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

namespace LehrerApp.Desktop.Tests;

public sealed class DocumentationDialogViewModelTests
{
    [Fact]
    public void Save_ContentIstNull_WirftNichtUndSpeichertLeerenText()
    {
        // Regression: Avalonias TextBox.Text kann beim vollständigen Leeren des Felds über das
        // Zwei-Wege-Binding null statt "" liefern (beobachtet bei einem Fehlzeit-Eintrag ohne
        // Beschreibung) — Content.Trim() ohne Null-Schutz warf eine NullReferenceException.
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage())
        {
            Title = "Fehlt am Montag", TypeName = "Fehlzeit", Content = null!,
        };

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Equal("", vm.Result!.Content);
    }

    [Fact]
    public void Save_ElternbriefFelderSindNull_WirftNichtUndSpeichertLeerenText()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage())
        {
            Title = "Brief", TypeName = "Elternbrief",
            LetterDraftContent = null!, LetterResponseNote = null!,
        };

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Equal("", vm.Result!.ParentLetterData!.DraftContent);
        Assert.Equal("", vm.Result.ParentLetterData.ResponseNote);
    }

    [Fact]
    public void AddTag_NewTagIstNull_WirftNichtUndFuegtNichtsHinzu()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage())
        {
            NewTag = null!,
        };

        vm.AddTagCommand.Execute(null);

        Assert.Empty(vm.Tags);
    }

    [Fact]
    public void Save_UebernimmtHinzugefuegteLabelsUndVerhindertDuplikate()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage())
        {
            Title = "Vorfall im Unterricht", TypeName = "Vorkommnis",
        };
        vm.NewTag = "Kritisch";
        vm.AddTagCommand.Execute(null);
        vm.NewTag = "Kritisch"; // Duplikat, soll ignoriert werden
        vm.AddTagCommand.Execute(null);
        vm.NewTag = "Mit JGL abklären";
        vm.AddTagCommand.Execute(null);

        vm.SaveCommand.Execute(null);

        Assert.Equal(["Kritisch", "Mit JGL abklären"], vm.Result!.Tags);
    }

    [Fact]
    public void RemoveTag_EntferntDasLabelWiederAusDerListe()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage());
        vm.NewTag = "Beobachten";
        vm.AddTagCommand.Execute(null);

        vm.RemoveTagCommand.Execute("Beobachten");

        Assert.Empty(vm.Tags);
    }

    [Fact]
    public void Save_Elternanruf_UebernimmtGeplanteGespraechspunkte()
    {
        var studentId = Guid.NewGuid();
        var vm = new DocumentationDialogViewModel(studentId, null, new FakeAttachmentStorage())
        {
            Title = "Anruf wegen Hausaufgaben",
            TypeName = "Elternanruf",
        };
        vm.NewCallPoint = "Hausaufgabensituation ansprechen";
        vm.AddCallPointCommand.Execute(null);
        vm.NewCallPoint = "Nächste Schritte vereinbaren";
        vm.AddCallPointCommand.Execute(null);

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Equal(DocumentationType.ParentCall, vm.Result!.Type);
        Assert.Equal(2, vm.Result.ParentCallData!.Points.Count);
        Assert.All(vm.Result.ParentCallData.Points, p => Assert.False(p.IsDone));
        Assert.False(vm.Result.ParentCallData.IsConducted);
    }

    [Fact]
    public void Save_ElternanrufBearbeiten_BehaeltAbgehakteStatusFuerUnveraenderteePunkte()
    {
        var studentId = Guid.NewGuid();
        var existing = new Documentation
        {
            StudentId = studentId,
            Type = DocumentationType.ParentCall,
            Title = "Anruf",
            ParentCallData = new ParentCallData
            {
                Points = [new ParentCallPoint { Text = "Punkt A", IsDone = true }],
                IsConducted = true,
                ConductedDate = new DateOnly(2026, 1, 10),
                Impressions = "Gut verlaufen",
            },
        };

        var vm = new DocumentationDialogViewModel(studentId, existing, new FakeAttachmentStorage());
        vm.NewCallPoint = "Punkt B";
        vm.AddCallPointCommand.Execute(null);

        vm.SaveCommand.Execute(null);

        var points = vm.Result!.ParentCallData!.Points;
        Assert.True(points.Single(p => p.Text == "Punkt A").IsDone);
        Assert.False(points.Single(p => p.Text == "Punkt B").IsDone);
        Assert.True(vm.Result.ParentCallData.IsConducted);
        Assert.Equal("Gut verlaufen", vm.Result.ParentCallData.Impressions);
    }

    [Fact]
    public void Save_SitzplanEntwurf_WirdAbgeschlossenUndBehaeltStundenbezug()
    {
        var sessionId = Guid.NewGuid();
        var existing = new Documentation
        {
            StudentId = Guid.NewGuid(), Type = DocumentationType.Incident,
            Date = DateOnly.FromDateTime(DateTime.Today), Title = "Streit/Konflikt",
            IsDraft = true, ParticipationSessionId = sessionId, Tags = ["Streit/Konflikt"],
        };
        var vm = new DocumentationDialogViewModel(existing.StudentId, existing, new FakeAttachmentStorage());

        vm.SaveCommand.Execute(null);

        Assert.False(vm.Result!.IsDraft);
        Assert.Equal(sessionId, vm.Result.ParticipationSessionId);
    }

    [Fact]
    public void Save_Elternbrief_UebernimmtVersandUndRueckmeldung()
    {
        var studentId = Guid.NewGuid();
        var vm = new DocumentationDialogViewModel(studentId, null, new FakeAttachmentStorage())
        {
            Title = "Brief wegen Verhalten",
            TypeName = "Elternbrief",
            LetterDraftContent = "Sehr geehrte...",
            LetterSentDateText = "05.09.2025",
            LetterResponseReceived = true,
            LetterResponseDateText = "12.09.2025",
            LetterResponseNote = "Termin vereinbart",
        };

        vm.SaveCommand.Execute(null);

        var letter = vm.Result!.ParentLetterData!;
        Assert.Equal(new DateOnly(2025, 9, 5), letter.SentDate);
        Assert.True(letter.ResponseReceived);
        Assert.Equal(new DateOnly(2025, 9, 12), letter.ResponseDate);
        Assert.Equal("Termin vereinbart", letter.ResponseNote);
    }

    [Fact]
    public void Save_UngueltigesDatumBeimElternbrief_SetztFehlerUndSpeichertNicht()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage())
        {
            Title = "Brief", TypeName = "Elternbrief", LetterSentDateText = "nicht-valide",
        };

        vm.SaveCommand.Execute(null);

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

    [Fact]
    public void AddAttachment_GroessereDateiAlsDasLimit_SetztFehlerUndFuegtNichtHinzu()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage());
        using var huge = new MemoryStream(new byte[LehrerApp.Core.Interfaces.IAttachmentStorage.MaxSizeBytes + 1]);

        vm.AddAttachment("gross.bin", huge);

        Assert.Empty(vm.Attachments);
        Assert.NotEqual("", vm.AttachmentError);
    }

    [Fact]
    public void OhneStudentOptions_CanPickStudentIstFalse()
    {
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, new FakeAttachmentStorage());

        Assert.False(vm.CanPickStudent);
    }

    [Fact]
    public void MitStudentOptions_OhneAuswahl_SaveSetztFehlerUndSpeichertNicht()
    {
        var anna = new StudentOption(Guid.NewGuid(), "Anna Beispiel");
        var vm = new DocumentationDialogViewModel(Guid.Empty, null, new FakeAttachmentStorage(), [anna])
        {
            Title = "Vorfall", TypeName = "Vorkommnis",
        };

        vm.SaveCommand.Execute(null);

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

    [Fact]
    public void MitStudentOptions_AuswahlGetroffen_SaveUebernimmtSchuelerUndGruppe()
    {
        var groupId = Guid.NewGuid();
        var anna = new StudentOption(Guid.NewGuid(), "Anna Beispiel");
        var ben = new StudentOption(Guid.NewGuid(), "Ben Muster");
        var vm = new DocumentationDialogViewModel(Guid.Empty, null, new FakeAttachmentStorage(),
            [anna, ben], groupId)
        {
            Title = "Vorfall", TypeName = "Vorkommnis", SelectedStudent = ben,
        };

        vm.SaveCommand.Execute(null);

        Assert.NotNull(vm.Result);
        Assert.Equal(ben.Id, vm.Result!.StudentId);
        Assert.Equal(groupId, vm.Result.GroupId);
    }

    [Fact]
    public void MitStudentOptions_Bearbeiten_SchuelerIstVorausgewaehlt()
    {
        var anna = new StudentOption(Guid.NewGuid(), "Anna Beispiel");
        var ben = new StudentOption(Guid.NewGuid(), "Ben Muster");
        var existing = new Documentation { StudentId = ben.Id, Title = "Alt" };

        var vm = new DocumentationDialogViewModel(ben.Id, existing, new FakeAttachmentStorage(), [anna, ben]);

        Assert.Equal(ben, vm.SelectedStudent);
    }

    [Fact]
    public void DiscardUnsavedAttachments_EntferntNurNieGespeicherteAnhaenge()
    {
        var storage = new FakeAttachmentStorage();
        var vm = new DocumentationDialogViewModel(Guid.NewGuid(), null, storage)
        {
            Title = "Brief", TypeName = "Elternbrief",
        };
        using var content = new MemoryStream([1, 2, 3]);
        vm.AddAttachment("brief.pdf", content);
        var storageId = vm.Attachments.Single().StorageId;

        vm.DiscardUnsavedAttachments();

        Assert.Null(storage.OpenRead(storageId));
    }
}