finished unit tests and docstrings

MalwareMultiScan.Scanner/Services/Implementations/ScanHostedService.cs

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+using System;
+using System.Diagnostics;
+using System.Threading;
+using System.Threading.Tasks;
+using EasyNetQ;
+using MalwareMultiScan.Backends.Interfaces;
+using MalwareMultiScan.Backends.Messages;
+using MalwareMultiScan.Scanner.Services.Interfaces;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+
+namespace MalwareMultiScan.Scanner.Services.Implementations
+{
+    /// <inheritdoc />
+    public class ScanHostedService : IScanHostedService
+    {
+        private readonly IScanBackend _backend;
+        private readonly IBus _bus;
+        private readonly IConfiguration _configuration;
+        private readonly ILogger<ScanHostedService> _logger;
+
+        /// <summary>
+        /// Initialise scan hosted service.
+        /// </summary>
+        /// <param name="logger">Logger.</param>
+        /// <param name="backend">Scan backend.</param>
+        /// <param name="bus">EasyNetQ bus.</param>
+        /// <param name="configuration">Configuration.</param>
+        public ScanHostedService(
+            ILogger<ScanHostedService> logger,
+            IScanBackend backend, IBus bus,
+            IConfiguration configuration)
+        {
+            _logger = logger;
+            _bus = bus;
+            _configuration = configuration;
+            _backend = backend;
+        }
+
+        /// <inheritdoc />
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            _bus.Receive<ScanRequestMessage>(_backend.Id, Scan);
+
+            _logger.LogInformation(
+                $"Started scan hosting service for the backend {_backend.Id}");
+
+            return Task.CompletedTask;
+        }
+
+        /// <inheritdoc />
+        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")));
+
+            var result = new ScanResultMessage
+            {
+                Id = message.Id,
+                Backend = _backend.Id
+            };
+
+            var stopwatch = new Stopwatch();
+
+            stopwatch.Start();
+
+            try
+            {
+                result.Threats = await _backend.ScanAsync(
+                    message.Uri, cancellationTokenSource.Token);
+
+                result.Succeeded = true;
+
+                _logger.LogInformation(
+                    $"Backend {_backend.Id} completed a scan of {message.Id} " +
+                    $"with result '{string.Join(", ", result.Threats)}'");
+            }
+            catch (Exception exception)
+            {
+                result.Succeeded = false;
+
+                _logger.LogError(
+                    exception, "Scanning failed with exception");
+            }
+            finally
+            {
+                stopwatch.Stop();
+            }
+
+            result.Duration = stopwatch.ElapsedMilliseconds / 1000;
+
+            _logger.LogInformation(
+                $"Sending scan results with status {result.Succeeded}");
+
+            await _bus.SendAsync(
+                _configuration.GetValue<string>("ResultsSubscriptionId"), result);
+        }
+    }
+}