using LehrerApp.Core.Models;
using LehrerApp.Desktop.Services;
using Xunit;

namespace LehrerApp.Desktop.Tests;

public sealed class AnnualPlanSyncServiceTests
{
    private static string Calendar(params string[] events) =>
        "BEGIN:VCALENDAR\nVERSION:2.0\n" + string.Join("", events) + "END:VCALENDAR\n";

    private static string Event(string uid, string title, string date = "20260823") =>
        $"BEGIN:VEVENT\nUID:{uid}\nDTSTART;VALUE=DATE:{date}\nSUMMARY:{title}\nEND:VEVENT\n";

    private static AnnualPlanSyncService Build(FakeAnnualPlanEvents events) =>
        new(new HttpClient(), TestSupport.BuildAnnualPlanSettingsService(), events);

    [Fact]
    public void ProcessIcsText_LegtAn_AktualisiertIdempotent_UndEntferntVerschwundeneTermine()
    {
        var events = new FakeAnnualPlanEvents();
        using var service = Build(events);

        var first = service.ProcessIcsText(Calendar(Event("1", "Konferenz"), Event("2", "Messe")));
        var originalId = events.GetByExternalId("1")!.Id;
        var unchanged = service.ProcessIcsText(Calendar(Event("1", "Konferenz"), Event("2", "Messe")));
        var changed = service.ProcessIcsText(Calendar(Event("1", "Konferenz verschoben", "20260824")));

        Assert.Equal((2, 0, 0), (first.Added, first.Updated, first.Deleted));
        Assert.Equal(0, unchanged.ChangeCount);
        Assert.Equal((0, 1, 1), (changed.Added, changed.Updated, changed.Deleted));
        Assert.Equal(originalId, events.GetByExternalId("1")!.Id);
        Assert.Null(events.GetByExternalId("2"));
    }

    [Fact]
    public void ProcessIcsText_DefekterTeilimport_VeraendertBestehendenBestandNicht()
    {
        var events = new FakeAnnualPlanEvents();
        events.Add(new AnnualPlanEvent
        {
            ExternalId = "bestand", Title = "Bestehend",
            StartDate = new DateOnly(2026, 8, 23), EndDate = new DateOnly(2026, 8, 23), IsAllDay = true,
        });
        using var service = Build(events);
        var broken = Calendar(Event("neu", "Neu"),
            "BEGIN:VEVENT\nUID:defekt\nSUMMARY:Ohne Datum\nEND:VEVENT\n");

        Assert.Throws<FormatException>(() => service.ProcessIcsText(broken));

        var remaining = Assert.Single(events.GetAll());
        Assert.Equal("bestand", remaining.ExternalId);
    }

    [Fact]
    public void Clear_EntferntDenLokalenFeedCache()
    {
        var events = new FakeAnnualPlanEvents();
        events.Add(new AnnualPlanEvent
        {
            ExternalId = "1", StartDate = new DateOnly(2026, 8, 23),
            EndDate = new DateOnly(2026, 8, 23), IsAllDay = true,
        });
        using var service = Build(events);
        var notified = false;
        service.DataChanged += () => notified = true;

        service.Clear();

        Assert.Empty(events.GetAll());
        Assert.True(notified);
    }
}