using System.Reflection;
using System.Xml.Linq;
using OpenAC.MosswartMassacre.FlagTracker;
using OpenAC.MosswartMassacre.Metas;
using OpenAC.MosswartMassacre.Tests.Fakes;
using OpenAC.MosswartMassacre.Views;

namespace OpenAC.MosswartMassacre.Tests.Views;

/// <summary>
/// The plugin shows as the original did: one button on the plugin bar, "MM"
/// with the original window's icon, opening one tabbed window. The Mossy
/// Tracker tab opens the tracker window, which has no bar button of its own,
/// and the Metas tab holds the meta and nav downloads.
/// </summary>
/// <remarks>
/// The tabs are driven the way the host drives them: each binding is looked
/// up by the name the markup gives it and read or invoked by reflection.
/// </remarks>
public sealed class OneWindowTests
{
    private const uint OriginalIcon = 0x06001E37;

    private static PluginHarness WithUi()
    {
        var harness = new PluginHarness(arrange: host => host.HasUi = true);
        harness.Login();
        return harness;
    }

    [Fact]
    public void The_plugin_bar_gets_one_button_MM_with_the_original_icon()
    {
        using PluginHarness harness = WithUi();

        RegisteredPanel shelf = Assert.Single(harness.Host.Ui.Panels, panel => panel.Descriptor.ShowInSidePanel);
        Assert.Equal("main", shelf.Descriptor.WindowId);
        Assert.Equal("MM", shelf.Descriptor.IconText);
        Assert.Equal(OriginalIcon, shelf.Descriptor.IconSurfaceId);
        Assert.EndsWith(MainWindow.MarkupFile, shelf.MarkupPath, StringComparison.Ordinal);
        Assert.IsType<MainWindow>(shelf.Binding);

        // The only other window is the tracker, opened from its tab.
        RegisteredPanel other = Assert.Single(harness.Host.Ui.Panels, panel => !panel.Descriptor.ShowInSidePanel);
        Assert.Equal("flagtracker", other.Descriptor.WindowId);
        Assert.Equal(2, harness.Host.Ui.Panels.Count);
    }

    [Fact]
    public void The_main_window_has_the_original_tabs_plus_metas()
    {
        XElement root = LoadMain();

        string[] tabs = [.. root.Elements("tab").Select(tab => (string?)tab.Attribute("text") ?? string.Empty)];
        Assert.Equal(["Main", "Settings", "Statistics", "Mossy Tracker", "Metas", "Tools"], tabs);
        foreach (string tab in tabs)
            Assert.NotNull(PageOf(root, tab));
    }

    [Fact]
    public void The_mossy_tracker_tab_opens_the_tracker_window()
    {
        using PluginHarness harness = WithUi();
        MainWindow window = harness.Feature<MainWindow>();
        FlagTrackerViewModel tracker = harness.Feature<FlagTrackerFeature>().Panel!;
        XElement page = PageOf(LoadMain(), "Mossy Tracker")!;

        XElement tab = LoadMain().Elements("tab").Single(t => (string?)t.Attribute("text") == "Mossy Tracker");
        Invoke(window, (string?)tab.Attribute("onclick"));
        Assert.True(Read<bool>(window, (string?)page.Attribute("visible")));

        XElement button = Assert.Single(page.Elements("button"), b => (string?)b.Attribute("text") == "Open Mossy Tracker");
        Assert.False(tracker.IsVisible);
        Invoke(window, (string?)button.Attribute("onclick"));

        Assert.True(tracker.IsVisible);
        Assert.Equal(["flagtracker"], harness.Host.Ui.ShowPanelCalls);
    }

    [Fact]
    public void The_metas_tab_is_bound_to_the_meta_sync_and_names_the_real_folders()
    {
        using PluginHarness harness = WithUi();
        MainWindow window = harness.Feature<MainWindow>();
        MetasViewModel metas = harness.Feature<MetaSyncFeature>().Panel!;
        XElement page = PageOf(LoadMain(), "Metas")!;

        // The file list, its search and the download buttons are all here.
        XElement list = Assert.Single(page.Elements("list"));
        string[] columnItems = [.. list.Elements("column").Select(column => (string?)column.Attribute("items") ?? string.Empty)];
        Assert.Equal(3, columnItems.Length);
        Assert.Equal(["No files loaded"], Read<IReadOnlyList<string>>(window, columnItems[1]));
        Assert.Single(page.Elements("field"), field => (string?)field.Attribute("onchange") is not null);
        string[] buttons = [.. page.Elements("button").Select(b => (string?)b.Attribute("text") ?? string.Empty)];
        Assert.Contains("Refresh List", buttons);
        Assert.Contains("Check Updates", buttons);
        Assert.Contains("Download Outdated", buttons);
        Assert.Contains("Download", buttons);

        // The labels name the folders the automation plugin loads from.
        string vtankRoot = harness.Host.VtankProfiles.RootPath!;
        string[] labels = [.. page.Elements("label").Select(label => Text(window, (string?)label.Attribute("text")))];
        Assert.Contains(labels, text => text.EndsWith(Path.Combine(vtankRoot, "mosstank", "metas"), StringComparison.Ordinal));
        Assert.Contains(labels, text => text.EndsWith(Path.Combine(vtankRoot, "mosstank", "navs"), StringComparison.Ordinal));

        // Typing in the tab's search reaches the meta sync and redraws the list.
        XElement search = page.Elements("field").Single(f => (string?)f.Attribute("onchange") is not null);
        Invoke(window, (string?)search.Attribute("onchange"), "zzz");
        Assert.Equal("zzz", metas.SearchText);
        Assert.Equal(["No matches"], Read<IReadOnlyList<string>>(window, columnItems[1]));
        Assert.Equal("zzz", Text(window, (string?)search.Attribute("text")));
    }

    [Fact]
    public void The_metas_tab_changes_the_repository_address()
    {
        using PluginHarness harness = WithUi();
        MainWindow window = harness.Feature<MainWindow>();
        XElement page = PageOf(LoadMain(), "Metas")!;
        XElement field = Assert.Single(page.Elements("field"), f => (string?)f.Attribute("onsubmit") is not null);

        Assert.Equal(MetaSyncManager.DefaultRepositoryUrl, Text(window, (string?)field.Attribute("text")));
        Invoke(window, (string?)field.Attribute("onsubmit"), " https://example.org/club/metas ");
        Assert.Equal("https://example.org/club/metas", harness.Context.Settings.Current.MetasRepositoryUrl);
        Assert.Equal("https://example.org/club/metas", Text(window, (string?)field.Attribute("text")));
    }

    // ── markup helpers ──

    private static XElement LoadMain() =>
        XDocument.Load(Path.Combine(AppContext.BaseDirectory, MainWindow.MarkupFile)).Root!;

    /// <summary>The group a tab shows: the one whose visibility is the tab's selected binding.</summary>
    private static XElement? PageOf(XElement root, string tabText)
    {
        XElement? tab = root.Elements("tab").SingleOrDefault(t => (string?)t.Attribute("text") == tabText);
        string? selected = (string?)tab?.Attribute("selected");
        return selected is null
            ? null
            : root.Elements("group").SingleOrDefault(group => (string?)group.Attribute("visible") == selected);
    }

    private static PropertyInfo Property(object binding, string? expression)
    {
        Assert.NotNull(expression);
        Assert.Matches("^\\{[^{}]+\\}$", expression);
        PropertyInfo? property = binding.GetType().GetProperty(expression[1..^1]);
        Assert.True(property is not null, $"{expression} names no public property on {binding.GetType().Name}.");
        return property;
    }

    private static T Read<T>(object binding, string? expression) =>
        Assert.IsAssignableFrom<T>(Property(binding, expression).GetValue(binding));

    /// <summary>A label's text: the literal, or the bound value.</summary>
    private static string Text(object binding, string? text) =>
        text is not null && text.StartsWith('{') ? Read<object>(binding, text).ToString() ?? string.Empty : text ?? string.Empty;

    private static void Invoke(object binding, string? expression) =>
        Read<Action>(binding, expression)();

    private static void Invoke(object binding, string? expression, string argument) =>
        Read<Action<string>>(binding, expression)(argument);
}