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

// 导航栏控制器
public class NavbarController : MonoBehaviour
{
    [Serializable]
    public class NavItem
    {
        [Tooltip("导航栏按钮组件")]
        public Button button;

        [Tooltip("需要控制显示/隐藏的右侧页面")]
        public GameObject targetPanel;

        [Tooltip("高亮指示器；如果它是按钮的子物体，可自动查找")]
        public Image Indicator;
    }

    [Header("导航项配置")]
    public List<NavItem> navItems = new List<NavItem>();

    [Header("外观设置")]
    public Color selectedColor = new Color(0f, 0.282f, 1f, 1f);
    public Color hoverColor = new Color(0.122f, 0.122f, 0.122f, 1f);

    // 当前选中的索引，-1 表示没有选中项
    private int currentIndex = -1;

    private void Start()
    {
        InitializeNavigation();
        AutoSelectFirstValidItem();
    }

    // 在编辑器中自动补全按钮子物体中的高亮指示器。
    private void OnValidate()
    {
        ResolveAutomaticReferences();
    }

    private void InitializeNavigation()
    {
        ResolveAutomaticReferences();

        for (int i = 0; i < navItems.Count; i++)
        {
            NavItem item = navItems[i];
            if (!ValidateNavItem(item))
                continue;

            SetItemActive(item, false);

            int itemIndex = i;
            item.button.onClick.AddListener(() => OnNavButtonClick(itemIndex));
        }
    }

    private void OnNavButtonClick(int targetIndex)
    {
        SwitchToPanel(targetIndex);
    }

    private void SwitchToPanel(int newIndex)
    {
        if (!IsValidIndex(newIndex) || newIndex == currentIndex)
            return;

        NavItem newItem = navItems[newIndex];
        if (!ValidateNavItem(newItem))
            return;

        if (IsValidIndex(currentIndex))
        {
            NavItem previousItem = navItems[currentIndex];
            if (ValidateNavItem(previousItem))
                SetItemActive(previousItem, false);
        }

        SetItemActive(newItem, true);
        currentIndex = newIndex;
    }

    private void SetItemActive(NavItem item, bool isSelected)
    {
        item.targetPanel.SetActive(isSelected);
        SetBtnVisualState(item, isSelected, false);
    }

    private void SetBtnVisualState(NavItem item, bool isSelected, bool isHovered)
    {
        if (item == null || item.Indicator == null)
            return;

        bool shouldShow = isSelected || isHovered;
        item.Indicator.gameObject.SetActive(shouldShow);

        if (shouldShow)
            item.Indicator.color = isSelected ? selectedColor : hoverColor;
    }

    private void AutoSelectFirstValidItem()
    {
        for (int i = 0; i < navItems.Count; i++)
        {
            if (ValidateNavItem(navItems[i]))
            {
                SwitchToPanel(i);
                return;
            }
        }

        Debug.LogError("没有找到有效的导航项配置！");
    }

    private bool ValidateNavItem(NavItem item)
    {
        bool isValid = item != null &&
                       item.button != null &&
                       item.targetPanel != null &&
                       item.Indicator != null;

        if (!isValid)
        {
            Debug.LogWarning("发现无效导航项配置，请检查以下对象：\n" +
                             $"Button: {item?.button?.name ?? "null"}\n" +
                             $"Panel: {item?.targetPanel?.name ?? "null"}\n" +
                             $"Indicator: {item?.Indicator?.name ?? "null"}");
        }

        return isValid;
    }

    // 根据约定自动查找按钮子物体中名称以 Indicator 结尾的 Image。
    private void ResolveAutomaticReferences()
    {
        if (navItems == null)
            return;

        foreach (NavItem item in navItems)
        {
            if (item == null || item.button == null || item.Indicator != null)
                continue;

            Image[] images = item.button.GetComponentsInChildren<Image>(true);
            foreach (Image image in images)
            {
                if (image != item.button.image &&
                    image.name.EndsWith("Indicator", StringComparison.OrdinalIgnoreCase))
                {
                    item.Indicator = image;
                    break;
                }
            }
        }
    }

    private bool IsValidIndex(int index)
    {
        return index >= 0 && index < navItems.Count;
    }

    // 用于 Event Trigger：指针进入
    public void OnPointerEnter(int itemIndex)
    {
        if (!IsValidIndex(itemIndex) || itemIndex == currentIndex)
            return;

        SetBtnVisualState(navItems[itemIndex], false, true);
    }

    // 用于 Event Trigger：指针离开
    public void OnPointerExit(int itemIndex)
    {
        if (!IsValidIndex(itemIndex) || itemIndex == currentIndex)
            return;

        SetBtnVisualState(navItems[itemIndex], false, false);
    }
}