using LehrerApp.Core.Models;
using LehrerApp.Desktop.ViewModels.Groups;
using Xunit;

namespace LehrerApp.Desktop.Tests;

/// Deckt die Kandidatensuche für den "Vorhandene Stunde verknüpfen"-Button im Stunden-anlegen-
/// Dialog ab (Nutzer-Feedback: per JSON-Import/KI ohne Stundennummer angelegte Stunden tauchen im
/// Stundenplan nicht auf, da der dort verwendete FindLessonForSlot per Datum+Stundennummer sucht).
public class LessonFixItSearchTests
{
    [Fact]
    public void FindCandidates_FindetVerwaisteStundeOhneStundennummerAmSelbenTag()
    {
        var lessons = new FakeLessons();
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var date = new DateOnly(2026, 9, 8);
        var orphan = new Lesson { UnitId = unitId, GroupId = groupId, Date = date, LessonNumber = null, Topic = "Reflexionsgesetz" };
        lessons.Add(orphan);

        var candidates = LessonFixItSearch.FindCandidates(lessons, groupId, date);

        var found = Assert.Single(candidates);
        Assert.Equal(orphan.Id, found.Id);
    }

    [Fact]
    public void FindCandidates_FindetStundeAmSelbenTagMitAbweichenderStundennummer()
    {
        var lessons = new FakeLessons();
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var date = new DateOnly(2026, 9, 8);
        var wrongPeriod = new Lesson { UnitId = unitId, GroupId = groupId, Date = date, LessonNumber = 7, Topic = "Reflexionsgesetz" };
        lessons.Add(wrongPeriod);

        var candidates = LessonFixItSearch.FindCandidates(lessons, groupId, date);

        var found = Assert.Single(candidates);
        Assert.Equal(wrongPeriod.Id, found.Id);
    }

    [Fact]
    public void FindCandidates_SortiertExaktesDatumVorNahenTerminenOhneStundennummer()
    {
        var lessons = new FakeLessons();
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var date = new DateOnly(2026, 9, 8);
        var near = new Lesson { UnitId = unitId, GroupId = groupId, Date = date.AddDays(-2), LessonNumber = null, Topic = "Nah" };
        var exact = new Lesson { UnitId = unitId, GroupId = groupId, Date = date, LessonNumber = null, Topic = "Exakt" };
        lessons.Add(near); lessons.Add(exact);

        var candidates = LessonFixItSearch.FindCandidates(lessons, groupId, date);

        Assert.Equal(2, candidates.Count);
        Assert.Equal(exact.Id, candidates[0].Id);
        Assert.Equal(near.Id, candidates[1].Id);
    }

    [Fact]
    public void FindCandidates_IgnoriertStundenAusserhalbDesZeitfenstersUndAnderenGruppen()
    {
        var lessons = new FakeLessons();
        var groupId = Guid.NewGuid();
        var otherGroupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var date = new DateOnly(2026, 9, 8);
        lessons.Add(new Lesson { UnitId = unitId, GroupId = groupId, Date = date.AddDays(-30), LessonNumber = null, Topic = "Zu weit weg" });
        lessons.Add(new Lesson { UnitId = unitId, GroupId = otherGroupId, Date = date, LessonNumber = null, Topic = "Andere Gruppe" });
        // Gesetzte Stundennummer, aber exakt am gesuchten Datum — bewusst als Kandidat enthalten
        // (z.B. falsch nummerierter Import); der Nutzer entscheidet im Bestätigungs-/
        // Auswahldialog, ob sie passt.
        lessons.Add(new Lesson { UnitId = unitId, GroupId = groupId, Date = date, LessonNumber = 3, Topic = "Falsch nummeriert, aber am gesuchten Tag" });

        var candidates = LessonFixItSearch.FindCandidates(lessons, groupId, date);

        var found = Assert.Single(candidates);
        Assert.Equal("Falsch nummeriert, aber am gesuchten Tag", found.Topic);
    }

    [Fact]
    public void FindCandidates_LeerOhnePassendeStunde()
    {
        var lessons = new FakeLessons();
        var groupId = Guid.NewGuid();
        var date = new DateOnly(2026, 9, 8);

        var candidates = LessonFixItSearch.FindCandidates(lessons, groupId, date);

        Assert.Empty(candidates);
    }
}