using LehrerApp.Core.Models;
using LehrerApp.Desktop.Services.Mcp;
using LehrerApp.Desktop.Services.Mcp.Tools;
using Xunit;

namespace LehrerApp.Desktop.Tests;

public sealed class McpToolsTests
{
    // ── McpToolScope ─────────────────────────────────────────────────────────────────────────

    [Fact]
    public void AllowedReadTools_EnthaeltGenauDieErwartetenReadTools()
    {
        Assert.Equal(
            new[]
            {
                "download_lesson_attachment", "get_exams", "get_grades", "get_lesson_plans",
                "get_schedule", "get_students", "get_time_entries",
            },
            McpToolScope.AllowedReadTools.OrderBy(n => n, StringComparer.Ordinal));
    }

    [Fact]
    public void AllowedWriteTools_EnthaeltGenauDieErwartetenWriteTools()
    {
        Assert.Equal(
            new[]
            {
                "add_lesson_phase", "create_grade_entry", "create_lesson", "create_time_entry",
                "create_unit", "remove_lesson_phase", "update_lesson", "update_lesson_phase",
                "update_student_group_assignment", "update_unit",
            },
            McpToolScope.AllowedWriteTools.OrderBy(n => n, StringComparer.Ordinal));
    }

    [Fact]
    public void AllowedTools_EnthaeltKeineDokumentationstypen()
    {
        // Gesprächsnotizen/Vorfälle/Förderpläne dürfen technisch nie über MCP erreichbar sein
        // (siehe Planungsdokument) - die Namenskonvention "documentation"/"vorgang" darf nie auftauchen.
        var allNames = McpToolScope.AllowedReadTools.Concat(McpToolScope.AllowedWriteTools);
        Assert.DoesNotContain(allNames, n =>
            n.Contains("documentation", StringComparison.OrdinalIgnoreCase) ||
            n.Contains("vorgang", StringComparison.OrdinalIgnoreCase) ||
            n.Contains("note", StringComparison.OrdinalIgnoreCase));
    }

    // ── StudentTools ─────────────────────────────────────────────────────────────────────────

    [Fact]
    public void GetStudents_OhneFilter_LiefertNurAktiveSchueler()
    {
        var active = new Student { FirstName = "Anna", LastName = "Aktiv", IsActive = true };
        var inactive = new Student { FirstName = "Ida", LastName = "Inaktiv", IsActive = false };
        var tool = new StudentTools(new FakeStudents([active, inactive]));

        var result = tool.GetStudents();

        Assert.Single(result);
        Assert.Equal(active.Id, result[0].Id);
    }

    [Fact]
    public void GetStudents_IncludeInactive_LiefertAuchInaktive()
    {
        var active = new Student { FirstName = "Anna", LastName = "Aktiv", IsActive = true };
        var inactive = new Student { FirstName = "Ida", LastName = "Inaktiv", IsActive = false };
        var tool = new StudentTools(new FakeStudents([active, inactive]));

        var result = tool.GetStudents(includeInactive: true);

        Assert.Equal(2, result.Count);
    }

    // ── ExamTools ────────────────────────────────────────────────────────────────────────────

    [Fact]
    public void GetExams_OhneIncludeResults_LiefertKeineErgebnisse()
    {
        var groupId = Guid.NewGuid();
        var exam = new Exam { GroupId = groupId, Title = "Klausur 1" };
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = Guid.NewGuid(), TotalPoints = 10 });
        var tool = new ExamTools(new FakeExams([exam]), results);

        var dto = Assert.Single(tool.GetExams(groupId));

        Assert.Null(dto.Results);
    }

    [Fact]
    public void GetExams_MitIncludeResults_LiefertErgebnisseJeSchueler()
    {
        var groupId = Guid.NewGuid();
        var studentId = Guid.NewGuid();
        var exam = new Exam { GroupId = groupId, Title = "Klausur 1" };
        var results = new FakeResults();
        results.Add(new ExamResult { ExamId = exam.Id, StudentId = studentId, TotalPoints = 12.5, Grade = "2+" });
        var tool = new ExamTools(new FakeExams([exam]), results);

        var dto = Assert.Single(tool.GetExams(groupId, includeResults: true));

        var result = Assert.Single(dto.Results!);
        Assert.Equal(studentId, result.StudentId);
        Assert.Equal("2+", result.Grade);
    }

    // ── GradeTools ───────────────────────────────────────────────────────────────────────────

    [Fact]
    public void GetGrades_MitStudentId_FiltertAufEinenSchueler()
    {
        var groupId = Guid.NewGuid();
        var studentA = Guid.NewGuid();
        var studentB = Guid.NewGuid();
        var grades = new FakeGrades();
        grades.Add(new Grade { GroupId = groupId, StudentId = studentA, Value = "2" });
        grades.Add(new Grade { GroupId = groupId, StudentId = studentB, Value = "3" });
        var tool = new GradeTools(grades, new FakeStudents([]), new FakeMcpConfirmation());

        var dto = Assert.Single(tool.GetGrades(groupId, studentA));

        Assert.Equal(studentA, dto.StudentId);
    }

    [Fact]
    public async Task CreateGradeEntry_NutzerBestaetigt_SpeichertNote()
    {
        var student = new Student { FirstName = "Anna", LastName = "Aktiv" };
        var grades = new FakeGrades();
        var confirmation = new FakeMcpConfirmation { Response = true };
        var tool = new GradeTools(grades, new FakeStudents([student]), confirmation);
        var groupId = Guid.NewGuid();

        var result = await tool.CreateGradeEntry(
            student.Id, groupId, GradeCategory.Oral, "2+", new DateOnly(2026, 1, 10));

        Assert.True(result.Applied);
        Assert.NotNull(result.Id);
        Assert.Single(grades.GetByGroup(groupId));
        // Bestätigungstext muss für einen Menschen lesbar sein (Name statt bloßer GUID).
        Assert.Contains("Anna", confirmation.LastMessage);
        Assert.DoesNotContain(student.Id.ToString(), confirmation.LastMessage);
    }

    [Fact]
    public async Task CreateGradeEntry_NutzerLehntAb_SpeichertNichts()
    {
        var student = new Student { FirstName = "Anna", LastName = "Aktiv" };
        var grades = new FakeGrades();
        var confirmation = new FakeMcpConfirmation { Response = false };
        var tool = new GradeTools(grades, new FakeStudents([student]), confirmation);
        var groupId = Guid.NewGuid();

        var result = await tool.CreateGradeEntry(
            student.Id, groupId, GradeCategory.Oral, "2+", new DateOnly(2026, 1, 10));

        Assert.False(result.Applied);
        Assert.Empty(grades.GetByGroup(groupId));
        Assert.Equal(1, confirmation.CallCount);
    }

    // ── ScheduleTools ────────────────────────────────────────────────────────────────────────

    [Fact]
    public void GetSchedule_MitGroupId_FiltertNachGruppe()
    {
        var groupId = Guid.NewGuid();
        var slots = new FakeTimetableSlots();
        slots.Add(new TimetableSlot { GroupId = groupId, Weekday = DayOfWeek.Monday, PeriodNumber = 1 });
        slots.Add(new TimetableSlot { GroupId = Guid.NewGuid(), Weekday = DayOfWeek.Tuesday, PeriodNumber = 2 });
        var tool = new ScheduleTools(slots);

        var dto = Assert.Single(tool.GetSchedule(groupId));

        Assert.Equal(groupId, dto.GroupId);
    }

    // ── TimeEntryTools ───────────────────────────────────────────────────────────────────────

    [Fact]
    public void GetTimeEntries_FiltertAufDenAngegebenenZeitraum()
    {
        var entries = new FakeTimeEntries();
        entries.Add(new TimeEntry { Date = new DateOnly(2026, 1, 5), DurationMinutes = 30 });
        entries.Add(new TimeEntry { Date = new DateOnly(2026, 2, 1), DurationMinutes = 45 });
        var tool = new TimeEntryTools(entries, new FakeGroups([]), new FakeMcpConfirmation());

        var dto = Assert.Single(tool.GetTimeEntries(new DateOnly(2026, 1, 1), new DateOnly(2026, 1, 31)));

        Assert.Equal(30, dto.DurationMinutes);
    }

    [Fact]
    public async Task CreateTimeEntry_NutzerBestaetigt_SpeichertEintrag()
    {
        var entries = new FakeTimeEntries();
        var confirmation = new FakeMcpConfirmation { Response = true };
        var tool = new TimeEntryTools(entries, new FakeGroups([]), confirmation);

        var result = await tool.CreateTimeEntry("Korrektur", new DateOnly(2026, 1, 10), 30);

        Assert.True(result.Applied);
        Assert.Single(entries.GetByDateRange(new DateOnly(2026, 1, 1), new DateOnly(2026, 1, 31)));
    }

    [Fact]
    public async Task CreateTimeEntry_NutzerLehntAb_SpeichertNichts()
    {
        var entries = new FakeTimeEntries();
        var confirmation = new FakeMcpConfirmation { Response = false };
        var tool = new TimeEntryTools(entries, new FakeGroups([]), confirmation);

        var result = await tool.CreateTimeEntry("Korrektur", new DateOnly(2026, 1, 10), 30);

        Assert.False(result.Applied);
        Assert.Empty(entries.GetByDateRange(new DateOnly(2026, 1, 1), new DateOnly(2026, 1, 31)));
    }

    // ── LessonPlanTools ──────────────────────────────────────────────────────────────────────

    private static LessonPlanTools BuildLessonPlanTools(
        FakeUnits? units = null, FakeLessons? lessons = null, FakeGroups? groups = null,
        FakeAttachmentStorage? attachments = null, FakeMcpConfirmation? confirmation = null) =>
        new(units ?? new FakeUnits(), lessons ?? new FakeLessons(), groups ?? new FakeGroups([]),
            attachments ?? new FakeAttachmentStorage(), confirmation ?? new FakeMcpConfirmation());

    [Fact]
    public void GetLessonPlans_LiefertEinheitenDerGruppeUndStundenImZeitraum()
    {
        var groupId = Guid.NewGuid();
        var units = new FakeUnits();
        units.Add(new Unit { GroupId = groupId, Title = "Optik" });
        var lessons = new FakeLessons();
        lessons.Add(new Lesson { GroupId = groupId, Date = new DateOnly(2026, 1, 5), Topic = "Brechung" });
        lessons.Add(new Lesson { GroupId = groupId, Date = new DateOnly(2026, 3, 1), Topic = "Später" });
        var tool = BuildLessonPlanTools(units, lessons);

        var result = tool.GetLessonPlans(groupId, new DateOnly(2026, 1, 1), new DateOnly(2026, 1, 31));

        Assert.Single(result.Units);
        var lesson = Assert.Single(result.Lessons);
        Assert.Equal("Brechung", lesson.Topic);
    }

    [Fact]
    public async Task CreateUnit_NutzerBestaetigt_SpeichertEinheit()
    {
        var group = new LearningGroup { Name = "7a" };
        var units = new FakeUnits();
        var tool = BuildLessonPlanTools(units: units, groups: new FakeGroups([group]));

        var result = await tool.CreateUnit(group.Id, "Optik");

        Assert.True(result.Applied);
        Assert.Single(units.GetByGroup(group.Id));
    }

    [Fact]
    public async Task UpdateUnit_OhneAenderung_FragtNichtNach()
    {
        var unit = new Unit { Title = "Optik", Status = UnitStatus.Planned };
        var units = new FakeUnits();
        units.Add(unit);
        var confirmation = new FakeMcpConfirmation();
        var tool = BuildLessonPlanTools(units: units, confirmation: confirmation);

        var result = await tool.UpdateUnit(unit.Id, title: "Optik", status: UnitStatus.Planned);

        Assert.True(result.Applied);
        Assert.Equal(0, confirmation.CallCount);
    }

    [Fact]
    public async Task CreateLesson_UnbekannteEinheit_LiefertFehlerOhneNachfrage()
    {
        var confirmation = new FakeMcpConfirmation();
        var tool = BuildLessonPlanTools(confirmation: confirmation);

        var result = await tool.CreateLesson(Guid.NewGuid(), new DateOnly(2026, 1, 5), "Brechung");

        Assert.False(result.Applied);
        Assert.Equal(0, confirmation.CallCount);
    }

    [Fact]
    public async Task CreateLesson_NutzerBestaetigt_UebernimmtGruppeVonDerEinheit()
    {
        var groupId = Guid.NewGuid();
        var unit = new Unit { GroupId = groupId, Title = "Optik" };
        var units = new FakeUnits();
        units.Add(unit);
        var lessons = new FakeLessons();
        var tool = BuildLessonPlanTools(units, lessons);

        var result = await tool.CreateLesson(unit.Id, new DateOnly(2026, 1, 5), "Brechung");

        Assert.True(result.Applied);
        var lesson = Assert.Single(lessons.GetByUnit(unit.Id));
        Assert.Equal(groupId, lesson.GroupId);
    }

    [Fact]
    public async Task UpdateLesson_AendertNurAngegebeneFelder()
    {
        var lesson = new Lesson { Topic = "Brechung", Homework = "S. 12" };
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons);

        var result = await tool.UpdateLesson(lesson.Id, topic: "Brechung II");

        Assert.True(result.Applied);
        var updated = lessons.GetById(lesson.Id)!;
        Assert.Equal("Brechung II", updated.Topic);
        Assert.Equal("S. 12", updated.Homework);
    }

    [Fact]
    public async Task AddLessonPhase_NutzerBestaetigt_HaengtPhaseAn()
    {
        var lesson = new Lesson { Topic = "Brechung" };
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons);

        var result = await tool.AddLessonPhase(lesson.Id, "Einstieg", 10);

        Assert.True(result.Applied);
        var phase = Assert.Single(lessons.GetById(lesson.Id)!.Phases);
        Assert.Equal("Einstieg", phase.Name);
        Assert.Equal(result.Id, phase.Id);
    }

    [Fact]
    public async Task UpdateLessonPhase_AendertNurAngegebeneFelder()
    {
        var phase = new LessonPhaseStep { Name = "Einstieg", DurationMinutes = 10, Material = "Folie" };
        var lesson = new Lesson { Topic = "Brechung" };
        lesson.Phases.Add(phase);
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons);

        var result = await tool.UpdateLessonPhase(lesson.Id, phase.Id, durationMinutes: 15);

        Assert.True(result.Applied);
        var updated = lessons.GetById(lesson.Id)!.Phases.Single();
        Assert.Equal(15, updated.DurationMinutes);
        Assert.Equal("Folie", updated.Material);
    }

    [Fact]
    public async Task RemoveLessonPhase_NutzerBestaetigt_EntferntPhase()
    {
        var phase = new LessonPhaseStep { Name = "Einstieg", DurationMinutes = 10 };
        var lesson = new Lesson { Topic = "Brechung" };
        lesson.Phases.Add(phase);
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons);

        var result = await tool.RemoveLessonPhase(lesson.Id, phase.Id);

        Assert.True(result.Applied);
        Assert.Empty(lessons.GetById(lesson.Id)!.Phases);
    }

    [Fact]
    public void DownloadLessonAttachment_LiefertBase64Inhalt()
    {
        var storage = new FakeAttachmentStorage();
        var storageId = storage.Upload("blatt.pdf", new MemoryStream("PDF-Inhalt"u8.ToArray()));
        var lesson = new Lesson { Topic = "Brechung" };
        lesson.Attachments.Add(new DocumentAttachment { StorageId = storageId, FileName = "blatt.pdf", SizeBytes = 10 });
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons, attachments: storage);

        var result = tool.DownloadLessonAttachment(lesson.Id, storageId);

        Assert.Equal("blatt.pdf", result.FileName);
        Assert.Equal("PDF-Inhalt", System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(result.Base64Content)));
    }

    [Fact]
    public void DownloadLessonAttachment_ZuGross_WirftFehler()
    {
        var lesson = new Lesson { Topic = "Brechung" };
        lesson.Attachments.Add(new DocumentAttachment
        {
            StorageId = "big", FileName = "video.mp4", SizeBytes = LessonPlanTools.MaxInlineAttachmentBytes + 1,
        });
        var lessons = new FakeLessons();
        lessons.Add(lesson);
        var tool = BuildLessonPlanTools(lessons: lessons);

        Assert.Throws<InvalidOperationException>(() => tool.DownloadLessonAttachment(lesson.Id, "big"));
    }

    // ── GroupMembershipTools ─────────────────────────────────────────────────────────────────

    [Fact]
    public async Task UpdateStudentGroupAssignment_KeineBestehendeMitgliedschaft_LegtNeueAn()
    {
        var student = new Student { FirstName = "Anna", LastName = "Aktiv" };
        var group = new LearningGroup { Name = "7a" };
        var memberships = new FakeMemberships([]);
        var confirmation = new FakeMcpConfirmation { Response = true };
        var tool = new GroupMembershipTools(memberships, new FakeStudents([student]), new FakeGroups([group]), confirmation);

        var result = await tool.UpdateStudentGroupAssignment(student.Id, group.Id, niveau: Niveau.E);

        Assert.True(result.Applied);
        var membership = Assert.Single(memberships.GetByStudent(student.Id));
        Assert.Equal(Niveau.E, membership.Niveau);
        Assert.Contains("Anna", confirmation.LastMessage);
    }

    [Fact]
    public async Task UpdateStudentGroupAssignment_BestehendeMitgliedschaftUnveraendert_FragtNichtNochmalNach()
    {
        var student = new Student { FirstName = "Anna", LastName = "Aktiv" };
        var group = new LearningGroup { Name = "7a" };
        var existing = new GroupMembership { StudentId = student.Id, GroupId = group.Id, Niveau = Niveau.G };
        var memberships = new FakeMemberships([existing]);
        var confirmation = new FakeMcpConfirmation { Response = true };
        var tool = new GroupMembershipTools(memberships, new FakeStudents([student]), new FakeGroups([group]), confirmation);

        var result = await tool.UpdateStudentGroupAssignment(student.Id, group.Id, niveau: Niveau.G);

        Assert.True(result.Applied);
        Assert.Equal(0, confirmation.CallCount);
    }

    [Fact]
    public async Task UpdateStudentGroupAssignment_UnbekannterSchueler_LiefertFehlerOhneNachfrage()
    {
        var group = new LearningGroup { Name = "7a" };
        var confirmation = new FakeMcpConfirmation { Response = true };
        var tool = new GroupMembershipTools(new FakeMemberships([]), new FakeStudents([]), new FakeGroups([group]), confirmation);

        var result = await tool.UpdateStudentGroupAssignment(Guid.NewGuid(), group.Id);

        Assert.False(result.Applied);
        Assert.Equal(0, confirmation.CallCount);
    }
}