using Avalonia.Controls;
using DodoSSH.Client.App.Views;
using DodoSSH.Client.Session;
using DodoSSH.Client.Shell.ViewModels;

namespace DodoSSH.Client.App.Layout.Tests;

/// <summary>
/// The update banner, measured at the width the window is allowed to shrink to.
/// </summary>
/// <remarks>
/// <para>
/// This is the control in the application least protected by anything else. It is a fixed-height row with
/// two buttons on the right and a version string of unknown length in the middle, and it is <em>not</em>
/// inside a <see cref="ScrollViewer"/> — so the harness's scrolling exemption does not apply and both
/// buttons are genuinely measured. The failure it exists to catch is RESTART NOW pushed off the right edge
/// by a long version, which nobody would see until the day there was an update to install.
/// </para>
/// <para>
/// It cannot be measured through <c>MainWindow</c>, which is why the banner is its own control: WebView2's
/// adapter refuses the headless session's thread. See <c>LayoutHarnessTests.WhyTheWindowItselfIsNeverShown</c>.
/// </para>
/// </remarks>
public sealed class UpdateBannerTests
{
    private static CancellationToken Token => TestContext.Current.CancellationToken;

    /// <summary>
    /// A channel that reports an update is ready, so the banner has something to draw.
    /// </summary>
    /// <remarks>
    /// Local to this suite rather than shared with <c>DodoSSH.Client.App.Tests</c>: what a layout test needs
    /// is a view model in a given state, and threading the other suite's fake through a project reference
    /// would couple two suites that otherwise share nothing.
    /// </remarks>
    private sealed class ReadyChannel : IUpdateChannel
    {
        public bool IsSupported => true;

        public string CurrentVersion => "1.0.0";

        public Task<AvailableUpdate?> CheckAsync(CancellationToken cancellationToken) =>
            Task.FromResult<AvailableUpdate?>(new AvailableUpdate(LongVersion));

        public Task DownloadAsync(
            AvailableUpdate update,
            IProgress<int> progress,
            CancellationToken cancellationToken)
        {
            progress.Report(100);

            return Task.CompletedTask;
        }

        public void ApplyAndRestart(AvailableUpdate update)
        {
        }
    }

    /// <summary>
    /// A version longer than anything this project should ever tag, which is the point.
    /// </summary>
    /// <remarks>
    /// MinVer produces exactly this shape on an untagged commit — <c>0.0.0-alpha.0.114</c> — and a release
    /// candidate would produce something close to it. A banner that only fits <c>1.2.3</c> would look fine
    /// in every screenshot and break on the first prerelease anybody actually shipped.
    /// </remarks>
    private const string LongVersion = "10.20.30-release-candidate.4";

    private static async Task<UpdateViewModel> ReadyViewModelAsync()
    {
        var directory = Path.Combine(Path.GetTempPath(), $"dodossh-banner-{Guid.CreateVersion7():N}");

        var updates = new UpdateViewModel(
            new ReadyChannel(),
            new ClientSettingsStore(new ClientPaths(directory)),
            TimeProvider.System,
            () => 3,
            restart: _ => Task.CompletedTask);

        await updates.CheckOnceAsync(TestContext.Current.CancellationToken);

        if (Directory.Exists(directory))
        {
            Directory.Delete(directory, recursive: true);
        }

        return updates;
    }

    [Fact]
    public async Task TheUpdateBannerFitsAtTheWindowsMinimumWidth()
    {
        var updates = await ReadyViewModelAsync();

        await LayoutHarness.OnTheUiThreadAsync(
            () =>
            {
                var banner = new UpdateBanner { DataContext = updates };

                var window = LayoutHarness.HostAtMinimumSize(
                    banner, LayoutHarness.MinimumWidth, LayoutHarness.UpdateBannerHeight);

                try
                {
                    LayoutHarness.Unreachable(window).ShouldBeEmpty();
                }
                finally
                {
                    window.Close();
                }
            },
            Token);
    }

    /// <remarks>
    /// Held to the number <see cref="LayoutHarness.UpdateBannerHeight"/> states, the same way the titlebar,
    /// tab strip and status bar are. A banner that grew with its contents would shrink the terminal by an
    /// amount nothing predicts, and would do it while somebody is reading it.
    /// </remarks>
    [Fact]
    public async Task TheUpdateBannerIsTheHeightItSaysItIs()
    {
        var updates = await ReadyViewModelAsync();

        await LayoutHarness.OnTheUiThreadAsync(
            () =>
            {
                var banner = new UpdateBanner { DataContext = updates };

                var window = LayoutHarness.HostAtMinimumSize(
                    banner, LayoutHarness.MinimumWidth, LayoutHarness.UpdateBannerHeight);

                try
                {
                    banner.Bounds.Height.ShouldBe(LayoutHarness.UpdateBannerHeight);
                }
                finally
                {
                    window.Close();
                }
            },
            Token);
    }
}