using System.Reactive.Linq;
using System.Reactive.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NSubstitute;
using PLib.Application.Library;
using PLib.Desktop.Services;
using PLib.Desktop.Settings;
using PLib.Desktop.ViewModels;
using Shouldly;

namespace PLib.Tests.Settings;

public sealed class SettingsViewModelTests
{
    private readonly IAppSettingsStore _store = Substitute.For<IAppSettingsStore>();

    [Fact]
    public async Task Opening_and_saving_without_touching_anything_changes_nothing()
    {
        // Both of these are displayed in a lossier unit than they are stored in: 65 536 bytes
        // shows as 0,06 MB. Converting the untouched field back used to yield 62 915, which
        // silently rewrote the setting and forced a full rescan on every visit to the panel.
        var options = new LibraryOptions
        {
            Folders = [@"C:\videos"],
            MinimumFileSizeInBytes = 65_536,
            ThumbnailPositionRatio = 0.15,
        };

        var (viewModel, outcome) = await SaveAsync(options);

        outcome.RescanRequired.ShouldBeFalse();
        Written.MinimumFileSizeInBytes.ShouldBe(65_536);
        Written.ThumbnailPositionRatio.ShouldBe(0.15);
        viewModel.HasFolders.ShouldBeTrue();
    }

    [Fact]
    public async Task Editing_the_minimum_size_does_write_the_new_value()
    {
        var (_, outcome) = await SaveAsync(
            new LibraryOptions { Folders = [@"C:\videos"], MinimumFileSizeInBytes = 65_536 },
            viewModel => viewModel.MinimumFileSizeMegabytes = 4);

        Written.MinimumFileSizeInBytes.ShouldBe(4 * 1024 * 1024);
        outcome.RescanRequired.ShouldBeTrue();
    }

    [Fact]
    public async Task Removing_a_folder_is_carried_into_the_saved_settings()
    {
        var (_, outcome) = await SaveAsync(
            new LibraryOptions { Folders = [@"C:\a", @"C:\b"] },
            viewModel => viewModel.Folders[0].RemoveCommand.Execute().Subscribe());

        Written.Folders.ShouldBe([@"C:\b"]);
        outcome.RescanRequired.ShouldBeTrue();
    }

    [Fact]
    public async Task Cancelling_writes_nothing()
    {
        var viewModel = Create(new LibraryOptions { Folders = [@"C:\videos"] });
        var closed = viewModel.Closed.FirstAsync().ToTask();

        viewModel.MinimumFileSizeMegabytes = 999;
        await viewModel.CancelCommand.Execute().FirstAsync().ToTask(TestContext.Current.CancellationToken);

        (await closed).Saved.ShouldBeFalse();
        _store.ReceivedCalls().ShouldBeEmpty();
    }

    private AppSettings Written =>
        (AppSettings)_store.ReceivedCalls().Single(call => call.GetMethodInfo().Name == nameof(IAppSettingsStore.SaveAsync))
            .GetArguments()[0]!;

    private async Task<(SettingsViewModel ViewModel, SettingsDialogOutcome Outcome)> SaveAsync(
        LibraryOptions options,
        Action<SettingsViewModel>? edit = null)
    {
        var viewModel = Create(options);
        var closed = viewModel.Closed.FirstAsync().ToTask();

        edit?.Invoke(viewModel);
        await viewModel.SaveCommand.Execute().FirstAsync().ToTask(TestContext.Current.CancellationToken);

        return (viewModel, await closed);
    }

    private SettingsViewModel Create(LibraryOptions options) => new(
        Substitute.For<IServiceScopeFactory>(),
        Monitor(options),
        Monitor(new AppearanceOptions()),
        _store,
        Substitute.For<IFolderPicker>(),
        Substitute.For<IThemeService>(),
        NullLogger<SettingsViewModel>.Instance);

    private static IOptionsMonitor<T> Monitor<T>(T value)
    {
        var monitor = Substitute.For<IOptionsMonitor<T>>();
        monitor.CurrentValue.Returns(value);
        return monitor;
    }
}