using AuroraDesk.Presentation.ViewModels.Base;
using Microsoft.Extensions.Logging;
using ReactiveUI;
using System;
using System.Collections.ObjectModel;
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 客户端页面 ViewModel
/// </summary>
public class UdpClientPageViewModel : RoutableViewModel
{
    private readonly ILogger<UdpClientPageViewModel>? _logger;
    private UdpClient? _udpClient;
    private CancellationTokenSource? _receiveCancellationTokenSource;
    private bool _isConnected;
    private string _serverIp = "192.168.14.58";
    private int _serverPort = 50505;
    private int _localPort = 0; // 0 表示系统自动分配
    private string _message = string.Empty;
    private string _statusMessage = "未连接";
    private readonly ObservableCollection<ReceivedMessageEntry> _receivedMessages = new();
    private readonly ObservableCollection<string> _sentMessages = new();
    private int _receivedMessageIndex;
    private bool _isAutoScrollToBottom = true;

    public UdpClientPageViewModel(
        IScreen hostScreen,
        ILogger<UdpClientPageViewModel>? logger = null)
        : base(hostScreen, "UdpClient")
    {
        _logger = logger;
        
        // 创建命令
        ConnectCommand = ReactiveCommand.CreateFromTask(ConnectAsync, 
            this.WhenAnyValue(x => x.IsConnected, isConnected => !isConnected));
        DisconnectCommand = ReactiveCommand.Create(Disconnect, 
            this.WhenAnyValue(x => x.IsConnected));
        SendMessageCommand = ReactiveCommand.CreateFromTask(SendMessageAsync,
            this.WhenAnyValue(x => x.IsConnected, x => x.Message,
                (isConnected, message) => isConnected && !string.IsNullOrWhiteSpace(message)));
        ClearMessagesCommand = ReactiveCommand.Create(ClearMessages);
    }

    /// <summary>
    /// 是否已连接
    /// </summary>
    public bool IsConnected
    {
        get => _isConnected;
        set => this.RaiseAndSetIfChanged(ref _isConnected, value);
    }

    /// <summary>
    /// 服务器 IP 地址
    /// </summary>
    public string ServerIp
    {
        get => _serverIp;
        set => this.RaiseAndSetIfChanged(ref _serverIp, value);
    }

    /// <summary>
    /// 服务器端口
    /// </summary>
    public int ServerPort
    {
        get => _serverPort;
        set => this.RaiseAndSetIfChanged(ref _serverPort, value);
    }

    /// <summary>
    /// 本地端口
    /// </summary>
    public int LocalPort
    {
        get => _localPort;
        set => this.RaiseAndSetIfChanged(ref _localPort, value);
    }

    /// <summary>
    /// 要发送的消息
    /// </summary>
    public string Message
    {
        get => _message;
        set => this.RaiseAndSetIfChanged(ref _message, value);
    }

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

    /// <summary>
    /// 是否自动滚动到底部
    /// </summary>
    public bool IsAutoScrollToBottom
    {
        get => _isAutoScrollToBottom;
        set => this.RaiseAndSetIfChanged(ref _isAutoScrollToBottom, value);
    }

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

    /// <summary>
    /// 已发送的消息列表
    /// </summary>
    public ObservableCollection<string> SentMessages => _sentMessages;

    /// <summary>
    /// 连接命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> ConnectCommand { get; }

    /// <summary>
    /// 断开连接命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> DisconnectCommand { get; }

    /// <summary>
    /// 发送消息命令
    /// </summary>
    public ReactiveCommand<Unit, Unit> SendMessageCommand { get; }

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

    /// <summary>
    /// 连接到服务器
    /// </summary>
    private async Task ConnectAsync()
    {
        try
        {
            if (!IPAddress.TryParse(ServerIp, out var ipAddress))
            {
                StatusMessage = $"无效的 IP 地址: {ServerIp}";
                _logger?.LogWarning("无效的 IP 地址: {Ip}", ServerIp);
                return;
            }

            if (ServerPort < 1 || ServerPort > 65535)
            {
                StatusMessage = $"无效的端口: {ServerPort}";
                _logger?.LogWarning("无效的端口: {Port}", ServerPort);
                return;
            }

            // 创建 UDP 客户端
            _udpClient = new UdpClient(LocalPort);
            _udpClient.EnableBroadcast = true;
            
            var localEndPoint = (IPEndPoint)_udpClient.Client.LocalEndPoint!;
            LocalPort = localEndPoint.Port;
            
            IsConnected = true;
            StatusMessage = $"已连接到 {ServerIp}:{ServerPort} (本地端口: {LocalPort})";
            _logger?.LogInformation("UDP 客户端已连接到 {ServerIp}:{ServerPort}, 本地端口: {LocalPort}", 
                ServerIp, ServerPort, LocalPort);

            // 启动接收任务
            _receiveCancellationTokenSource = new CancellationTokenSource();
            _ = Task.Run(() => ReceiveMessagesAsync(_receiveCancellationTokenSource.Token));
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "连接失败");
            StatusMessage = $"连接失败: {ex.Message}";
            Disconnect();
        }
    }

    /// <summary>
    /// 断开连接
    /// </summary>
    private void Disconnect()
    {
        try
        {
            _receiveCancellationTokenSource?.Cancel();
            _receiveCancellationTokenSource?.Dispose();
            _receiveCancellationTokenSource = null;

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

            IsConnected = false;
            StatusMessage = "已断开连接";
            _logger?.LogInformation("UDP 客户端已断开连接");
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "断开连接时出错");
        }
    }

    /// <summary>
    /// 发送消息
    /// </summary>
    private async Task SendMessageAsync()
    {
        if (_udpClient == null || string.IsNullOrWhiteSpace(Message))
            return;

        try
        {
            if (!IPAddress.TryParse(ServerIp, out var ipAddress))
            {
                StatusMessage = $"无效的 IP 地址: {ServerIp}";
                return;
            }

            var remoteEndPoint = new IPEndPoint(ipAddress, ServerPort);
            var data = Encoding.UTF8.GetBytes(Message);
            
            await _udpClient.SendAsync(data, data.Length, remoteEndPoint);
            
            var timestamp = DateTime.Now.ToString("HH:mm:ss");
            var displayMessage = $"[{timestamp}] 发送: {Message}";
            
            await Dispatcher.UIThread.InvokeAsync(() =>
            {
                SentMessages.Add(displayMessage);
            });
            
            _logger?.LogInformation("发送消息到 {ServerIp}:{ServerPort}: {Message}", 
                ServerIp, ServerPort, Message);
            
            Message = string.Empty; // 清空输入框
        }
        catch (Exception ex)
        {
            _logger?.LogError(ex, "发送消息失败");
            StatusMessage = $"发送失败: {ex.Message}";
        }
    }

    /// <summary>
    /// 接收消息（后台任务）
    /// </summary>
    private async Task ReceiveMessagesAsync(CancellationToken cancellationToken)
    {
        while (!cancellationToken.IsCancellationRequested && _udpClient != null)
        {
            try
            {
                var result = await _udpClient.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}";
                
                var index = Interlocked.Increment(ref _receivedMessageIndex);

                await Dispatcher.UIThread.InvokeAsync(() =>
                {
                    ReceivedMessages.Add(new ReceivedMessageEntry(index, displayMessage));
                });
                
                _logger?.LogDebug("收到消息: {Message} 来自 {EndPoint}", receivedData, remoteEndPoint);
            }
            catch (ObjectDisposedException)
            {
                // UDP 客户端已关闭，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();
        Interlocked.Exchange(ref _receivedMessageIndex, 0);
        SentMessages.Clear();
        _logger?.LogInformation("已清空消息列表");
    }

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

public sealed record ReceivedMessageEntry(int Index, string DisplayText);