ViewThingViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using NeuroAccessMaui.Resources.Languages;
using NeuroAccessMaui.Services;
using NeuroAccessMaui.Services.Contacts;
using NeuroAccessMaui.Services.Localization;
using NeuroAccessMaui.Services.Notification;
using NeuroAccessMaui.Services.UI;
using NeuroAccessMaui.UI.Pages.Contacts.Chat;
using NeuroAccessMaui.UI.Pages.Contracts.MyContracts.ObjectModels;
using NeuroAccessMaui.UI.Pages.Main.XmppForm;
using NeuroAccessMaui.UI.Pages.Things.MyThings;
using NeuroAccessMaui.UI.Pages.Things.ReadSensor;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Globalization;
using System.Text;
using Waher.Networking.XMPP;
using Waher.Networking.XMPP.Concentrator;
using Waher.Networking.XMPP.Contracts;
using Waher.Networking.XMPP.Control;
using Waher.Networking.XMPP.DataForms;
using Waher.Networking.XMPP.Sensor;
using Waher.Networking.XMPP.ServiceDiscovery;
using Waher.Persistence;
using Waher.Things;
 
namespace NeuroAccessMaui.UI.Pages.Things.ViewThing
{
    public partial class ViewThingViewModel : QrXmppViewModel
    {
        private readonly Dictionary<string, PresenceEventArgs> presences = new(StringComparer.InvariantCultureIgnoreCase);
        private readonly ViewThingNavigationArgs? navigationArguments;
        private readonly ContactInfo? thing;
 
        public ViewThingViewModel(ViewThingNavigationArgs? Args)
            : base()
        {
            this.navigationArguments = Args;
            this.thing = Args?.Thing;
 
            this.Tags = [];
            this.Notifications = [];
 
            if (this.thing?.MetaData is not null)
            {
                foreach (Property Tag in this.thing.MetaData)
                    this.Tags.Add(new HumanReadableTag(Tag));
            }
 
            this.InContacts = !string.IsNullOrEmpty(this.thing?.ObjectId);
            this.IsOwner = this.thing?.Owner ?? false;
            this.IsSensor = this.thing?.IsSensor ?? false;
            this.IsActuator = this.thing?.IsActuator ?? false;
            this.IsConcentrator = this.thing?.IsConcentrator ?? false;
            this.IsNodeInConcentrator = !string.IsNullOrEmpty(this.thing?.NodeId) || !string.IsNullOrEmpty(this.thing?.SourceId) || !string.IsNullOrEmpty(this.thing?.Partition);
            this.SupportsSensorEvents = this.thing?.SupportsSensorEvents ?? false;
 
            this.InContactsAndNotOwner = this.InContacts && !this.IsOwner;
            this.NotInContacts = !this.InContacts;
            this.IsConnectedAndOwner = this.IsConnected && this.IsOwner;
            this.IsConnectedAndSensor = this.IsConnected && this.IsSensor;
            this.IsConnectedAndActuator = this.IsConnected && this.IsActuator;
            this.IsConnectedAndNotConcentrator = this.IsConnected && !this.IsConcentrator;
        }
 
        protected override async Task OnInitialize()
        {
            await base.OnInitialize();
 
            if (this.navigationArguments?.Events is not null)
            {
                this.Notifications.Clear();
 
                int c = 0;
 
                foreach (NotificationEvent Event in this.navigationArguments.Events)
                {
                    this.Notifications.Add(new EventModel(Event.Received,
                        await Event.GetCategoryIcon(),
                        await Event.GetDescription(),
                        Event));
 
                    if (Event.Type == NotificationEventType.Contacts)
                        c++;
                }
 
                this.NrPendingChatMessages = c;
                this.HasPendingChatMessages = c > 0;
            }
 
            this.HasNotifications = this.Notifications.Count > 0;
 
            await this.CalcThingIsOnline();
 
            ServiceRef.XmppService.OnPresence += this.Xmpp_OnPresence;
            ServiceRef.XmppService.OnRosterItemAdded += this.Xmpp_OnRosterItemAdded;
            ServiceRef.XmppService.OnRosterItemUpdated += this.Xmpp_OnRosterItemUpdated;
            ServiceRef.XmppService.OnRosterItemRemoved += this.Xmpp_OnRosterItemRemoved;
            ServiceRef.TagProfile.Changed += this.TagProfile_Changed;
            ServiceRef.NotificationService.OnNewNotification += this.NotificationService_OnNewNotification;
            ServiceRef.NotificationService.OnNotificationsDeleted += this.NotificationService_OnNotificationsDeleted;
 
            if (this.IsConnected && this.IsThingOnline)
                await this.CheckCapabilities();
 
            this.GenerateQrCode(this.Link);
        }
 
 
        protected override Task XmppService_ConnectionStateChanged(object? _, XmppState NewState)
        {
            base.XmppService_ConnectionStateChanged(_, NewState);
 
            MainThread.BeginInvokeOnMainThread(async () => await this.CalcThingIsOnline());
 
            return Task.CompletedTask;
        }
 
        private async Task CheckCapabilities()
        {
            if (this.InContacts &&
                this.thing is not null &&
                (!this.thing.IsSensor.HasValue ||
                !this.thing.IsActuator.HasValue ||
                !this.thing.IsConcentrator.HasValue ||
                !this.thing.SupportsSensorEvents.HasValue))
            {
                string? FullJid = this.GetFullJid();
 
                if (!string.IsNullOrEmpty(FullJid))
                {
                    try
                    {
                        ServiceDiscoveryEventArgs e = await ServiceRef.XmppService.SendServiceDiscoveryRequest(FullJid);
                        if (!this.InContacts)
                            return;
 
                        this.thing.IsSensor = e.HasAnyFeature(SensorClient.NamespacesSensorData);
                        this.thing.SupportsSensorEvents = e.HasAnyFeature(SensorClient.NamespacesSensorEvents);
                        this.thing.IsActuator = e.HasAnyFeature(ControlClient.NamespacesControl);
                        this.thing.IsConcentrator = e.HasAnyFeature(ConcentratorServer.NamespacesConcentrator);
 
                        if (this.InContacts && !string.IsNullOrEmpty(this.thing.ObjectId))
                            await Database.Update(this.thing);
 
                        MainThread.BeginInvokeOnMainThread(() =>
                        {
                            this.IsSensor = this.thing.IsSensor ?? false;
                            this.IsActuator = this.thing.IsActuator ?? false;
                            this.IsConcentrator = this.thing.IsConcentrator ?? false;
                            this.SupportsSensorEvents = this.thing.SupportsSensorEvents ?? false;
                        });
                    }
                    catch (Exception ex)
                    {
                        ServiceRef.LogService.LogException(ex);
                    }
                }
            }
        }
 
        protected override async Task OnDispose()
        {
            ServiceRef.XmppService.OnPresence -= this.Xmpp_OnPresence;
            ServiceRef.XmppService.OnRosterItemAdded -= this.Xmpp_OnRosterItemAdded;
            ServiceRef.XmppService.OnRosterItemUpdated -= this.Xmpp_OnRosterItemUpdated;
            ServiceRef.XmppService.OnRosterItemRemoved -= this.Xmpp_OnRosterItemRemoved;
            ServiceRef.TagProfile.Changed -= this.TagProfile_Changed;
            ServiceRef.NotificationService.OnNewNotification -= this.NotificationService_OnNewNotification;
            ServiceRef.NotificationService.OnNotificationsDeleted -= this.NotificationService_OnNotificationsDeleted;
 
            await base.OnDispose();
        }
 
        private async Task Xmpp_OnPresence(object? Sender, PresenceEventArgs e)
        {
            switch (e.Type)
            {
                case PresenceType.Available:
                    this.presences[e.FromBareJID] = e;
 
                    if (!this.InContacts && string.Equals(e.FromBareJID, this.thing?.BareJid, StringComparison.OrdinalIgnoreCase))
                    {
                        if (string.IsNullOrEmpty(this.thing?.ObjectId))
                            await Database.Insert(this.thing);
 
                        MainThread.BeginInvokeOnMainThread(async () =>
                        {
                            this.InContacts = true;
                        });
                    }
 
                    await this.CalcThingIsOnline();
 
                    break;
 
                case PresenceType.Unavailable:
                    this.presences.Remove(e.FromBareJID);
                    break;
            }
        }
 
        private async Task CalcThingIsOnline()
        {
 
            if (this.thing is null)
                MainThread.BeginInvokeOnMainThread(() => this.IsThingOnline = false);
            else
            {
                try
                {
                    await MainThread.InvokeOnMainThreadAsync(() => this.IsThingOnline = this.IsOnline(this.thing.BareJid));
                    if (this.IsThingOnline)
                        await this.CheckCapabilities();
                }
                catch (Exception ex)
                {
                    ServiceRef.LogService.LogException(ex);
                    await ServiceRef.UiService.DisplayException(ex);
                }
 
            }
        }
 
        async partial void OnInContactsChanged(bool value)
        {
            await this.CalcThingIsOnline();
        }
        private bool IsOnline(string BareJid)
        {
            if (this.presences.TryGetValue(BareJid, out PresenceEventArgs? e))
                return e.IsOnline;
            try
            {
                RosterItem? Item = ServiceRef.XmppService?.GetRosterItem(BareJid);
                if (Item is not null && Item.HasLastPresence)
                    return Item.LastPresence.IsOnline;
            }
            catch (Exception)
            {
                //ignore
            }
 
            return false;
        }
 
        private string? GetFullJid()
        {
            if (this.thing is null)
                return null;
            else
            {
                if (this.presences.TryGetValue(this.thing.BareJid, out PresenceEventArgs? e))
                    return (e?.IsOnline == true) ? e.From : null;
 
                try
                {
                    RosterItem? Item = ServiceRef.XmppService.GetRosterItem(this.thing.BareJid);
 
                    if (Item is null || !Item.HasLastPresence || !Item.LastPresence.IsOnline)
                        return null;
                    else
                        return Item.LastPresenceFullJid;
                }
                catch (Exception)
                {
                    return null;
                }
 
            }
        }
 
        private void TagProfile_Changed(object? Sender, PropertyChangedEventArgs e)
        {
            MainThread.BeginInvokeOnMainThread(async () => await this.CalcThingIsOnline());
        }
 
        #region Properties
 
        public ObservableCollection<HumanReadableTag> Tags { get; }
 
        public ObservableCollection<EventModel> Notifications { get; }
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(RemoveFromListCommand))]
        [NotifyCanExecuteChangedFor(nameof(AddToListCommand))]
        private bool inContacts;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(RemoveFromListCommand))]
        [NotifyCanExecuteChangedFor(nameof(AddToListCommand))]
        private bool notInContacts;
 
 
        protected override void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            base.OnPropertyChanged(e);
            MainThread.BeginInvokeOnMainThread(() =>
            {
 
                switch (e.PropertyName)
                {
                    case nameof(this.IsBusy):
                        this.ReadSensorCommand.NotifyCanExecuteChanged();
                        this.ControlActuatorCommand.NotifyCanExecuteChanged();
                        this.ChatCommand.NotifyCanExecuteChanged();
                        break;
                }
 
                //This looks a bit cursed
                switch (e.PropertyName)
                {
                    case nameof(this.InContacts):
                    case nameof(this.IsOwner):
                        this.InContactsAndNotOwner = this.InContacts && !this.IsOwner;
                        this.NotInContacts = !this.InContacts;
                        break;
                }
 
                switch (e.PropertyName)
                {
                    case nameof(this.IsConnected):
                    case nameof(this.IsOwner):
                        this.IsConnectedAndOwner = this.IsConnected && this.IsOwner;
                        break;
                }
 
                switch (e.PropertyName)
                {
                    case nameof(this.IsConnected):
                    case nameof(this.IsSensor):
                        this.IsConnectedAndSensor = this.IsConnected && this.IsSensor;
                        break;
                }
 
                switch (e.PropertyName)
                {
                    case nameof(this.IsConnected):
                    case nameof(this.IsActuator):
                        this.IsConnectedAndActuator = this.IsConnected && this.IsActuator;
                        break;
                }
 
                switch (e.PropertyName)
                {
                    case nameof(this.IsConnected):
                    case nameof(this.IsConcentrator):
                        this.IsConnectedAndNotConcentrator = this.IsConnected && !this.IsConcentrator;
                        break;
                }
            });
        }
 
        public string? FriendlyName => this.thing?.FriendlyName ?? this.thing?.BareJid ?? string.Empty;
 
        [ObservableProperty]
        private bool isOwner;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(RemoveFromListCommand))]
        [NotifyCanExecuteChangedFor(nameof(AddToListCommand))]
        private bool inContactsAndNotOwner;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(DeleteRulesCommand))]
        [NotifyCanExecuteChangedFor(nameof(DisownThingCommand))]
        private bool isConnectedAndOwner;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ReadSensorCommand))]
        private bool isConnectedAndSensor;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ControlActuatorCommand))]
        private bool isConnectedAndActuator;
 
        [ObservableProperty]
        private bool isConnectedAndNotConcentrator;
 
        [ObservableProperty]
        private bool isThingOnline;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ReadSensorCommand))]
        private bool isSensor;
 
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ControlActuatorCommand))]
        private bool isActuator;
 
        [ObservableProperty]
        private bool isConcentrator;
 
        [ObservableProperty]
        private bool isNodeInConcentrator;
 
        [ObservableProperty]
        private bool supportsSensorEvents;
        [ObservableProperty]
        private bool hasNotifications;
 
        [ObservableProperty]
        private bool hasPendingChatMessages;
 
        [ObservableProperty]
        private int nrPendingChatMessages;
 
        #endregion
 
        [RelayCommand]
        private static Task Click(object obj)
        {
            if (obj is HumanReadableTag Tag)
                return ViewClaimThing.ViewClaimThingViewModel.LabelClicked(Tag.Name, Tag.Value, Tag.LocalizedValue);
            else if (obj is string s)
                return ViewClaimThing.ViewClaimThingViewModel.LabelClicked(string.Empty, s, s);
            else
                return Task.CompletedTask;
        }
 
        [RelayCommand]
        private async Task CopyQr(object Item)
        {
            try
            {
                this.SetIsBusy(true);
 
                await Clipboard.SetTextAsync(this.Link);
                await ServiceRef.UiService.DisplayAlert(
                    ServiceRef.Localizer[nameof(AppResources.SuccessTitle)],
                    ServiceRef.Localizer[nameof(AppResources.SuccessTitle)]);
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
            finally
            {
                this.SetIsBusy(false);
            }
        }
 
        [RelayCommand(CanExecute = nameof(IsConnectedAndOwner))]
        private async Task DeleteRules()
        {
            if (this.thing is null)
                return;
 
            try
            {
                if (!await ServiceRef.UiService.DisplayAlert(
                    ServiceRef.Localizer[nameof(AppResources.Question)], ServiceRef.Localizer[nameof(AppResources.DeleteRulesQuestion)],
                    ServiceRef.Localizer[nameof(AppResources.Yes)], ServiceRef.Localizer[nameof(AppResources.Cancel)]))
                {
                    return;
                }
 
                if (!await App.AuthenticateUser(AuthenticationPurpose.DeleteRules, true))
                    return;
 
                TaskCompletionSource<bool> Result = new();
 
                ServiceRef.XmppService.DeleteDeviceRules(this.thing.RegistryJid, this.thing.BareJid, this.thing.NodeId,
                    this.thing.SourceId, this.thing.Partition, (sender, e) =>
                {
                    if (e.Ok)
                        Result.TrySetResult(true);
                    else if (e.StanzaError is not null)
                        Result.TrySetException(e.StanzaError);
                    else
                        Result.TrySetResult(false);
 
                    return Task.CompletedTask;
                }, null);
 
 
                if (!await Result.Task)
                    return;
 
                await ServiceRef.UiService.DisplayAlert(ServiceRef.Localizer[nameof(AppResources.SuccessTitle)],
                    ServiceRef.Localizer[nameof(AppResources.RulesDeleted)]);
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand(CanExecute = nameof(IsConnectedAndOwner))]
        private async Task DisownThing()
        {
            if (this.thing is null)
                return;
 
            try
            {
                if (!await ServiceRef.UiService.DisplayAlert(
                    ServiceRef.Localizer[nameof(AppResources.Question)], ServiceRef.Localizer[nameof(AppResources.DisownThingQuestion)],
                    ServiceRef.Localizer[nameof(AppResources.Yes)], ServiceRef.Localizer[nameof(AppResources.Cancel)]))
                {
                    return;
                }
 
                if (!await App.AuthenticateUser(AuthenticationPurpose.DisownThing, true))
                    return;
 
                (bool Succeeded, bool Done) = await ServiceRef.NetworkService.TryRequest(() =>
                    ServiceRef.XmppService.Disown(this.thing.RegistryJid, this.thing.BareJid, this.thing.SourceId, this.thing.Partition, this.thing.NodeId));
 
                if (!Succeeded)
                    return;
 
                if (this.InContacts)
                {
                    if (!string.IsNullOrEmpty(this.thing?.ObjectId))
                    {
                        await Database.Delete(this.thing);
                        await Database.Provider.Flush();
 
                        this.thing.ObjectId = null;
                    }
 
                    if (this.thing is not null)
                        this.thing.ObjectId = null;
 
                    this.InContacts = false;
                }
 
                await ServiceRef.UiService.DisplayAlert(ServiceRef.Localizer[nameof(AppResources.SuccessTitle)],
                    ServiceRef.Localizer[nameof(AppResources.ThingDisowned)]);
                await this.GoBack();
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand(CanExecute = nameof(NotInContacts))]
        private async Task AddToList()
        {
            if (this.thing is null)
                return;
            try
            {
                if (!await App.AuthenticateUser(AuthenticationPurpose.AddToListOfThings))
                    return;
 
                RosterItem? Item = ServiceRef.XmppService.GetRosterItem(this.thing.BareJid);
                if (Item is null || Item.State == SubscriptionState.None || Item.State == SubscriptionState.From)
                {
                    string IdXml;
 
                    if (ServiceRef.TagProfile.LegalIdentity is null)
                        IdXml = string.Empty;
                    else
                    {
                        StringBuilder Xml = new();
                        ServiceRef.TagProfile.LegalIdentity.Serialize(Xml, true, true, true, true, true, true, true);
                        IdXml = Xml.ToString();
                    }
                    ServiceRef.XmppService.RequestPresenceSubscription(this.thing.BareJid);
                    await ServiceRef.UiService.DisplayAlert(ServiceRef.Localizer[nameof(AppResources.SuccessTitle)], ServiceRef.Localizer[nameof(AppResources.ARequestHasBeenSentToTheOwner)]);
                    MainThread.BeginInvokeOnMainThread(() => this.NotInContacts = false);
                }
                await MainThread.InvokeOnMainThreadAsync(async () =>
                {
                    if (!this.InContacts)
                    {
                        if (string.IsNullOrEmpty(this.thing.ObjectId))
                            await Database.Insert(this.thing);
 
                        this.InContacts = true;
                    }
 
                    await this.CalcThingIsOnline();
                });
 
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand(CanExecute = nameof(InContactsAndNotOwner))]
        private async Task RemoveFromList()
        {
            if (this.thing is null)
                return;
 
            try
            {
                if (!await App.AuthenticateUser(AuthenticationPurpose.RemoveFromListOfThings))
                    return;
 
                if (this.InContacts)
                {
                    if (!string.IsNullOrEmpty(this.thing.ObjectId))
                    {
                        await Database.Delete(this.thing);
                        this.thing.ObjectId = null;
                    }
 
                    ServiceRef.XmppService.RequestPresenceUnsubscription(this.thing.BareJid);
 
                    if (ServiceRef.XmppService.GetRosterItem(this.thing.BareJid) is not null)
                        ServiceRef.XmppService.RemoveRosterItem(this.thing.BareJid);
 
                    await this.GoBack();
                }
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
        private bool CanReadSensor => !this.IsBusy && this.IsConnectedAndSensor;
 
        [RelayCommand(CanExecute = nameof(CanReadSensor))]
        private async Task ReadSensor()
        {
            await MainThread.InvokeOnMainThreadAsync(() => this.SetIsBusy(true));
 
            if (this.thing is null)
                return;
 
            ViewThingNavigationArgs Args = new(this.thing, MyThingsViewModel.GetNotificationEvents(this.thing) ?? []);
 
            await ServiceRef.UiService.GoToAsync(nameof(ReadSensorPage), Args, BackMethod.Pop);
 
            await MainThread.InvokeOnMainThreadAsync(() => this.SetIsBusy(false));
 
        }
 
        private bool CanControlActuator => !this.IsBusy && this.IsConnectedAndActuator;
 
        [RelayCommand(CanExecute = nameof(CanControlActuator))]
        private async Task ControlActuator()
        {
            await MainThread.InvokeOnMainThreadAsync(() => this.SetIsBusy(true));
 
            if (this.thing is null)
                return;
 
            try
            {
                string? FullJid = this.GetFullJid();
                if (string.IsNullOrEmpty(FullJid))
                    return;
 
                LanguageInfo SelectedLanguage = App.SelectedLanguage;
 
                if (string.IsNullOrEmpty(this.thing.NodeId) && string.IsNullOrEmpty(this.thing.SourceId) && string.IsNullOrEmpty(this.thing.Partition))
                    ServiceRef.XmppService.GetControlForm(FullJid, SelectedLanguage.Name, this.ControlFormCallback, null);
                else
                {
                    ThingReference ThingRef = new(this.thing.NodeId, this.thing.SourceId, this.thing.Partition);
                    ServiceRef.XmppService.GetControlForm(FullJid, SelectedLanguage.Name, this.ControlFormCallback, null, ThingRef);
                }
            }
            catch (Exception ex)
            {
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        private Task ControlFormCallback(object? Sender, DataFormEventArgs e)
        {
            if (e.Ok)
            {
                MainThread.BeginInvokeOnMainThread(async () =>
                {
                    await ServiceRef.UiService.GoToAsync(nameof(XmppFormPage), new XmppFormNavigationArgs(e.Form));
                });
            }
            else
            {
                ServiceRef.UiService.DisplayException(e.StanzaError ?? new Exception("Unable to get control form."));
            }
            MainThread.BeginInvokeOnMainThread(() => this.SetIsBusy(false));
            return Task.CompletedTask;
        }
 
 
        private bool CanChat => !this.IsBusy && this.IsConnectedAndNotConcentrator;
 
        [RelayCommand(CanExecute = nameof(CanChat))]
        private async Task Chat()
        {
            await MainThread.InvokeOnMainThreadAsync(() => this.SetIsBusy(true));
 
            if (this.thing is null)
                return;
 
            try
            {
                string LegalId = this.thing.LegalId;
                string FriendlyName = this.thing.FriendlyName;
                ChatNavigationArgs Args = new(LegalId, this.thing.BareJid, FriendlyName);
 
                await ServiceRef.UiService.GoToAsync(nameof(ChatPage), Args, BackMethod.Inherited, this.thing.BareJid);
            }
            catch (Exception ex)
            {
                await ServiceRef.UiService.DisplayException(ex);
            }
            finally
            {
                await MainThread.InvokeOnMainThreadAsync(() => this.SetIsBusy(false));
 
            }
        }
 
        private void NotificationService_OnNotificationsDeleted(object? Sender, NotificationEventsArgs e)
        {
            if (this.thing is null)
                return;
 
            MainThread.BeginInvokeOnMainThread(() =>
            {
                bool IsNode = this.IsNodeInConcentrator;
                string Key = this.thing.ThingNotificationCategoryKey;
                int NrChatMessagesRemoved = 0;
 
                foreach (NotificationEvent Event in e.Events)
                {
                    switch (Event.Type)
                    {
                        case NotificationEventType.Contacts:
                            if (IsNode)
                                continue;
 
                            if (Event.Category != this.thing.BareJid)
                                continue;
                            break;
 
                        case NotificationEventType.Things:
                            if (Event.Category != Key)
                                continue;
                            break;
 
                        default:
                            continue;
                    }
 
                    int i = 0;
 
                    foreach (EventModel Model in this.Notifications)
                    {
                        if (Model.Event.ObjectId == Event.ObjectId)
                        {
                            this.Notifications.RemoveAt(i);
 
                            if (Event.Type == NotificationEventType.Contacts)
                                NrChatMessagesRemoved++;
 
                            break;
                        }
 
                        i++;
                    }
                }
 
                this.NrPendingChatMessages -= NrChatMessagesRemoved;
                this.HasNotifications = this.Notifications.Count > 0;
                this.HasPendingChatMessages = this.NrPendingChatMessages > 0;
            });
        }
 
        private void NotificationService_OnNewNotification(object? Sender, NotificationEventArgs e)
        {
            MainThread.BeginInvokeOnMainThread(async () =>
            {
                try
                {
                    await this.CalcThingIsOnline();
 
                    switch (e.Event.Type)
                    {
                        case NotificationEventType.Contacts:
                            if (this.IsNodeInConcentrator)
                                return;
 
                            if (e.Event.Category != this.thing?.BareJid)
                                return;
                            break;
 
                        case NotificationEventType.Things:
                            if (e.Event.Category != this.thing?.ThingNotificationCategoryKey)
                                return;
                            break;
 
                        default:
                            return;
                    }
 
                    this.Notifications.Add(new EventModel(e.Event.Received,
                        await e.Event.GetCategoryIcon(),
                        await e.Event.GetDescription(),
                        e.Event));
 
                    this.HasNotifications = true;
 
                    if (e.Event.Type == NotificationEventType.Contacts)
                    {
                        this.NrPendingChatMessages++;
                        this.HasPendingChatMessages = true;
                    }
                }
                catch (Exception ex)
                {
                    ServiceRef.LogService.LogException(ex);
                }
            });
        }
 
        private Task Xmpp_OnRosterItemRemoved(object? Sender, RosterItem Item)
        {
            this.presences.Remove(Item.BareJid);
            MainThread.BeginInvokeOnMainThread(async () => await this.CalcThingIsOnline());
            return Task.CompletedTask;
        }
 
        private Task Xmpp_OnRosterItemUpdated(object? Sender, RosterItem Item)
        {
            MainThread.BeginInvokeOnMainThread(async () => await this.CalcThingIsOnline());
            return Task.CompletedTask;
        }
 
        private Task Xmpp_OnRosterItemAdded(object? Sender, RosterItem Item)
        {
            MainThread.BeginInvokeOnMainThread(async () => await this.CalcThingIsOnline());
            return Task.CompletedTask;
        }
 
        #region ILinkableView
 
        public override bool IsLinkable => true;
 
        public override bool EncodeAppLinks => true;
 
        public override string Link
        {
            get
            {
                StringBuilder sb = new();
                bool HasJid = false;
                bool HasSourceId = false;
                bool HasPartition = false;
                bool HasNodeId = false;
                bool HasRegistry = false;
 
                sb.Append("iotdisco:");
 
                if (this.thing is not null)
                {
                    if (this.thing.MetaData is not null)
                    {
                        foreach (Property P in this.thing.MetaData)
                        {
 
                            switch (P.Name.ToUpper(CultureInfo.InvariantCulture))
                            {
                                case Constants.XmppProperties.Altitude:
                                case Constants.XmppProperties.Latitude:
                                case Constants.XmppProperties.Longitude:
                                case Constants.XmppProperties.Version:
                                    sb.Append('#');
                                    break;
 
                                case Constants.XmppProperties.Jid:
                                    HasJid = true;
                                    break;
 
                                case Constants.XmppProperties.SourceId:
                                    HasSourceId = true;
                                    break;
 
                                case Constants.XmppProperties.Partition:
                                    HasPartition = true;
                                    break;
 
                                case Constants.XmppProperties.NodeId:
                                    HasNodeId = true;
                                    break;
 
                                case Constants.XmppProperties.Registry:
                                    HasRegistry = true;
                                    break;
                            }
                            sb.Append(Uri.EscapeDataString(P.Name));
                            sb.Append('=');
                            sb.Append(Uri.EscapeDataString(P.Value));
                            sb.Append(';');
 
                        }
                    }
 
                    if (!HasJid)
                    {
                        sb.Append("JID=");
                        sb.Append(Uri.EscapeDataString(this.thing.BareJid));
                    }
 
                    if (!HasSourceId && !string.IsNullOrEmpty(this.thing.SourceId))
                    {
                        sb.Append(";SID=");
                        sb.Append(Uri.EscapeDataString(this.thing.SourceId));
                    }
 
                    if (!HasPartition && !string.IsNullOrEmpty(this.thing.Partition))
                    {
                        sb.Append(";PT=");
                        sb.Append(Uri.EscapeDataString(this.thing.Partition));
                    }
 
                    if (!HasNodeId && !string.IsNullOrEmpty(this.thing.NodeId))
                    {
                        sb.Append(";NID=");
                        sb.Append(Uri.EscapeDataString(this.thing.NodeId));
                    }
 
                    if (!HasRegistry && !string.IsNullOrEmpty(this.thing.RegistryJid))
                    {
                        sb.Append(";R=");
                        sb.Append(Uri.EscapeDataString(this.thing.RegistryJid));
                    }
                }
 
                return sb.ToString();
            }
        }
 
        public override Task<string> Title => Task.FromResult(this.thing?.FriendlyName ?? string.Empty);
 
        public override bool HasMedia => false;
 
        public override byte[]? Media => null;
 
        public override string? MediaContentType => null;
 
        #endregion
    }
}