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

namespace LehrerApp.Desktop.Tests;

public sealed class CreateLetterDialogViewModelTests : IDisposable
{
    private readonly string _directory = Path.Combine(Path.GetTempPath(), $"lehrerapp-letter-vm-tests-{Guid.NewGuid():N}");
    public CreateLetterDialogViewModelTests() => Directory.CreateDirectory(_directory);

    [Fact]
    public void OhneVorlage_KannKeinenBriefErzeugen()
    {
        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), new TemplateStore(_directory));
        Assert.False(vm.CanGenerate);
        Assert.Contains(vm.Issues, i => i.Message.Contains("Vorlage", StringComparison.OrdinalIgnoreCase));
    }

    [Fact]
    public void VerwendeteBriefanredeFehlt_BlockiertErzeugung()
    {
        var vm = Build(StudentWithContact(null), StoreWithTemplate(
            new PlaceholderDefinition("Anrede", PlaceholderType.Text, true)));
        Assert.False(vm.CanGenerate);
        Assert.Contains(vm.Issues, i => i.Message.Contains("Anrede", StringComparison.OrdinalIgnoreCase));
    }

    [Fact]
    public void VollstaendigeDaten_ErzeugenFlachesPdf()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true));
        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), store);
        vm.LetterText = "Dies ist der Inhalt.";
        var output = Path.Combine(_directory, "Brief.pdf");

        Assert.True(vm.Generate(output));
        Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
    }

    [Fact]
    public void KonstanterPflichttext_BenoetigtKeineExterneEingabe()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline,
            Required: true, IsConstant: true, ConstantValue: "Fest im Vorlagenpaket"));
        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), store);
        var output = Path.Combine(_directory, "Konstant.pdf");

        Assert.True(vm.CanGenerate);
        Assert.True(vm.Generate(output));
        Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
    }

    [Fact]
    public async Task AdvancedContent_Anwesenheitskalender_WirdAlsDrawingGerendert()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition(
            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
        var drawing = StudentAttendanceCalendarDrawingBuilder.Build("Lena Beispiel", new DateOnly(2026, 9, 1), [], []);
        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]), (_, _, _, _) => drawing);
        var output = Path.Combine(_directory, "Kalender.pdf");

        Assert.True(vm.UsesAttendanceCalendar);
        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
            new DateOnly(2026, 8, 19), 3, AttendanceCalendarSize.Large));
        Assert.True(vm.AttendanceCalendarConfigured);
        Assert.Contains("August 2026", vm.AttendanceCalendarSummary);
        Assert.Contains("3 Monate", vm.AttendanceCalendarSummary);
        Assert.Contains("Groß", vm.AttendanceCalendarSummary);
        Assert.True(vm.Generate(output));
        Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
    }

    // Regression: Der DrawingValue-Builder hat früher immer eine feste Breite (170) angenommen,
    // unabhängig davon, wie breit die DRAWBOX in der jeweiligen Vorlage tatsächlich deklariert war -
    // bei breiteren (oder in "pt" statt "mm" deklarierten) Boxen blieb dadurch ein Großteil der
    // eigentlich verfügbaren Fläche ungenutzt leer (sichtbar in echten Elternbriefen als "Luft"
    // rechts/unterhalb des Kalenders). Der Dialog muss die real deklarierte Breite ermitteln und an
    // den Builder weiterreichen.
    [Fact]
    public void AdvancedContent_Anwesenheitskalender_NutztDieImLayoutDeklarierteBoxbreite()
    {
        var manifest = new TemplateManifest
        {
            Id = $"brief-{Guid.NewGuid():N}", Name = "Elternbrief",
            Placeholders = [new(StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true)],
        };
        var source = Path.Combine(_directory, $"{Guid.NewGuid():N}.lavorlage");
        TemplatePackage.Create(source, manifest,
            $"PAGE 210 297 mm\nDRAWBOX 20 20 250 80 ${StudentAttendanceCalendarDrawingBuilder.PlaceholderName}",
            new Dictionary<string, byte[]>());
        var store = new TemplateStore(Path.Combine(_directory, $"store-{Guid.NewGuid():N}"));
        store.Import(source);
        float? receivedWidth = null; float? receivedMillimeterScale = null;

        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
            (_, width, millimeterScale, _) => { receivedWidth = width; receivedMillimeterScale = millimeterScale; return new DrawingValue([], 0); });

        Assert.True(vm.UsesAttendanceCalendar);
        Assert.Equal(250, receivedWidth);
        Assert.Equal(1, receivedMillimeterScale);
    }

    // Regression: Eine reale, aus einem Word-Dokument übernommene Vorlage deklariert die Seite in
    // "pt" statt "mm" (PAGE ... pt). Ohne Umrechnung würde das mm-entworfene Kalenderraster dort nur
    // rund ein Drittel der vorgesehenen physischen Größe erreichen (1 "mm-Einheit" würde als 1pt statt
    // als ~2.83pt gerendert).
    [Fact]
    public void AdvancedContent_Anwesenheitskalender_RechnetBoxbreiteBeiPunktBasierterVorlageUm()
    {
        var manifest = new TemplateManifest
        {
            Id = $"brief-{Guid.NewGuid():N}", Name = "Elternbrief",
            Placeholders = [new(StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true)],
        };
        var source = Path.Combine(_directory, $"{Guid.NewGuid():N}.lavorlage");
        TemplatePackage.Create(source, manifest,
            $"PAGE 595.32 841.92 pt\nDRAWBOX 71 350 487 177 ${StudentAttendanceCalendarDrawingBuilder.PlaceholderName}",
            new Dictionary<string, byte[]>());
        var store = new TemplateStore(Path.Combine(_directory, $"store-{Guid.NewGuid():N}"));
        store.Import(source);
        float? receivedWidth = null; float? receivedMillimeterScale = null;

        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
            (_, width, millimeterScale, _) => { receivedWidth = width; receivedMillimeterScale = millimeterScale; return new DrawingValue([], 0); });

        Assert.True(vm.UsesAttendanceCalendar);
        Assert.Equal(487, receivedWidth);
        Assert.NotNull(receivedMillimeterScale);
        Assert.Equal(2.8346f, receivedMillimeterScale!.Value, 0.001f);
    }

    [Fact]
    public async Task AttendanceKalenderKonfigurieren_LoestGezieltenDatenAbrufFuerDenZeitraumAus()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition(
            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
        AttendanceCalendarOptions? requested = null;
        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
            (_, _, _, _) => new DrawingValue([], 0), attendanceDataRefresher: (options, _) =>
            { requested = options; return Task.CompletedTask; });

        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
            new DateOnly(2026, 9, 1), 2, AttendanceCalendarSize.Medium));

        Assert.NotNull(requested);
        Assert.Equal(new DateOnly(2026, 9, 1), requested!.NormalizedStartMonth);
        Assert.Equal(2, requested.NormalizedMonthCount);
        Assert.False(vm.IsRefreshingAttendanceData);
        Assert.Equal("", vm.AttendanceRefreshError);
    }

    [Fact]
    public async Task AttendanceKalenderKonfigurieren_ZeigtFehlerBeiFehlgeschlagenemAbrufAnStattZuBlockieren()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition(
            StudentAttendanceCalendarDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
            (_, _, _, _) => new DrawingValue([], 0),
            attendanceDataRefresher: (_, _) => throw new WebUntisIntegrationException("Keine Verbindung."));

        await vm.SetAttendanceCalendarOptionsAsync(new AttendanceCalendarOptions(
            new DateOnly(2026, 9, 1), 1, AttendanceCalendarSize.Medium));

        Assert.True(vm.AttendanceCalendarConfigured);
        Assert.Contains("Keine Verbindung.", vm.AttendanceRefreshError);
        Assert.False(vm.IsRefreshingAttendanceData);
    }

    [Fact]
    public void AdvancedContent_Fehlzeitenliste_AktiviertKonfigurationsschritt()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition(
            StudentAbsenceDayListDrawingBuilder.PlaceholderName, PlaceholderType.Drawing, true));
        var drawing = StudentAbsenceDayListDrawingBuilder.Build("Lena Beispiel",
            new AttendanceCalendarOptions(new DateOnly(2026, 9, 1), 1), []);
        var vm = new CreateLetterDialogViewModel(StudentWithContact("Sehr geehrte Frau Muster,"), store,
            new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]),
            attendanceCalendarFactory: null, absenceDayListFactory: (_, _, _, _) => drawing);

        Assert.False(vm.UsesAttendanceCalendar);
        Assert.True(vm.UsesAbsenceDayList);
        Assert.True(vm.UsesAttendanceAdvancedContent);
        Assert.True(vm.CanGenerate);
    }

    [Fact]
    public void EigenerPlatzhalter_KannImDialogEingegebenWerden()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true),
            new PlaceholderDefinition("Betreff", PlaceholderType.Text, true));
        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), store);
        vm.LetterText = "Dies ist der Inhalt.";

        var betreff = Assert.Single(vm.CustomPlaceholders);
        Assert.Equal("Betreff", betreff.Name);
        Assert.False(vm.CanGenerate);
        Assert.Contains(vm.Issues, i => i.Message.Contains("Betreff", StringComparison.OrdinalIgnoreCase));

        betreff.TextValue = "Wichtiger Termin";
        var output = Path.Combine(_directory, "MitBetreff.pdf");

        Assert.True(vm.CanGenerate);
        Assert.True(vm.Generate(output));
        Assert.Equal("%PDF", System.Text.Encoding.ASCII.GetString(File.ReadAllBytes(output), 0, 4));
    }

    [Fact]
    public void StudentName_WirdAutomatischMitVollemNamenBefuellt()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true),
            new PlaceholderDefinition("Student.Name", PlaceholderType.Text, true));
        var vm = Build(StudentWithContact("Sehr geehrte Frau Muster,"), store);
        vm.LetterText = "Dies ist der Inhalt.";

        Assert.Empty(vm.CustomPlaceholders);
        Assert.True(vm.CanGenerate);
        var output = Path.Combine(_directory, "StudentName.pdf");
        Assert.True(vm.Generate(output));
    }

    [Fact]
    public void Anrede_WirdAusKontaktVorbelegtUndBleibtEditierbar()
    {
        var store = StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true),
            new PlaceholderDefinition("Datum", PlaceholderType.Date, true),
            new PlaceholderDefinition("Brieftext", PlaceholderType.Multiline, true));
        var vm = Build(StudentWithContact(null), store);
        vm.LetterText = "Dies ist der Inhalt.";

        Assert.Equal("", vm.Anrede);
        Assert.False(vm.CanGenerate);
        Assert.Contains(vm.Issues, i => i.Message.Contains("Anrede", StringComparison.OrdinalIgnoreCase));

        vm.Anrede = "Sehr geehrte Familie Beispiel,";
        var output = Path.Combine(_directory, "AnredeManuell.pdf");

        Assert.True(vm.CanGenerate);
        Assert.True(vm.Generate(output));
    }

    [Fact]
    public void AddressPreview_FolgtDemGewaehltenKontaktUndAktualisiertSichBeimWechsel()
    {
        var student = new Student
        {
            FirstName = "Lena", LastName = "Beispiel",
            Contacts =
            [
                new Contact { Name = "Frau Beispiel", Relation = "Mutter", Street = "Erste Str. 1", PostalCode = "11111", City = "Erststadt" },
                new Contact { Name = "Herr Beispiel", Relation = "Vater", Street = "Zweite Str. 2", PostalCode = "22222", City = "Zweitstadt" },
            ],
        };
        var vm = Build(student, StoreWithTemplate(new PlaceholderDefinition("Anrede", PlaceholderType.Text, true)));

        Assert.Equal(2, vm.Contacts.Count);
        Assert.Contains("Frau Beispiel", vm.AddressPreview);
        Assert.Contains("Erste Str. 1", vm.AddressPreview);

        vm.SelectedContact = vm.Contacts.Single(c => c.Model.Name == "Herr Beispiel");

        Assert.Contains("Herr Beispiel", vm.AddressPreview);
        Assert.Contains("Zweite Str. 2", vm.AddressPreview);
        Assert.DoesNotContain("Frau Beispiel", vm.AddressPreview);
    }

    [Fact]
    public void SelectContactDialog_StartetBeimAktuellenKontaktUndAktualisiertVorschau()
    {
        var contacts = new List<LetterContactChoice>
        {
            new(new Contact { Name = "Frau Beispiel", Street = "Erste Str. 1", PostalCode = "11111", City = "Erststadt" }),
            new(new Contact { Name = "Herr Beispiel", Street = "Zweite Str. 2", PostalCode = "22222", City = "Zweitstadt" }),
        };
        var dialogVm = new SelectContactDialogViewModel(contacts, contacts[1]);

        Assert.Same(contacts[1], dialogVm.SelectedContact);
        Assert.Contains("Zweite Str. 2", dialogVm.AddressPreview);

        dialogVm.SelectedContact = contacts[0];

        Assert.Contains("Erste Str. 1", dialogVm.AddressPreview);
    }

    private CreateLetterDialogViewModel Build(Student student, TemplateStore store) =>
        new(student, store, new QuestTemplateRenderer(), new FakeMemberships([]), new FakeGroups([]));

    private TemplateStore StoreWithTemplate(params PlaceholderDefinition[] definitions)
    {
        var source = Path.Combine(_directory, $"{Guid.NewGuid():N}.lavorlage");
        var manifest = new TemplateManifest { Id = $"brief-{Guid.NewGuid():N}", Name = "Elternbrief", Placeholders = [.. definitions] };
        var lines = new List<string> { "PAGE 210 297 mm" };
        var y = 20;
        foreach (var definition in definitions)
        {
            var element = definition.Type switch
            {
                PlaceholderType.Multiline => "TEXTBOX",
                PlaceholderType.Drawing => "DRAWBOX",
                _ => "TEXT",
            };
            lines.Add(element switch
            {
                "TEXTBOX" => $"TEXTBOX 20 {y} 170 80 ${definition.Name}",
                "DRAWBOX" => $"DRAWBOX 20 {y} 170 80 ${definition.Name}",
                _ => $"TEXT 20 {y} ${definition.Name}",
            });
            y += 20;
        }
        TemplatePackage.Create(source, manifest, string.Join('\n', lines), new Dictionary<string, byte[]>());
        var store = new TemplateStore(Path.Combine(_directory, $"store-{Guid.NewGuid():N}")); store.Import(source); return store;
    }

    private static Student StudentWithContact(string? salutation) => new()
    {
        FirstName = "Lena", LastName = "Beispiel",
        Contacts = [new Contact { Name = "Frau Muster", Relation = "Mutter", LetterSalutation = salutation,
            Street = "Hauptstraße 1", PostalCode = "12345", City = "Musterstadt" }],
    };
    public void Dispose() { if (Directory.Exists(_directory)) Directory.Delete(_directory, true); }
}