using Microsoft.Extensions.Logging;
using MyAvaloniaApp.Services;
using MyAvaloniaApp.ViewModels.Base;
using MyAvaloniaApp.ViewModels.Pages;
using ReactiveUI;
using System;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reactive;
using System.Reactive.Linq;

namespace MyAvaloniaApp.ViewModels;

/// <summary>
/// 主窗口的 ViewModel，使用完整的 ReactiveUI 路由系统
/// </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 ObservableCollection<TabItem> _tabs = new();
    private NavigationItem? _selectedNavigationItem;
    private TabItem? _selectedTab;
    
    private readonly ILogger<MainWindowViewModel>? _logger;
    private readonly IDataService? _dataService;
    private readonly IResourceService? _resourceService;
    private readonly IScreen _screen;
    
    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);
    }
    
    public ObservableCollection<TabItem> Tabs
    {
        get => _tabs;
        set => this.RaiseAndSetIfChanged(ref _tabs, value);
    }
    
    public NavigationItem? SelectedNavigationItem
    {
        get => _selectedNavigationItem;
        set => this.RaiseAndSetIfChanged(ref _selectedNavigationItem, value);
    }
    
    public TabItem? SelectedTab
    {
        get => _selectedTab;
        set => this.RaiseAndSetIfChanged(ref _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; }
    
    public MainWindowViewModel(IScreen screen, ILogger<MainWindowViewModel>? logger = null, IDataService? dataService = null, IResourceService? resourceService = null)
    {
        _screen = screen;
        _logger = logger;
        _dataService = dataService;
        _resourceService = resourceService;
        
        _logger?.LogInformation("MainWindowViewModel 已创建");
        
        // 初始化导航项（需要在订阅 Router 之前）
        InitializeNavigationItems();
        
        // 创建导航命令
        NavigateCommand = ReactiveCommand.Create<NavigationItem>(NavigateToPage);
        
        // 创建关闭标签页命令
        CloseTabCommand = ReactiveCommand.Create<TabItem>(CloseTab);
        
        // 创建选择标签页命令
        SelectTabCommand = ReactiveCommand.Create<TabItem>(SelectTab);
        
        // 监听导航项选择变化
        // 注意：这些订阅会在 ViewModel 的整个生命周期内保持活跃
        // 由于 MainWindowViewModel 是单例或长生命周期对象，这是可以接受的
        // 如果需要更精细的订阅管理，可以在 View 的 WhenActivated 中使用
        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
        this.WhenAnyValue(x => x.SelectedTab)
            .Where(tab => tab != null)
            .Subscribe(tab => _logger?.LogInformation("切换到标签页: {Title}", tab!.Title));
        
        // 监听 Router.CurrentViewModel 变化，同步标签页
        // 这个订阅对于路由系统正常工作至关重要，必须保持活跃
        _screen.Router
            .CurrentViewModel
            .Subscribe(viewModel =>
            {
                OnRouterViewModelChanged(viewModel);
            });
    }
    
    private void InitializeNavigationItems()
    {
        _navigationItems = new ObservableCollection<NavigationItem>
        {
            new NavigationItem 
            { 
                Id = "dashboard", 
                Title = _resourceService?.GetString("NavDashboard") ?? "仪表板", 
                IconType = HeroIconsAvalonia.Enums.IconType.Home,
                ViewModel = new DashboardPageViewModel(_screen)
            },
            new NavigationItem 
            { 
                Id = "users", 
                Title = _resourceService?.GetString("NavUsers") ?? "用户管理", 
                IconType = HeroIconsAvalonia.Enums.IconType.Users,
                Children = new ObservableCollection<NavigationItem>
                {
                    new NavigationItem 
                    { 
                        Id = "users-list", 
                        Title = "用户列表", 
                        IconType = HeroIconsAvalonia.Enums.IconType.UserGroup,
                        ViewModel = new UsersPageViewModel(_screen)
                    },
                    new NavigationItem 
                    { 
                        Id = "users-roles", 
                        Title = "角色管理", 
                        IconType = HeroIconsAvalonia.Enums.IconType.ShieldCheck,
                        ViewModel = new UsersPageViewModel(_screen)
                    },
                    new NavigationItem 
                    { 
                        Id = "users-permissions", 
                        Title = "权限设置", 
                        IconType = HeroIconsAvalonia.Enums.IconType.Key,
                        ViewModel = new UsersPageViewModel(_screen)
                    }
                }
            },
            new NavigationItem 
            { 
                Id = "settings", 
                Title = _resourceService?.GetString("NavSettings") ?? "系统设置", 
                IconType = HeroIconsAvalonia.Enums.IconType.Cog6Tooth,
                Children = new ObservableCollection<NavigationItem>
                {
                    new NavigationItem 
                    { 
                        Id = "settings-general", 
                        Title = "常规设置", 
                        IconType = HeroIconsAvalonia.Enums.IconType.Cog,
                        ViewModel = new SettingsPageViewModel(_screen)
                    },
                    new NavigationItem 
                    { 
                        Id = "settings-security", 
                        Title = "安全设置", 
                        IconType = HeroIconsAvalonia.Enums.IconType.LockClosed,
                        ViewModel = new SettingsPageViewModel(_screen)
                    },
                    new NavigationItem 
                    { 
                        Id = "settings-backup", 
                        Title = "备份恢复", 
                        IconType = HeroIconsAvalonia.Enums.IconType.CloudArrowUp,
                        ViewModel = new SettingsPageViewModel(_screen)
                    }
                }
            },
            new NavigationItem 
            { 
                Id = "reports", 
                Title = _resourceService?.GetString("NavReports") ?? "报表统计", 
                IconType = HeroIconsAvalonia.Enums.IconType.ChartBar,
                ViewModel = new ReportsPageViewModel(_screen)
            },
            new NavigationItem 
            { 
                Id = "help", 
                Title = _resourceService?.GetString("NavHelp") ?? "帮助中心", 
                IconType = HeroIconsAvalonia.Enums.IconType.QuestionMarkCircle,
                ViewModel = new HelpPageViewModel(_screen)
            },
            new NavigationItem
            {
                Id = "dialog-host",
                Title = "对话框示例",
                IconType = HeroIconsAvalonia.Enums.IconType.ChatBubbleLeftRight,
                ViewModel = new DialogHostPageViewModel(_screen)
            },
            new NavigationItem 
            { 
                Id = "icons", 
                Title = _resourceService?.GetString("NavIcons") ?? "图标库", 
                IconType = HeroIconsAvalonia.Enums.IconType.Sparkles,
                ViewModel = new IconsPageViewModel(_screen, _logger as Microsoft.Extensions.Logging.ILogger<IconsPageViewModel>)
            },
            new NavigationItem 
            { 
                Id = "editor", 
                Title = "代码编辑器", 
                IconType = HeroIconsAvalonia.Enums.IconType.CodeBracket,
                ViewModel = new EditorPageViewModel(_screen, _logger as Microsoft.Extensions.Logging.ILogger<EditorPageViewModel>)
            }
        };
        
        // 默认选中第一个导航项并导航
        if (_navigationItems.Count > 0 && _navigationItems[0].ViewModel != null)
        {
            _navigationItems[0].IsSelected = true;
            SelectedNavigationItem = _navigationItems[0];
            // 初始导航到仪表板
            var initialViewModel = _navigationItems[0].ViewModel;
            if (initialViewModel != null)
            {
                _screen.Router.Navigate.Execute(initialViewModel);
            }
        }
    }
    
    private void NavigateToPage(NavigationItem navigationItem)
    {
        if (navigationItem == null) return;
        
        // 检查是否是子级菜单项
        bool isChildItem = _navigationItems.Any(parent => parent.Children.Contains(navigationItem));
        
        if (isChildItem)
        {
            // 子级菜单项：处理导航
            if (navigationItem.ViewModel == null) return;
            
            // 取消所有导航项的选中状态
            foreach (var item in _navigationItems)
            {
                item.IsSelected = false;
                foreach (var child in item.Children)
                {
                    child.IsSelected = false;
                }
            }
            
            // 设置当前子项为选中状态
            navigationItem.IsSelected = true;
            SelectedNavigationItem = navigationItem;
            
            // 使用 ReactiveUI 路由导航
            _screen.Router.Navigate.Execute(navigationItem.ViewModel);
            
            _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
                navigationItem.IsExpanded = false;
                
                // 取消所有导航项的选中状态
                foreach (var item in _navigationItems)
                {
                    item.IsSelected = false;
                    foreach (var child in item.Children)
                    {
                        child.IsSelected = false;
                    }
                }
                
                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
                foreach (var item in _navigationItems)
                {
                    if (item != navigationItem && item.HasChildren)
                    {
                        item.IsExpanded = false;
                        item.IsSelected = false;
                        foreach (var child in item.Children)
                        {
                            child.IsSelected = false;
                        }
                    }
                }
                
                navigationItem.IsExpanded = true;
                
                // 选中第一个子项并导航
                if (navigationItem.Children.Count > 0)
                {
                    var firstChild = navigationItem.Children[0];
                    firstChild.IsSelected = true;
                    SelectedNavigationItem = firstChild;
                    
                    if (firstChild.ViewModel != null)
                    {
                        _screen.Router.Navigate.Execute(firstChild.ViewModel);
                    }
                }
                
                _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
            foreach (var item in _navigationItems)
            {
                if (item.HasChildren)
                {
                    item.IsExpanded = false;
                }
                item.IsSelected = false;
                foreach (var child in item.Children)
                {
                    child.IsSelected = false;
                }
            }
            
            navigationItem.IsSelected = true;
            SelectedNavigationItem = navigationItem;
            
            // 使用 ReactiveUI 路由导航
            if (navigationItem.ViewModel != null)
            {
                _screen.Router.Navigate.Execute(navigationItem.ViewModel);
            }
            
            _logger?.LogInformation("导航到页面: {Title}", navigationItem.Title);
        }
    }
    
    /// <summary>
    /// Router.CurrentViewModel 变化时的处理
    /// </summary>
    private void OnRouterViewModelChanged(IRoutableViewModel? viewModel)
    {
        if (viewModel == null) return;
        
        // 查找对应的导航项
        var navigationItem = FindNavigationItemByViewModel(viewModel);
        if (navigationItem == null) return;
        
        // 创建或更新标签页
        var existingTab = _tabs.FirstOrDefault(t => t.Id == navigationItem.Id);
        if (existingTab != null)
        {
            foreach (var tab in _tabs)
            {
                tab.IsSelected = false;
            }
            existingTab.IsSelected = true;
            SelectedTab = existingTab;
        }
        else
        {
            var newTab = new TabItem
            {
                Id = navigationItem.Id,
                Title = navigationItem.Title,
                IconType = navigationItem.IconType,
                ViewModel = viewModel,
                IsSelected = true,
                CanClose = navigationItem.Id != "dashboard"
            };
            
            foreach (var tab in _tabs)
            {
                tab.IsSelected = false;
            }
            
            _tabs.Add(newTab);
            SelectedTab = newTab;
        }
        
        _logger?.LogInformation("Router 导航到: {Title}", navigationItem.Title);
    }
    
    private NavigationItem? FindNavigationItemByViewModel(IRoutableViewModel viewModel)
    {
        foreach (var item in _navigationItems)
        {
            if (item.ViewModel == viewModel)
            {
                return item;
            }
            
            foreach (var child in item.Children)
            {
                if (child.ViewModel == viewModel)
                {
                    return child;
                }
            }
        }
        
        return null;
    }
    
    private void SelectTab(TabItem tab)
    {
        if (tab == null) return;
        
        foreach (var t in _tabs)
        {
            t.IsSelected = false;
        }
        
        tab.IsSelected = true;
        SelectedTab = 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);
    }
    
    private void CloseTab(TabItem tab)
    {
        if (tab == null || !tab.CanClose) return;
        
        var tabIndex = _tabs.IndexOf(tab);
        _tabs.Remove(tab);
        
        if (tab.IsSelected && _tabs.Count > 0)
        {
            var newSelectedIndex = Math.Min(tabIndex, _tabs.Count - 1);
            _tabs[newSelectedIndex].IsSelected = true;
            SelectedTab = _tabs[newSelectedIndex];
            
            // 导航到新选中的标签页
            var newSelectedViewModel = _tabs[newSelectedIndex].ViewModel;
            if (newSelectedViewModel != null)
            {
                _screen.Router.Navigate.Execute(newSelectedViewModel);
            }
        }
        
        _logger?.LogInformation("关闭标签页: {Title}", tab.Title);
    }
}