using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.AiPlanning;
using LehrerApp.Core.Models;
using LehrerApp.Desktop.Services;
using System.Collections.ObjectModel;
using System.Globalization;

namespace LehrerApp.Desktop.ViewModels.Groups;

// ── Anzeige: Experimentart, GHS-Piktogramme (Nutzerwunsch neben 4.2 "Anhänge je Stunde") ────────

public static class ExperimentKindDisplay
{
    public static string[] Options { get; } = ["Lehrerversuch", "Schülerversuch", "Demonstrationsversuch"];

    public static string Label(ExperimentKind kind) => kind switch
    {
        ExperimentKind.Schuelerversuch => "Schülerversuch",
        ExperimentKind.Demonstrationsversuch => "Demonstrationsversuch",
        _ => "Lehrerversuch",
    };

    public static ExperimentKind FromLabel(string? label) => label switch
    {
        "Schülerversuch" => ExperimentKind.Schuelerversuch,
        "Demonstrationsversuch" => ExperimentKind.Demonstrationsversuch,
        _ => ExperimentKind.Lehrerversuch,
    };

    /// Für die KI-Antwort, die den unmarkierten Enum-Namen ("Schuelerversuch") statt der
    /// deutschen Anzeige-Bezeichnung liefert (siehe ai-backend/gbu.php "Antwortformat").
    public static ExperimentKind FromWireValue(string? value) =>
        Enum.TryParse<ExperimentKind>(value, ignoreCase: true, out var kind) ? kind : ExperimentKind.Lehrerversuch;
}

public static class GhsPictogramDisplay
{
    private static readonly (GhsPictogram Value, string Code, string Label)[] All =
    [
        (GhsPictogram.Explosive, "GHS01", "Explosionsgefährlich"),
        (GhsPictogram.Flammable, "GHS02", "Entzündbar"),
        (GhsPictogram.Oxidizing, "GHS03", "Brandfördernd"),
        (GhsPictogram.CompressedGas, "GHS04", "Gase unter Druck"),
        (GhsPictogram.Corrosive, "GHS05", "Ätzend"),
        (GhsPictogram.Toxic, "GHS06", "Giftig"),
        (GhsPictogram.Harmful, "GHS07", "Gesundheitsschädlich/Reizend"),
        (GhsPictogram.HealthHazard, "GHS08", "Gesundheitsgefährdend"),
        (GhsPictogram.Environmental, "GHS09", "Umweltgefährdend"),
    ];

    public static string Code(GhsPictogram value) => All.First(o => o.Value == value).Code;
    public static string Label(GhsPictogram value) => All.First(o => o.Value == value).Label;

    public static GhsPictogram? FromCode(string? code)
    {
        if (string.IsNullOrWhiteSpace(code)) return null;
        foreach (var option in All)
            if (string.Equals(option.Code, code.Trim(), StringComparison.OrdinalIgnoreCase))
                return option.Value;
        return null;
    }

    public static List<GhsPictogramOption> BuildOptions(IEnumerable<GhsPictogram>? selected = null)
    {
        var selectedSet = (selected ?? []).ToHashSet();
        return All.Select(o => new GhsPictogramOption(o.Value, $"{o.Code} · {o.Label}") { IsSelected = selectedSet.Contains(o.Value) }).ToList();
    }
}

public partial class GhsPictogramOption(GhsPictogram value, string label) : ObservableObject
{
    public GhsPictogram Value { get; } = value;
    public string Label { get; } = label;
    [ObservableProperty] private bool _isSelected;
}

// ── Zeile im Gefahrstoff-Editor (Wizard-Schritt 2) ───────────────────────────────────────────────

public partial class HazardSubstanceEditItem : ObservableObject
{
    [ObservableProperty] private string _name = "";
    [ObservableProperty] private string _amount = "";
    [ObservableProperty] private string _hStatements = "";
    [ObservableProperty] private string _pStatements = "";
    public ObservableCollection<GhsPictogramOption> PictogramOptions { get; }
    public Action<HazardSubstanceEditItem>? OnRemove { get; set; }

    public HazardSubstanceEditItem(HazardSubstance? source = null)
    {
        PictogramOptions = new ObservableCollection<GhsPictogramOption>(
            GhsPictogramDisplay.BuildOptions(source?.GhsPictograms));
        if (source is null) return;
        Name = source.Name;
        Amount = source.Amount;
        HStatements = source.HStatements;
        PStatements = source.PStatements;
    }

    [RelayCommand]
    private void Remove() => OnRemove?.Invoke(this);

    public HazardSubstance ToModel() => new()
    {
        Name = Name.Trim(),
        Amount = Amount.Trim(),
        HStatements = HStatements.Trim(),
        PStatements = PStatements.Trim(),
        GhsPictograms = PictogramOptions.Where(o => o.IsSelected).Select(o => o.Value).ToList(),
    };
}

// ── Wizard: Gefährdungsbeurteilung anlegen/bearbeiten ────────────────────────────────────────────

/// <summary>
/// Mehrschrittiger Assistent für eine Gefährdungsbeurteilung zu einem Experiment (Nutzerwunsch
/// neben 4.2 "Anhänge je Stunde"). Persistiert NICHT selbst — der Aufrufer (LessonDialog)
/// serialisiert <see cref="Result"/> zu JSON und hängt es über die bestehende
/// Anhang-Infrastruktur an die Lesson an (Dateiname endet auf ".gbu.json", siehe TODO.md 4.2).
/// KI-Unterstützung ist optional: ohne <paramref name="ai"/>/<paramref name="unit"/>/
/// <paramref name="lesson"/> bleibt <see cref="CanUseAi"/> false und der Assistent funktioniert
/// rein manuell.
/// </summary>
public partial class HazardAssessmentWizardViewModel : ObservableObject
{
    private static readonly string[] StepTitlesArray =
        ["Basisdaten", "Gefahrstoffe", "Gefährdungen & Schutzmaßnahmen", "Erste Hilfe & Entsorgung", "Zusammenfassung"];

    private readonly AiPlanningService? _ai;
    private readonly AiSettingsService? _aiSettings;
    private readonly Unit? _unit;
    private readonly Lesson? _lesson;

    [ObservableProperty] private int _stepIndex;
    [ObservableProperty] private string _title = "";
    [ObservableProperty] private string _titleError = "";
    [ObservableProperty] private string _groupLabel = "";
    [ObservableProperty] private string _dateText = DateOnly.FromDateTime(DateTime.Today).ToString("dd.MM.yyyy");
    [ObservableProperty] private string _kindName = ExperimentKindDisplay.Options[0];
    [ObservableProperty] private string _procedure = "";

    public ObservableCollection<HazardSubstanceEditItem> Substances { get; } = [];
    public bool HasSubstances => Substances.Count > 0;

    [ObservableProperty] private string _newHazard = "";
    public ObservableCollection<string> Hazards { get; } = [];
    [ObservableProperty] private string _newProtectiveMeasure = "";
    public ObservableCollection<string> ProtectiveMeasures { get; } = [];

    [ObservableProperty] private string _firstAid = "";
    [ObservableProperty] private string _disposal = "";
    [ObservableProperty] private string _notes = "";

    [ObservableProperty] private bool _isAiAssisted;
    [ObservableProperty] private bool _isAiBusy;
    [ObservableProperty] private string _aiError = "";
    public string AiButtonLabel => IsAiBusy ? "KI fragt..." : "🤖 KI-Entwurf erstellen";

    public bool CanUseAi => _ai is not null && _aiSettings is { Enabled: true, IsLoggedIn: true }
        && _unit is not null && _lesson is not null;

    public string[] StepTitles => StepTitlesArray;
    public string StepTitle => StepTitles[StepIndex];
    public string StepProgressLabel => $"Schritt {StepIndex + 1} von {StepTitles.Length}";
    public int StepCount => StepTitles.Length;
    public bool IsFirstStep => StepIndex == 0;
    public bool IsLastStep => StepIndex == StepTitles.Length - 1;
    public bool IsBasicsStep => StepIndex == 0;
    public bool IsSubstancesStep => StepIndex == 1;
    public bool IsHazardsStep => StepIndex == 2;
    public bool IsFirstAidStep => StepIndex == 3;
    public bool IsSummaryStep => StepIndex == 4;
    public string[] KindOptions => ExperimentKindDisplay.Options;
    public string DialogTitle => _editing ? "Gefährdungsbeurteilung bearbeiten" : "Gefährdungsbeurteilung erstellen";

    private readonly bool _editing;

    public HazardAssessment? Result { get; private set; }

    public HazardAssessmentWizardViewModel(HazardAssessment? editing, string defaultGroupLabel,
        AiPlanningService? ai = null, AiSettingsService? aiSettings = null, Unit? unit = null, Lesson? lesson = null)
    {
        _ai = ai; _aiSettings = aiSettings; _unit = unit; _lesson = lesson;
        Substances.CollectionChanged += (_, _) => OnPropertyChanged(nameof(HasSubstances));
        GroupLabel = defaultGroupLabel;
        _editing = editing is not null;
        if (editing is null) return;

        Title = editing.Title;
        GroupLabel = editing.GroupLabel;
        DateText = editing.Date?.ToString("dd.MM.yyyy") ?? "";
        KindName = ExperimentKindDisplay.Label(editing.Kind);
        Procedure = editing.Procedure;
        foreach (var s in editing.Substances) Substances.Add(NewSubstanceItem(s));
        foreach (var h in editing.Hazards) Hazards.Add(h);
        foreach (var m in editing.ProtectiveMeasures) ProtectiveMeasures.Add(m);
        FirstAid = editing.FirstAid;
        Disposal = editing.Disposal;
        Notes = editing.Notes;
        IsAiAssisted = editing.IsAiAssisted;
    }

    partial void OnIsAiBusyChanged(bool value) => OnPropertyChanged(nameof(AiButtonLabel));

    partial void OnStepIndexChanged(int value)
    {
        OnPropertyChanged(nameof(StepTitle));
        OnPropertyChanged(nameof(StepProgressLabel));
        OnPropertyChanged(nameof(IsFirstStep));
        OnPropertyChanged(nameof(IsLastStep));
        OnPropertyChanged(nameof(IsBasicsStep));
        OnPropertyChanged(nameof(IsSubstancesStep));
        OnPropertyChanged(nameof(IsHazardsStep));
        OnPropertyChanged(nameof(IsFirstAidStep));
        OnPropertyChanged(nameof(IsSummaryStep));
    }

    private HazardSubstanceEditItem NewSubstanceItem(HazardSubstance? source = null)
    {
        var item = new HazardSubstanceEditItem(source) { OnRemove = RemoveSubstance };
        return item;
    }

    [RelayCommand]
    private void AddSubstance() => Substances.Add(NewSubstanceItem());

    private void RemoveSubstance(HazardSubstanceEditItem item) => Substances.Remove(item);

    [RelayCommand]
    private void AddHazard()
    {
        if (string.IsNullOrWhiteSpace(NewHazard)) return;
        Hazards.Add(NewHazard.Trim());
        NewHazard = "";
    }

    [RelayCommand]
    private void RemoveHazard(string? hazard) { if (hazard is not null) Hazards.Remove(hazard); }

    [RelayCommand]
    private void AddProtectiveMeasure()
    {
        if (string.IsNullOrWhiteSpace(NewProtectiveMeasure)) return;
        ProtectiveMeasures.Add(NewProtectiveMeasure.Trim());
        NewProtectiveMeasure = "";
    }

    [RelayCommand]
    private void RemoveProtectiveMeasure(string? measure) { if (measure is not null) ProtectiveMeasures.Remove(measure); }

    [RelayCommand]
    private void Next()
    {
        if (IsFirstStep && string.IsNullOrWhiteSpace(Title))
        {
            TitleError = "Titel erforderlich.";
            return;
        }
        TitleError = "";
        if (!IsLastStep) StepIndex++;
    }

    [RelayCommand]
    private void Back() { if (!IsFirstStep) StepIndex--; }

    /// <summary>
    /// Fragt einen KI-Entwurf zu genau dieser Lesson ab (Thema + Verlaufsplan als Kontext) und
    /// übernimmt ihn in die Wizard-Felder — überschreibt dabei bewusst den aktuellen Stand, damit
    /// nach einem erneuten Klick klar ist, was tatsächlich von der KI kommt. Die Lehrkraft prüft
    /// und passt danach in den einzelnen Schritten an; der Rechtssicherheits-Hinweis wird über
    /// <see cref="IsAiAssisted"/> in den PDF-Export übernommen.
    /// </summary>
    [RelayCommand]
    private async Task RequestAiDraft()
    {
        if (!CanUseAi) return;
        var token = _aiSettings!.GetToken();
        if (token is null)
        {
            AiError = "Nicht angemeldet. Bitte in den Einstellungen bei der KI-Unterstützung anmelden.";
            return;
        }

        AiError = ""; IsAiBusy = true;
        try
        {
            var aiLesson = new AiLesson
            {
                Id = _lesson!.Id,
                Date = _lesson.Date,
                LessonNumber = _lesson.LessonNumber,
                Topic = _lesson.Topic,
                StartTime = _lesson.StartTime,
                Phases = _lesson.Phases.Select(p => new AiPhaseStep
                {
                    Name = p.Name, DurationMinutes = p.DurationMinutes,
                    Activity = p.Activity, Material = p.Material, Shorthand = p.Shorthand,
                }).ToList(),
            };

            var response = await _ai!.RequestHazardAssessmentDraftAsync(_unit!, aiLesson, token);
            ApplyAiResponse(response);
        }
        catch (AiBackendException ex)
        {
            AiError = ex.Message;
        }
        finally
        {
            IsAiBusy = false;
        }
    }

    private void ApplyAiResponse(AiHazardAssessmentResponse response)
    {
        if (string.IsNullOrWhiteSpace(Title)) Title = _lesson?.Topic ?? "";
        KindName = ExperimentKindDisplay.Label(ExperimentKindDisplay.FromWireValue(response.ExperimentKind));
        Procedure = response.Procedure;

        Substances.Clear();
        foreach (var s in response.Substances)
            Substances.Add(NewSubstanceItem(new HazardSubstance
            {
                Name = s.Name,
                Amount = s.Amount,
                HStatements = s.HStatements,
                PStatements = s.PStatements,
                GhsPictograms = s.GhsPictograms
                    .Select(GhsPictogramDisplay.FromCode)
                    .Where(p => p.HasValue)
                    .Select(p => p!.Value)
                    .ToList(),
            }));

        Hazards.Clear();
        foreach (var h in response.Hazards) Hazards.Add(h);
        ProtectiveMeasures.Clear();
        foreach (var m in response.ProtectiveMeasures) ProtectiveMeasures.Add(m);
        FirstAid = response.FirstAid;
        Disposal = response.Disposal;
        IsAiAssisted = true;
    }

    [RelayCommand]
    private void Save()
    {
        if (string.IsNullOrWhiteSpace(Title))
        {
            TitleError = "Titel erforderlich.";
            StepIndex = 0;
            return;
        }
        TitleError = "";

        DateOnly? date = null;
        if (!string.IsNullOrWhiteSpace(DateText) &&
            DateOnly.TryParseExact(DateText, "dd.MM.yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out var parsed))
            date = parsed;

        Result = new HazardAssessment
        {
            Title = Title.Trim(),
            GroupLabel = GroupLabel.Trim(),
            Date = date,
            Kind = ExperimentKindDisplay.FromLabel(KindName),
            Procedure = Procedure.Trim(),
            Substances = Substances.Select(s => s.ToModel()).ToList(),
            Hazards = Hazards.ToList(),
            ProtectiveMeasures = ProtectiveMeasures.ToList(),
            FirstAid = FirstAid.Trim(),
            Disposal = Disposal.Trim(),
            Notes = Notes.Trim(),
            IsAiAssisted = IsAiAssisted,
        };
    }
}