using System;
using System.Collections.Generic;
using UnityEngine;

namespace MedievalShopkeeper
{
    public class ShopInventory : MonoBehaviour
    {
        public static ShopInventory Instance { get; private set; }

        // Tracks how many of each item are in the virtual "backroom" storage
        private Dictionary<ItemData, int> stock = new Dictionary<ItemData, int>();

        public event Action OnInventoryUpdated;

        [Header("Prefabs")]
        [Tooltip("The crate/box prefab spawned when taking stock out to carry. Attach a StockBox component to it!")]
        [SerializeField] private GameObject defaultStockBoxPrefab;

        private void Awake()
        {
            if (Instance != null && Instance != this)
            {
                Destroy(gameObject);
                return;
            }
            Instance = this;
        }

        public int GetStockCount(ItemData item)
        {
            if (item == null) return 0;
            return stock.TryGetValue(item, out int count) ? count : 0;
        }

        public bool BuyStock(ItemData item, int quantity)
        {
            if (item == null || quantity <= 0) return false;

            int totalCost = item.buyPrice * quantity;
            if (GameManager.Instance != null && GameManager.Instance.TrySpendMoney(totalCost))
            {
                AddStock(item, quantity);
                Debug.Log($"[ShopInventory] Bought {quantity}x {item.itemName}. Cost: {totalCost}");
                return true;
            }

            Debug.LogWarning($"[ShopInventory] Cannot afford {quantity}x {item.itemName}. Need: {totalCost}");
            return false;
        }

        public void AddStock(ItemData item, int quantity)
        {
            if (item == null || quantity <= 0) return;

            if (stock.ContainsKey(item))
                stock[item] += quantity;
            else
                stock[item] = quantity;

            OnInventoryUpdated?.Invoke();
        }

        public bool RemoveStock(ItemData item, int quantity)
        {
            if (item == null || quantity <= 0) return false;

            if (stock.ContainsKey(item) && stock[item] >= quantity)
            {
                stock[item] -= quantity;
                if (stock[item] == 0)
                {
                    stock.Remove(item); // Clean up empty entries
                }
                OnInventoryUpdated?.Invoke();
                return true;
            }

            return false;
        }

        /// <summary>
        /// Spawns a physical StockBox in the player's hands from the backroom inventory.
        /// </summary>
        public void WithdrawToPlayer(ItemData item, int quantity, PlayerController player)
        {
            if (player == null || player.IsCarryingItem) 
            {
                Debug.LogWarning("[ShopInventory] Player is already carrying something or is null!");
                return;
            }

            // Verify we actually have enough stock
            if (GetStockCount(item) < quantity)
            {
                Debug.LogWarning($"[ShopInventory] Not enough {item.itemName} in stock to withdraw {quantity}. Max available: {GetStockCount(item)}");
                // Auto-adjust to max available instead of failing? Let's just fail for safety/feedback.
                return;
            }

            // Spawn the box
            GameObject boxObj = null;
            if (defaultStockBoxPrefab != null)
            {
                boxObj = Instantiate(defaultStockBoxPrefab);
            }
            else
            {
                // Fallback cube if no prefab assigned
                boxObj = GameObject.CreatePrimitive(PrimitiveType.Cube);
                boxObj.transform.localScale = new Vector3(0.5f, 0.5f, 0.5f);
                boxObj.name = "Fallback Crate";
                Destroy(boxObj.GetComponent<Collider>()); // prevent physical collisions while carried
                // Give it a brown color
                var rend = boxObj.GetComponent<Renderer>();
                if (rend != null) rend.material.color = new Color(0.5f, 0.3f, 0.1f);
            }

            // Attach and configure StockBox component
            StockBox stockBox = boxObj.GetComponent<StockBox>();
            if (stockBox == null)
            {
                stockBox = boxObj.AddComponent<StockBox>();
            }

            stockBox.Initialize(item, quantity);

            // Deduct from virtual storage
            RemoveStock(item, quantity);

            // Physically carry it
            player.CarryItem(boxObj);
            Debug.Log($"[ShopInventory] Player withdrew {quantity}x {item.itemName}. Remaining in storage: {GetStockCount(item)}");
        }
    }
}