using System;
using Items;
using Terrain;
using UnityEngine;
using UnityEngine.UI;

namespace UI {
    public class UIItemSlot : MonoBehaviour {

        public bool linked;
        public ItemSlot itemSlot;
        public Image slotImage;
        public Image slotIcon;
        public Text slotAmount;
        public World world;

        private void Awake() {
            world = GameObject.Find("World").GetComponent<World>();
        }

        public bool HasItem => itemSlot?.HasItem == true;

        public void Link(in ItemSlot slot) {
            itemSlot = slot;
            linked = true;
            itemSlot.LinkUISlot(this);
            UpdateSlot();
        }

        public void Unlink() {
            itemSlot.UnlinkUISlot();
            itemSlot = null;
            linked = false;
            UpdateSlot();
        }

        public void UpdateSlot() {
            if (HasItem) {
                slotIcon.sprite = world.blockTypes[itemSlot.Stack.Block].icon;
                slotAmount.text = itemSlot.Stack.Amount.ToString();
                slotIcon.enabled = true;
                slotAmount.enabled = true;
            } else Clear();
        }

        private void Clear() {
            slotIcon.enabled = false;
            slotAmount.enabled = false;
            slotIcon.sprite = null;
            slotAmount.text = null;
        }

        private void OnDestroy() {
            if (linked)
                itemSlot.UnlinkUISlot();
        }
    }
    
    [Serializable]
    public class ItemSlot {
        public ItemStack Stack;
        private UIItemSlot _slot;

        public bool creative;

        public ItemSlot(in UIItemSlot slot) {
            _slot = slot;
            _slot.Link(this);
        }

        public ItemSlot(in UIItemSlot slot, in ItemStack stack) {
            Stack = stack;
            _slot = slot;
            _slot.Link(this);
        }

        public void LinkUISlot(in UIItemSlot slot) => _slot = slot;
        public void UnlinkUISlot() => _slot = null;

        public void EmptySlot() {
            Stack = null;
            if (_slot != null)
                _slot.UpdateSlot();
        }

        public int Take(int amount) {
            if (amount > Stack.Amount) {
                int result = Stack.Amount;
                EmptySlot();
                return result;
            }
            
            if (amount < Stack.Amount) {
                Stack.Amount -= amount;
                if (_slot != null) _slot.UpdateSlot();
                return amount;
            }
            
            EmptySlot();
            return amount;
        }
        
        public ItemStack TakeAll() {
            ItemStack result = new ItemStack(Stack.Block, Stack.Amount);
            EmptySlot();
            return result;
        }

        public void InsertStack(in ItemStack stack) {
            Stack = stack;
            if (_slot != null) _slot.UpdateSlot();
        }

        public bool HasItem => Stack != null;
    }
}