using System.IO;
using System.Net.Http;
using CursorLang.Core.Models;
using CursorLang.Core.Services;
using CursorLang.Settings.ViewModels;
using CursorLang.Tests.Shared;

namespace CursorLang.Settings.Tests.ViewModels;

/// <summary>
/// The updates section of the settings window: what it shows at every step and
/// what it asks of the service behind it.
/// </summary>
public sealed class UpdateViewModelTests
{
    // The section has something to say at every moment, the one before the first
    // answer included: the status line is never an empty spot in the window
    [Fact]
    public void Before_the_first_check_the_section_says_so()
    {
        using UpdateViewModel viewModel = Create(new FakeUpdateService());

        Assert.Equal(UpdateStatus.Idle, viewModel.Status);
        Assert.Equal("en:UpdateNotChecked", viewModel.StatusText);
        Assert.False(viewModel.IsDownloadOffered);
        Assert.False(viewModel.IsInstallOffered);
        Assert.True(viewModel.CanCheck);
    }

    [Fact]
    public async Task An_update_found_is_offered_for_download()
    {
        var updates = new FakeUpdateService { Release = Release("2.0.0.0") };
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.CheckCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.Available, viewModel.Status);
        Assert.True(viewModel.IsDownloadOffered);
        Assert.False(viewModel.IsInstallOffered);
        Assert.Equal("https://host/releases/tag", viewModel.ReleaseUrl?.ToString());
        Assert.True(viewModel.IsReleaseLinkShown);
        Assert.Equal("en:UpdateAvailable", viewModel.StatusText);
    }

    [Fact]
    public async Task With_the_latest_version_installed_there_is_nothing_to_offer()
    {
        using UpdateViewModel viewModel = Create(new FakeUpdateService());

        await viewModel.CheckCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.UpToDate, viewModel.Status);
        Assert.False(viewModel.IsDownloadOffered);
        Assert.False(viewModel.IsReleaseLinkShown);
    }

    [Fact]
    public async Task A_check_by_the_button_says_when_it_did_not_work_out()
    {
        var updates = new FakeUpdateService { Failure = new HttpRequestException("no network") };
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.CheckCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.Failed, viewModel.Status);
        Assert.Equal("en:UpdateFailed", viewModel.StatusText);
    }

    // The window is opened by hand, and the answer is what the section is there
    // for: a dead network is part of the answer rather than a reason to say nothing
    [Fact]
    public async Task A_check_when_the_window_opens_says_when_it_did_not_work_out()
    {
        var updates = new FakeUpdateService { Failure = new HttpRequestException("no network") };
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.StartAsync();

        Assert.Equal(UpdateStatus.Failed, viewModel.Status);
        Assert.Equal("en:UpdateFailed", viewModel.StatusText);
    }

    // Nothing is remembered between openings: an answer from yesterday is worth
    // less than today's, and the request costs nothing at this rate
    [Fact]
    public async Task Every_opening_of_the_window_asks_anew()
    {
        var updates = new FakeUpdateService();
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.StartAsync();
        Assert.Equal(1, updates.CheckCalls);

        await viewModel.StartAsync();
        Assert.Equal(2, updates.CheckCalls);
    }

    [Fact]
    public async Task A_package_from_Store_is_left_to_Store()
    {
        var updates = new FakeUpdateService { IsSupported = false, Release = Release("2.0.0.0") };
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.StartAsync();
        await viewModel.CheckCommand.ExecuteAsync(null);

        Assert.False(viewModel.IsSupported);
        Assert.Equal(0, updates.CheckCalls);
    }

    [Fact]
    public async Task A_downloaded_package_is_offered_for_installation()
    {
        using TempFolder folder = new();
        string package = folder.File("CursorLang-2.0.0.0.msixbundle");
        await File.WriteAllTextAsync(package, "package", TestContext.Current.CancellationToken);

        var updates = new FakeUpdateService { Release = Release("2.0.0.0"), PackagePath = package };
        using UpdateViewModel viewModel = Create(updates);

        await viewModel.CheckCommand.ExecuteAsync(null);
        await viewModel.DownloadCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.Ready, viewModel.Status);
        Assert.True(viewModel.IsInstallOffered);
        Assert.False(viewModel.IsDownloadOffered);

        viewModel.InstallCommand.Execute(null);

        Assert.Equal([package], updates.Installed);
    }

    [Fact]
    public async Task While_the_package_is_downloading_the_section_shows_it()
    {
        var updates = new FakeUpdateService
        {
            Release = Release("2.0.0.0"),
            DownloadGate = new TaskCompletionSource(),
        };

        using UpdateViewModel viewModel = Create(updates);
        await viewModel.CheckCommand.ExecuteAsync(null);

        Task download = viewModel.DownloadCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.Downloading, viewModel.Status);
        Assert.True(viewModel.IsProgressShown);
        Assert.True(viewModel.IsBusy);
        Assert.False(viewModel.CanCheck);

        updates.DownloadGate.SetResult();
        await download;
    }

    [Fact]
    public async Task A_download_that_did_not_work_out_is_told_about()
    {
        var updates = new FakeUpdateService { Release = Release("2.0.0.0") };
        using UpdateViewModel viewModel = Create(updates);
        await viewModel.CheckCommand.ExecuteAsync(null);

        updates.Failure = new HttpRequestException("the connection dropped");
        await viewModel.DownloadCommand.ExecuteAsync(null);

        Assert.Equal(UpdateStatus.Failed, viewModel.Status);
    }

    // The temp folder is cleared by Windows as it sees fit, and the app has no
    // business handing a file that is gone to the installer
    [Fact]
    public async Task A_package_gone_from_the_disk_is_offered_for_download_again()
    {
        var updates = new FakeUpdateService
        {
            Release = Release("2.0.0.0"),
            PackagePath = Path.Combine(Path.GetTempPath(), "CursorLang.Tests", "never-written.msixbundle"),
        };

        using UpdateViewModel viewModel = Create(updates);
        await viewModel.CheckCommand.ExecuteAsync(null);
        await viewModel.DownloadCommand.ExecuteAsync(null);

        viewModel.InstallCommand.Execute(null);

        Assert.Empty(updates.Installed);
        Assert.Equal(UpdateStatus.Available, viewModel.Status);
    }

    [Fact]
    public async Task The_status_is_written_in_the_chosen_language()
    {
        var localization = new FakeLocalizationService();
        using UpdateViewModel viewModel = Create(new FakeUpdateService(), localization: localization);

        await viewModel.CheckCommand.ExecuteAsync(null);
        Assert.Equal("en:UpdateUpToDate", viewModel.StatusText);

        localization.CurrentLanguage = "ru";
        Assert.Equal("ru:UpdateUpToDate", viewModel.StatusText);
    }

    [Fact]
    public async Task Closing_unsubscribes_from_the_language()
    {
        var localization = new FakeLocalizationService();
        UpdateViewModel viewModel = Create(new FakeUpdateService(), localization: localization);
        await viewModel.CheckCommand.ExecuteAsync(null);

        List<string?> changed = [];
        viewModel.PropertyChanged += (_, e) => changed.Add(e.PropertyName);

        viewModel.Dispose();
        localization.CurrentLanguage = "ru";

        Assert.Empty(changed);
    }

    private static ReleaseInfo Release(string version) => new(
        Version.Parse(version),
        $"v{version}",
        new Uri("https://host/releases/tag"),
        new ReleaseAsset($"CursorLang-{version}.msixbundle", new Uri("https://host/package"), 0));

    private static UpdateViewModel Create(
        IUpdateService updates,
        ILocalizationService? localization = null) =>
        new(updates, localization ?? new FakeLocalizationService());
}