MyAvaloniaDemo/AuroraDesk.Presentation/ViewModels/Pages/UdpServerPageViewModel.cs

using AuroraDesk.Presentation.ViewModels.Base;
using Microsoft.Extensions.Logging;
using ReactiveUI;
using System;
using System.Collections.ObjectModel;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Reactive;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Avalonia.Threading;

namespace AuroraDesk.Presentation.ViewModels.Pages;

/// <summary>
/// UDP 服务端页面 ViewModel
/// </summary>
public class UdpServerPageViewModel : RoutableViewModel
{
    private readonly ILogger<UdpServerPageViewModel>? _logger;
    private UdpClient? _udpServer;
    private CancellationTokenSource? _listenCancellationTokenSource;
    private bool _isListening;
    private int _listenPort = 8080;
    private string _statusMessage = "未启动";
    private readonly ObservableCollection<string> _receivedMessages = new();
    private readonly ObservableCollection<ClientInfo> _clients = new();

    public UdpServerPageViewModel(
        IScreen hostScreen,
        ILogger<UdpServerPageViewModel>? logger = null)
        : base(hostScreen, "UdpServer")
    {
        _logger = logger;
        
        // 创建命令
        StartListeningCommand = ReactiveCommand.CreateFromTask(StartListeningAsync,
            this.WhenAnyValue(x => x.IsListening, isListening => !isListening));
        StopListeningCommand = ReactiveCommand.Create(StopListening,
            this.WhenAnyValue(x => x.IsListening));
        ClearMessagesCommand = ReactiveCommand.Create(ClearMessages);
        ClearClientsCommand = ReactiveCommand.Create(ClearClients);
    }

    /// <summary>
    /// 是否正在监听
    /// </summary>
    public bool IsListening
    {
        get => _isListening;
        set => this.RaiseAndSetIfChanged(ref _isListening, value);
    }

    /// <summary>
    /// 监听端口
    /// </summary>
    public int ListenPort
    {
        get => _listenPort;
        set => this.RaiseAndSetIfChanged(ref _listenPort, value);
    }

    /// <summary>
    /// 状态消息
    /// </summary>
    public string StatusMessage
    {
        get => _statusMessage;
        set => this.RaiseAndSetIfChanged(ref _statusMessage, value);
    }

    /// <summary>
    /// 接收到的消息列表
    /// </summary>
    public ObservableCollection<string> ReceivedMessages => _receivedMessages;

    /// <summary>
    /// 客户端列表
    /// </summary>
    public ObservableCollection<ClientInfo> Clients => _clients;

    /// <summary>
    /// 开始监听命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> StartListeningCommand { get; }

    /// <summary>
    /// 停止监听命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> StopListeningCommand { get; }

    /// <summary>
    /// 清空消息命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> ClearMessagesCommand { get; }

    /// <summary>
    /// 清空客户端命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> ClearClientsCommand { get; }

    /// <summary>
    /// 开始监听
    /// </summary>
    private async Task StartListeningAsync()
    {
        try
        {
            if (ListenPort < 1 || ListenPort > 65535)
            {
                StatusMessage = $"无效的端口: {ListenPort}";
                _logger?.LogWarning("无效的端口: {Port}", ListenPort);
                return;
            }

            // 创建 UDP 服务器
            var localEndPoint = new IPEndPoint(IPAddress.Any, ListenPort);
            _udpServer = new UdpClient(localEndPoint);
            _udpServer.EnableBroadcast = true;
            
            IsListening = true;
            StatusMessage = $"正在监听端口 {ListenPort}...";
            _logger?.LogInformation("UDP 服务器开始监听端口 {Port}", ListenPort);

            // 启动接收任务
            _listenCancellationTokenSource = new CancellationTokenSource();
            _ = Task.Run(() => ListenForMessagesAsync(_listenCancellationTokenSource.Token));
        }
        catch (SocketException ex) when (ex.SocketErrorCode == SocketError.AddressAlreadyInUse)
        {
            StatusMessage = $"端口 {ListenPort} 已被占用";
            _logger?.LogWarning("端口 {Port} 已被占用", ListenPort);
            IsListening = false;
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "启动监听失败");
            StatusMessage = $"启动失败: {ex.Message}";
            IsListening = false;
        }
    }

    /// <summary>
    /// 停止监听
    /// </summary>
    private void StopListening()
    {
        try
        {
            _listenCancellationTokenSource?.Cancel();
            _listenCancellationTokenSource?.Dispose();
            _listenCancellationTokenSource = null;

            _udpServer?.Close();
            _udpServer?.Dispose();
            _udpServer = null;

            IsListening = false;
            StatusMessage = "已停止监听";
            _logger?.LogInformation("UDP 服务器已停止监听");
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "停止监听时出错");
        }
    }

    /// <summary>
    /// 监听消息（后台任务）
    /// </summary>
    private async Task ListenForMessagesAsync(CancellationToken cancellationToken)
    {
        while (!cancellationToken.IsCancellationRequested && _udpServer != null)
        {
            try
            {
                var result = await _udpServer.ReceiveAsync();
                var receivedData = Encoding.UTF8.GetString(result.Buffer);
                var remoteEndPoint = result.RemoteEndPoint;
                var timestamp = DateTime.Now.ToString("HH:mm:ss");
                var displayMessage = $"[{timestamp}] 来自 {remoteEndPoint.Address}:{remoteEndPoint.Port}: {receivedData}";
                
                await Dispatcher.UIThread.InvokeAsync(() =>
                {
                    ReceivedMessages.Add(displayMessage);
                    
                    // 更新客户端列表
                    var clientAddress = remoteEndPoint.Address.ToString();
                    var clientPort = remoteEndPoint.Port;
                    var clientKey = $"{clientAddress}:{clientPort}";
                    
                    var existingClient = Clients.FirstOrDefault(c => c.Address == clientAddress && c.Port == clientPort);
                    if (existingClient == null)
                    {
                        Clients.Add(new ClientInfo
                        {
                            Address = clientAddress,
                            Port = clientPort,
                            FirstSeen = DateTime.Now,
                            LastSeen = DateTime.Now,
                            MessageCount = 1
                        });
                    }
                    else
                    {
                        existingClient.LastSeen = DateTime.Now;
                        existingClient.MessageCount++;
                    }
                });
                
                _logger?.LogDebug("收到消息: {Message} 来自 {EndPoint}", receivedData, remoteEndPoint);
                
                // 自动回复（可选）
                var responseMessage = $"收到: {receivedData}";
                var responseData = Encoding.UTF8.GetBytes(responseMessage);
                await _udpServer.SendAsync(responseData, responseData.Length, remoteEndPoint);
            }
            catch (ObjectDisposedException)
            {
                // UDP 服务器已关闭，正常退出
                break;
            }
            catch (SocketException ex) when (ex.SocketErrorCode == SocketError.Interrupted)
            {
                // 操作被取消，正常退出
                break;
            }
            catch (Exception ex)
            {
                _logger?.LogError(ex, "接收消息时出错");
                await Task.Delay(1000, cancellationToken); // 等待后重试
            }
        }
    }

    /// <summary>
    /// 清空消息
    /// </summary>
    private void ClearMessages()
    {
        ReceivedMessages.Clear();
        _logger?.LogInformation("已清空消息列表");
    }

    /// <summary>
    /// 清空客户端列表
    /// </summary>
    private void ClearClients()
    {
        Clients.Clear();
        _logger?.LogInformation("已清空客户端列表");
    }

    /// <summary>
    /// 清理资源
    /// </summary>
    public void Dispose()
    {
        StopListening();
    }
}

/// <summary>
/// 客户端信息
/// </summary>
public class ClientInfo : ReactiveObject
{
    private string _address = string.Empty;
    private int _port;
    private DateTime _firstSeen;
    private DateTime _lastSeen;
    private int _messageCount;

    public string Address
    {
        get => _address;
        set => this.RaiseAndSetIfChanged(ref _address, value);
    }

    public int Port
    {
        get => _port;
        set => this.RaiseAndSetIfChanged(ref _port, value);
    }

    public DateTime FirstSeen
    {
        get => _firstSeen;
        set => this.RaiseAndSetIfChanged(ref _firstSeen, value);
    }

    public DateTime LastSeen
    {
        get => _lastSeen;
        set => this.RaiseAndSetIfChanged(ref _lastSeen, value);
    }

    public int MessageCount
    {
        get => _messageCount;
        set => this.RaiseAndSetIfChanged(ref _messageCount, value);
    }

    public string DisplayName => $"{Address}:{Port}";
}