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

namespace LehrerApp.Desktop.Tests;

public sealed class SubstitutionEntryDialogViewModelTests
{
    private static SubstitutionEntryDialogViewModel BuildVm(
        FakeSubstitutionEntries? substitutions = null, FakeGroups? groups = null,
        FakeUnits? units = null, FakeLessons? lessons = null) =>
        new(substitutions ?? new FakeSubstitutionEntries(), groups ?? new FakeGroups([]),
            units ?? new FakeUnits(), lessons ?? new FakeLessons());

    [Fact]
    public void Save_Aufsicht_GueltigeEingabe_ErzeugtSupervisionEntry()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Aufsicht";
        vm.AfterPeriod = 2;
        vm.Description = "Vertretung für Hr. Müller";

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        var saved = Assert.Single(substitutions.GetAll());
        Assert.Equal(SubstitutionKind.Supervision, saved.Kind);
        Assert.Equal(2, saved.AfterPeriod);
        Assert.Equal("Vertretung für Hr. Müller", saved.Description);
    }

    [Fact]
    public void Save_Aufsicht_FehlenderGrund_SetztFehlerUndSpeichertNicht()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Aufsicht";
        vm.AfterPeriod = 2;

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.Empty(substitutions.GetAll());
        Assert.NotEqual("", vm.ValidationError);
    }

    [Fact]
    public void Save_Stunde_FremdeGruppe_ErzeugtEintragOhneGroupId()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Stunde";
        vm.PeriodNumber = 3;
        vm.GroupLabel = "8a";
        vm.Description = "Vertretung Erdkunde";

        vm.SaveCommand.Execute(null);

        var saved = Assert.Single(substitutions.GetAll());
        Assert.Null(saved.GroupId);
        Assert.Equal("8a", saved.GroupLabel);
        Assert.Equal(SubstitutionKind.Lesson, saved.Kind);
    }

    [Fact]
    public void Save_Stunde_EigeneGruppeOhnePromote_ErzeugtKeineLesson()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var unit = new Unit { GroupId = group.Id, Title = "Optik" };
        var units = new FakeUnits(); units.Add(unit);
        var lessons = new FakeLessons();
        var vm = BuildVm(groups: new FakeGroups([group]), units: units, lessons: lessons);
        vm.DateText = "12.03.2026";
        vm.KindName = "Stunde";
        vm.PeriodNumber = 3;
        vm.SelectedOwnGroup = group;
        vm.Description = "Stillarbeit";

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Empty(lessons.GetByUnit(unit.Id));
    }

    [Fact]
    public void Save_Stunde_EigeneGruppeMitPromote_ErzeugtZusaetzlichLesson()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var unit = new Unit { GroupId = group.Id, Title = "Optik" };
        var units = new FakeUnits(); units.Add(unit);
        var lessons = new FakeLessons();
        var vm = BuildVm(groups: new FakeGroups([group]), units: units, lessons: lessons);
        vm.DateText = "12.03.2026";
        vm.KindName = "Stunde";
        vm.PeriodNumber = 3;
        vm.SelectedOwnGroup = group; // füllt UnitsOfSelectedGroup + SelectedUnit
        vm.Description = "Brechung (vorgezogen)";
        vm.PromoteToLesson = true;

        vm.SaveCommand.Execute(null);

        var lesson = Assert.Single(lessons.GetByUnit(unit.Id));
        Assert.Equal(group.Id, lesson.GroupId);
        Assert.Equal(3, lesson.LessonNumber);
        Assert.Equal("Brechung (vorgezogen)", lesson.Topic);
        Assert.Equal(new DateOnly(2026, 3, 12), lesson.Date);
    }

    [Fact]
    public void SelectedOwnGroupChanged_FuelltGroupLabelUndEinheitenListe()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var unit = new Unit { GroupId = group.Id, Title = "Optik" };
        var units = new FakeUnits(); units.Add(unit);
        var vm = BuildVm(groups: new FakeGroups([group]), units: units);

        vm.SelectedOwnGroup = group;

        Assert.Equal("Q1 Chemie", vm.GroupLabel);
        Assert.Single(vm.UnitsOfSelectedGroup);
        Assert.Equal(unit.Id, vm.SelectedUnit!.Id);
    }

    [Fact]
    public void CanPromoteToLesson_FalseWennGruppeKeineEinheitenHat()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var vm = BuildVm(groups: new FakeGroups([group]));
        vm.KindName = "Stunde";

        vm.SelectedOwnGroup = group;

        Assert.False(vm.CanPromoteToLesson);
    }

    [Fact]
    public void Save_UngueltigesDatum_SetztFehler()
    {
        var vm = BuildVm();
        vm.DateText = "keinDatum";
        vm.KindName = "Aufsicht";
        vm.Description = "x";

        vm.SaveCommand.Execute(null);

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

    // ── Sondereinsatz ─────────────────────────────────────────────────────────

    [Fact]
    public void Save_Sondereinsatz_Ganztaegig_ErzeugtEintragOhneStundenbereich()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Sondereinsatz";
        vm.IsAllDay = true;
        vm.Description = "Ausflug ins Museum";

        vm.SaveCommand.Execute(null);

        var saved = Assert.Single(substitutions.GetAll());
        Assert.Equal(SubstitutionKind.SpecialAssignment, saved.Kind);
        Assert.True(saved.IsAllDay);
        Assert.Null(saved.FromPeriod);
        Assert.Null(saved.ToPeriod);
    }

    [Fact]
    public void Save_Sondereinsatz_MitStundenbereich_SpeichertVonBis()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Sondereinsatz";
        vm.IsAllDay = false;
        vm.FromPeriod = 3;
        vm.ToPeriod = 4;
        vm.Description = "Berufsmesse";

        vm.SaveCommand.Execute(null);

        var saved = Assert.Single(substitutions.GetAll());
        Assert.False(saved.IsAllDay);
        Assert.Equal(3, saved.FromPeriod);
        Assert.Equal(4, saved.ToPeriod);
    }

    [Fact]
    public void Save_Sondereinsatz_BisVorVon_SetztFehler()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Sondereinsatz";
        vm.IsAllDay = false;
        vm.FromPeriod = 5;
        vm.ToPeriod = 2;
        vm.Description = "Berufsmesse";

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.Empty(substitutions.GetAll());
        Assert.NotEqual("", vm.ValidationError);
    }

    [Fact]
    public void Save_Sondereinsatz_OhneBeschreibung_SetztFehler()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Sondereinsatz";

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.Empty(substitutions.GetAll());
        Assert.NotEqual("", vm.ValidationError);
    }

    [Fact]
    public void Save_Sondereinsatz_OhneGruppe_SpeichertLeeresGroupLabel()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Sondereinsatz";
        vm.Description = "Berufsmesse";

        vm.SaveCommand.Execute(null);

        var saved = Assert.Single(substitutions.GetAll());
        Assert.Null(saved.GroupId);
        Assert.Equal("", saved.GroupLabel);
    }

    [Fact]
    public void CanPromoteToLesson_FalseFuerSondereinsatz()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var unit = new Unit { GroupId = group.Id, Title = "Optik" };
        var units = new FakeUnits(); units.Add(unit);
        var vm = BuildVm(groups: new FakeGroups([group]), units: units);
        vm.KindName = "Sondereinsatz";

        vm.SelectedOwnGroup = group;

        Assert.False(vm.CanPromoteToLesson);
    }

    // ── Ausfall ───────────────────────────────────────────────────────────────

    [Fact]
    public void Save_Ausfall_GueltigeEingabe_ErzeugtEintragMitPeriodeUndGrund()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Ausfall";
        vm.PeriodNumber = 2;
        vm.Description = "6a auf Klassenfahrt";

        vm.SaveCommand.Execute(null);

        var saved = Assert.Single(substitutions.GetAll());
        Assert.Equal(SubstitutionKind.Cancelled, saved.Kind);
        Assert.Equal(2, saved.PeriodNumber);
        Assert.Equal("6a auf Klassenfahrt", saved.Description);
    }

    [Fact]
    public void Save_Ausfall_OhneGrund_IstErlaubt()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Ausfall";
        vm.PeriodNumber = 2;

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Single(substitutions.GetAll());
    }

    [Fact]
    public void Save_Ausfall_UngueltigePeriode_SetztFehler()
    {
        var substitutions = new FakeSubstitutionEntries();
        var vm = BuildVm(substitutions);
        vm.DateText = "12.03.2026";
        vm.KindName = "Ausfall";
        vm.PeriodNumber = 11;

        vm.SaveCommand.Execute(null);

        Assert.Null(vm.Result);
        Assert.Empty(substitutions.GetAll());
        Assert.NotEqual("", vm.ValidationError);
    }

    [Fact]
    public void CanPromoteToLesson_FalseFuerAusfall()
    {
        var group = new LearningGroup { Name = "Q1 Chemie" };
        var unit = new Unit { GroupId = group.Id, Title = "Optik" };
        var units = new FakeUnits(); units.Add(unit);
        var vm = BuildVm(groups: new FakeGroups([group]), units: units);
        vm.KindName = "Ausfall";

        vm.SelectedOwnGroup = group;

        Assert.False(vm.CanPromoteToLesson);
    }
}