Relay/RelayClient/MainPage.xaml.cs

namespace RelayClient;

public partial class MainPage : ContentPage
{
    private readonly string _username;

    public MainPage(string username)
    {
        InitializeComponent();

        _username = username;
        UserLabel.Text = $"Logged in as: {_username}";

        ChatSimulator.MessageSent += OnMessageSent;
    }

    private void SendButton_OnClicked(object? sender, EventArgs e)
    {
        SendMessage();
    }

    private void MessageEntry_OnCompleted(object? sender, EventArgs e)
    {
        SendMessage();
    }

    private void SendMessage()
    {
        var text = MessageEntry.Text?.Trim();

        if (string.IsNullOrWhiteSpace(text))
            return;

        ChatSimulator.Send(_username, text);

        Console.WriteLine($"[{_username}] sent message: {text}");

        MessageEntry.Text = string.Empty;
        MessageEntry.Focus();
    }

    private void OnMessageSent(ChatMessage message)
    {
        MainThread.BeginInvokeOnMainThread(async () =>
        {
            bool isOwnMessage = message.SenderUsername == _username;

            var bubble = new Border
            {
                StrokeThickness = 1,
                Padding = 10,
                Margin = isOwnMessage
                    ? new Thickness(40, 0, 0, 0)
                    : new Thickness(0, 0, 40, 0),
                HorizontalOptions = isOwnMessage
                    ? LayoutOptions.End
                    : LayoutOptions.Start,
                Content = new VerticalStackLayout
                {
                    Spacing = 2,
                    Children =
                    {
                        new Label
                        {
                            Text = message.SenderUsername,
                            FontAttributes = FontAttributes.Bold,
                            FontSize = 12
                        },
                        new Label
                        {
                            Text = message.Text,
                            FontSize = 14
                        },
                        new Label
                        {
                            Text = message.Timestamp.ToString("h:mm tt"),
                            FontSize = 10
                        }
                    }
                }
            };

            MessagesLayout.Children.Add(bubble);
            await MessagesScrollView.ScrollToAsync(MessagesLayout, ScrollToPosition.End, true);
        });
    }

    protected override void OnDisappearing()
    {
        ChatSimulator.MessageSent -= OnMessageSent;
        base.OnDisappearing();
    }
}