using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using LehrerApp.Data;
using LehrerApp.Desktop.Services;
using LehrerApp.Desktop.ViewModels.Planning;
using LehrerApp.Sync;
using LehrerApp.Sync.Crypto;
using System.Collections.ObjectModel;
using System.Globalization;
using System.Security.Cryptography;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace LehrerApp.Desktop.ViewModels.Settings;

public partial class SettingsViewModel
{
    // ── Kompetenzkatalog ──────────────────────────────────────────────────────

    [ObservableProperty] private SubjectListItem? _catalogSubject;
    [ObservableProperty] private int              _catalogGradeLevel = 10;
    [ObservableProperty] private string           _newDomainName     = "";
    [ObservableProperty] private string           _newDomainCode     = "";
    [ObservableProperty] private string           _catalogValidation = "";

    public ObservableCollection<DomainEditItem> Domains { get; } = [];

    // ── Katalog: Laden ────────────────────────────────────────────────────────

    partial void OnCatalogSubjectChanged(SubjectListItem? value)  => LoadCatalog();
    partial void OnCatalogGradeLevelChanged(int value)            => LoadCatalog();

    private void LoadCatalog()
    {
        Domains.Clear();
        CatalogValidation = "";
        if (CatalogSubject is null) return;
        foreach (var d in _domainRepo.GetBySubjectAndGrade(CatalogSubject.Id, CatalogGradeLevel))
            Domains.Add(CreateDomainEditItem(d));
        RefreshDomainMoveState();
    }

    // ── Katalog: Bereich hinzufügen / löschen ────────────────────────────────

    [RelayCommand]
    private void AddDomain()
    {
        if (CatalogSubject is null) { CatalogValidation = "Bitte zuerst ein Fach auswählen."; return; }
        if (string.IsNullOrWhiteSpace(NewDomainName)) { CatalogValidation = "Bereichsname erforderlich."; return; }

        var domain = new CompetencyDomain
        {
            SubjectId  = CatalogSubject.Id,
            GradeLevel = CatalogGradeLevel,
            Name       = NewDomainName.Trim(),
            Code       = NewDomainCode.Trim(),
            SortOrder  = Domains.Count,
        };
        _domainRepo.Save(domain);
        Domains.Add(CreateDomainEditItem(domain));
        RefreshDomainMoveState();
        NewDomainName = ""; NewDomainCode = ""; CatalogValidation = "";
    }

    [RelayCommand]
    private void DeleteDomain(DomainEditItem? item)
    {
        if (item is null) return;
        _domainRepo.Delete(item.Id);
        Domains.Remove(item);
        PersistDomainOrder();
    }

    private DomainEditItem CreateDomainEditItem(CompetencyDomain domain) =>
        new(domain, _domainRepo, item => MoveDomain(item, -1), item => MoveDomain(item, 1));

    private void MoveDomain(DomainEditItem item, int offset)
    {
        var oldIndex = Domains.IndexOf(item);
        var newIndex = oldIndex + offset;
        if (oldIndex < 0 || newIndex < 0 || newIndex >= Domains.Count) return;
        Domains.Move(oldIndex, newIndex);
        PersistDomainOrder();
    }

    private void PersistDomainOrder()
    {
        for (var i = 0; i < Domains.Count; i++) Domains[i].SetSortOrder(i);
        RefreshDomainMoveState();
    }

    private void RefreshDomainMoveState()
    {
        for (var i = 0; i < Domains.Count; i++)
            Domains[i].SetMoveState(i > 0, i < Domains.Count - 1);
    }
}

// ── DomainEditItem ────────────────────────────────────────────────────────────

public partial class DomainEditItem : ObservableObject
{
    private readonly CompetencyDomain            _domain;
    private readonly ICompetencyDomainRepository _repo;

    public Guid   Id          { get; }
    public string Name        { get; }
    public string Code        { get; }
    public string DisplayName { get; }

    [ObservableProperty] private string _newItemCode = "";
    [ObservableProperty] private string _newItemDesc = "";

    public ObservableCollection<CompetencyItemVm> Items { get; } = [];
    public IRelayCommand MoveUpCommand { get; }
    public IRelayCommand MoveDownCommand { get; }

    public DomainEditItem(CompetencyDomain domain, ICompetencyDomainRepository repo,
        Action<DomainEditItem>? onMoveUp = null, Action<DomainEditItem>? onMoveDown = null)
    {
        _domain     = domain;
        _repo       = repo;
        Id          = domain.Id;
        Name        = domain.Name;
        Code        = domain.Code;
        DisplayName = string.IsNullOrEmpty(domain.Code)
            ? domain.Name
            : $"{domain.Name}  ({domain.Code})";

        MoveUpCommand = new RelayCommand(() => onMoveUp?.Invoke(this), () => _canMoveUp);
        MoveDownCommand = new RelayCommand(() => onMoveDown?.Invoke(this), () => _canMoveDown);

        _domain.Items = domain.Items.OrderBy(i => i.SortOrder).ToList();
        foreach (var item in _domain.Items)
            Items.Add(CreateItemViewModel(item));
        RefreshItemMoveState();
    }

    private bool _canMoveUp;
    private bool _canMoveDown;

    internal void SetMoveState(bool canMoveUp, bool canMoveDown)
    {
        _canMoveUp = canMoveUp;
        _canMoveDown = canMoveDown;
        MoveUpCommand.NotifyCanExecuteChanged();
        MoveDownCommand.NotifyCanExecuteChanged();
    }

    internal void SetSortOrder(int sortOrder)
    {
        if (_domain.SortOrder == sortOrder) return;
        _domain.SortOrder = sortOrder;
        _repo.Save(_domain);
    }

    [RelayCommand]
    private void AddItem()
    {
        if (string.IsNullOrWhiteSpace(NewItemDesc)) return;
        var item = new CompetencyItem
        {
            Code        = NewItemCode.Trim(),
            Description = NewItemDesc.Trim(),
            SortOrder   = _domain.Items.Count,
        };
        _domain.Items.Add(item);
        _repo.Save(_domain);
        Items.Add(CreateItemViewModel(item));
        RefreshItemMoveState();
        NewItemCode = ""; NewItemDesc = "";
    }

    private void DeleteItem(CompetencyItemVm vm)
    {
        _domain.Items.RemoveAll(i => i.Id == vm.ItemId);
        Items.Remove(vm);
        PersistItemOrder();
    }

    private CompetencyItemVm CreateItemViewModel(CompetencyItem item) =>
        new(item, DeleteItem, vm => MoveItem(vm, -1), vm => MoveItem(vm, 1));

    private void MoveItem(CompetencyItemVm item, int offset)
    {
        var oldIndex = Items.IndexOf(item);
        var newIndex = oldIndex + offset;
        if (oldIndex < 0 || newIndex < 0 || newIndex >= Items.Count) return;
        Items.Move(oldIndex, newIndex);
        PersistItemOrder();
    }

    private void PersistItemOrder()
    {
        _domain.Items = Items.Select(x => x.Model).ToList();
        for (var i = 0; i < _domain.Items.Count; i++) _domain.Items[i].SortOrder = i;
        _repo.Save(_domain);
        RefreshItemMoveState();
    }

    private void RefreshItemMoveState()
    {
        for (var i = 0; i < Items.Count; i++)
            Items[i].SetMoveState(i > 0, i < Items.Count - 1);
    }
}

// ── CompetencyItemVm ──────────────────────────────────────────────────────────

public class CompetencyItemVm
{
    internal CompetencyItem Model { get; }
    public Guid   ItemId  { get; }
    public string Code    { get; }
    public string Description { get; }
    public string Display { get; }
    public IRelayCommand DeleteCommand { get; }
    public IRelayCommand MoveUpCommand { get; }
    public IRelayCommand MoveDownCommand { get; }

    public CompetencyItemVm(CompetencyItem item, Action<CompetencyItemVm> onDelete,
        Action<CompetencyItemVm>? onMoveUp = null, Action<CompetencyItemVm>? onMoveDown = null)
    {
        Model       = item;
        ItemId      = item.Id;
        Code        = item.Code;
        Description = item.Description;
        Display     = string.IsNullOrEmpty(item.Code)
            ? item.Description
            : $"[{item.Code}]  {item.Description}";
        DeleteCommand = new RelayCommand(() => onDelete(this));
        MoveUpCommand = new RelayCommand(() => onMoveUp?.Invoke(this), () => _canMoveUp);
        MoveDownCommand = new RelayCommand(() => onMoveDown?.Invoke(this), () => _canMoveDown);
    }

    private bool _canMoveUp;
    private bool _canMoveDown;

    internal void SetMoveState(bool canMoveUp, bool canMoveDown)
    {
        _canMoveUp = canMoveUp;
        _canMoveDown = canMoveDown;
        MoveUpCommand.NotifyCanExecuteChanged();
        MoveDownCommand.NotifyCanExecuteChanged();
    }
}

// ── GradingKeyTemplateEditItem (1.3.2) ─────────────────────────────────────────