Using IHostingService for TTS listening and playing in background.

TTSListening.cs

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+using System.Runtime.InteropServices;
+using System.Web;
+using Microsoft.Extensions.Hosting;
+using NAudio.Wave;
+using NAudio.Wave.SampleProviders;
+using Serilog;
+using TwitchChatTTS.Chat.Speech;
+
+namespace TwitchChatTTS
+{
+    public class TTSListening : IHostedService
+    {
+        private readonly AudioPlaybackEngine _playback;
+        private readonly TTSPlayer _player;
+        private readonly ILogger _logger;
+
+
+        public TTSListening(AudioPlaybackEngine playback, TTSPlayer player, ILogger logger)
+        {
+            _playback = playback;
+            _player = player;
+            _logger = logger;
+        }
+
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            Task.Run(async () =>
+            {
+                while (true)
+                {
+                    try
+                    {
+                        if (cancellationToken.IsCancellationRequested)
+                        {
+                            _logger.Warning("TTS Listening - Cancellation requested.");
+                            return;
+                        }
+
+                        var group = _player.ReceiveBuffer();
+                        if (group == null)
+                        {
+                            await Task.Delay(200, cancellationToken);
+                            continue;
+                        }
+
+                        if (cancellationToken.IsCancellationRequested)
+                        {
+                            _logger.Warning("TTS Listening - Cancellation requested.");
+                            return;
+                        }
+
+                        FetchMasterAudio(group);
+                    }
+                    catch (COMException e)
+                    {
+                        _logger.Error(e, "Failed to send request for TTS [HResult: " + e.HResult + "]");
+                    }
+                    catch (Exception e)
+                    {
+                        _logger.Error(e, "Failed to send request for TTS.");
+                    }
+                }
+            });
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            return Task.CompletedTask;
+        }
+
+        private Task FetchMasterAudio(TTSGroupedMessage group)
+        {
+            return Task.Run(() =>
+                {
+                    var list = new List<ISampleProvider>();
+                    foreach (var message in group.Messages)
+                    {
+                        if (string.IsNullOrEmpty(message.Message))
+                        {
+                            using (var reader = new AudioFileReader(message.File))
+                            {
+                                var data = _playback.ConvertSound(reader.ToWaveProvider());
+                                var resampled = new WdlResamplingSampleProvider(data, _playback.SampleRate);
+                                list.Add(resampled);
+                            }
+                            continue;
+                        }
+                        if (string.IsNullOrEmpty(message.Voice))
+                        {
+                            _logger.Error($"No voice has been selected for this message [message: {message.Message}]");
+                            continue;
+                        }
+
+                        try
+                        {
+                            string url = $"https://api.streamelements.com/kappa/v2/speech?voice={message.Voice}&text={HttpUtility.UrlEncode(message.Message.Trim())}";
+                            var nws = new NetworkWavSound(url);
+                            var provider = new CachedWavProvider(nws);
+                            var data = _playback.ConvertSound(provider);
+                            var resampled = new WdlResamplingSampleProvider(data, _playback.SampleRate);
+                            list.Add(resampled);
+                        }
+                        catch (Exception e)
+                        {
+                            _logger.Error(e, "Failed to fetch TTS message for ");
+                        }
+                    }
+
+                    var merged = new ConcatenatingSampleProvider(list);
+                    group.Audio = merged;
+                    _player.Ready(group);
+                });
+        }
+    }
+}