using Avalonia;
using Avalonia.Controls;
using Avalonia.Headless.XUnit;
using Avalonia.Styling;
using Avalonia.Threading;
using Avalonia.VisualTree;
using AvParser.Core.Settings;
using AvParser.UI.Localization;
using AvParser.UI.Navigation;
using AvParser.UI.Responsive;
using AvParser.UI.Services;
using AvParser.UI.ViewModels;
using AvParser.UI.Views;
using ReactiveUI.Primitives.Concurrency;

namespace AvParser.UI.HeadlessTests;

public class ShellViewTests
{
    /// <summary>
    /// Shows the shell inside a window of the requested width.
    /// </summary>
    /// <remarks>
    /// A real <see cref="Window"/> is required — a detached control never builds its visual tree,
    /// so there would be no <see cref="SplitView"/> to assert on. The width is set on the window
    /// rather than by calling Measure/Arrange by hand: a manual arrange is undone by the window's
    /// own next layout pass, which made these assertions depend on pump ordering.
    /// </remarks>
    private static (ShellView View, ShellViewModel ViewModel, Window Window) ShowShell(double width)
    {
        var navigation = new NavigationService([
            new FakePage("Page.Dashboard"),
            new FakePage("Page.Parse", "IconDocument"),
        ]);

        // ImmediateSequencer, not the real main-thread one: derived properties then settle within
        // the same layout pass, so a single RunJobs() is enough for the bindings to catch up.
        var viewModel = new ShellViewModel(navigation, new FakeThemeService(), ImmediateSequencer.Instance);
        var view = new ShellView { DataContext = viewModel };
        var window = new Window
        {
            Width = width,
            Height = 800,
            Content = view,
        };

        window.Show();
        Dispatcher.UIThread.RunJobs();

        return (view, viewModel, window);
    }

    private static void Resize(Window window, double width)
    {
        window.Width = width;
        Dispatcher.UIThread.RunJobs();
    }

    private static SplitView NavPaneOf(Visual view) => view.GetVisualDescendants().OfType<SplitView>().Single();

    [AvaloniaTheory]
    [InlineData(500, SplitViewDisplayMode.Overlay)]
    [InlineData(900, SplitViewDisplayMode.CompactInline)]
    [InlineData(1400, SplitViewDisplayMode.Inline)]
    public void The_navigation_pane_adapts_to_the_shell_width(double width, SplitViewDisplayMode expected)
    {
        var (view, _, _) = ShowShell(width);

        NavPaneOf(view).DisplayMode.ShouldBe(expected);
    }

    [AvaloniaTheory]
    [InlineData(500, Breakpoint.Compact)]
    [InlineData(900, Breakpoint.Medium)]
    [InlineData(1400, Breakpoint.Expanded)]
    public void The_shell_hands_its_breakpoint_to_the_view_model(double width, Breakpoint expected)
    {
        var (_, viewModel, _) = ShowShell(width);

        viewModel.Breakpoint.ShouldBe(expected);
    }

    [AvaloniaFact]
    public void Narrowing_the_shell_closes_the_pane_and_widening_reopens_it()
    {
        var (_, viewModel, window) = ShowShell(1400);
        viewModel.IsPaneOpen.ShouldBeTrue();

        Resize(window, 480);
        viewModel.IsPaneOpen.ShouldBeFalse();

        Resize(window, 1400);
        viewModel.IsPaneOpen.ShouldBeTrue();
    }

    [AvaloniaFact]
    public void The_rail_lists_every_registered_page()
    {
        var (view, _, _) = ShowShell(1400);

        view.GetVisualDescendants().OfType<ListBox>().Single().ItemCount.ShouldBe(2);
    }

    [AvaloniaFact]
    public void Selecting_a_rail_entry_swaps_the_hosted_page()
    {
        var (view, viewModel, _) = ShowShell(1400);
        var second = viewModel.Pages[1];

        viewModel.SelectedPage = second;
        Dispatcher.UIThread.RunJobs();

        var host = view.GetVisualDescendants().OfType<TransitioningContentControl>().Single();
        host.Content.ShouldBeSameAs(second);
        viewModel.Title.ShouldBe(Localizer.Instance["Page.Parse"]);
    }

    /// <summary>
    /// Guards against the shell stylesheet silently matching nothing.
    /// </summary>
    /// <remarks>
    /// Avalonia type selectors match the exact type, so <c>UserControl.shell</c> does not match
    /// <see cref="ShellView"/> (which derives from <c>ReactiveUserControl&lt;T&gt;</c>). That
    /// failure is completely silent — the app renders, just with default metrics — so it needs an
    /// explicit assertion on a value only the stylesheet can produce.
    /// </remarks>
    [AvaloniaFact]
    public void The_shell_stylesheet_is_actually_applied()
    {
        var (view, _, _) = ShowShell(1400);

        // 248 comes from the NavPaneWidth token; SplitView's own default is 320.
        NavPaneOf(view).OpenPaneLength.ShouldBe(248d);
        NavPaneOf(view).CompactPaneLength.ShouldBe(56d);

        var pageHost = view.GetVisualDescendants().OfType<Border>().Single(b => b.Name == "PageHost");
        pageHost.Padding.ShouldBe(new Thickness(24));

        var paneToggle = view.GetVisualDescendants().OfType<Button>().Single(b => b.Name == "PaneToggle");
        paneToggle.IsVisible.ShouldBeFalse();
    }

    [AvaloniaFact]
    public void The_hamburger_reappears_once_the_pane_stops_being_inline()
    {
        var (view, _, _) = ShowShell(520);

        var paneToggle = view.GetVisualDescendants().OfType<Button>().Single(b => b.Name == "PaneToggle");
        paneToggle.IsVisible.ShouldBeTrue();
    }

    [AvaloniaFact]
    public void Labels_collapse_away_on_the_icon_rail()
    {
        var (view, _, _) = ShowShell(900);

        var labels = view.GetVisualDescendants()
            .OfType<TextBlock>()
            .Where(t => t.Classes.Contains("navLabel"))
            .ToList();

        labels.ShouldNotBeEmpty();
        labels.ShouldAllBe(label => !label.IsVisible);
    }

    [AvaloniaFact]
    public void The_theme_tokens_actually_change_with_the_variant()
    {
        var application = Application.Current.ShouldNotBeNull();

        application.TryFindResource("AppSurfaceBrush", ThemeVariant.Light, out var light).ShouldBeTrue();
        application.TryFindResource("AppSurfaceBrush", ThemeVariant.Dark, out var dark).ShouldBeTrue();

        // If this fails, Styles/Index.axaml was not loaded by the test app and every other style
        // assertion in this assembly is meaningless.
        dark!.ToString().ShouldNotBe(light!.ToString());
    }

    [AvaloniaFact]
    public void Theme_service_maps_the_app_theme_onto_an_avalonia_variant()
    {
        ThemeService.ToVariant(AppTheme.Light).ShouldBe(ThemeVariant.Light);
        ThemeService.ToVariant(AppTheme.Dark).ShouldBe(ThemeVariant.Dark);
        ThemeService.ToVariant(AppTheme.System).ShouldBe(ThemeVariant.Default);
    }
}