntoSlot(droppedItem.gameObject);
            }
        }
        public void OnPointerExit(PointerEventData eventData)
        {
            //PointerIsHoveredOver = false;
        }

        public void OnPointerEnter(PointerEventData eventData)
        {
            //PointerIsHoveredOver = true;
        }
    }
}