using GeometryTD.CustomEvent;
using GeometryTD.Definition;
using UnityEngine;
using UnityEngine.EventSystems;

namespace GeometryTD.UI
{
    public class CombineArea : MonoBehaviour, IDropHandler
    {
        [SerializeField] private CombineSlotItem[] _slots;

        public void OnInit(CombineAreaContext context)
        {
            if (_slots == null)
            {
                return;
            }

            for (int i = 0; i < _slots.Length; i++)
            {
                if (_slots[i] != null)
                {
                    _slots[i].OnInit(i);
                }
            }
        }

        public void OnReset()
        {
            if (_slots == null)
            {
                return;
            }

            foreach (var slot in _slots)
            {
                if (slot != null)
                {
                    slot.OnReset();
                }
            }
        }

        public void OnCombineClick()
        {
            if (!TryGetBoundItemId(TowerCompSlotType.Muzzle, out long muzzleItemId) ||
                !TryGetBoundItemId(TowerCompSlotType.Bearing, out long bearingItemId) ||
                !TryGetBoundItemId(TowerCompSlotType.Base, out long baseItemId))
            {
                return;
            }

            GameEntry.Event.Fire(this, RepoCombineRequestedEventArgs.Create(muzzleItemId, bearingItemId, baseItemId));
        }

        public bool TryAssignItem(RepoItemContext itemContext)
        {
            if (itemContext == null || itemContext.ComponentSlotType == TowerCompSlotType.None)
            {
                return false;
            }

            CombineSlotItem targetSlot = FindSlot(itemContext.ComponentSlotType);
            if (targetSlot == null || targetSlot.HasItem)
            {
                return false;
            }

            targetSlot.BindItem(itemContext);
            return true;
        }

        public bool TryClearSlot(int slotIndex, out long removedItemId)
        {
            removedItemId = 0;
            if (_slots == null || slotIndex < 0 || slotIndex >= _slots.Length)
            {
                return false;
            }

            CombineSlotItem slot = _slots[slotIndex];
            if (slot == null || !slot.HasItem)
            {
                return false;
            }

            removedItemId = slot.BoundItemId;
            slot.ClearSlot();
            return true;
        }

        public void OnDrop(PointerEventData eventData)
        {
            if (eventData == null)
            {
                return;
            }

            GameObject pointerDrag = eventData.pointerDrag;
            if (pointerDrag == null)
            {
                return;
            }

            IRepoDragItemView dragItem = pointerDrag.GetComponent<IRepoDragItemView>() ??
                                         pointerDrag.GetComponentInParent<IRepoDragItemView>();
            if (dragItem == null)
            {
                return;
            }

            bool assigned = TryAssignItem(dragItem.ComponentContext);
            dragItem.SetDropResult(assigned);
        }

        private CombineSlotItem FindSlot(TowerCompSlotType slotType)
        {
            if (_slots == null)
            {
                return null;
            }

            for (int i = 0; i < _slots.Length; i++)
            {
                CombineSlotItem slot = _slots[i];
                if (slot != null && slot.AcceptSlotType == slotType)
                {
                    return slot;
                }
            }

            return null;
        }

        private bool TryGetBoundItemId(TowerCompSlotType slotType, out long boundItemId)
        {
            boundItemId = 0;
            CombineSlotItem slot = FindSlot(slotType);
            if (slot == null || !slot.HasItem || slot.BoundItemId <= 0)
            {
                return false;
            }

            boundItemId = slot.BoundItemId;
            return true;
        }
    }
}