using ClawdDotNet.App.Settings;
using Shouldly;

namespace ClawdDotNet.App.Tests.Settings;

/// <summary>
/// What happens to the settings that no longer exist here (#528, stage 1).
///
/// <para><b>The occasion.</b> Five keys moved from <see cref="AppSettings"/> into the
/// instance. System.Text.Json silently skips unknown keys, and
/// <c>Save</c> does not write them again afterwards — whoever had entered their own log or
/// backup directory would therefore lose the value without finding out.
/// A move without fallback logic is fine; one without an announcement is not.</para>
///
/// <para>Deliberately no takeover into the instances: an application-wide path, copied into all
/// instances, would again be the same folder for all — i.e. exactly the state
/// stage 1 eliminates.</para>
/// </summary>
public sealed class SettingsManagerTests : IDisposable
{
    private readonly string _dir = Path.Combine(
        Path.GetTempPath(), "clawd-tests", "settings-" + Guid.NewGuid().ToString("N")[..8]);

    private string Datei => Path.Combine(_dir, "Settings.json");

    public SettingsManagerTests() => Directory.CreateDirectory(_dir);

    public void Dispose()
    {
        try { Directory.Delete(_dir, recursive: true); }
        catch { /* A leftover test folder does not turn a run red. */ }
    }

    private SettingsManager Loaded(string json)
    {
        File.WriteAllText(Datei, json);
        var manager = new SettingsManager(_dir);
        manager.Load();
        return manager;
    }

    [Fact]
    public void An_old_file_reports_its_abandoned_keys()
    {
        var manager = Loaded("""
            {
              "logDirectory": "/var/log/clawd",
              "backupDirectory": "/srv/sicherungen",
              "backupKeepCount": 30,
              "autoBackupEnabled": true,
              "autoBackupTime": "02:30",
              "minimumLogLevel": "Debug"
            }
            """);

        manager.AbandonedKeys.ShouldBe(
            ["logDirectory", "backupDirectory", "backupKeepCount",
             "autoBackupEnabled", "autoBackupTime"],
            ignoreOrder: true);
    }

    [Fact]
    public void Whatever_else_the_file_contains_is_still_read()
    {
        // The announcement must not change the fact that the rest arrives.
        var manager = Loaded("""
            {
              "logDirectory": "/var/log/clawd",
              "minimumLogLevel": "Debug",
              "maxLogLinesInUi": 4000
            }
            """);

        manager.AppSettings.MinimumLogLevel.ShouldBe("Debug");
        manager.AppSettings.MaxLogLinesInUi.ShouldBe(4000);
    }

    [Fact]
    public void A_fresh_file_reports_nothing()
    {
        Loaded("""{ "minimumLogLevel": "Info" }""").AbandonedKeys.ShouldBeEmpty();
    }

    [Fact]
    public void Saving_drops_the_abandoned_keys()
    {
        var manager = Loaded("""{ "logDirectory": "/var/log/clawd" }""");
        manager.Save();

        File.ReadAllText(Datei).ShouldNotContain("logDirectory");

        // And the second load has nothing more to report.
        var again = new SettingsManager(_dir);
        again.Load();
        again.AbandonedKeys.ShouldBeEmpty();
    }

    [Fact]
    public void An_unreadable_file_does_not_prevent_the_start()
    {
        var manager = Loaded("{ das ist kein JSON");

        manager.AppSettings.MinimumLogLevel.ShouldBe("Info");
        manager.AbandonedKeys.ShouldBeEmpty();
    }
}