MyWalletViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using EDaler;
using EDaler.Events;
using EDaler.Uris;
using Microsoft.Maui.Controls.Shapes;
using NeuroAccessMaui.Resources.Languages;
using NeuroAccessMaui.Services;
using NeuroAccessMaui.Services.Contacts;
using NeuroAccessMaui.Services.Notification;
using NeuroAccessMaui.Services.Notification.Wallet;
using NeuroAccessMaui.Services.UI;
using NeuroAccessMaui.Services.Wallet;
using NeuroAccessMaui.UI.Pages.Contacts.MyContacts;
using NeuroAccessMaui.UI.Pages.Contracts;
using NeuroAccessMaui.UI.Pages.Contracts.MyContracts;
using NeuroAccessMaui.UI.Pages.Contracts.MyContracts.ObjectModels;
using NeuroAccessMaui.UI.Pages.Contracts.NewContract;
using NeuroAccessMaui.UI.Pages.Main;
using NeuroAccessMaui.UI.Pages.Main.Apps;
using NeuroAccessMaui.UI.Pages.Wallet.BuyEDaler;
using NeuroAccessMaui.UI.Pages.Wallet.MyWallet.ObjectModels;
using NeuroAccessMaui.UI.Pages.Wallet.RequestPayment;
using NeuroAccessMaui.UI.Pages.Wallet.SellEDaler;
using NeuroAccessMaui.UI.Pages.Wallet.ServiceProviders;
using NeuroFeatures;
using NeuroFeatures.EventArguments;
using System.Xml;
using Waher.Networking.XMPP.Contracts;
using Waher.Persistence;
 
namespace NeuroAccessMaui.UI.Pages.Wallet.MyWallet
{
    public partial class MyWalletViewModel(WalletNavigationArgs? Args) : XmppViewModel()
    {
        private readonly WalletNavigationArgs? navigationArguments = Args;
        private DateTime lastEDalerEvent;
        private DateTime lastTokenEvent;
        private bool hasMoreTokens;
        private bool hasTotals;
        private bool hasTokens;
 
        public override async Task OnInitializeAsync()
        {
            await base.OnInitializeAsync();
 
            this.EDalerFrontGlyph = "https://" + ServiceRef.TagProfile.Domain + "/Images/eDalerFront200.png";
            this.EDalerBackGlyph = "https://" + ServiceRef.TagProfile.Domain + "/Images/eDalerBack200.png";
 
            if (this.navigationArguments is not null)
            {
                SortedDictionary<CaseInsensitiveString, NotificationEvent[]> NotificationEvents = this.GetNotificationEvents();
 
                await this.AssignProperties(this.navigationArguments.Balance, this.navigationArguments.PendingAmount,
                    this.navigationArguments.PendingCurrency, this.navigationArguments.PendingPayments, this.navigationArguments.Events,
                    this.navigationArguments.More, ServiceRef.XmppService.LastEDalerEvent, NotificationEvents);
            }
 
            ServiceRef.XmppService.EDalerBalanceUpdated += this.Wallet_BalanceUpdated;
            ServiceRef.XmppService.NeuroFeatureAdded += this.Wallet_TokenAdded;
            ServiceRef.XmppService.NeuroFeatureRemoved += this.Wallet_TokenRemoved;
            ServiceRef.NotificationService.OnNewNotification += this.NotificationService_OnNewNotification;
        }
 
        public override async Task OnAppearingAsync()
        {
            await base.OnAppearingAsync();
 
            if (((this.Balance is not null) && (ServiceRef.XmppService.LastEDalerBalance is not null) &&
                (this.Balance.Amount != ServiceRef.XmppService.LastEDalerBalance.Amount ||
                this.Balance.Currency != ServiceRef.XmppService.LastEDalerBalance.Currency ||
                this.Balance.Timestamp != ServiceRef.XmppService.LastEDalerBalance.Timestamp)) ||
                this.lastEDalerEvent != ServiceRef.XmppService.LastEDalerEvent)
            {
                await this.ReloadEDalerWallet(ServiceRef.XmppService.LastEDalerBalance ?? this.Balance);
            }
 
 
            if (this.hasTokens && this.lastTokenEvent != ServiceRef.XmppService.LastNeuroFeatureEvent)
                await this.LoadTokens(true);
        }
 
        public override async Task OnDisposeAsync()
        {
            ServiceRef.XmppService.EDalerBalanceUpdated -= this.Wallet_BalanceUpdated;
            ServiceRef.XmppService.NeuroFeatureAdded -= this.Wallet_TokenAdded;
            ServiceRef.XmppService.NeuroFeatureRemoved -= this.Wallet_TokenRemoved;
            ServiceRef.NotificationService.OnNewNotification -= this.NotificationService_OnNewNotification;
 
            await base.OnDisposeAsync();
        }
 
        private SortedDictionary<CaseInsensitiveString, NotificationEvent[]> GetNotificationEvents()
        {
            SortedDictionary<CaseInsensitiveString, NotificationEvent[]> Result = ServiceRef.NotificationService.GetEventsByCategory(NotificationEventType.Wallet);
            int NrBalance = 0;
            int NrToken = 0;
 
            foreach (NotificationEvent[] Events in Result.Values)
            {
                foreach (NotificationEvent Event in Events)
                {
                    if (Event is BalanceNotificationEvent)
                        NrBalance++;
                    else if (Event is TokenNotificationEvent)
                        NrToken++;
                }
            }
 
            this.NrBalanceNotifications = NrBalance;
            this.NrTokenNotifications = NrToken;
 
            return Result;
        }
 
        private async Task AssignProperties(Balance? Balance, decimal PendingAmount, string? PendingCurrency,
            EDaler.PendingPayment[]? PendingPayments, EDaler.AccountEvent[]? Events, bool More, DateTime LastEvent,
            SortedDictionary<CaseInsensitiveString, NotificationEvent[]> NotificationEvents)
        {
            if (Balance is not null)
            {
                this.Balance = Balance;
                this.Amount = Balance.Amount;
                this.ReservedAmount = Balance.Reserved;
                this.Currency = Balance.Currency;
                this.Timestamp = Balance.Timestamp;
            }
 
            this.lastEDalerEvent = LastEvent;
 
            this.PendingAmount = PendingAmount;
            this.PendingCurrency = PendingCurrency;
            this.HasPending = (PendingPayments?.Length ?? 0) > 0;
            this.HasEvents = (Events?.Length ?? 0) > 0;
            this.HasMoreEvents = More;
 
            Dictionary<string, string> FriendlyNames = [];
            string? FriendlyName;
 
            ObservableItemGroup<IUniqueItem> NewPaymentItems = new(nameof(this.PaymentItems), []);
 
            if (PendingPayments is not null)
            {
                List<IUniqueItem> NewPendingPayments = new(PendingPayments.Length);
 
                foreach (EDaler.PendingPayment Payment in PendingPayments)
                {
                    if (!FriendlyNames.TryGetValue(Payment.To, out FriendlyName))
                    {
                        FriendlyName = await ContactInfo.GetFriendlyName(Payment.To);
                        FriendlyNames[Payment.To] = FriendlyName;
                    }
 
                    NewPendingPayments.Add(new PendingPaymentItem(Payment, FriendlyName));
                }
 
                if (NewPendingPayments.Count > 0)
                    NewPaymentItems.Add(new ObservableItemGroup<IUniqueItem>(nameof(PendingPaymentItem), NewPendingPayments));
            }
 
            if (Events is not null)
            {
                List<IUniqueItem> NewAccountEvents = new(Events.Length);
 
                foreach (EDaler.AccountEvent Event in Events)
                {
                    if (!FriendlyNames.TryGetValue(Event.Remote, out FriendlyName))
                    {
                        FriendlyName = await ContactInfo.GetFriendlyName(Event.Remote);
                        FriendlyNames[Event.Remote] = FriendlyName;
                    }
 
                    if (!NotificationEvents.TryGetValue(Event.TransactionId.ToString(), out NotificationEvent[]? CategoryEvents))
                        CategoryEvents = [];
 
                    NewAccountEvents.Add(new AccountEventItem(Event, this, FriendlyName, CategoryEvents));
                }
 
                if (NewAccountEvents.Count > 0)
                    NewPaymentItems.Add(new ObservableItemGroup<IUniqueItem>(nameof(AccountEventItem), NewAccountEvents));
            }
 
            MainThread.BeginInvokeOnMainThread(() => ObservableItemGroup<IUniqueItem>.UpdateGroupsItems(this.PaymentItems, NewPaymentItems));
        }
 
        private Task Wallet_BalanceUpdated(object? Sender, BalanceEventArgs e)
        {
            Task.Run(() => this.ReloadEDalerWallet(e.Balance));
            return Task.CompletedTask;
        }
 
        private async Task ReloadEDalerWallet(Balance? Balance)
        {
            try
            {
                (decimal PendingAmount, string PendingCurrency, EDaler.PendingPayment[] PendingPayments) = await ServiceRef.XmppService.GetPendingEDalerPayments();
                (EDaler.AccountEvent[] Events, bool More) = await ServiceRef.XmppService.GetEDalerAccountEvents(Constants.BatchSizes.AccountEventBatchSize);
                IUniqueItem? OldItems = this.PaymentItems.FirstOrDefault(el => string.Equals(el.UniqueName, nameof(AccountEventItem), StringComparison.Ordinal));
 
                // Reload also items which were loaded earlier by the LoadMoreAccountEvents
                if (More &&
                    (OldItems is ObservableItemGroup<IUniqueItem> OldAccountEvents) &&
                    (OldAccountEvents.LastOrDefault() is AccountEventItem OldLastEvent) &&
                    (Events.LastOrDefault() is EDaler.AccountEvent NewLastEvent) &&
                    (OldLastEvent.Timestamp < NewLastEvent.Timestamp))
                {
                    List<EDaler.AccountEvent> AllEvents = new(Events);
                    EDaler.AccountEvent[] Events2;
                    bool More2 = true;
 
                    while (More2)
                    {
                        EDaler.AccountEvent LastEvent = AllEvents.Last();
                        (Events2, More2) = await ServiceRef.XmppService.GetEDalerAccountEvents(Constants.BatchSizes.AccountEventBatchSize, LastEvent.Timestamp);
 
                        if (More2)
                        {
                            More = true;
 
                            for (int i = 0; i < Events2.Length; i++)
                            {
                                EDaler.AccountEvent Event = Events2[i];
                                AllEvents.Add(Event);
 
                                if (OldLastEvent.Timestamp.Equals(Event.Timestamp))
                                {
                                    More2 = false;
                                    break;
                                }
                            }
                        }
                        else
                        {
                            More = false;
                            AllEvents.AddRange(Events2);
                        }
                    }
 
                    Events = [.. AllEvents];
                }
 
                SortedDictionary<CaseInsensitiveString, NotificationEvent[]> NotificationEvents = this.GetNotificationEvents();
 
                MainThread.BeginInvokeOnMainThread(async () => await this.AssignProperties(Balance, PendingAmount, PendingCurrency,
                    PendingPayments, Events, More, ServiceRef.XmppService.LastEDalerEvent, NotificationEvents));
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
            }
        }
 
        #region Properties
 
        [ObservableProperty]
        private Balance? balance;
 
        [ObservableProperty]
        private decimal amount;
 
        [ObservableProperty]
        private string? currency;
 
        [ObservableProperty]
        private bool hasPending;
 
        [ObservableProperty]
        private bool isFrontViewShowing;
 
        [ObservableProperty]
        private decimal pendingAmount;
 
        [ObservableProperty]
        private string? pendingCurrency;
 
        [ObservableProperty]
        private decimal reservedAmount;
 
        [ObservableProperty]
        private DateTime timestamp;
 
        [ObservableProperty]
        private string? eDalerFrontGlyph;
 
        [ObservableProperty]
        private string? eDalerBackGlyph;
 
        [ObservableProperty]
        private bool hasEvents;
 
        [ObservableProperty]
        private bool hasMoreEvents;
 
        [ObservableProperty]
        private int nrBalanceNotifications;
 
        [ObservableProperty]
        private int nrTokenNotifications;
 
        public ObservableItemGroup<IUniqueItem> PaymentItems { get; } = new(nameof(PaymentItems), []);
 
        public ObservableItemGroup<IUniqueItem> Tokens { get; } = new(nameof(Tokens), []);
 
        public ObservableItemGroup<IUniqueItem> Totals { get; } = new(nameof(Totals), []);
 
        #endregion
 
        [RelayCommand]
        private Task Back()
        {
            return this.GoBack();
        }
 
        [RelayCommand]
        private static async Task ScanQrCode()
        {
            await Services.UI.QR.QrCode.ScanQrCodeAndHandleResult();
        }
 
        [RelayCommand(CanExecute = nameof(IsConnected))]
        private async Task RequestPayment()
        {
            try
            {
                IBuyEDalerServiceProvider[] ServiceProviders = await ServiceRef.XmppService.GetServiceProvidersForBuyingEDalerAsync();
 
                if (ServiceProviders.Length == 0)
                {
                    EDalerBalanceNavigationArgs Args = new(this.Balance);
 
                    await ServiceRef.NavigationService.GoToAsync(nameof(RequestPaymentPage), Args, BackMethod.CurrentPage);
                }
                else
                {
                    List<IBuyEDalerServiceProvider> ServiceProviders2 = [];
 
                    ServiceProviders2.AddRange(ServiceProviders);
                    ServiceProviders2.Add(new EmptyBuyEDalerServiceProvider());
 
                    ServiceProvidersNavigationArgs e = new(ServiceProviders2.ToArray(),
                        ServiceRef.Localizer[nameof(AppResources.BuyEDaler)],
                        ServiceRef.Localizer[nameof(AppResources.SelectServiceProviderBuyEDaler)]);
 
                    await ServiceRef.NavigationService.GoToAsync(nameof(ServiceProvidersPage), e, BackMethod.Pop);
 
                    IBuyEDalerServiceProvider? ServiceProvider = (IBuyEDalerServiceProvider?)(e.ServiceProvider is null ? null : await e.ServiceProvider.Task);
 
                    if (ServiceProvider is not null)
                    {
                        if (string.IsNullOrEmpty(ServiceProvider.Id))
                        {
                            EDalerBalanceNavigationArgs Args = new(this.Balance);
 
                            await ServiceRef.NavigationService.GoToAsync(nameof(RequestPaymentPage), Args, BackMethod.CurrentPage);
                        }
                        else if (string.IsNullOrEmpty(ServiceProvider.BuyEDalerTemplateContractId))
                        {
                            TaskCompletionSource<decimal?> Result = new();
                            BuyEDalerNavigationArgs Args = new(this.Balance?.Currency, Result);
 
                            await ServiceRef.NavigationService.GoToAsync(nameof(BuyEDalerPage), Args, BackMethod.CurrentPage);
 
                            decimal? Amount = await Result.Task;
 
                            if (Amount.HasValue && Amount.Value > 0)
                            {
                                PaymentTransaction Transaction = await ServiceRef.XmppService.InitiateBuyEDaler(ServiceProvider.Id, ServiceProvider.Type,
                                    Amount.Value, this.Balance?.Currency);
 
                                WaitForComletion(Transaction);
                            }
                        }
                        else
                        {
                            CreationAttributesEventArgs e2 = await ServiceRef.XmppService.GetNeuroFeatureCreationAttributes();
                            Dictionary<CaseInsensitiveString, object> Parameters = new()
                            {
                                { "Visibility", "CreatorAndParts" },
                                { "Role", "Buyer" },
                                { "Currency", this.Balance?.Currency ?? e2.Currency },
                                { "TrustProvider", e2.TrustProviderId }
                            };
 
                            await ServiceRef.ContractOrchestratorService.OpenContract(ServiceProvider.BuyEDalerTemplateContractId,
                                ServiceRef.Localizer[nameof(AppResources.BuyEDaler)], Parameters);
 
                            OptionsTransaction OptionsTransaction = await ServiceRef.XmppService.InitiateBuyEDalerGetOptions(ServiceProvider.Id, ServiceProvider.Type);
                            IDictionary<CaseInsensitiveString, object>[] Options = await OptionsTransaction.Wait();
 
                            if (ServiceRef.NavigationService.CurrentPage is IContractOptionsPage ContractOptionsPage)
                                MainThread.BeginInvokeOnMainThread(async () => await ContractOptionsPage.ShowContractOptions(Options));
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        private static async void WaitForComletion(PaymentTransaction Transaction)
        {
            try
            {
                await Transaction.Wait();
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand(CanExecute = nameof(IsConnected))]
        private async Task MakePayment()
        {
            try
            {
                ISellEDalerServiceProvider[] ServiceProviders = await ServiceRef.XmppService.GetServiceProvidersForSellingEDalerAsync();
 
                if (ServiceProviders.Length == 0)
                {
                    ContactListNavigationArgs Args = new(ServiceRef.Localizer[nameof(AppResources.SelectContactToPay)], SelectContactAction.MakePayment)
                    {
                        CanScanQrCode = true,
                        AllowAnonymous = true,
                        AnonymousText = ServiceRef.Localizer[nameof(AppResources.Open)]
                    };
 
                    await ServiceRef.NavigationService.GoToAsync(nameof(MyContactsPage), Args, BackMethod.CurrentPage);
                }
                else
                {
                    List<ISellEDalerServiceProvider> ServiceProviders2 = [];
 
                    ServiceProviders2.AddRange(ServiceProviders);
                    ServiceProviders2.Add(new EmptySellEDalerServiceProvider());
 
                    ServiceProvidersNavigationArgs e = new(ServiceProviders2.ToArray(),
                        ServiceRef.Localizer[nameof(AppResources.SellEDaler)],
                        ServiceRef.Localizer[nameof(AppResources.SelectServiceProviderSellEDaler)]);
 
                    await ServiceRef.NavigationService.GoToAsync(nameof(ServiceProvidersPage), e, BackMethod.Pop);
 
                    ISellEDalerServiceProvider? ServiceProvider = (ISellEDalerServiceProvider?)(e.ServiceProvider is null ? null : await e.ServiceProvider.Task);
 
                    if (ServiceProvider is not null)
                    {
                        if (string.IsNullOrEmpty(ServiceProvider.Id))
                        {
                            ContactListNavigationArgs Args = new(ServiceRef.Localizer[nameof(AppResources.SelectContactToPay)], SelectContactAction.MakePayment)
                            {
                                CanScanQrCode = true,
                                AllowAnonymous = true,
                                AnonymousText = ServiceRef.Localizer[nameof(AppResources.Open)],
                            };
 
                            await ServiceRef.NavigationService.GoToAsync(nameof(MyContactsPage), Args, BackMethod.CurrentPage);
                        }
                        else if (string.IsNullOrEmpty(ServiceProvider.SellEDalerTemplateContractId))
                        {
                            TaskCompletionSource<decimal?> Result = new();
                            SellEDalerNavigationArgs Args = new(this.Balance?.Currency, Result);
 
                            await ServiceRef.NavigationService.GoToAsync(nameof(SellEDalerPage), Args, BackMethod.CurrentPage);
 
                            decimal? Amount = await Result.Task;
 
                            if (Amount.HasValue && Amount.Value > 0)
                            {
                                PaymentTransaction Transaction = await ServiceRef.XmppService.InitiateSellEDaler(ServiceProvider.Id, ServiceProvider.Type,
                                    Amount.Value, this.Balance?.Currency);
 
                                WaitForComletion(Transaction);
                            }
                        }
                        else
                        {
                            CreationAttributesEventArgs e2 = await ServiceRef.XmppService.GetNeuroFeatureCreationAttributes();
                            Dictionary<CaseInsensitiveString, object> Parameters = new()
                            {
                                { "Visibility", "CreatorAndParts" },
                                { "Role", "Seller" },
                                { "Currency", this.Balance?.Currency ?? e2.Currency },
                                { "TrustProvider", e2.TrustProviderId }
                            };
 
                            await ServiceRef.ContractOrchestratorService.OpenContract(ServiceProvider.SellEDalerTemplateContractId,
                                ServiceRef.Localizer[nameof(AppResources.SellEDaler)], Parameters);
 
                            OptionsTransaction OptionsTransaction = await ServiceRef.XmppService.InitiateSellEDalerGetOptions(ServiceProvider.Id, ServiceProvider.Type);
                            IDictionary<CaseInsensitiveString, object>[] Options = await OptionsTransaction.Wait();
 
                            if (ServiceRef.NavigationService.CurrentPage is IContractOptionsPage ContractOptionsPage)
                                MainThread.BeginInvokeOnMainThread(async () => await ContractOptionsPage.ShowContractOptions(Options));
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand]
        private async Task ShowPaymentItem(object Item)
        {
            if (Item is PendingPaymentItem PendingItem)
            {
                if (!ServiceRef.XmppService.TryParseEDalerUri(PendingItem.Uri, out EDalerUri Uri, out string Reason))
                {
                    await ServiceRef.UiService.DisplayAlert(ServiceRef.Localizer[nameof(AppResources.ErrorTitle)],
                        ServiceRef.Localizer[nameof(AppResources.InvalidEDalerUri), Reason]);
                    return;
                }
 
                await ServiceRef.NavigationService.GoToAsync(nameof(PendingPayment.PendingPaymentPage), new EDalerUriNavigationArgs(Uri, PendingItem.FriendlyName));
            }
            else if (Item is AccountEventItem EventItem)
                await ServiceRef.NavigationService.GoToAsync(nameof(AccountEvent.AccountEventPage), new AccountEvent.AccountEventNavigationArgs(EventItem));
        }
 
        [RelayCommand]
        private async Task LoadMoreAccountEvents()
        {
            if (this.HasMoreEvents)
            {
                this.HasMoreEvents = false; // So multiple requests are not made while scrolling.
                bool More = true;
 
                try
                {
                    EDaler.AccountEvent[]? Events = null;
                    IUniqueItem? OldItems = this.PaymentItems.FirstOrDefault(el => string.Equals(el.UniqueName, nameof(AccountEventItem), StringComparison.Ordinal));
 
                    if (OldItems is null)
                        (Events, More) = await ServiceRef.XmppService.GetEDalerAccountEvents(Constants.BatchSizes.AccountEventBatchSize);
                    else
                    {
                        ObservableItemGroup<IUniqueItem> OldAccountEvents = (ObservableItemGroup<IUniqueItem>)OldItems;
 
                        if (OldAccountEvents.LastOrDefault() is AccountEventItem LastEvent)
                        {
                            (Events, More) = await ServiceRef.XmppService.GetEDalerAccountEvents(Constants.BatchSizes.AccountEventBatchSize, LastEvent.Timestamp);
                        }
                    }
 
                    if (Events is not null)
                    {
                        List<IUniqueItem> NewAccountEvents = [];
                        Dictionary<string, string> FriendlyNames = [];
                        SortedDictionary<CaseInsensitiveString, NotificationEvent[]> NotificationEvents = this.GetNotificationEvents();
 
                        foreach (EDaler.AccountEvent Event in Events)
                        {
                            if (!FriendlyNames.TryGetValue(Event.Remote, out string? FriendlyName))
                            {
                                FriendlyName = await ContactInfo.GetFriendlyName(Event.Remote);
                                FriendlyNames[Event.Remote] = FriendlyName;
                            }
 
                            if (!NotificationEvents.TryGetValue(Event.TransactionId.ToString(), out NotificationEvent[]? CategoryEvents))
                                CategoryEvents = [];
 
                            NewAccountEvents.Add(new AccountEventItem(Event, this, FriendlyName, CategoryEvents));
                        }
 
                        MainThread.BeginInvokeOnMainThread(() =>
                        {
 
                            if (OldItems is ObservableItemGroup<IUniqueItem> SubItems)
                            {
                                foreach (IUniqueItem Item in NewAccountEvents)
                                    SubItems.Add(Item);
                            }
                            else
                            {
                                this.PaymentItems.Add(new ObservableItemGroup<IUniqueItem>(nameof(AccountEventItem), NewAccountEvents));
                                this.HasMoreEvents = More;
                            }
                        });
                    }
                }
                catch (Exception ex)
                {
                    ServiceRef.LogService.LogException(ex);
                }
            }
        }
 
        public async void BindTokens()
        {
            try
            {
                await this.LoadTokens(false);
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
            }
        }
 
        private async Task LoadTokens(bool Reload)
        {
            this.lastTokenEvent = ServiceRef.XmppService.LastNeuroFeatureEvent;
 
            if (!this.hasTotals || Reload)
            {
                this.hasTotals = true; // prevent fast reentering
 
                try
                {
                    TokenTotalsEventArgs tteArgs = await ServiceRef.XmppService.GetNeuroFeatureTotals();
 
                    if (tteArgs.Ok)
                    {
                        ObservableItemGroup<IUniqueItem> NewTotals = new(nameof(this.Totals), []);
 
                        if (tteArgs.Totals is not null)
                        {
                            foreach (TokenTotal Total in tteArgs.Totals)
                            {
                                NewTotals.Add(new TokenTotalItem(Total));
                            }
                        }
 
                        MainThread.BeginInvokeOnMainThread(() => ObservableItemGroup<IUniqueItem>.UpdateGroupsItems(this.Totals, NewTotals));
                    }
 
                    this.hasTotals = tteArgs.Ok;
                }
                catch (Exception ex)
                {
                    this.hasTotals = false;
                    ServiceRef.LogService.LogException(ex);
                }
            }
 
            if (!this.hasTokens || Reload)
            {
                this.hasTokens = true; // prevent fast reentering
 
                try
                {
                    SortedDictionary<CaseInsensitiveString, TokenNotificationEvent[]> NotificationEvents =
                        ServiceRef.NotificationService.GetEventsByCategory<TokenNotificationEvent>(NotificationEventType.Wallet);
 
                    TokensEventArgs teArgs = await ServiceRef.XmppService.GetNeuroFeatures(0, Constants.BatchSizes.TokenBatchSize);
                    SortedDictionary<CaseInsensitiveString, NotificationEvent[]> EventsByCateogy = this.GetNotificationEvents();
 
                    ObservableItemGroup<IUniqueItem> NewTokens = new(nameof(this.Tokens), []);
                    List<TokenNotificationEvent> ToDelete = [];
 
                    foreach (KeyValuePair<CaseInsensitiveString, TokenNotificationEvent[]> P in NotificationEvents)
                    {
                        Token? Token = null;
 
                        foreach (TokenNotificationEvent TokenEvent in P.Value)
                        {
                            Token = await TokenEvent.GetTokenAsync();
                            if (Token is not null)
                                break;
                        }
 
                        if (Token is not null)
                        {
                            NewTokens.Add(new TokenItem(Token, P.Value));
                        }
                        else
                        {
                            foreach (TokenNotificationEvent TokenEvent in P.Value)
                            {
                                if (TokenEvent is TokenRemovedNotificationEvent)
                                {
                                    Geometry Icon = await TokenEvent.GetCategoryIcon();
                                    string Description = await TokenEvent.GetDescription();
 
                                    NewTokens.Add(new EventModel(TokenEvent.Received, Icon, Description, TokenEvent));
                                }
                                else
                                {
                                    ToDelete.Add(TokenEvent);
                                }
                            }
                        }
                    }
 
                    if (ToDelete.Count > 0)
                        await ServiceRef.NotificationService.DeleteEvents([.. ToDelete]);
 
                    if (teArgs.Ok)
                    {
                        if (teArgs.Tokens is not null)
                        {
                            foreach (Token Token in teArgs.Tokens)
                            {
                                if (NotificationEvents.ContainsKey(Token.TokenId))
                                    continue;
 
                                if (!EventsByCateogy.TryGetValue(Token.TokenId, out NotificationEvent[]? Events))
                                    Events = [];
 
                                NewTokens.Add(new TokenItem(Token, Events));
                            }
                        }
 
                        this.hasMoreTokens = teArgs?.Tokens is not null && teArgs.Tokens.Length == Constants.BatchSizes.TokenBatchSize;
 
                        MainThread.BeginInvokeOnMainThread(() => ObservableItemGroup<IUniqueItem>.UpdateGroupsItems(this.Tokens, NewTokens));
                    }
 
                    this.hasTokens = teArgs?.Ok ?? false;
                }
                catch (Exception ex)
                {
                    this.hasTokens = false;
                    ServiceRef.LogService.LogException(ex);
                }
            }
        }
 
        internal void ViewsFlipped(bool IsFrontViewShowing)
        {
            this.IsFrontViewShowing = IsFrontViewShowing;
        }
 
        [RelayCommand]
        private async Task CreateToken()
        {
            try
            {
                TaskCompletionSource<Contract?> TemplateSelection = new();
                MyContractsNavigationArgs Args = new(ContractsListMode.TokenCreationTemplates, TemplateSelection);
 
                await ServiceRef.NavigationService.GoToAsync(nameof(MyContractsPage), Args, BackMethod.Pop);
 
                Contract? Template = await TemplateSelection.Task;
                if (Template is null)
                    return;
 
                Dictionary<CaseInsensitiveString, object> Parameters = [];
                Template.Visibility = ContractVisibility.Public;
 
                if (Template.ForMachinesLocalName == "Create" && Template.ForMachinesNamespace == NeuroFeaturesClient.NamespaceNeuroFeatures)
                {
                    CreationAttributesEventArgs e2 = await ServiceRef.XmppService.GetNeuroFeatureCreationAttributes();
                    XmlDocument Doc = new()
                    {
                        PreserveWhitespace = true
                    };
                    Doc.LoadXml(Template.ForMachines.OuterXml);
 
                    XmlNamespaceManager NamespaceManager = new(Doc.NameTable);
                    NamespaceManager.AddNamespace("nft", NeuroFeaturesClient.NamespaceNeuroFeatures);
 
                    string? CreatorRole = Doc.SelectSingleNode("/nft:Create/nft:Creator/nft:RoleReference/@role", NamespaceManager)?.Value;
                    string? OwnerRole = Doc.SelectSingleNode("/nft:Create/nft:Owner/nft:RoleReference/@role", NamespaceManager)?.Value;
                    string? TrustProviderRole = Doc.SelectSingleNode("/nft:Create/nft:TrustProvider/nft:RoleReference/@role", NamespaceManager)?.Value;
                    string? CurrencyParameter = Doc.SelectSingleNode("/nft:Create/nft:Currency/nft:ParameterReference/@parameter", NamespaceManager)?.Value;
                    string? CommissionParameter = Doc.SelectSingleNode("/nft:Create/nft:CommissionPercent/nft:ParameterReference/@parameter", NamespaceManager)?.Value;
 
                    if (Template.Parts is null)
                    {
                        List<Part> Parts = [];
 
                        if (!string.IsNullOrEmpty(CreatorRole))
                        {
                            Parts.Add(new Part()
                            {
                                LegalId = ServiceRef.TagProfile.LegalIdentity?.Id,
                                Role = CreatorRole
                            });
                        }
 
                        if (!string.IsNullOrEmpty(TrustProviderRole))
                        {
                            Parts.Add(new Part()
                            {
                                LegalId = e2.TrustProviderId,
                                Role = TrustProviderRole
                            });
                        }
 
                        Template.Parts = [.. Parts];
                        Template.PartsMode = ContractParts.ExplicitlyDefined;
                    }
                    else
                    {
                        foreach (Part Part in Template.Parts)
                        {
                            if (Part.Role == CreatorRole || Part.Role == OwnerRole)
                                Part.LegalId = ServiceRef.TagProfile.LegalIdentity?.Id;
                            else if (Part.Role == TrustProviderRole)
                                Part.LegalId = e2.TrustProviderId;
                        }
                    }
 
                    if (!string.IsNullOrEmpty(CurrencyParameter))
                        Parameters[CurrencyParameter] = e2.Currency;
 
                    if (!string.IsNullOrEmpty(CommissionParameter))
                        Parameters[CommissionParameter] = e2.Commission;
                }
 
                NewContractNavigationArgs NewContractArgs = new(Template, true, Parameters);
 
                await ServiceRef.NavigationService.GoToAsync(nameof(NewContractPage), NewContractArgs, BackMethod.CurrentPage);
            }
            catch (Exception ex)
            {
                await ServiceRef.UiService.DisplayException(ex);
            }
        }
 
        [RelayCommand]
        private async Task LoadMoreTokens()
        {
            if (this.hasMoreTokens)
            {
                this.hasMoreTokens = false; // So multiple requests are not made while scrolling.
 
                try
                {
                    TokensEventArgs e = await ServiceRef.XmppService.GetNeuroFeatures(this.Tokens.Count, Constants.BatchSizes.TokenBatchSize);
                    SortedDictionary<CaseInsensitiveString, NotificationEvent[]> EventsByCateogy = this.GetNotificationEvents();
 
                    MainThread.BeginInvokeOnMainThread(() =>
                    {
                        if (e.Ok)
                        {
                            if (e.Tokens is not null)
                            {
                                foreach (Token Token in e.Tokens)
                                {
                                    if (!EventsByCateogy.TryGetValue(Token.TokenId, out NotificationEvent[]? Events))
                                        Events = [];
 
                                    this.Tokens.Add(new TokenItem(Token, Events));
                                }
 
                                this.hasMoreTokens = e.Tokens.Length == Constants.BatchSizes.TokenBatchSize;
                            }
                        }
                    });
                }
                catch (Exception ex)
                {
                    ServiceRef.LogService.LogException(ex);
                }
            }
        }
 
        private Task Wallet_TokenAdded(object _, TokenEventArgs e)
        {
            if (!ServiceRef.NotificationService.TryGetNotificationEvents(NotificationEventType.Wallet, e.Token.TokenId, out NotificationEvent[]? Events))
                Events = [];
 
            MainThread.BeginInvokeOnMainThread(() =>
            {
                TokenItem Item = new(e.Token, Events);
 
                if (this.Tokens.Count == 0)
                    this.Tokens.Add(Item);
                else
                    this.Tokens.Insert(0, Item);
            });
 
            return Task.CompletedTask;
        }
 
        private Task Wallet_TokenRemoved(object _, TokenEventArgs e)
        {
            MainThread.BeginInvokeOnMainThread(() =>
            {
                int i, c = this.Tokens.Count;
 
                for (i = 0; i < c; i++)
                {
                    if (this.Tokens[i] is TokenItem Item && Item.TokenId == e.Token.TokenId)
                    {
                        this.Tokens.RemoveAt(i);
                        break;
                    }
                }
            });
 
            return Task.CompletedTask;
        }
 
        private Task NotificationService_OnNewNotification(object? Sender, NotificationEventArgs e)
        {
            if (e.Event.Type == NotificationEventType.Wallet)
            {
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    if (e.Event is BalanceNotificationEvent)
                        this.NrBalanceNotifications++;
                    else if (e.Event is TokenNotificationEvent)
                        this.NrTokenNotifications++;
                });
            }
 
            return Task.CompletedTask;
        }
 
        // Go to Apps page
        [RelayCommand]
        public async Task ViewApps()
        {
            try
            {
                await ServiceRef.NavigationService.GoToAsync(nameof(AppsPage));
            }
            catch (Exception Ex)
            {
                ServiceRef.LogService.LogException(Ex);
            }
        }
 
        [RelayCommand]
        public async Task ViewMainPage()
        {
            try
            {
                await ServiceRef.NavigationService.PopToRootAsync();
            }
            catch (Exception Ex)
            {
                ServiceRef.LogService.LogException(Ex);
            }
        }
    }
}