【C#プログラム入門 レベル2】ポンコツ2人組がWPFでBluetoothを使ってファイルを送受信するプログラムに挑戦してみました！

<Window x:Class="BluetoothSample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Bluetooth File Transfer" Height="350" Width="500">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <StackPanel Orientation="Horizontal" Grid.Row="0" Margin="10">
            <Button Content="Send File" Width="100" Margin="5" Click="SendFileButton_Click"/>
            <Button Content="Receive File" Width="100" Margin="5" Click="ReceiveFileButton_Click"/>
        </StackPanel>

        <ListBox x:Name="DiscoveredDevicesListBox" Grid.Row="1" Margin="10"
                 DisplayMemberPath="DeviceName" SelectionMode="Single"/>
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;
using Microsoft.Win32;
using InTheHand.Net;
using InTheHand.Net.Sockets;
using InTheHand.Net.Bluetooth;

namespace BluetoothSample
{
    public partial class MainWindow : Window
    {
        private BluetoothClient _bluetoothClient;
        private readonly Guid _uuid = new Guid("00001101-0000-1000-8000-00805F9B34FB"); // SPP UUID
        private ObservableCollection<BluetoothDeviceInfo> _discoveredDevices;

        public MainWindow()
        {
            InitializeComponent();
            _bluetoothClient = new BluetoothClient();
            _discoveredDevices = new ObservableCollection<BluetoothDeviceInfo>();

            DiscoveredDevicesListBox.ItemsSource = _discoveredDevices;
            Loaded += MainWindow_Loaded; // MainWindowのLoadedイベントにハンドラを追加
        }

        private async Task DiscoverDevices()
        {
            try
            {
                IReadOnlyCollection<BluetoothDeviceInfo> devices = _bluetoothClient.DiscoverDevices();

                if (devices != null && devices.Count > 0)
                {
                    List<BluetoothDeviceInfo> deviceList = devices.ToList();

                    await Dispatcher.InvokeAsync(() =>
                    {
                        _discoveredDevices.Clear();
                        foreach (BluetoothDeviceInfo device in deviceList)
                        {
                            _discoveredDevices.Add(device);
                        }
                    });
                }
                else
                {
                    MessageBox.Show("Bluetooth デバイスが見つかりません。");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"デバイスの検出エラー: {ex.Message}");
            }
        }

        private async void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            await DiscoverDevices();
            await PairDevices();
        }

        private Task PairDevices()
        {
            foreach (BluetoothDeviceInfo device in _discoveredDevices)
            {
                try
                {
                    if (!device.Authenticated)
                    {
                        if (!BluetoothSecurity.PairRequest(device.DeviceAddress, null))
                        {
                            MessageBox.Show("デバイスとのペアリングに失敗しました: " + device.DeviceName);
                        }
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"デバイスとのペアリングエラー {device.DeviceName}: {ex.Message}");
                }
            }

            return Task.CompletedTask;
        }

        private async void SendFileButton_Click(object sender, RoutedEventArgs e)
        {
            if (DiscoveredDevicesListBox.SelectedItem is BluetoothDeviceInfo selectedDevice)
            {
                OpenFileDialog openFileDialog = new OpenFileDialog();
                if (openFileDialog.ShowDialog() == true)
                {
                    string selectedFile = openFileDialog.FileName;
                    await SendFileOverBluetooth(selectedFile, selectedDevice);

                    // 受信側でファイルを受け入れるために受信メソッドを呼び出す
                    string saveFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "ReceivedFile.txt");
                    await ReceiveFileOverBluetooth(saveFilePath);
                }
            }
            else
            {
                MessageBox.Show("Bluetooth デバイスを選択してください。");
            }
        }

        private async void ReceiveFileButton_Click(object sender, RoutedEventArgs e)
        {
            if (DiscoveredDevicesListBox.SelectedItem is BluetoothDeviceInfo selectedDevice)
            {
                try
                {
                    var saveFileDialog = new SaveFileDialog();
                    if (saveFileDialog.ShowDialog() == true)
                    {
                        string saveFilePath = saveFileDialog.FileName;

                        MessageBox.Show("ファイル転送が開始されることを待機しています...");

                        using (var listener = new BluetoothListener(_uuid))
                        {
                            listener.Start();

                            using (var client = await Task.Run(() => listener.AcceptBluetoothClient()))
                            {
                                using (var fileStream = new FileStream(saveFilePath, FileMode.Create))
                                using (var bluetoothStream = client.GetStream())
                                {
                                    await bluetoothStream.CopyToAsync(fileStream);
                                    MessageBox.Show("ファイルは正常に受信され、次の場所に保存されました。 " + saveFilePath);
                                }
                            }

                            listener.Stop();
                        }
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"ファイル受信エラー: {ex.Message}");
                }
            }
            else
            {
                MessageBox.Show("Bluetooth デバイスを選択してください。");
            }
        }

        private async Task<bool> SendFileOverBluetooth(string filePath, BluetoothDeviceInfo device)
        {
            try
            {
                using (var fileStream = new FileStream(filePath, FileMode.Open))
                {
                    var peer = new BluetoothEndPoint(device.DeviceAddress, BluetoothService.SerialPort);

                    using (var client = new BluetoothClient())
                    {
                        client.Connect(peer);

                        var bluetoothClientStream = client.GetStream();
                        if (bluetoothClientStream != null)
                        {
                            await fileStream.CopyToAsync(bluetoothClientStream);
                            MessageBox.Show("ファイルは正常に送信されました。");
                            return true;
                        }
                        else
                        {
                            MessageBox.Show("Bluetooth 接続の確立に失敗しました。");
                            return false;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"ファイル送信エラー: {ex.Message}");
                return false;
            }
        }

        private async Task<bool> ReceiveFileOverBluetooth(string saveFilePath)
        {
            try
            {
                using (var listener = new BluetoothListener(_uuid))
                {
                    listener.Start();

                    using (var client = await Task.Run(() => listener.AcceptBluetoothClient()))
                    {
                        using (var fileStream = new FileStream(saveFilePath, FileMode.Create))
                        using (var bluetoothStream = client.GetStream())
                        {
                            await bluetoothStream.CopyToAsync(fileStream);
                            MessageBox.Show("ファイルは正常に受信され、次の場所に保存されました。 " + saveFilePath);
                            return true;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"ファイル受信エラー: {ex.Message}");
                return false;
            }
        }
    }
}