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

namespace LehrerApp.Desktop.Tests;

public sealed class LessonSchedulingServiceTests
{
    [Fact]
    public void UnitPicker_SchlaegtLaufendeEinheitVor_UndSpeichertNeuanlageNochNicht()
    {
        var groupId = Guid.NewGuid();
        var planned = new Unit { GroupId = groupId, Title = "Später", Status = UnitStatus.Planned };
        var active = new Unit { GroupId = groupId, Title = "Aktuell", Status = UnitStatus.Active };
        var repo = new FakeUnits();
        repo.Add(planned); repo.Add(active);
        var vm = new TimetableUnitPickerViewModel(repo, groupId, "10c", new(2026, 9, 2), 3);

        Assert.Equal(active.Id, vm.SelectedUnit?.Model.Id);
        vm.NewUnitTitle = "Neue Reihe";
        vm.SaveCommand.Execute(null);

        Assert.True(vm.ResultIsNew);
        Assert.Equal("Neue Reihe", vm.Result?.Title);
        Assert.Null(repo.GetById(vm.Result!.Id));
    }

    [Fact]
    public void Move_AendertDatumUndStunde_UndRuecktNurNichtDurchgefuehrteFolgestundenNach()
    {
        var unitId = Guid.NewGuid();
        var groupId = Guid.NewGuid();
        var moved = new Lesson { UnitId = unitId, GroupId = groupId, Date = new(2026, 9, 1), LessonNumber = 2 };
        var draftFollowing = new Lesson { UnitId = unitId, GroupId = groupId, Date = new(2026, 9, 3), Status = LessonStatus.Draft };
        var conducted = new Lesson { UnitId = unitId, GroupId = groupId, Date = new(2026, 9, 4), Status = LessonStatus.Conducted };
        var repo = new FakeLessons();
        repo.Add(moved); repo.Add(draftFollowing); repo.Add(conducted);

        new LessonSchedulingService(repo).Move(moved, new(2026, 9, 8), 5, shiftFollowing: true);

        Assert.Equal(new DateOnly(2026, 9, 8), moved.Date);
        Assert.Equal(5, moved.LessonNumber);
        Assert.Equal(new DateOnly(2026, 9, 10), draftFollowing.Date);
        Assert.Equal(new DateOnly(2026, 9, 4), conducted.Date);
    }

    [Fact]
    public void Move_RuecktAuchAusgefalleneFolgestundenNichtNach()
    {
        var unitId = Guid.NewGuid();
        var groupId = Guid.NewGuid();
        var moved = new Lesson { UnitId = unitId, GroupId = groupId, Date = new(2026, 9, 1) };
        var cancelledFollowing = new Lesson { UnitId = unitId, GroupId = groupId, Date = new(2026, 9, 4), Status = LessonStatus.Cancelled };
        var repo = new FakeLessons();
        repo.Add(moved); repo.Add(cancelledFollowing);

        new LessonSchedulingService(repo).Move(moved, new(2026, 9, 8), null, shiftFollowing: true);

        Assert.Equal(new DateOnly(2026, 9, 4), cancelledFollowing.Date);
    }

    [Fact]
    public void SplitAndMoveSecondPart_AusgefalleneQuellstundeSetztFortsetzungAufEntwurfZurueck()
    {
        var source = new Lesson
        {
            UnitId = Guid.NewGuid(), GroupId = Guid.NewGuid(), Date = new(2026, 9, 1),
            Status = LessonStatus.Cancelled,
            Phases = [new LessonPhaseStep { Name = "Einstieg", DurationMinutes = 60 }],
        };
        var repo = new FakeLessons();
        repo.Add(source);

        var continuation = new LessonSchedulingService(repo).SplitAndMoveSecondPart(source, 30,
            new(2026, 9, 3), 1, null);

        Assert.Equal(LessonStatus.Draft, continuation.Status);
    }

    [Fact]
    public void SplitAndMoveSecondPart_TeiltAuchEineUeberDieGrenzeLaufendePhase()
    {
        var source = new Lesson
        {
            UnitId = Guid.NewGuid(), GroupId = Guid.NewGuid(), Date = new(2026, 9, 1),
            LessonNumber = 3, Topic = "Fotosynthese", Homework = "Aufgabe 2",
            Phases =
            [
                new LessonPhaseStep { Name = "Einstieg", DurationMinutes = 30 },
                new LessonPhaseStep { Name = "Experiment", DurationMinutes = 30 },
                new LessonPhaseStep { Name = "Sicherung", DurationMinutes = 20 },
            ],
        };
        var repo = new FakeLessons();
        repo.Add(source);

        var continuation = new LessonSchedulingService(repo).SplitAndMoveSecondPart(source, 45,
            new(2026, 9, 3), 6, new TimeOnly(12, 15));

        Assert.Equal([30, 15], source.Phases.Select(p => p.DurationMinutes));
        Assert.Equal([15, 20], continuation.Phases.Select(p => p.DurationMinutes));
        Assert.Equal("Fotosynthese – Fortsetzung", continuation.Topic);
        Assert.Null(source.Homework);
        Assert.Equal("Aufgabe 2", continuation.Homework);
        Assert.Equal(6, continuation.LessonNumber);
    }

    [Fact]
    public void Move_LehntBelegtenZielterminAb()
    {
        var groupId = Guid.NewGuid();
        var source = new Lesson { GroupId = groupId, Date = new(2026, 9, 1), LessonNumber = 1 };
        var occupied = new Lesson { GroupId = groupId, Date = new(2026, 9, 2), LessonNumber = 4 };
        var repo = new FakeLessons();
        repo.Add(source); repo.Add(occupied);

        var error = Assert.Throws<InvalidOperationException>(() =>
            new LessonSchedulingService(repo).Move(source, occupied.Date, 4, false));

        Assert.Contains("bereits eine Planung", error.Message);
    }
}