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

namespace LehrerApp.Desktop.Tests;

/// Tests für den Schüler-Leistungsüberblick (Nutzer-Feedback): Klausuren/Mitarbeit/Sonstige
/// im Überblick, berechnete Zeugnisnote, Zielnoten- und Was-wäre-wenn-Rechner sowie der
/// Bewerter-/Schülermodus-Unterschied (Kursdurchschnitt, Bearbeitbarkeit).
public sealed class StudentPerformanceOverviewViewModelTests
{
    private static readonly Guid GroupId = Guid.NewGuid();
    private static readonly Guid StudentId = Guid.NewGuid();
    private static readonly Guid OtherStudentId = Guid.NewGuid();

    private static StudentPerformanceOverviewViewModel BuildViewModel(
        FakeExams? exams = null, FakeResults? results = null, FakeGrades? grades = null,
        FakeSchemes? schemes = null, GradingSystem system = GradingSystem.Grades1To6)
    {
        var scheme = new GradingScheme { ExamsPercent = 50, ParticipationPercent = 40, OtherPercent = 10 };
        var schemesRepo = schemes ?? new FakeSchemes();
        if (schemes is null) schemesRepo.SetForGroup(GroupId, scheme);

        return new StudentPerformanceOverviewViewModel(
            grades ?? new FakeGrades(), exams ?? new FakeExams([]), results ?? new FakeResults(),
            new FakeMemberships([]), schemesRepo, new GradingService(),
            GroupId, StudentId, GroupType.Class, system, "Beispiel, Anna", "Testkurs", "2025/26");
    }

    [Fact]
    public void ExamRows_ZeigtEigeneNoteUndKursdurchschnitt()
    {
        var exam = new Exam { Id = Guid.NewGuid(), GroupId = GroupId, Title = "K1", Date = new DateOnly(2025, 9, 10) };
        var exams = new FakeExams([exam]);
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = StudentId, Grade = "2" });
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = OtherStudentId, Grade = "4" });

        var vm = BuildViewModel(exams, results);

        var row = Assert.Single(vm.ExamRows);
        Assert.Equal("2", row.OwnGradeDisplay);
        Assert.Equal("3.0", row.ClassAverageDisplay);
    }

    [Fact]
    public void ExamHistory_ZeigtEigenenVerlaufUndMarkiertNotenabfall()
    {
        var exam1 = new Exam { Id = Guid.NewGuid(), GroupId = GroupId, Title = "K1", Date = new DateOnly(2025, 9, 10) };
        var exam2 = new Exam { Id = Guid.NewGuid(), GroupId = GroupId, Title = "K2", Date = new DateOnly(2025, 9, 24) };
        var exams = new FakeExams([exam1, exam2]);
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam1.Id, StudentId = StudentId, Grade = "2" });
        results.Add(new ExamResult { ExamId = exam2.Id, StudentId = StudentId, Grade = "5" }); // Abfall + mangelhaft

        var vm = BuildViewModel(exams, results);

        Assert.Equal(2, vm.ExamHistory.Points.Count);
        Assert.False(vm.ExamHistory.Points[0].IsWarning);
        Assert.True(vm.ExamHistory.Points[1].IsWarning);
        Assert.Contains("Abfall", vm.ExamHistory.Points[1].WarningText);
        Assert.Contains("Versetzungsgefährdung", vm.ExamHistory.Points[1].WarningText);
        Assert.True(vm.ExamHistory.Points[1].BarHeight < vm.ExamHistory.Points[0].BarHeight);
    }

    [Fact]
    public void AktuelleZeugnisnote_KombiniertAlleDreiBereiche()
    {
        var exam = new Exam { Id = Guid.NewGuid(), GroupId = GroupId, Title = "K1", Date = new DateOnly(2025, 9, 10) };
        var exams = new FakeExams([exam]);
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = StudentId, Grade = "2" });
        var grades = new FakeGrades();
        grades.Add(new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Participation,
            Date = new DateOnly(2025, 9, 5), Value = "3" });
        grades.Add(new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Other,
            Date = new DateOnly(2025, 9, 5), Value = "1" });

        var vm = BuildViewModel(exams, results, grades);

        // (2*50 + 3*40 + 1*10) / 100 = 2.3 -> kaufmännisch 2
        Assert.Equal("Note 2", vm.CurrentReportGradeDisplay);
    }

    [Fact]
    public void Zielnote_BerechnetNoetigenKlausurschnitt()
    {
        var grades = new FakeGrades();
        grades.Add(new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Participation,
            Date = new DateOnly(2025, 9, 5), Value = "3" });
        grades.Add(new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Other,
            Date = new DateOnly(2025, 9, 5), Value = "2" });
        var vm = BuildViewModel(grades: grades);

        vm.TargetGradeText = "2";
        vm.TargetBucketName = "Klausuren";

        // Ziel 2,0 = (x*50 + 3*40 + 2*10)/100 => 200 = 50x+120+20 => x = 1,2
        Assert.Contains("1.2", vm.TargetResultDisplay);
    }

    [Fact]
    public void WasWaereWenn_ZeigtZeugnisnoteMitZusaetzlicherKlausurAn()
    {
        var exam = new Exam { Id = Guid.NewGuid(), GroupId = GroupId, Title = "K1", Date = new DateOnly(2025, 9, 10) };
        var exams = new FakeExams([exam]);
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = StudentId, Grade = "2" });
        var grades = new FakeGrades();
        grades.Add(new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Participation,
            Date = new DateOnly(2025, 9, 5), Value = "2" });

        var vm = BuildViewModel(exams, results, grades);

        vm.WhatIfExamGradeText = "6";

        // Klausuren neu: (2+6)/2=4 (50%), Mitarbeit 2 (40%, Sonstige fehlt) -> (4*50+2*40)/90 = 3,11 -> kaufm. 3
        Assert.Contains("3", vm.WhatIfResultDisplay);
    }

    [Fact]
    public void SaveCommand_AufMitarbeitszeile_SpeichertUndAktualisiertDurchschnitt()
    {
        var grades = new FakeGrades();
        var grade = new Grade { StudentId = StudentId, GroupId = GroupId, Category = GradeCategory.Participation,
            Date = new DateOnly(2025, 9, 5), Value = "3" };
        grades.Add(grade);
        var vm = BuildViewModel(grades: grades);

        var row = Assert.Single(vm.ParticipationRows);
        row.Value = "1";
        row.SaveCommand.Execute(null);

        Assert.Equal("1.0", vm.ParticipationAverageDisplay);
        Assert.Equal("1", grades.GetByStudentAndGroup(StudentId, GroupId).Single().Value);
    }

    [Fact]
    public void OhneWerteImZeitraum_ZeigtHinweisStattZeugnisnote()
    {
        var vm = BuildViewModel();

        Assert.Contains("Noch nicht berechenbar", vm.CurrentReportGradeDisplay);
    }
}