using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System.Collections.Generic;

public class InventoryUI : MonoBehaviour
{
    [SerializeField] private Transform inventoryContent; // Panel > ScrollView > Viewport > Content
    [SerializeField] private GameObject inventoryItemPrefab;
    [SerializeField] private Transform weaponSlot;
    [SerializeField] private Transform armorSlot;
    [SerializeField] private Inventory inventory;
    
    private Canvas canvas;
    private GameObject contextMenu;
    private InventoryItemUI selectedItem;

    void Start()
    {
        canvas = GetComponentInParent<Canvas>();
        if (inventory == null)
            inventory = FindObjectOfType<Inventory>();
        
        RefreshInventoryUI();
    }

    public void RefreshInventoryUI()
    {
        // Clear existing items
        foreach (Transform child in inventoryContent)
            Destroy(child.gameObject);

        // Populate inventory slots
        var slots = inventory.GetInventorySlots();
        foreach (var slot in slots)
        {
            CreateInventoryItemUI(slot.item, slot.quantity);
        }

        // Update equipment slots
        UpdateEquipmentSlots();
    }

    private void CreateInventoryItemUI(Item item, int quantity)
    {
        GameObject itemUI = Instantiate(inventoryItemPrefab, inventoryContent);
        InventoryItemUI itemScript = itemUI.GetComponent<InventoryItemUI>();
        itemScript.Initialize(item, quantity, this);
    }

    private void UpdateEquipmentSlots()
    {
        Item equippedWeapon = inventory.GetEquippedItem(Item.ItemType.Weapon);
        Item equippedArmor = inventory.GetEquippedItem(Item.ItemType.Armor);

        UpdateEquipSlot(weaponSlot, equippedWeapon);
        UpdateEquipSlot(armorSlot, equippedArmor);
    }

    private void UpdateEquipSlot(Transform slot, Item item)
    {
        Image slotImage = slot.GetComponent<Image>();
        if (item != null && item.itemIcon != null)
        {
            slotImage.sprite = item.itemIcon;
            slotImage.color = Color.white;
        }
        else
        {
            slotImage.sprite = null;
            slotImage.color = new Color(1, 1, 1, 0.3f);
        }
    }

    public void ShowContextMenu(InventoryItemUI itemUI, Item item)
    {
        selectedItem = itemUI;

        if (contextMenu != null)
            Destroy(contextMenu);

        contextMenu = new GameObject("ContextMenu");
        contextMenu.transform.SetParent(canvas.transform, false);

        VerticalLayoutGroup layout = contextMenu.AddComponent<VerticalLayoutGroup>();
        layout.childForceExpandHeight = false;
        layout.childForceExpandWidth = false;
        layout.spacing = 2;

        LayoutElement layoutElement = contextMenu.AddComponent<LayoutElement>();
        layoutElement.preferredWidth = 120;
        layoutElement.preferredHeight = 140;

        RectTransform rectTransform = contextMenu.GetComponent<RectTransform>();
        rectTransform.sizeDelta = new Vector2(120, 140);
        rectTransform.anchoredPosition = Input.mousePosition / canvas.scaleFactor;

        Image bgImage = contextMenu.AddComponent<Image>();
        bgImage.color = new Color(0.1f, 0.1f, 0.1f, 0.9f);

        // Add menu options based on item type
        if (item.itemType == Item.ItemType.Weapon || item.itemType == Item.ItemType.Armor)
            AddMenuButton(contextMenu, "Equip", () => OnEquip(item));
        
        if (item.itemType == Item.ItemType.Consumable)
            AddMenuButton(contextMenu, "Use", () => OnUse(item));

        AddMenuButton(contextMenu, "Info", () => OnInfo(item));
        AddMenuButton(contextMenu, "Drop", () => OnDrop(item));

        // Close menu on click elsewhere
        StartCoroutine(WaitForClickOutside());
    }

    private void AddMenuButton(GameObject parent, string label, UnityEngine.Events.UnityAction onClick)
    {
        GameObject buttonObj = new GameObject(label);
        buttonObj.transform.SetParent(parent.transform, false);

        Button button = buttonObj.AddComponent<Button>();
        Text text = buttonObj.AddComponent<Text>();
        text.text = label;
        text.font = Resources.GetBuiltinResource<Font>("Arial.ttf");
        text.alignment = TextAnchor.MiddleCenter;
        text.color = Color.white;
        text.fontSize = 12;

        RectTransform rect = buttonObj.GetComponent<RectTransform>();
        rect.sizeDelta = new Vector2(100, 30);

        LayoutElement layoutElement = buttonObj.AddComponent<LayoutElement>();
        layoutElement.preferredWidth = 100;
        layoutElement.preferredHeight = 30;

        button.onClick.AddListener(onClick);
        button.onClick.AddListener(() => Destroy(contextMenu));
    }

    private void OnEquip(Item item)
    {
        inventory.EquipItem(item.itemName);
        RefreshInventoryUI();
    }

    private void OnUse(Item item)
    {
        inventory.UseItem(item.itemName);
        RefreshInventoryUI();
    }

    private void OnInfo(Item item)
    {
        Debug.Log($"--- {item.itemName} ---\n{item.itemDescription}\nType: {item.itemType}\nID: {item.itemID}");
        // TODO: Show item info panel
    }

    private void OnDrop(Item item)
    {
        inventory.DropItem(item.itemName, 1);
        RefreshInventoryUI();
    }

    private System.Collections.IEnumerator WaitForClickOutside()
    {
        while (true)
        {
            if (Input.GetMouseButtonDown(0) && contextMenu != null)
            {
                // Destroy menu when clicking anywhere (simplified approach)
                Destroy(contextMenu);
                yield break;
            }
            yield return null;
        }
    }
}