using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared;
using ZB.MOM.WW.OtOpcUa.AdminUI.Uns;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.Raw;

/// <summary>R04 P5: the Raw tree renders a flat, paged row list through Virtualize, with cached menus.</summary>
[Trait("Category", "Unit")]
public sealed class RawTreeRowsTests
{
    private static RawNode Node(string key, RawNodeKind kind = RawNodeKind.Tag, bool lazy = false, bool enabled = true) =>
        new() { Kind = kind, Key = key, DisplayName = key, HasLazyChildren = lazy, Enabled = enabled };

    private static RawNode Device(string key, int tags)
    {
        var d = Node(key, RawNodeKind.Device, lazy: true);
        for (var i = 0; i < tags; i++) d.Children.Add(Node($"{key}/t{i}"));
        d.Loaded = true;
        d.Expanded = true;
        return d;
    }

    [Fact]
    public void Collapsed_nodes_show_no_children()
    {
        var dev = Device("dev", 3);
        dev.Expanded = false;

        RawTreeRows.Flatten([dev]).Select(r => r.Key).ShouldBe(["dev"]);
    }

    [Fact]
    public void Expanded_nodes_flatten_depth_first_in_display_order_with_depth()
    {
        var root = Node("cluster", RawNodeKind.Cluster, lazy: true);
        root.Expanded = true;
        var drv = Node("drv", RawNodeKind.Driver, lazy: true);
        drv.Expanded = true;
        drv.Children.Add(Device("devA", 2));
        root.Children.Add(drv);
        root.Children.Add(Node("folderB", RawNodeKind.Folder, lazy: true));

        var rows = RawTreeRows.Flatten([root]);

        rows.Select(r => (r.Key, r.Depth)).ShouldBe(
        [
            ("cluster", 0), ("drv", 1), ("devA", 2), ("devA/t0", 3), ("devA/t1", 3), ("folderB", 1),
        ]);
    }

    [Fact]
    public void A_5k_tag_device_shows_one_page_then_a_show_more_row()
    {
        var dev = Device("dev", 5000);

        var rows = RawTreeRows.Flatten([dev]);

        rows.Count.ShouldBe(1 + RawTreeRows.DefaultPageSize + 1);
        var more = rows[^1];
        more.Kind.ShouldBe(RawTreeRowKind.ShowMore);
        more.Remaining.ShouldBe(5000 - RawTreeRows.DefaultPageSize);
        more.Depth.ShouldBe(1);

        RawTreeRows.ShowMore(dev);
        var after = RawTreeRows.Flatten([dev]);
        after.Count(r => r.Kind == RawTreeRowKind.Node).ShouldBe(1 + 2 * RawTreeRows.DefaultPageSize);
        after[^1].Remaining.ShouldBe(5000 - 2 * RawTreeRows.DefaultPageSize);
    }

    [Fact]
    public void A_level_at_or_under_the_page_size_has_no_show_more_row()
    {
        var rows = RawTreeRows.Flatten([Device("dev", RawTreeRows.DefaultPageSize)]);
        rows.ShouldNotContain(r => r.Kind == RawTreeRowKind.ShowMore);
        // Positive control: one more child does produce one.
        RawTreeRows.Flatten([Device("dev", RawTreeRows.DefaultPageSize + 1)])
            .Count(r => r.Kind == RawTreeRowKind.ShowMore).ShouldBe(1);
    }

    [Fact]
    public void Show_more_row_follows_the_whole_subtree_of_the_last_shown_child()
    {
        var dev = Node("dev", RawNodeKind.Device, lazy: true);
        dev.Expanded = true;
        dev.VisibleChildLimit = 1;
        var grp = Node("grp", RawNodeKind.TagGroup, lazy: true);
        grp.Expanded = true;
        grp.Children.Add(Node("grp/t"));
        dev.Children.Add(grp);
        dev.Children.Add(Node("dev/hidden"));

        RawTreeRows.Flatten([dev]).Select(r => r.Key).ShouldBe(["dev", "grp", "grp/t", "more:dev"]);
    }

    [Fact]
    public void Loading_and_error_rows_replace_children()
    {
        var loading = Device("a", 2);
        loading.Loading = true;
        var failed = Device("b", 2);
        failed.Error = "boom";

        RawTreeRows.Flatten([loading, failed]).Select(r => r.Kind).ShouldBe(
        [
            RawTreeRowKind.Node, RawTreeRowKind.Loading, RawTreeRowKind.Node, RawTreeRowKind.Error,
        ]);
    }

    [Fact]
    public void Menu_cache_reuses_the_list_and_rebuilds_when_a_dependency_changes()
    {
        var cache = new RawNodeMenuCache();
        var builds = 0;
        IReadOnlyList<ContextMenuItem> Build(RawNode _) { builds++; return [new ContextMenuItem { Label = "x" }]; }

        var node = Node("drv", RawNodeKind.Driver);
        var first = cache.GetOrBuild(node, pickerMode: false, Build);
        cache.GetOrBuild(node, pickerMode: false, Build).ShouldBeSameAs(first);
        builds.ShouldBe(1);

        // Picker mode is a different menu entirely.
        cache.GetOrBuild(node, pickerMode: true, Build).ShouldNotBeSameAs(first);
        builds.ShouldBe(2);

        // A reload replaces the node instance (Enabled is init-only), so the new node gets its own menu.
        var reloaded = Node("drv", RawNodeKind.Driver, enabled: false);
        cache.GetOrBuild(reloaded, pickerMode: true, Build);
        builds.ShouldBe(3);
    }

    [Fact]
    public void RawTree_renders_through_Virtualize_and_the_menu_cache()
    {
        var src = AdminUiSource.Read("Components", "Shared", "Raw", "RawTree.razor");
        src.ShouldContain("<Virtualize Items=\"@RawTreeRows.Flatten(Roots)\"");
        src.ShouldContain("_menus.GetOrBuild(node, PickerMode, MenuFor)");
        src.ShouldNotContain("@RenderNode(child, depth + 1)");
    }
}