using System.Collections.Specialized;
using System.ComponentModel;
using FluidExplorer.ViewModels;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Automation;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Data;
using Microsoft.UI.Xaml.Media;

namespace FluidExplorer.Views;

/// <summary>
/// 窗口内容宿主：标签栏（位于标题栏区域）+ 文件操作队列面板。
/// 标签容器由代码手工创建与同步，不依赖 TabView 的 ItemsSource 绑定（后者在增删标签时不稳定）。
/// </summary>
public sealed partial class ShellView : UserControl
{
    private readonly Dictionary<ExplorerTabViewModel, TabViewItem> _containers = [];
    private bool _syncingSelection;

    public ShellView()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty ViewModelProperty = DependencyProperty.Register(
        nameof(ViewModel),
        typeof(MainViewModel),
        typeof(ShellView),
        new PropertyMetadata(null, OnViewModelChanged));

    public MainViewModel? ViewModel
    {
        get => (MainViewModel?)GetValue(ViewModelProperty);
        set => SetValue(ViewModelProperty, value);
    }

    /// <summary>标题栏拖动区（宿主窗口用 SetTitleBar 指向它）。</summary>
    public FrameworkElement DragRegion => TitleBarDragRegion;

    /// <summary>供主题切换使用的根元素。</summary>
    public FrameworkElement ThemedRoot => RootGrid;

    public void ShowOperationQueue()
    {
        if (ViewModel is not null) ViewModel.IsQueueExpanded = true;
        QueuePanel.Visibility = Visibility.Visible;
    }

    // ── 标签页容器同步 ──────────────────────────────────────────────────────
    private static void OnViewModelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var shell = (ShellView)d;
        if (e.OldValue is MainViewModel old)
        {
            old.Tabs.CollectionChanged -= shell.OnTabsChanged;
            old.PropertyChanged -= shell.OnViewModelPropertyChanged;
        }
        if (e.NewValue is MainViewModel fresh)
        {
            fresh.Tabs.CollectionChanged += shell.OnTabsChanged;
            fresh.PropertyChanged += shell.OnViewModelPropertyChanged;
            shell.SyncAllTabs();
        }
    }

    private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName != nameof(MainViewModel.SelectedTab) || ViewModel?.SelectedTab is not { } tab) return;
        if (_containers.TryGetValue(tab, out var container) && !ReferenceEquals(TabHost.SelectedItem, container))
        {
            _syncingSelection = true;
            TabHost.SelectedItem = container;
            _syncingSelection = false;
        }
    }

    private void OnTabsChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        try
        {
            ApplyTabsChanged(e);
        }
        catch (Exception ex)
        {
            // 标签容器同步失败不能让异常逃进 WinRT 回调（会变成 stowed exception 结束进程）
            App.Log($"标签页容器同步失败: {ex}");
        }
    }

    private void ApplyTabsChanged(NotifyCollectionChangedEventArgs e)
    {
        if (e.Action == NotifyCollectionChangedAction.Reset)
        {
            SyncAllTabs();
            return;
        }

        if (e.OldItems is not null)
        {
            foreach (ExplorerTabViewModel tab in e.OldItems)
            {
                if (_containers.Remove(tab, out var container)) TabHost.TabItems.Remove(container);
            }
        }

        if (e.NewItems is not null)
        {
            foreach (ExplorerTabViewModel tab in e.NewItems) AddContainer(tab);
        }

        if (ViewModel?.SelectedTab is { } selected && _containers.TryGetValue(selected, out var target))
        {
            _syncingSelection = true;
            TabHost.SelectedItem = target;
            _syncingSelection = false;
        }
    }

    private void SyncAllTabs()
    {
        TabHost.TabItems.Clear();
        _containers.Clear();
        if (ViewModel is null) return;
        foreach (var tab in ViewModel.Tabs) AddContainer(tab);
        if (ViewModel.SelectedTab is { } selected && _containers.TryGetValue(selected, out var target))
        {
            _syncingSelection = true;
            TabHost.SelectedItem = target;
            _syncingSelection = false;
        }
    }

    private void AddContainer(ExplorerTabViewModel tab)
    {
        if (_containers.ContainsKey(tab)) return;

        var header = new StackPanel { Orientation = Orientation.Horizontal, Spacing = 8, VerticalAlignment = VerticalAlignment.Center };
        var icon = new FontIcon { FontSize = 14 };
        if (Application.Current.Resources.TryGetValue("SymbolThemeFontFamily", out var family) && family is FontFamily fontFamily)
            icon.FontFamily = fontFamily;
        icon.SetBinding(FontIcon.GlyphProperty, new Binding
        {
            Path = new PropertyPath(nameof(ExplorerTabViewModel.Glyph)),
            Source = tab,
            Mode = BindingMode.OneWay
        });

        var text = new TextBlock { MaxWidth = 200, TextTrimming = TextTrimming.CharacterEllipsis, VerticalAlignment = VerticalAlignment.Center };
        text.SetBinding(TextBlock.TextProperty, new Binding
        {
            Path = new PropertyPath(nameof(ExplorerTabViewModel.Header)),
            Source = tab,
            Mode = BindingMode.OneWay
        });

        header.Children.Add(icon);
        header.Children.Add(text);

        var container = new TabViewItem
        {
            Header = header,
            Content = new ExplorerTabView { TabViewModel = tab },
            DataContext = tab
        };
        AutomationProperties.SetName(container, tab.Header);

        _containers[tab] = container;
        TabHost.TabItems.Add(container);
    }

    private void OnTabSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (_syncingSelection || ViewModel is null) return;
        if (TabHost.SelectedItem is TabViewItem { DataContext: ExplorerTabViewModel tab })
            ViewModel.SelectedTab = tab;
    }

    private void OnAddTabButtonClick(TabView sender, object args)
    {
        // 延后到 TabView 自身的点击/布局处理完成后再增删标签集合，并吞掉任何异常：
        // 从 DispatcherQueue 回调里逃出去的异常会变成 stowed exception 直接结束进程。
        DispatcherQueue.TryEnqueue(() =>
        {
            try
            {
                ViewModel?.NewTabCommand.Execute(null);
            }
            catch (Exception ex)
            {
                App.Log($"添加标签页失败: {ex}");
            }
        });
    }

    private void OnTabCloseRequested(TabView sender, TabViewTabCloseRequestedEventArgs args)
    {
        if (ViewModel is null) return;
        if (args.Item is TabViewItem { DataContext: ExplorerTabViewModel tab })
        {
            if (ViewModel.Tabs.Count <= 1)
            {
                App.MainWindowInstance.Close();
                return;
            }
            ViewModel.CloseTabCommand.Execute(tab);
            return;
        }

        App.MainWindowInstance.Close();
    }

    private void OnTabDroppedOutside(TabView sender, TabViewTabDroppedOutsideEventArgs args)
    {
        // 单窗口策略：拖出标签时仅保留在当前窗口，避免状态分散
        if (args.Tab is TabViewItem { DataContext: ExplorerTabViewModel tab } && ViewModel is not null)
            ViewModel.SelectedTab = tab;
    }

    private void OnClearFinishedJobsClick(object sender, RoutedEventArgs e) => ViewModel?.ClearFinishedJobsCommand.Execute(null);

    private void OnCollapseQueueClick(object sender, RoutedEventArgs e)
    {
        if (ViewModel is not null) ViewModel.IsQueueExpanded = false;
        QueuePanel.Visibility = Visibility.Collapsed;
    }

    private void OnPauseJobClick(object sender, RoutedEventArgs e)
    {
        if (sender is FrameworkElement { Tag: JobRowViewModel row }) ViewModel?.PauseJobCommand.Execute(row);
    }

    private void OnCancelJobClick(object sender, RoutedEventArgs e)
    {
        if (sender is FrameworkElement { Tag: JobRowViewModel row }) ViewModel?.CancelJobCommand.Execute(row);
    }
}