using Microsoft.Extensions.Logging;
using AuroraDesk.Core.Interfaces;
using AuroraDesk.Presentation.ViewModels.Base;
using AuroraDesk.Core.Entities;
using ReactiveUI;
using System;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reactive;
using System.Reactive.Disposables;
using System.Reactive.Linq;

namespace AuroraDesk.Presentation.ViewModels;

/// <summary>
/// 主窗口的 ViewModel，使用完整的 ReactiveUI 路由系统
/// 重构后遵循整洁架构原则：
/// - 职责分离：导航状态管理委托给 INavigationStateService
/// - 标签页管理委托给 ITabManagementService
/// - 使用字典缓存优化查找性能（O(1) 时间复杂度）
/// - 减少不必要的状态重置循环
/// </summary>
public class MainWindowViewModel : ReactiveObject
{
    private string _title = "My Avalonia App - ReactiveUI 路由";
    private string _headerTitle = "系统管理平台";
    private string _headerSubtitle = "欢迎使用现代化管理界面";
    private ObservableCollection<NavigationItem> _navigationItems = new();
    private NavigationItem? _selectedNavigationItem;
    
    private readonly ILogger<MainWindowViewModel>? _logger;
    private readonly INavigationService _navigationService;
    private readonly INavigationStateService _navigationStateService;
    private readonly ITabManagementService _tabManagementService;
    private readonly IScreen _screen;
    
    // 使用 CompositeDisposable 管理订阅，确保资源释放
    private readonly System.Reactive.Disposables.CompositeDisposable _disposables = new();
    
    public string Title
    {
        get => _title;
        set => this.RaiseAndSetIfChanged(ref _title, value);
    }
    
    public string HeaderTitle
    {
        get => _headerTitle;
        set => this.RaiseAndSetIfChanged(ref _headerTitle, value);
    }
    
    public string HeaderSubtitle
    {
        get => _headerSubtitle;
        set => this.RaiseAndSetIfChanged(ref _headerSubtitle, value);
    }
    
    public ObservableCollection<NavigationItem> NavigationItems
    {
        get => _navigationItems;
        set => this.RaiseAndSetIfChanged(ref _navigationItems, value);
    }
    
    /// <summary>
    /// 标签页集合（委托给 TabManagementService）
    /// </summary>
    public ObservableCollection<TabItem> Tabs => _tabManagementService.Tabs;
    
    public NavigationItem? SelectedNavigationItem
    {
        get => _selectedNavigationItem;
        set => this.RaiseAndSetIfChanged(ref _selectedNavigationItem, value);
    }
    
    /// <summary>
    /// 当前选中的标签页（委托给 TabManagementService）
    /// </summary>
    public TabItem? SelectedTab
    {
        get => _tabManagementService.SelectedTab;
        set => _tabManagementService.SelectedTab = value;
    }
    
    /// <summary>
    /// 路由状态（暴露给 UI 使用）
    /// </summary>
    public RoutingState Router => _screen.Router;
    
    // 响应式命令
    public ReactiveCommand<NavigationItem, Unit> NavigateCommand { get; }
    public ReactiveCommand<TabItem, Unit> CloseTabCommand { get; }
    public ReactiveCommand<TabItem, Unit> SelectTabCommand { get; }
    
    // 关闭确认对话框 Interaction
    public Interaction<CloseConfirmViewModel, bool> CloseConfirmInteraction { get; }
    
    /// <summary>
    /// 请求关闭确认
    /// </summary>
    public async System.Threading.Tasks.Task<bool> RequestCloseConfirmAsync()
    {
        var viewModel = new CloseConfirmViewModel();
        var result = await CloseConfirmInteraction.Handle(viewModel);
        _logger?.LogInformation("用户选择: {Result}", result ? "确认关闭" : "取消关闭");
        return result;
    }
    
    public MainWindowViewModel(
        IScreen screen, 
        INavigationService navigationService,
        INavigationStateService navigationStateService,
        ITabManagementService tabManagementService,
        ILogger<MainWindowViewModel>? logger = null)
    {
        _screen = screen;
        _navigationService = navigationService;
        _navigationStateService = navigationStateService;
        _tabManagementService = tabManagementService;
        _logger = logger;
        
        _logger?.LogInformation("MainWindowViewModel 已创建（重构版本 - 整洁架构）");
        
        // 从导航服务获取导航项
        NavigationItems = _navigationService.GetNavigationItems(_screen);
        
        // 初始化导航状态服务（建立字典缓存，优化查找性能）
        _navigationStateService.InitializeStateMap(NavigationItems);
        
        // 创建导航命令
        NavigateCommand = ReactiveCommand.Create<NavigationItem>(NavigateToPage);
        
        // 创建关闭标签页命令（委托给 TabManagementService，并在关闭后同步导航）
        CloseTabCommand = ReactiveCommand.Create<TabItem>(CloseTab);
        
        // 创建选择标签页命令（委托给 TabManagementService）
        SelectTabCommand = ReactiveCommand.Create<TabItem>(tab => SelectTab(tab));
        
        // 创建关闭确认对话框 Interaction
        CloseConfirmInteraction = new Interaction<CloseConfirmViewModel, bool>();
        
        // 监听导航项选择变化
        _disposables.Add(
            this.WhenAnyValue(x => x.SelectedNavigationItem)
                .Where(item => item != null)
                .Subscribe(item => _logger?.LogInformation("导航到: {Title}", item!.Title)));
        
        // 监听标签页选择变化（通过服务的事件流）
        _disposables.Add(
            _tabManagementService.SelectedTabChanged
                .Where(tab => tab != null)
                .Subscribe(tab => 
                {
                    this.RaisePropertyChanged(nameof(SelectedTab));
                    _logger?.LogInformation("切换到标签页: {Title}", tab!.Title);
                }));
        
        // 监听 Router.CurrentViewModel 变化，同步标签页
        _disposables.Add(
            _screen.Router
                .CurrentViewModel
                .Subscribe(viewModel => OnRouterViewModelChanged(viewModel)));
        
        // 初始化导航：自动导航到仪表板页面
        _disposables.Add(
            Observable.Start(() =>
            {
                var dashboardItem = NavigationItems.FirstOrDefault(item => item.Id == "dashboard");
                if (dashboardItem != null && dashboardItem.ViewModel != null)
                {
                    // 使用状态服务选中导航项
                    _navigationStateService.SelectItem(dashboardItem);
                    SelectedNavigationItem = dashboardItem;
                    
                    // 导航到仪表板
                    _navigationService.NavigateToPage(dashboardItem);
                    _logger?.LogInformation("自动导航到仪表板页面");
                }
            }, RxApp.MainThreadScheduler)
            .Subscribe());
    }
    
    // 以下状态管理方法已移除，现在委托给 INavigationStateService
    // - ResetAllNavigationItemsState() -> _navigationStateService.ResetAllStates()
    // - ResetAllNavigationItemsSelectionOnly() -> _navigationStateService.ResetSelectionOnly()
    // - ResetOtherNavigationItemsState() -> _navigationStateService.ResetOtherStates()
    // 这样可以分离职责，并且使用字典缓存优化性能（O(1) vs O(n*m)）
    
    /// <summary>
    /// 导航到指定页面
    /// 重构后：使用 INavigationStateService 管理状态，减少耦合
    /// </summary>
    private void NavigateToPage(NavigationItem navigationItem)
    {
        if (navigationItem == null) return;
        
        // 使用状态服务查找父项（使用字典缓存，O(1) 时间复杂度）
        var parentItem = _navigationStateService.FindParentItem(navigationItem);
        bool isChildItem = parentItem != null;
        
        if (isChildItem)
        {
            // 子级菜单项：处理导航
            if (navigationItem.ViewModel == null) return;
            
            // 如果已经选中，直接返回，避免重复操作
            if (navigationItem.IsSelected && SelectedNavigationItem == navigationItem) return;
            
            // 使用状态服务重置选中状态（保持展开状态）
            _navigationStateService.ResetSelectionOnly();
            
            // 确保父项保持展开状态
            if (parentItem != null && !parentItem.IsExpanded)
            {
                parentItem.IsExpanded = true;
            }
            
            // 使用状态服务选中当前子项
            _navigationStateService.SelectItem(navigationItem);
            SelectedNavigationItem = navigationItem;
            
            // 使用导航服务进行导航
            _navigationService.NavigateToPage(navigationItem);
            
            _logger?.LogInformation("导航到子页面: {Title}", navigationItem.Title);
        }
        else if (navigationItem.HasChildren)
        {
            // 父级菜单项：处理展开/收起逻辑
            if (navigationItem.IsExpanded)
            {
                // 如果已经展开，则收起
                _navigationStateService.ToggleExpand(navigationItem);
                _navigationStateService.ResetAllStates();
                SelectedNavigationItem = null;
                
                _logger?.LogInformation("收起导航项: {Title}", navigationItem.Title);
            }
            else
            {
                // 如果未展开，则展开并选中第一个子项
                _navigationStateService.ResetOtherStates(navigationItem);
                _navigationStateService.ToggleExpand(navigationItem);
                
                // 选中第一个子项并导航
                if (navigationItem.Children.Count > 0)
                {
                    var firstChild = navigationItem.Children[0];
                    if (firstChild.ViewModel != null)
                    {
                        _navigationStateService.SelectItem(firstChild);
                        SelectedNavigationItem = firstChild;
                        _navigationService.NavigateToPage(firstChild);
                    }
                }
                
                _logger?.LogInformation("展开导航项: {Title}", navigationItem.Title);
            }
        }
        else
        {
            // 无子项的父级导航项，直接选中并导航
            // 如果已经选中，直接返回，避免重复操作
            if (navigationItem.IsSelected && SelectedNavigationItem == navigationItem) return;
            
            // 优化：检查是否已经有对应的 Tab 存在，如果有就直接切换到那个 Tab
            // 使用字典查找，时间复杂度 O(1)
            var existingTab = _tabManagementService.FindTabById(navigationItem.Id);
            if (existingTab != null)
            {
                // 直接切换到已存在的 Tab，避免重新创建和导航
                _navigationStateService.ResetAllStates();
                _navigationStateService.SelectItem(navigationItem);
                SelectedNavigationItem = navigationItem;
                SelectTab(existingTab);
                _logger?.LogInformation("切换到已存在的标签页: {Title}", navigationItem.Title);
                return;
            }
            
            // 使用状态服务重置所有状态并选中当前项
            _navigationStateService.ResetAllStates();
            _navigationStateService.SelectItem(navigationItem);
            SelectedNavigationItem = navigationItem;
            
            // 使用导航服务进行导航
            if (navigationItem.ViewModel != null)
            {
                _navigationService.NavigateToPage(navigationItem);
            }
            
            _logger?.LogInformation("导航到页面: {Title}", navigationItem.Title);
        }
    }
    
    /// <summary>
    /// Router.CurrentViewModel 变化时的处理
    /// 重构后：委托给 TabManagementService 管理标签页
    /// </summary>
    private void OnRouterViewModelChanged(IRoutableViewModel? viewModel)
    {
        if (viewModel == null) return;
        
        // 使用状态服务查找导航项（使用字典缓存，O(1) 时间复杂度）
        var navigationItem = _navigationStateService.FindNavigationItemByViewModel(viewModel);
        if (navigationItem == null) return;
        
        // 委托给 TabManagementService 创建或更新标签页
        _tabManagementService.CreateOrUpdateTab(navigationItem, viewModel);
        
        _logger?.LogInformation("Router 导航到: {Title}", navigationItem.Title);
    }
    
    /// <summary>
    /// 选择标签页
    /// 重构后：委托给 TabManagementService，并同步 Router
    /// 优化：如果当前已经是目标 ViewModel，跳过导航避免重复渲染
    /// </summary>
    private void SelectTab(TabItem tab)
    {
        if (tab == null) return;
        
        // 如果当前 Router 已经显示的是这个 ViewModel，跳过导航避免重复渲染
        if (tab.ViewModel != null && _screen.Router.CurrentViewModel == tab.ViewModel)
        {
            // 只更新标签页状态，不触发 Router 导航
            _tabManagementService.SelectTab(tab);
            _logger?.LogDebug("标签页已处于当前视图，跳过导航: {Title}", tab.Title);
            return;
        }
        
        // 委托给 TabManagementService 选择标签页
        _tabManagementService.SelectTab(tab);
        
        // 使用 Router 导航到对应的 ViewModel
        if (tab.ViewModel != null)
        {
            _screen.Router.Navigate.Execute(tab.ViewModel);
        }
        
        _logger?.LogInformation("选择标签页: {Title}", tab.Title);
    }
    
    /// <summary>
    /// 关闭标签页
    /// 重构后：委托给 TabManagementService，并在关闭后同步 Router 导航
    /// </summary>
    private void CloseTab(TabItem tab)
    {
        if (tab == null || !tab.CanClose) return;
        
        var wasSelected = tab.IsSelected;
        var tabIndex = _tabManagementService.Tabs.IndexOf(tab);
        
        // 委托给 TabManagementService 关闭标签页
        _tabManagementService.CloseTab(tab);
        
        // 如果关闭的是当前选中的标签页，且还有其他标签页，需要导航到新选中的标签页
        if (wasSelected && _tabManagementService.Tabs.Count > 0)
        {
            var newSelectedTab = _tabManagementService.SelectedTab;
            if (newSelectedTab?.ViewModel != null)
            {
                _screen.Router.Navigate.Execute(newSelectedTab.ViewModel);
            }
        }
        // 如果没有标签页了，可能需要导航到默认页面（如仪表板）
        else if (_tabManagementService.Tabs.Count == 0)
        {
            var dashboardItem = NavigationItems.FirstOrDefault(item => item.Id == "dashboard");
            if (dashboardItem?.ViewModel != null)
            {
                _screen.Router.Navigate.Execute(dashboardItem.ViewModel);
            }
        }
        
        _logger?.LogInformation("关闭标签页: {Title}", tab.Title);
    }
    
    
    /// <summary>
    /// 释放资源
    /// </summary>
    public void Dispose()
    {
        _disposables?.Dispose();
        if (_tabManagementService is IDisposable disposable)
        {
            disposable.Dispose();
        }
    }
}