using AvParser.Core.Collecting;
using AvParser.UI.Tests.Fakes;
using AvParser.UI.ViewModels;
using Microsoft.Extensions.Logging.Abstractions;
using ReactiveUI.Primitives;
using ReactiveUI.Primitives.Concurrency;

namespace AvParser.UI.Tests;

public class GalleryViewModelTests
{
    private static StoredMedia Media(string url, MediaKind kind = MediaKind.Png, bool animated = false) =>
        new(
            Guid.NewGuid().ToString("N") + Guid.NewGuid().ToString("N"),
            kind,
            MediaKinds.ExtensionFor(kind),
            4096,
            "url-list",
            url,
            DateTimeOffset.UtcNow
        )
        {
            Width = 800,
            Height = 600,
            IsAnimated = animated,
        };

    private static (GalleryViewModel Page, FakeMediaStore Store, FakeThumbnailCache Thumbnails) Build(
        params StoredMedia[] items
    )
    {
        var store = new FakeMediaStore();
        store.Browse.AddRange(items);
        store.SourceIds.Add("url-list");

        var thumbnails = new FakeThumbnailCache();
        var page = new GalleryViewModel(
            store,
            thumbnails,
            NullLogger<GalleryViewModel>.Instance,
            ImmediateSequencer.Instance
        );

        return (page, store, thumbnails);
    }

    [Fact]
    public async Task What_the_store_holds_becomes_tiles()
    {
        var (page, _, _) = Build(Media("https://a.test/1.png"), Media("https://a.test/2.gif", MediaKind.Gif));

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        page.Items.Count.ShouldBe(2);
        page.TotalCount.ShouldBe(2);
        page.StatusMessage.ShouldBeNull();
    }

    [Fact]
    public async Task Every_tile_asks_for_a_thumbnail()
    {
        var (page, _, thumbnails) = Build(Media("https://a.test/1.png"), Media("https://a.test/2.png"));

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        // By distinct hash rather than call count: the page also loads once on construction, and
        // what matters is that every tile got asked for, at the tile's own width.
        thumbnails.Requested.Select(r => r.Sha256).Distinct().Count().ShouldBe(2);
        thumbnails.Requested.ShouldAllBe(r => r.Width == GalleryItemViewModel.ThumbnailWidth);
    }

    [Fact]
    public async Task Content_nothing_can_decode_is_flagged_rather_than_left_blank()
    {
        // The fake decodes nothing, which is exactly what the real cache does for a video.
        var (page, _, _) = Build(Media("https://a.test/clip.mp4", MediaKind.Mp4));

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        var tile = page.Items.ShouldHaveSingleItem();
        tile.Thumbnail.ShouldBeNull();
        tile.HasNoPreview.ShouldBeTrue();
        tile.KindText.ShouldBe("MP4");
    }

    [Fact]
    public async Task An_empty_store_says_so_instead_of_showing_a_blank_page()
    {
        var (page, _, _) = Build();

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        page.Items.ShouldBeEmpty();
        page.StatusMessage.ShouldNotBeNull().ShouldContain("Nothing here yet");
    }

    [Fact]
    public async Task The_filters_reach_the_query()
    {
        var (page, store, _) = Build(Media("https://a.test/1.png"));

        page.SelectedSourceId = "url-list";
        page.AnimatedOnly = true;
        page.SearchText = "kitten";
        page.SelectedKinds = page.KindFilters.Single(option => option.Value == MediaKindFilter.Images);

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        var query = store.LastBrowse.ShouldNotBeNull();
        query.SourceId.ShouldBe("url-list");
        query.AnimatedOnly.ShouldBeTrue();
        query.Search.ShouldBe("kitten");
        query.Kinds.ShouldBe(MediaKindFilter.Images);
    }

    [Fact]
    public async Task An_unset_source_filter_means_all_of_them()
    {
        var (page, store, _) = Build(Media("https://a.test/1.png"));

        page.SelectedSourceId = "   ";
        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        store.LastBrowse.ShouldNotBeNull().SourceId.ShouldBeNull();
    }

    [Fact]
    public async Task Paging_moves_the_offset_and_stops_at_the_ends()
    {
        var (page, store, _) = Build(Media("https://a.test/1.png"));
        store.TotalOverride = 250;

        await page.LoadAsync(0, TestContext.Current.CancellationToken);
        page.PageText.ShouldContain("1");

        await page.LoadAsync(1, TestContext.Current.CancellationToken);
        store.LastBrowse!.Skip.ShouldBe(120);

        // A negative page is a clamp, not a crash.
        await page.LoadAsync(-3, TestContext.Current.CancellationToken);
        page.PageIndex.ShouldBe(0);
    }

    [Fact]
    public async Task Opening_a_tile_opens_the_viewer_and_closing_it_clears_the_selection()
    {
        var (page, _, _) = Build(Media("https://a.test/1.png"));
        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        page.IsViewerOpen.ShouldBeFalse();

        page.Selected = page.Items[0];
        page.IsViewerOpen.ShouldBeTrue();

        await page.CloseViewerCommand.Execute().ToTask(TestContext.Current.CancellationToken);

        page.Selected.ShouldBeNull();
        page.IsViewerOpen.ShouldBeFalse();
        page.Preview.ShouldBeNull();
    }

    [Fact]
    public async Task A_store_that_throws_reports_it_rather_than_taking_the_page_down()
    {
        var (page, store, _) = Build(Media("https://a.test/1.png"));
        store.BrowseThrows = true;

        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        page.StatusMessage.ShouldNotBeNull().ShouldContain("Could not read the store");
        page.IsLoading.ShouldBeFalse();
    }

    [Fact]
    public async Task Disposing_twice_is_safe()
    {
        // Not hypothetical: every page is registered under its own type and under PageViewModel, so
        // the container disposes it once per registration. The second call used to cancel an
        // already-disposed token source and bring the process down on every exit.
        var (page, _, _) = Build(Media("https://a.test/1.png"));
        await page.LoadAsync(0, TestContext.Current.CancellationToken);

        page.Dispose();

        Should.NotThrow(page.Dispose);
    }
}