using UnityEngine;
using UnityEngine.UI;
using TMPro;
using Ashwild.Inventory;
using Ashwild.UI;

namespace Ashwild.Storage
{
    /// <summary>
    /// The chest window: the local player's whole inventory on the left, the opened chest's contents
    /// on the right. It is a local UI panel — opened by interacting with a <see cref="Chest"/>, closed
    /// with Escape — driven by the GameUIManager panel stack like the inventory. The inventory grid is
    /// client-authoritative data; the chest grid renders the chest's replicated view and every move is
    /// routed through the chest's server-authoritative RPCs, so two players sharing a chest stay in sync.
    ///
    /// Register this panel in <c>GameUIManager.panels</c> so the stack can open/close it. The controller
    /// object stays active; Show/Hide only toggle the visual window and (un)bind the change events.
    /// </summary>
    public class ChestUI : UIPanel
    {
        /// <summary>
        /// Marks this as a local window: input is locked and the cursor shows, but the world keeps
        /// running (never pauses), exactly like the inventory.
        /// </summary>
        public override PanelKind Kind => PanelKind.Chest;

        /// <summary>
        /// The single chest window in the scene, reached by a chest's Interact().
        /// </summary>
        public static ChestUI Instance { get; private set; }

        #region Serialized Fields

        [Header("Window")]
        [Tooltip("Visual window toggled on open/close; the controller object itself stays active.")]
        [SerializeField] private GameObject windowRoot;
        [SerializeField] private TextMeshProUGUI titleText;

        [Header("Grids")]
        [Tooltip("Parent the player-inventory cells are laid out under (left side).")]
        [SerializeField] private Transform inventoryContainer;
        [Tooltip("Parent the chest cells are laid out under (right side).")]
        [SerializeField] private Transform chestContainer;
        [Tooltip("Prefab with a ChestSlotUI, instantiated for every cell on both sides.")]
        [SerializeField] private GameObject slotPrefab;

        [Header("Drag Ghost")]
        [SerializeField] private GameObject ghostObject;
        [SerializeField] private Image ghostIcon;
        [SerializeField] private TextMeshProUGUI ghostQuantityText;

        [Header("Transfer Buttons")]
        [SerializeField] private Button depositAllButton;
        [SerializeField] private Button withdrawAllButton;

        #endregion

        #region State

        private ChestSlotUI[] inventorySlots;
        private ChestSlotUI[] chestSlots;
        private Chest boundChest;

        /// <summary>
        /// The chest currently displayed on the right side (null while closed).
        /// </summary>
        public Chest Chest => boundChest;

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Registers the singleton (in addition to the base panel setup).
        /// </summary>
        protected override void Awake()
        {
            base.Awake();
            Instance = this;
        }

        /// <summary>
        /// Sets up the shared ghost, parks the window closed and wires the transfer-all buttons.
        /// </summary>
        private void Start()
        {
            ChestSlotUI.SetupGhost(ghostObject, ghostIcon, ghostQuantityText);
            if (windowRoot != null) windowRoot.SetActive(false);

            if (depositAllButton != null) depositAllButton.onClick.AddListener(HandleDepositAll);
            if (withdrawAllButton != null) withdrawAllButton.onClick.AddListener(HandleWithdrawAll);
        }

        /// <summary>
        /// Clears the singleton and drops the button listeners on teardown.
        /// </summary>
        private void OnDestroy()
        {
            if (depositAllButton != null) depositAllButton.onClick.RemoveListener(HandleDepositAll);
            if (withdrawAllButton != null) withdrawAllButton.onClick.RemoveListener(HandleWithdrawAll);
            if (Instance == this) Instance = null;
        }

        #endregion

        #region Open / Panel Lifecycle

        /// <summary>
        /// Binds a chest and opens the window through the panel stack (cursor + input lock handled by
        /// the GameUIManager). Called from a chest's Interact().
        /// </summary>
        public void Open(Chest chest)
        {
            if (chest == null) return;
            boundChest = chest;

            if (UIManager.Instance != null)
                UIManager.Instance.OpenPanel(this);
        }

        /// <summary>
        /// Opens the window: builds the grids for the bound chest, binds change events and refreshes.
        /// </summary>
        public override void Show()
        {
            if (windowRoot != null) windowRoot.SetActive(true);

            EnsureInventoryGrid();
            BuildChestGrid();
            BindChanges();

            if (titleText != null && boundChest != null) titleText.text = boundChest.DisplayName;

            RefreshInventory();
            RefreshChest();
        }

        /// <summary>
        /// Closes the window, unbinds change events and releases the chest.
        /// </summary>
        public override void Hide()
        {
            if (ghostObject != null) ghostObject.SetActive(false);
            UnbindChanges();
            boundChest = null;
            if (windowRoot != null) windowRoot.SetActive(false);
        }

        /// <summary>
        /// Instant close used when the manager initializes panels — just parks the window closed.
        /// </summary>
        public override void HideInstant()
        {
            if (ghostObject != null) ghostObject.SetActive(false);
            UnbindChanges();
            boundChest = null;
            if (windowRoot != null) windowRoot.SetActive(false);
        }

        #endregion

        #region Grid Building

        /// <summary>
        /// Builds the left grid from the local player's full inventory once; reused across opens since
        /// the inventory size never changes.
        /// </summary>
        private void EnsureInventoryGrid()
        {
            if (inventorySlots != null) return;

            PlayerInventory inv = PlayerInventory.Instance;
            if (inv == null) return;

            int count = inv.InventorySize;
            inventorySlots = new ChestSlotUI[count];
            for (int i = 0; i < count; i++)
            {
                ChestSlotUI slot = Instantiate(slotPrefab, inventoryContainer).GetComponent<ChestSlotUI>();
                slot.Initialize(this, ChestSlotContainer.Inventory, i);
                inventorySlots[i] = slot;
            }
        }

        /// <summary>
        /// Builds (or rebuilds when the size differs) the right grid to match the bound chest's slot
        /// count, so opening a small chest then a large one lays out the right number of cells.
        /// </summary>
        private void BuildChestGrid()
        {
            int count = boundChest != null ? boundChest.SlotCount : 0;
            if (chestSlots != null && chestSlots.Length == count) return;

            if (chestSlots != null)
                foreach (ChestSlotUI s in chestSlots)
                    if (s != null) Destroy(s.gameObject);

            chestSlots = new ChestSlotUI[count];
            for (int i = 0; i < count; i++)
            {
                ChestSlotUI slot = Instantiate(slotPrefab, chestContainer).GetComponent<ChestSlotUI>();
                slot.Initialize(this, ChestSlotContainer.Chest, i);
                chestSlots[i] = slot;
            }
        }

        #endregion

        #region Change Binding

        /// <summary>
        /// Subscribes to the inventory's and the chest's change notifications so cells refresh live.
        /// </summary>
        private void BindChanges()
        {
            PlayerInventory inv = PlayerInventory.Instance;
            if (inv != null) inv.onSlotChanged.AddListener(HandleInventorySlotChanged);
            if (boundChest != null) boundChest.SlotViewChanged += HandleChestSlotChanged;
        }

        /// <summary>
        /// Unsubscribes — mirrors BindChanges exactly.
        /// </summary>
        private void UnbindChanges()
        {
            PlayerInventory inv = PlayerInventory.Instance;
            if (inv != null) inv.onSlotChanged.RemoveListener(HandleInventorySlotChanged);
            if (boundChest != null) boundChest.SlotViewChanged -= HandleChestSlotChanged;
        }

        /// <summary>
        /// Refreshes a single inventory cell when its slot changes.
        /// </summary>
        private void HandleInventorySlotChanged(int index)
        {
            if (inventorySlots != null && index >= 0 && index < inventorySlots.Length)
                inventorySlots[index].Refresh();
        }

        /// <summary>
        /// Refreshes a single chest cell, or the whole grid when the collection was (re)seeded (-1).
        /// </summary>
        private void HandleChestSlotChanged(int index)
        {
            if (chestSlots == null) return;
            if (index < 0) { RefreshChest(); return; }
            if (index < chestSlots.Length) chestSlots[index].Refresh();
        }

        /// <summary>
        /// Redraws every inventory cell.
        /// </summary>
        private void RefreshInventory()
        {
            if (inventorySlots == null) return;
            for (int i = 0; i < inventorySlots.Length; i++) inventorySlots[i].Refresh();
        }

        /// <summary>
        /// Redraws every chest cell.
        /// </summary>
        private void RefreshChest()
        {
            if (chestSlots == null) return;
            for (int i = 0; i < chestSlots.Length; i++) chestSlots[i].Refresh();
        }

        #endregion

        #region Transfer Routing

        /// <summary>
        /// Routes a drag-drop between two cells into the matching operation: inventory swap, deposit,
        /// withdraw, or move within the chest.
        /// </summary>
        public void HandleTransfer(ChestSlotUI from, ChestSlotUI to)
        {
            if (from == null || to == null || boundChest == null) return;

            bool fromInv = from.Container == ChestSlotContainer.Inventory;
            bool toInv = to.Container == ChestSlotContainer.Inventory;

            if (fromInv && toInv) InventoryUI.OnSwapRequested(from.Index, to.Index);
            else if (fromInv) boundChest.RequestDepositToSlot(from.Index, to.Index);
            else if (toInv) boundChest.RequestWithdraw(from.Index);
            else boundChest.RequestMoveWithin(from.Index, to.Index);
        }

        /// <summary>
        /// Right-click quick transfer: an inventory cell deposits (auto-placed), a chest cell withdraws.
        /// </summary>
        public void HandleQuickTransfer(ChestSlotUI slot)
        {
            if (slot == null || boundChest == null) return;

            if (slot.Container == ChestSlotContainer.Inventory)
                boundChest.RequestDepositToSlot(slot.Index, -1);
            else
                boundChest.RequestWithdraw(slot.Index);
        }

        /// <summary>
        /// "Deposit all" button: stores every inventory item in the chest.
        /// </summary>
        private void HandleDepositAll()
        {
            if (boundChest != null) boundChest.RequestDepositAll();
        }

        /// <summary>
        /// "Take all" button: withdraws every chest item into the inventory.
        /// </summary>
        private void HandleWithdrawAll()
        {
            if (boundChest != null) boundChest.RequestWithdrawAll();
        }

        #endregion
    }
}