using UnityEngine;
using UnityEngine.UI;
using TMPro;

/// <summary>
/// Создаёт UI инвентаря программно.
/// Вызывается ТОЛЬКО из редакторных инструментов (InventorySceneSetup, PlayerBuilderTool).
/// Никакого runtime-создания: Start() отсутствует.
/// </summary>
public class InventoryUIBuilder : MonoBehaviour
{
    [Header("Settings")]
    public int hotbarSlots = 9;
    public int inventoryRows = 4;
    public int inventoryCols = 9;

    [Header("Visual Settings")]
    public float slotSize = 50f;
    public float slotSpacing = 4f;
    public float inventoryPadding = 10f;
    public float hotbarPadding = 10f;

    [Header("Colors")]
    [SerializeField] private Color inventoryPanelColor = new Color(0.15f, 0.15f, 0.15f, 0.95f);
    [SerializeField] private Color hotbarPanelColor = new Color(0.1f, 0.1f, 0.1f, 0.9f);
    [SerializeField] private Color slotEmptyColor = new Color(0.25f, 0.25f, 0.25f, 0.8f);

    [Header("Container References")]
    public RectTransform inventoryPanelRect;
    public RectTransform hotbarPanelRect;
    public Canvas inventoryCanvas;

    // Созданные слоты — читаются редакторным инструментом после BuildInventoryUI()
    [SerializeField] private Slot[] _inventorySlots;
    [SerializeField] private Slot[] _hotbarSlots;

    public Slot[] GetInventorySlots() => _inventorySlots;
    public Slot[] GetHotbarSlots()    => _hotbarSlots;

    // ── Построение UI ────────────────────────────────────────────────────────

    public void BuildInventoryUI()
    {
        // Получаем или добавляем Canvas
        var canvas = GetComponent<Canvas>();
        if (canvas == null)
        {
            canvas = gameObject.AddComponent<Canvas>();
            canvas.renderMode   = RenderMode.ScreenSpaceOverlay;
            canvas.sortingOrder = 100;
            gameObject.AddComponent<GraphicRaycaster>();
        }
        inventoryCanvas = canvas;

        // Панель инвентаря
        GameObject inventoryPanel = CreatePanel("InventoryPanel", transform, inventoryPanelColor);
        inventoryPanelRect = inventoryPanel.GetComponent<RectTransform>();

        float inventoryWidth  = inventoryCols * slotSize + (inventoryCols - 1) * slotSpacing + inventoryPadding * 2;
        float inventoryHeight = inventoryRows  * slotSize + (inventoryRows  - 1) * slotSpacing + (inventoryPadding + 30) * 2;

        inventoryPanelRect.anchorMin        = new Vector2(0.5f, 0.5f);
        inventoryPanelRect.anchorMax        = new Vector2(0.5f, 0.5f);
        inventoryPanelRect.pivot            = new Vector2(0.5f, 0.5f);
        inventoryPanelRect.anchoredPosition = Vector2.zero;
        inventoryPanelRect.sizeDelta        = new Vector2(inventoryWidth, inventoryHeight);

        CreateTitle(inventoryPanel.transform, "Инвентарь", new Vector2(0, inventoryHeight / 2 - 20));

        var inventoryGrid = CreateGrid(
            inventoryPanel.transform, "InventoryGrid",
            inventoryCols, inventoryRows,
            slotSize, slotSpacing,
            new Vector2(inventoryPadding, inventoryPadding + 30));

        _inventorySlots = CreateSlots(inventoryGrid, "InventorySlot_", 0, inventoryCols * inventoryRows);

        // Хотбар
        GameObject hotbarPanel = CreatePanel("HotbarPanel", transform, hotbarPanelColor);
        hotbarPanelRect = hotbarPanel.GetComponent<RectTransform>();

        float hotbarWidth = hotbarSlots * (slotSize + slotSpacing) + hotbarPadding * 2;

        hotbarPanelRect.anchorMin        = new Vector2(0.5f, 0f);
        hotbarPanelRect.anchorMax        = new Vector2(0.5f, 0f);
        hotbarPanelRect.pivot            = new Vector2(0.5f, 0f);
        hotbarPanelRect.anchoredPosition = new Vector2(0, 15);
        hotbarPanelRect.sizeDelta        = new Vector2(hotbarWidth, slotSize + hotbarPadding * 2);

        var hotbarGrid = CreateGrid(
            hotbarPanel.transform, "HotbarGrid",
            hotbarSlots, 1,
            slotSize, slotSpacing,
            new Vector2(hotbarPadding, hotbarPadding));

        _hotbarSlots = CreateSlots(hotbarGrid, "HotbarSlot_", 0, hotbarSlots);

        Debug.Log($"[InventoryUIBuilder] Built {inventoryCols * inventoryRows} inventory slots + {hotbarSlots} hotbar slots");
    }

    // ── Вспомогательные методы ────────────────────────────────────────────────

    GameObject CreatePanel(string name, Transform parent, Color color)
    {
        var panel = new GameObject(name);
        panel.transform.SetParent(parent, false);
        panel.AddComponent<RectTransform>();
        panel.AddComponent<Image>().color = color;
        return panel;
    }

    void CreateTitle(Transform parent, string text, Vector2 position)
    {
        var titleObj = new GameObject("Title");
        titleObj.transform.SetParent(parent, false);

        var rect = titleObj.AddComponent<RectTransform>();
        rect.anchorMin        = new Vector2(0, 1);
        rect.anchorMax        = new Vector2(1, 1);
        rect.pivot            = new Vector2(0.5f, 1);
        rect.anchoredPosition = position;
        rect.sizeDelta        = new Vector2(-20, 30);

        var tmp = titleObj.AddComponent<TextMeshProUGUI>();
        tmp.text      = text;
        tmp.fontSize  = 18;
        tmp.alignment = TextAlignmentOptions.Center;
        tmp.color     = Color.white;
    }

    Transform CreateGrid(Transform parent, string name, int cols, int rows, float cellSize, float spacing, Vector2 offset)
    {
        var gridObj = new GameObject(name);
        gridObj.transform.SetParent(parent, false);

        var rect = gridObj.AddComponent<RectTransform>();
        rect.anchorMin = Vector2.zero;
        rect.anchorMax = Vector2.one;
        rect.offsetMin = offset;
        rect.offsetMax = -offset;

        var grid = gridObj.AddComponent<GridLayoutGroup>();
        grid.cellSize        = new Vector2(cellSize, cellSize);
        grid.spacing         = new Vector2(spacing, spacing);
        grid.startCorner     = GridLayoutGroup.Corner.UpperLeft;
        grid.startAxis       = GridLayoutGroup.Axis.Horizontal;
        grid.constraint      = GridLayoutGroup.Constraint.FixedColumnCount;
        grid.constraintCount = cols;
        grid.padding         = new RectOffset(0, 0, 0, 0);

        return gridObj.transform;
    }

    Slot[] CreateSlots(Transform parent, string prefix, int startIndex, int count)
    {
        var slots = new Slot[count];

        for (int i = 0; i < count; i++)
        {
            var slotObj = new GameObject(prefix + (startIndex + i));
            slotObj.transform.SetParent(parent, false);

            var rect = slotObj.AddComponent<RectTransform>();
            rect.sizeDelta = new Vector2(slotSize, slotSize);

            var bg = slotObj.AddComponent<Image>();
            bg.color = slotEmptyColor;

            var slot = slotObj.AddComponent<Slot>();
            slot.slotIndex     = startIndex + i;
            slot.slotBackground = bg;

            // Иконка
            var iconObj  = new GameObject("Icon");
            iconObj.transform.SetParent(slotObj.transform, false);
            var iconRect = iconObj.AddComponent<RectTransform>();
            iconRect.anchorMin = Vector2.zero;
            iconRect.anchorMax = Vector2.one;
            iconRect.offsetMin = new Vector2(4, 4);
            iconRect.offsetMax = new Vector2(-4, -4);
            slot.iconImage = iconObj.AddComponent<Image>();
            slot.iconImage.preserveAspect = true;
            slot.iconImage.enabled = false;

            // Количество
            var amountObj  = new GameObject("AmountPanel");
            amountObj.transform.SetParent(slotObj.transform, false);
            var amountRect = amountObj.AddComponent<RectTransform>();
            amountRect.anchorMin        = Vector2.one;
            amountRect.anchorMax        = Vector2.one;
            amountRect.pivot            = new Vector2(1, 0);
            amountRect.anchoredPosition = new Vector2(-2, 2);
            amountRect.sizeDelta        = new Vector2(22, 22);
            slot.amountPanel = amountObj;

            amountObj.AddComponent<Image>().color = new Color(0, 0, 0, 0.7f);

            var amountTextObj  = new GameObject("Text");
            amountTextObj.transform.SetParent(amountObj.transform, false);
            var amountTextRect = amountTextObj.AddComponent<RectTransform>();
            amountTextRect.anchorMin = Vector2.zero;
            amountTextRect.anchorMax = Vector2.one;
            slot.amountText              = amountTextObj.AddComponent<TextMeshProUGUI>();
            slot.amountText.fontSize     = 14;
            slot.amountText.alignment    = TextAlignmentOptions.Right;
            slot.amountText.color        = Color.white;
            slot.amountText.fontStyle    = FontStyles.Bold;

            slot.amountPanel.SetActive(false);

            // Drag & Drop
            var dragDrop = slotObj.AddComponent<InventoryDragDrop>();
            dragDrop.slot      = slot;
            dragDrop.slotIndex = slot.slotIndex;

            slot.OnSlotClicked += OnSlotClicked;

            slots[i] = slot;
        }

        return slots;
    }

    // ── Выделение слота (runtime) ─────────────────────────────────────────────

    private int _selectedSlot = -1;

    private void OnSlotClicked(Slot slot)
    {
        if (_selectedSlot >= 0 && _inventorySlots != null && _selectedSlot < _inventorySlots.Length)
            _inventorySlots[_selectedSlot].SetSelected(false);

        slot.SetSelected(true);
        _selectedSlot = slot.slotIndex;

        Debug.Log($"[UI] Selected slot: {_selectedSlot} - {slot.GetItem()?.itemName ?? "Empty"}");
    }

    // ── Утилиты ───────────────────────────────────────────────────────────────

    public void Rebuild()
    {
        if (inventoryPanelRect != null)
            Destroy(inventoryPanelRect.gameObject);
        if (hotbarPanelRect != null)
            Destroy(hotbarPanelRect.gameObject);

        _inventorySlots = null;
        _hotbarSlots    = null;
        BuildInventoryUI();
    }

    public void ToggleInventory(bool show)
    {
        if (inventoryPanelRect != null)
            inventoryPanelRect.gameObject.SetActive(show);
    }
}