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

/// <summary>
/// UI Toolkit-based item selection UI for battle
/// </summary>
public class BattleItemSelector : MonoBehaviour
{
    [Header("UI References")]
    public UIDocument uiDocument;

    [Header("Settings")]
    public int maxItemsToShow = 10;

    private Character currentCharacter;
    private VisualElement rootElement;
    private VisualElement container;
    private VisualElement itemList;
    private Label titleLabel;
    private Label characterLabel;
    private VisualElement noItemsContainer;
    private Button cancelButton;
    private Button closeButton;

    // Events
    public event Action<string, int> OnItemSelected;
    public event Action OnSelectionCancelled;

    void Awake()
    {
        if (uiDocument == null)
            uiDocument = GetComponent<UIDocument>();

        if (uiDocument == null)
        {
            // Create UIDocument if it doesn't exist
            uiDocument = gameObject.AddComponent<UIDocument>();
        }
    }

    void Start()
    {
        InitializeUI();
        SetVisible(false);
    }

    void Update()
    {
        if (container != null && container.style.display == DisplayStyle.Flex)
        {
            if (Input.GetKeyDown(KeyCode.Escape))
            {
                OnSelectionCancelled?.Invoke();
                HideSelection();
            }
        }
    }

    private void InitializeUI()
    {
        // Load UXML and USS
        var visualTreeAsset = Resources.Load<VisualTreeAsset>("UI/ItemSelectionUI");
        var styleSheet = Resources.Load<StyleSheet>("UI/ItemSelectionUI");

        // Try simple version if main version fails
        if (visualTreeAsset == null)
        {
            Debug.LogWarning("Main UXML failed, trying simple version...");
            visualTreeAsset = Resources.Load<VisualTreeAsset>("UI/ItemSelectionUI_Simple");
        }

        if (visualTreeAsset == null)
        {
            Debug.LogError("Could not load any ItemSelectionUI.uxml from Resources/UI/");
            CreateFallbackUI();
            return;
        }

        rootElement = uiDocument.rootVisualElement;
        rootElement.Clear();

        // Clone the visual tree
        var clonedTree = visualTreeAsset.CloneTree();
        rootElement.Add(clonedTree);

        // Apply styles
        if (styleSheet != null)
        {
            rootElement.styleSheets.Add(styleSheet);
        }

        // Get UI elements
        container = rootElement.Q<VisualElement>("ItemSelectionContainer");
        itemList = rootElement.Q<VisualElement>("ItemList");
        titleLabel = rootElement.Q<Label>("TitleLabel");
        characterLabel = rootElement.Q<Label>("CharacterLabel");
        noItemsContainer = rootElement.Q<VisualElement>("NoItemsContainer");
        cancelButton = rootElement.Q<Button>("CancelButton");
        closeButton = rootElement.Q<Button>("CloseButton");

        // Setup event handlers
        if (cancelButton != null)
        {
            cancelButton.clicked += () =>
            {
                OnSelectionCancelled?.Invoke();
                HideSelection();
            };
        }

        if (closeButton != null)
        {
            closeButton.clicked += () =>
            {
                OnSelectionCancelled?.Invoke();
                HideSelection();
            };
        }
    }

    private void CreateFallbackUI()
    {
        Debug.LogWarning("Creating fallback BattleItemSelector UI");

        rootElement = uiDocument.rootVisualElement;
        rootElement.Clear();

        // Create basic container
        container = new VisualElement();
        container.name = "ItemSelectionContainer";
        container.style.position = Position.Absolute;
        container.style.top = 0;
        container.style.left = 0;
        container.style.right = 0;
        container.style.bottom = 0;
        container.style.backgroundColor = new Color(0, 0, 0, 0.7f);
        container.style.alignItems = Align.Center;
        container.style.justifyContent = Justify.Center;

        // Create modal
        var modal = new VisualElement();
        modal.style.backgroundColor = new Color(0.18f, 0.18f, 0.18f, 1f);
        modal.style.borderTopWidth = modal.style.borderBottomWidth = modal.style.borderLeftWidth = modal.style.borderRightWidth = 2;
        modal.style.borderTopColor = modal.style.borderBottomColor = modal.style.borderLeftColor = modal.style.borderRightColor = Color.gray;
        modal.style.borderTopLeftRadius = modal.style.borderTopRightRadius = modal.style.borderBottomLeftRadius = modal.style.borderBottomRightRadius = 8;
        modal.style.width = 400;
        modal.style.height = 500;
        modal.style.paddingTop = modal.style.paddingBottom = modal.style.paddingLeft = modal.style.paddingRight = 15;

        // Title
        titleLabel = new Label("Select Item");
        titleLabel.style.fontSize = 18;
        titleLabel.style.color = Color.white;
        titleLabel.style.unityFontStyleAndWeight = FontStyle.Bold;
        titleLabel.style.marginBottom = 10;
        titleLabel.style.unityTextAlign = TextAnchor.MiddleCenter;

        // Character label
        characterLabel = new Label();
        characterLabel.style.fontSize = 16;
        characterLabel.style.color = new Color(1f, 0.86f, 0.39f);
        characterLabel.style.unityFontStyleAndWeight = FontStyle.Bold;
        characterLabel.style.marginBottom = 15;
        characterLabel.style.unityTextAlign = TextAnchor.MiddleCenter;

        // Item list
        var scrollView = new ScrollView();
        scrollView.style.flexGrow = 1;
        scrollView.style.marginBottom = 15;

        itemList = new VisualElement();
        scrollView.Add(itemList);

        // No items message
        noItemsContainer = new VisualElement();
        noItemsContainer.style.alignItems = Align.Center;
        noItemsContainer.style.justifyContent = Justify.Center;
        noItemsContainer.style.flexGrow = 1;
        noItemsContainer.style.display = DisplayStyle.None;

        var noItemsLabel = new Label("No usable items available");
        noItemsLabel.style.color = new Color(0.6f, 0.6f, 0.6f);
        noItemsContainer.Add(noItemsLabel);

        // Cancel button
        cancelButton = new Button(() =>
        {
            OnSelectionCancelled?.Invoke();
            HideSelection();
        });
        cancelButton.text = "Cancel";
        cancelButton.style.paddingTop = cancelButton.style.paddingBottom = 8;
        cancelButton.style.paddingLeft = cancelButton.style.paddingRight = 16;

        // Assemble UI
        modal.Add(titleLabel);
        modal.Add(characterLabel);
        modal.Add(scrollView);
        modal.Add(noItemsContainer);
        modal.Add(cancelButton);

        container.Add(modal);
        rootElement.Add(container);
    }

    public void ShowItemSelection(Character character)
    {
        if (itemList == null)
        {
            Debug.LogError("❌ itemList is null - reinitializing UI");
            InitializeUI();
        }

        currentCharacter = character;

        if (characterLabel != null)
            characterLabel.text = $"{character.CharacterName}";

        if (titleLabel != null)
            titleLabel.text = "Select Item";

        PopulateItemList();
        SetVisible(true);
    }

    public void HideSelection()
    {
        SetVisible(false);
        ClearItemList();
        currentCharacter = null;
    }

    private void SetVisible(bool visible)
    {
        if (container != null)
        {
            container.style.display = visible ? DisplayStyle.Flex : DisplayStyle.None;
        }
    }

    private void PopulateItemList()
    {
        ClearItemList();

        var items = GetCharacterItems();

        if (items.Count == 0)
        {
            if (noItemsContainer != null)
                noItemsContainer.style.display = DisplayStyle.Flex;
            return;
        }

        if (noItemsContainer != null)
            noItemsContainer.style.display = DisplayStyle.None;

        for (int i = 0; i < items.Count && i < maxItemsToShow; i++)
        {
            CreateItemButton(items[i], i);
        }
    }

    private void CreateItemButton(ItemData item, int index)
    {
        // Safety check to prevent NullReferenceException
        if (itemList == null)
        {
            Debug.LogError("❌ itemList is null! UI initialization may have failed.");
            return;
        }

        var button = new Button();
        button.AddToClassList("item-button");

        // Item name with quantity
        string itemText = item.quantity > 1 ? $"{item.name} x{item.quantity}" : item.name;
        var nameLabel = new Label(itemText);
        nameLabel.AddToClassList("item-name");

        // Item description
        var descLabel = new Label(item.description);
        descLabel.AddToClassList("item-description");

        button.Add(nameLabel);
        button.Add(descLabel);

        // Only allow selection if item is usable and quantity > 0
        if (item.isUsable && item.quantity > 0)
        {
            button.clicked += () =>
            {
                OnItemSelected?.Invoke(item.name, index);
                HideSelection();
            };
        }
        else
        {
            button.SetEnabled(false);
            nameLabel.style.color = Color.gray;
            descLabel.style.color = Color.gray;
        }

        itemList.Add(button);
    }

    private void ClearItemList()
    {
        if (itemList != null)
        {
            itemList.Clear();
        }
    }

    private List<ItemData> GetCharacterItems()
    {
        if (currentCharacter == null)
        {
            Debug.LogWarning("📦 GetCharacterItems: currentCharacter is null");
            return new List<ItemData>();
        }

        var items = new List<ItemData>();

        // Method 1: Try to get items from Inventory component (ScriptableObject-based system)
        var inventory = currentCharacter.GetComponent<Inventory>();
        if (inventory != null)
        {
            // Get misc/consumable items from inventory
            foreach (var slot in inventory.Miscellaneous)
            {
                if (slot.item is MiscellaneousItem miscItem && miscItem.isConsumable)
                {
                    items.Add(new ItemData
                    {
                        name = miscItem.itemName,
                        description = miscItem.GetEffectDescription(),
                        quantity = slot.quantity,
                        isUsable = true
                    });
                }
            }
            return items;
        }

        // Method 2: Try to get items from CombatDataTransfer session data
        if (CombatDataTransfer.HasValidSession())
        {
            var session = CombatDataTransfer.GetCurrentSession();
            var characterData = session.playerTeam.Find(p => p.characterName == currentCharacter.CharacterName ||
                                                             currentCharacter.CharacterName.StartsWith(p.characterName));

            if (characterData != null && characterData.miscItems != null)
            {
                foreach (var itemName in characterData.miscItems)
                {
                    // Try to find the actual Item asset to get proper description
                    var itemAsset = FindItemAsset(itemName);
                    if (itemAsset is MiscellaneousItem miscItem && miscItem.isConsumable)
                    {
                        items.Add(new ItemData
                        {
                            name = miscItem.itemName,
                            description = miscItem.GetEffectDescription(),
                            quantity = 1, // Default quantity for string-based inventory
                            isUsable = true
                        });
                    }
                    else
                    {
                        // Fallback for items without ScriptableObject assets
                        string description = GetFallbackItemDescription(itemName);
                        items.Add(new ItemData
                        {
                            name = itemName,
                            description = description,
                            quantity = 1,
                            isUsable = true
                        });
                    }
                }

                return items;
            }
        }

        // Method 3: Fallback - try to access string-based inventory directly (if exposed)
        Debug.LogWarning($"📦 No inventory data found for {currentCharacter.CharacterName}. Using empty inventory.");

        return items; // Return empty list
    }

    /// <summary>
    /// Try to find an Item ScriptableObject asset by name
    /// </summary>
    private Item FindItemAsset(string itemName)
    {
        // Try to find in Resources folder first
        var item = Resources.Load<Item>($"Items/{itemName}");
        if (item != null) return item;

        // Try to find using Resources.LoadAll as fallback
        var allItems = Resources.LoadAll<Item>("Items");
        foreach (var itemAsset in allItems)
        {
            if (itemAsset.itemName == itemName)
                return itemAsset;
        }

        return null;
    }

    /// <summary>
    /// Get a fallback description for items that don't have ScriptableObject assets
    /// </summary>
    private string GetFallbackItemDescription(string itemName)
    {
        // Basic descriptions for common item names
        switch (itemName.ToLower())
        {
            case "health potion":
            case "healing potion":
                return "Restores health";
            case "mana potion":
            case "magic potion":
                return "Restores mana";
            case "antidote":
                return "Cures poison";
            case "strength elixir":
                return "Temporarily increases strength";
            case "rope":
            case "hemp rope":
                return "Useful utility item";
            case "torch":
                return "Provides light";
            default:
                return "A useful item";
        }
    }

    [System.Serializable]
    public class ItemData
    {
        public string name;
        public string description;
        public int quantity = 1;
        public bool isUsable = true;
    }

    void OnDestroy()
    {
        OnItemSelected = null;
        OnSelectionCancelled = null;
    }
}