IPClab456/IPClab.5/Service/TcpClientService.cs

using IPClab._5.Models;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace IPClab._5.Service;

public class TcpClientService
{
    private TcpClient? _client;
    private NetworkStream? _stream;
    private CancellationTokenSource? _cts;
    private long _totalBytesReceived;
    private long _totalBytesSent;

    public bool IsConnected => _client?.Connected ?? false;

    public async Task ConnectAsync(string ipAddress, int port, IProgress<NetworkEvent> progress)
    {
        if (IsConnected) return;

        _totalBytesReceived = 0;
        _totalBytesSent = 0;
        _client = new TcpClient();
        _cts = new CancellationTokenSource();

        try
        {
            progress.Report(new NetworkEvent { StatusText = "Connecting", Message = $"Connecting to {ipAddress}:{port}..." });

            await _client.ConnectAsync(ipAddress, port).ConfigureAwait(false);
            _stream = _client.GetStream();

            // Quality Control Step: Apply structural operation timeouts
            _stream.ReadTimeout = 5000;
            _stream.WriteTimeout = 5000;

            progress.Report(new NetworkEvent { StatusText = "Connected", Message = "Successfully connected to server." });

            // Fire and forget background incoming processing loop
            _ = Task.Run(() => ListenForServerPayloadsAsync(_cts.Token, progress), _cts.Token);
        }
        catch (Exception ex)
        {
            CleanUp();
            progress.Report(new NetworkEvent { StatusText = "Disconnected", Message = $"Connection failed: {ex.Message}", IsError = true });
            throw;
        }
    }

    public async Task SendMessageAsync(string message, IProgress<NetworkEvent> progress)
    {
        if (!IsConnected || _stream == null)
        {
            progress.Report(new NetworkEvent { StatusText = "Disconnected", Message = "Cannot send message. Client is offline.", IsError = true });
            return;
        }

        try
        {
            // Quality Control Requirement: Delimiter-based separation 
            byte[] data = Encoding.UTF8.GetBytes(message + "\n");
            await _stream.WriteAsync(data, 0, data.Length).ConfigureAwait(false);

            _totalBytesSent += data.Length;
            progress.Report(new NetworkEvent { StatusText = "Connected", Message = $"Sent: {message}", BytesTransferred = _totalBytesSent });
        }
        catch (Exception ex)
        {
            progress.Report(new NetworkEvent { StatusText = "Disconnected", Message = $"Send fault occurred: {ex.Message}", IsError = true });
            CleanUp();
        }
    }

    private async Task ListenForServerPayloadsAsync(CancellationToken token, IProgress<NetworkEvent> progress)
    {
        using (StreamReader reader = new StreamReader(_stream!, Encoding.UTF8))
        {
            while (!token.IsCancellationRequested && IsConnected)
            {
                try
                {
                    string? incomingPayload = await reader.ReadLineAsync(token).ConfigureAwait(false);

                    if (incomingPayload == null) break; // Clean TCP drop detected

                    long rawBytesCount = Encoding.UTF8.GetByteCount(incomingPayload) + Environment.NewLine.Length;
                    _totalBytesReceived += rawBytesCount;

                    progress.Report(new NetworkEvent
                    {
                        StatusText = "Connected",
                        Message = $"Received: {incomingPayload}",
                        BytesTransferred = _totalBytesReceived
                    });
                }
                catch (OperationCanceledException) when (token.IsCancellationRequested)
                {
                    break;
                }
                catch (Exception ex)
                {
                    progress.Report(new NetworkEvent { StatusText = "Disconnected", Message = $"Read thread error: {ex.Message}", IsError = true });
                    break;
                }
            }
        }

        CleanUp();
        progress.Report(new NetworkEvent { StatusText = "Disconnected", Message = "Disconnected from server cleanly." });
    }

    public void Disconnect()
    {
        CleanUp();
    }

    private void CleanUp()
    {
        _cts?.Cancel();
        _stream?.Dispose();
        _client?.Dispose();
        _stream = null;
        _client = null;
    }
}