using AvParser.Core.Collecting;
using AvParser.Core.Proxies;
using AvParser.Core.Settings;
using AvParser.Infrastructure.Settings;
using AvParser.Infrastructure.Storage;
using Microsoft.Extensions.Logging.Abstractions;

namespace AvParser.Infrastructure.Tests;

public sealed class JsonSettingsServiceTests : IDisposable
{
    private readonly string _directory = Path.Combine(
        Path.GetTempPath(),
        "AvParserTests",
        Guid.NewGuid().ToString("N")
    );

    private JsonSettingsService Create() => new(new AppPaths(_directory), NullLogger<JsonSettingsService>.Instance);

    private void WriteSettings(string json)
    {
        Directory.CreateDirectory(_directory);
        File.WriteAllText(Path.Combine(_directory, "settings.json"), json);
    }

    public void Dispose()
    {
        if (Directory.Exists(_directory))
        {
            Directory.Delete(_directory, recursive: true);
        }
    }

    [Fact]
    public void An_absent_file_yields_the_defaults()
    {
        using var service = Create();

        service.Current.ShouldBe(new AppSettings());
    }

    /// <summary>
    /// A settings file written before a setting existed must not zero that setting.
    /// </summary>
    /// <remarks>
    /// This is a regression test with a real bug behind it. Defaults used to live on property
    /// initialisers, which the source-generated deserialiser does not run — so an older file came
    /// back with <c>default(T)</c> everywhere, switching the proxy feed off, clearing the protocol
    /// filter and zeroing the probe timeout. The app then loaded an empty pool and looked as if
    /// the network had failed.
    /// </remarks>
    [Fact]
    public void A_file_from_an_older_version_keeps_the_defaults_for_settings_it_predates()
    {
        WriteSettings(
            """
            {
              "theme": "System",
              "lastParserId": "delimited",
              "windowWidth": 1280,
              "windowHeight": 800,
              "windowMaximized": false,
              "minimumLogLevel": "Information"
            }
            """
        );

        using var service = Create();
        var settings = service.Current;

        settings.ProxyUseFeed.ShouldBeTrue();
        settings.ProxyProtocols.ShouldBe(ProxyProtocolFilter.All);
        settings.ProxyProbeTimeoutSeconds.ShouldBe(8);
        settings.ProxyProbeConcurrency.ShouldBe(64);
        settings.ProxyProbeUrl.ShouldNotBeNullOrEmpty();
        settings.Language.ShouldBe(AppLanguage.System);

        // And the values the file did carry must survive.
        settings.LastParserId.ShouldBe("delimited");
        settings.MinimumLogLevel.ShouldBe("Information");
    }

    /// <summary>
    /// The same guarantee, for the collector settings added afterwards.
    /// </summary>
    /// <remarks>
    /// The failure this prevents is worse here than it was for the proxy pool: a zeroed
    /// <c>MaxItemBytes</c> would refuse everything, and a zeroed concurrency would deadlock the
    /// run outright.
    /// </remarks>
    [Fact]
    public void A_file_that_predates_the_collector_keeps_the_collector_defaults()
    {
        WriteSettings("""{ "theme": "Dark", "proxyMinimumLive": 25 }""");

        using var service = Create();
        var settings = service.Current;

        settings.MaxConcurrentDownloads.ShouldBe(4);
        settings.MaxConcurrentPerHost.ShouldBe(2);
        settings.HostDelayMs.ShouldBe(250);
        settings.MaxItemBytes.ShouldBe(33_554_432);
        settings.MinItemBytes.ShouldBe(1024);
        settings.MaxRedirects.ShouldBe(5);
        settings.ConnectTimeoutSeconds.ShouldBe(15);
        settings.HeaderTimeoutSeconds.ShouldBe(30);
        settings.IdleTimeoutSeconds.ShouldBe(20);
        settings.AllowedMediaKinds.ShouldBe(MediaKindFilter.All);
        settings.ShowcaseMode.ShouldBe(ShowcaseMode.HardLink);
        settings.CollectUserAgent.ShouldNotBeNullOrWhiteSpace();

        // And what the file did carry survives.
        settings.ProxyMinimumLive.ShouldBe(25);
    }

    [Fact]
    public void Collect_options_from_an_older_file_are_usable()
    {
        WriteSettings("""{ "theme": "Dark" }""");

        using var service = Create();
        var options = service.Current.ToCollectOptions();

        options.MaxConcurrentDownloads.ShouldBeGreaterThan(0);
        options.MaxItemBytes.ShouldBeGreaterThan(0);
        options.AllowedKinds.ShouldBe(MediaKindFilter.All);
        options.IdleTimeout.ShouldBeGreaterThan(TimeSpan.Zero);
    }

    [Fact]
    public void Collector_values_out_of_range_are_clamped_rather_than_thrown()
    {
        var options = new AppSettings(
            MaxConcurrentDownloads: 0,
            MaxConcurrentPerHost: -5,
            MaxItemBytes: 0,
            MaxRedirects: 9999,
            IdleTimeoutSeconds: 0,
            CollectUserAgent: "   "
        ).ToCollectOptions();

        options.MaxConcurrentDownloads.ShouldBe(1);
        options.MaxConcurrentPerHost.ShouldBe(1);
        options.MaxItemBytes.ShouldBe(1024);
        options.MaxRedirects.ShouldBe(20);
        options.IdleTimeout.ShouldBe(TimeSpan.FromSeconds(1));
        options.UserAgent.ShouldBe("AvParser/0.1");
    }

    [Fact]
    public void An_empty_media_filter_is_treated_as_everything()
    {
        // Switching every format off is far more likely to be an accident than an instruction to
        // collect nothing at all.
        new AppSettings(AllowedMediaKinds: MediaKindFilter.None)
            .ToCollectOptions()
            .AllowedKinds.ShouldBe(MediaKindFilter.All);
    }

    [Fact]
    public void The_proxy_gate_setting_reaches_the_collector()
    {
        new AppSettings(AllowDirectConnection: false).ToCollectOptions().RequireProxy.ShouldBeTrue();
        new AppSettings(AllowDirectConnection: true).ToCollectOptions().RequireProxy.ShouldBeFalse();
    }

    [Fact]
    public void Options_built_from_an_older_file_still_consult_the_feed()
    {
        WriteSettings("""{ "theme": "Dark" }""");

        using var service = Create();
        var options = service.Current.ToProxyOptions();

        options.UseFeed.ShouldBeTrue();
        options.Protocols.ShouldBe(ProxyProtocolFilter.All);
    }

    [Fact]
    public void An_empty_protocol_filter_is_treated_as_all()
    {
        // Nothing in the UI can produce None, but a hand-edited file can — and a pool that
        // silently matches nothing is the least useful possible reading of it.
        var options = new AppSettings(ProxyProtocols: ProxyProtocolFilter.None).ToProxyOptions();

        options.Protocols.ShouldBe(ProxyProtocolFilter.All);
    }

    [Fact]
    public void Out_of_range_values_are_clamped_rather_than_thrown()
    {
        var options = new AppSettings(
            ProxyProbeTimeoutSeconds: 0,
            ProxyProbeConcurrency: 100_000,
            ProxyProbeUrl: "not a url"
        ).ToProxyOptions();

        options.ProbeTimeout.ShouldBe(TimeSpan.FromSeconds(1));
        options.ProbeConcurrency.ShouldBe(512);
        options.ProbeUrl.ShouldBe(new ProxyOptions().ProbeUrl);
    }

    [Fact]
    public void A_corrupt_file_falls_back_to_the_defaults_instead_of_failing_to_start()
    {
        WriteSettings("{ this is not json");

        using var service = Create();

        service.Current.ShouldBe(new AppSettings());
    }

    [Fact]
    public async Task Updates_round_trip_through_the_file()
    {
        using (var service = Create())
        {
            service.Update(current => current with { Theme = AppTheme.Dark, ProxyUseFeed = false });
            await service.FlushAsync(TestContext.Current.CancellationToken);
        }

        using var reopened = Create();

        reopened.Current.Theme.ShouldBe(AppTheme.Dark);
        reopened.Current.ProxyUseFeed.ShouldBeFalse();
    }
}