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

namespace LehrerApp.Desktop.Tests;

/// Tests für die Serienerzeugung von Stunden aus dem Stundenplan (4.2.5).
public sealed class GenerateLessonSeriesDialogViewModelTests
{
    private static GenerateLessonSeriesDialogViewModel BuildVm(FakeTimetableSlots slots, FakeLessons lessons,
        FakeSchoolHolidays holidays, Guid unitId, Guid groupId, DateOnly? from = null, DateOnly? to = null)
    {
        // Bewusst kein "using": SchoolCalendarSettingsService liest den Pfad nur bei Bedarf.
        var tempPath = System.IO.Path.Combine(
            System.IO.Path.GetTempPath(), $"lehrerapp-lessonseries-tests-{Guid.NewGuid():N}");
        Directory.CreateDirectory(tempPath);

        var vm = new GenerateLessonSeriesDialogViewModel(slots, lessons, holidays,
            new PublicHolidayService(), new SchoolCalendarSettingsService(tempPath), unitId, groupId, null, null);
        if (from is not null) vm.FromDateText = from.Value.ToString("dd.MM.yyyy");
        if (to is not null) vm.ToDateText = to.Value.ToString("dd.MM.yyyy");
        return vm;
    }

    [Fact]
    public void Save_ErzeugtStundeProVorkommenDesWochentagsImZeitraum()
    {
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var to = from.AddDays(13); // deckt zwei Vorkommen des Wochentags von "from" ab (Tag 0 und 7)
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 1 });
        var lessons = new FakeLessons();
        var vm = BuildVm(slots, lessons, new FakeSchoolHolidays(), unitId, groupId, from, to);

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Equal(2, vm.Result!.Created);
        Assert.Equal(0, vm.Result.SkippedHoliday);
        Assert.Equal(0, vm.Result.SkippedExisting);
        Assert.All(lessons.GetByGroupAndRange(groupId, from, to), l => Assert.Equal(unitId, l.UnitId));
    }

    [Fact]
    public void Save_UeberspringtTerminInSchulferien()
    {
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var to = from.AddDays(13);
        var secondOccurrence = from.AddDays(7);
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 1 });
        var holidays = new FakeSchoolHolidays();
        holidays.Add(new SchoolHoliday { Name = "Ferien", StartDate = secondOccurrence, EndDate = secondOccurrence.AddDays(3) });
        var vm = BuildVm(slots, new FakeLessons(), holidays, unitId, groupId, from, to);

        vm.SaveCommand.Execute(null);

        Assert.Equal(1, vm.Result!.Created);
        Assert.Equal(1, vm.Result.SkippedHoliday);
    }

    [Fact]
    public void Save_UeberspringtBereitsVorhandeneStundeAmSelbenDatumUndPeriode()
    {
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var to = from.AddDays(13);
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 1 });
        var lessons = new FakeLessons();
        lessons.Add(new Lesson { UnitId = Guid.NewGuid(), GroupId = groupId, Date = from, LessonNumber = 1, Topic = "Bestehend" });
        var vm = BuildVm(slots, lessons, new FakeSchoolHolidays(), unitId, groupId, from, to);

        vm.SaveCommand.Execute(null);

        Assert.Equal(1, vm.Result!.Created);
        Assert.Equal(1, vm.Result.SkippedExisting);
        Assert.Equal(2, lessons.GetByGroupAndRange(groupId, from, to).Count); // 1 alt + 1 neu
    }

    [Fact]
    public void Save_Doppelstunde_ErzeugtNurEineStundeVerankertAnDerErstenPeriode()
    {
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 3 });
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 4 });
        var lessons = new FakeLessons();
        var vm = BuildVm(slots, lessons, new FakeSchoolHolidays(), unitId, groupId, from, from);

        vm.SaveCommand.Execute(null);

        Assert.Equal(1, vm.Result!.Created);
        var created = lessons.GetByGroupAndRange(groupId, from, from).Select(l => l.LessonNumber).ToList();
        Assert.Equal([3], created);
    }

    [Fact]
    public void Save_Dreifachstunde_ErzeugtNurEineStundeVerankertAnDerErstenPeriode()
    {
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 3 });
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 4 });
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 5 });
        var lessons = new FakeLessons();
        var vm = BuildVm(slots, lessons, new FakeSchoolHolidays(), unitId, groupId, from, from);

        vm.SaveCommand.Execute(null);

        Assert.Equal(1, vm.Result!.Created);
        var created = lessons.GetByGroupAndRange(groupId, from, from).Select(l => l.LessonNumber).ToList();
        Assert.Equal([3], created);
    }

    [Fact]
    public void Save_ZweiGetrennteEinzelstundenAmSelbenTagBleibenGetrennt()
    {
        // Perioden 1 und 3 sind NICHT aufeinanderfolgend (Periode 2 fehlt) — keine Doppelstunde,
        // beide bekommen eine eigene Lesson.
        var groupId = Guid.NewGuid();
        var unitId = Guid.NewGuid();
        var from = new DateOnly(2025, 9, 1);
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 1 });
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = from.DayOfWeek, PeriodNumber = 3 });
        var lessons = new FakeLessons();
        var vm = BuildVm(slots, lessons, new FakeSchoolHolidays(), unitId, groupId, from, from);

        vm.SaveCommand.Execute(null);

        Assert.Equal(2, vm.Result!.Created);
        var created = lessons.GetByGroupAndRange(groupId, from, from).Select(l => l.LessonNumber).OrderBy(n => n).ToList();
        Assert.Equal([1, 3], created);
    }

    [Fact]
    public void Save_OhneStundenplanEintrag_SetztFehlerUndErzeugtNichts()
    {
        var groupId = Guid.NewGuid();
        var vm = BuildVm(new FakeTimetableSlots(), new FakeLessons(), new FakeSchoolHolidays(), Guid.NewGuid(), groupId,
            new DateOnly(2025, 9, 1), new DateOnly(2025, 9, 14));

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.NotEqual("", vm.DateError);
    }

    [Fact]
    public void Save_UngueltigesDatumsformat_SetztFehler()
    {
        var vm = BuildVm(new FakeTimetableSlots(), new FakeLessons(), new FakeSchoolHolidays(), Guid.NewGuid(), Guid.NewGuid());
        vm.FromDateText = "keinDatum";

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.NotEqual("", vm.DateError);
    }

    [Fact]
    public void Save_EndeVorBeginn_SetztFehler()
    {
        var vm = BuildVm(new FakeTimetableSlots(), new FakeLessons(), new FakeSchoolHolidays(), Guid.NewGuid(), Guid.NewGuid(),
            new DateOnly(2025, 9, 10), new DateOnly(2025, 9, 1));

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.NotEqual("", vm.DateError);
    }
}