refactoring, documentation pending

MalwareMultiScan.Scanner/Services/ScanHostedService.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using EasyNetQ;
+using MalwareMultiScan.Backends.Interfaces;
+using MalwareMultiScan.Backends.Messages;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace MalwareMultiScan.Scanner.Services
+{
+    internal class ScanHostedService : IHostedService
+    {
+        private readonly IScanBackend _backend;
+        private readonly IConfiguration _configuration;
+        private readonly ILogger<ScanHostedService> _logger;
+
+        private IBus _bus;
+
+        public ScanHostedService(ILogger<ScanHostedService> logger, IConfiguration configuration, IScanBackend backend)
+        {
+            _logger = logger;
+            _configuration = configuration;
+            _backend = backend;
+        }
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            _bus = RabbitHutch.CreateBus(
+                _configuration.GetConnectionString("RabbitMQ"));
+
+            _bus.Receive<ScanRequestMessage>(_backend.Id, Scan);
+
+            _logger.LogInformation(
+                $"Started scan hosting service for the backend {_backend.Id}");
+
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            _bus.Dispose();
+
+            _logger.LogInformation(
+                $"Stopped scan hosting service for the backend {_backend.Id}");
+
+            return Task.CompletedTask;
+        }
+
+        private async Task Scan(ScanRequestMessage message)
+        {
+            _logger.LogInformation(
+                $"Starting scan of {message.Uri} via backend {_backend.Id} from {message.Id}");
+
+            var cancellationTokenSource = new CancellationTokenSource(
+                TimeSpan.FromSeconds(_configuration.GetValue<int>("MaxScanningTime")));
+
+            try
+            {
+                var result = new ScanResultMessage
+                {
+                    Id = message.Id,
+                    Backend = _backend.Id,
+
+                    Threats = await _backend.ScanAsync(
+                        message.Uri, cancellationTokenSource.Token)
+                };
+
+                _logger.LogInformation(
+                    $"Backend {_backend.Id} completed a scan of {message.Id} " +
+                    $"with result '{string.Join(", ", result.Threats)}'");
+
+                await _bus.SendAsync(_configuration.GetValue<string>("ResultsSubscriptionId"), result);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(
+                    exception, "Scanning failed with exception");
+            }
+        }
+    }
+}