Restore SEBPatch

SafeExamBrowser.Service/ServiceController.cs

@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2024 ETH Zürich, IT Services
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using SafeExamBrowser.Communication.Contracts.Events;
+using SafeExamBrowser.Communication.Contracts.Hosts;
+using SafeExamBrowser.Configuration.Contracts;
+using SafeExamBrowser.Core.Contracts.OperationModel;
+using SafeExamBrowser.Lockdown.Contracts;
+using SafeExamBrowser.Logging.Contracts;
+
+namespace SafeExamBrowser.Service
+{
+	internal class ServiceController
+	{
+		private ILogger logger;
+		private Func<string, ILogObserver> logWriterFactory;
+		private IOperationSequence bootstrapSequence;
+		private IOperationSequence sessionSequence;
+		private IServiceHost serviceHost;
+		private SessionContext sessionContext;
+		private ISystemConfigurationUpdate systemConfigurationUpdate;
+		private ILogObserver sessionWriter;
+
+		private ServiceConfiguration Session
+		{
+			get { return sessionContext.Configuration; }
+		}
+
+		private bool SessionIsRunning
+		{
+			get { return sessionContext.IsRunning; }
+		}
+
+		internal ServiceController(
+			ILogger logger,
+			Func<string, ILogObserver> logWriterFactory,
+			IOperationSequence bootstrapSequence,
+			IOperationSequence sessionSequence,
+			IServiceHost serviceHost,
+			SessionContext sessionContext,
+			ISystemConfigurationUpdate systemConfigurationUpdate)
+		{
+			this.logger = logger;
+			this.logWriterFactory = logWriterFactory;
+			this.bootstrapSequence = bootstrapSequence;
+			this.sessionSequence = sessionSequence;
+			this.serviceHost = serviceHost;
+			this.sessionContext = sessionContext;
+			this.systemConfigurationUpdate = systemConfigurationUpdate;
+		}
+
+		internal bool TryStart()
+		{
+			logger.Info("Initiating startup procedure...");
+
+			var result = bootstrapSequence.TryPerform();
+			var success = result == OperationResult.Success;
+
+			if (success)
+			{
+				RegisterEvents();
+
+				logger.Info("Service successfully initialized.");
+				logger.Log(string.Empty);
+			}
+			else
+			{
+				logger.Info("Service startup aborted!");
+				logger.Log(string.Empty);
+			}
+
+			return success;
+		}
+
+		internal void Terminate()
+		{
+			DeregisterEvents();
+
+			if (SessionIsRunning)
+			{
+				StopSession();
+			}
+
+			logger.Log(string.Empty);
+			logger.Info("Initiating termination procedure...");
+
+			var result = bootstrapSequence.TryRevert();
+			var success = result == OperationResult.Success;
+
+			if (success)
+			{
+				logger.Info("Service successfully terminated.");
+				logger.Log(string.Empty);
+			}
+			else
+			{
+				logger.Info("Service termination failed!");
+				logger.Log(string.Empty);
+			}
+		}
+
+		private void StartSession()
+		{
+			InitializeSessionLogging();
+			logger.Info(AppendDivider("Session Start Procedure"));
+
+			var result = sessionSequence.TryPerform();
+
+			if (result == OperationResult.Success)
+			{
+				logger.Info(AppendDivider("Session Running"));
+			}
+			else
+			{
+				logger.Info(AppendDivider("Session Start Failed"));
+			}
+		}
+
+		private void StopSession()
+		{
+			logger.Info(AppendDivider("Session Stop Procedure"));
+
+			var result = sessionSequence.TryRevert();
+
+			if (result == OperationResult.Success)
+			{
+				logger.Info(AppendDivider("Session Terminated"));
+			}
+			else
+			{
+				logger.Info(AppendDivider("Session Stop Failed"));
+			}
+
+			FinalizeSessionLogging();
+		}
+
+		private void RegisterEvents()
+		{
+			serviceHost.SessionStartRequested += ServiceHost_SessionStartRequested;
+			serviceHost.SessionStopRequested += ServiceHost_SessionStopRequested;
+			serviceHost.SystemConfigurationUpdateRequested += ServiceHost_SystemConfigurationUpdateRequested;
+		}
+
+		private void DeregisterEvents()
+		{
+			serviceHost.SessionStartRequested -= ServiceHost_SessionStartRequested;
+			serviceHost.SessionStopRequested -= ServiceHost_SessionStopRequested;
+			serviceHost.SystemConfigurationUpdateRequested -= ServiceHost_SystemConfigurationUpdateRequested;
+		}
+
+		private void ServiceHost_SessionStartRequested(SessionStartEventArgs args)
+		{
+			if (!SessionIsRunning)
+			{
+				sessionContext.Configuration = args.Configuration;
+
+				StartSession();
+			}
+			else
+			{
+				logger.Warn("Received session start request, even though a session is already running!");
+			}
+		}
+
+		private void ServiceHost_SessionStopRequested(SessionStopEventArgs args)
+		{
+			if (SessionIsRunning)
+			{
+				if (Session.SessionId == args.SessionId)
+				{
+					StopSession();
+				}
+				else
+				{
+					logger.Warn("Received session stop request with wrong session ID!");
+				}
+			}
+			else
+			{
+				logger.Warn("Received session stop request, even though no session is currently running!");
+			}
+		}
+
+		private void ServiceHost_SystemConfigurationUpdateRequested()
+		{
+			logger.Info("Received request to initiate system configuration update.");
+			systemConfigurationUpdate.ExecuteAsync();
+		}
+
+		private string AppendDivider(string message)
+		{
+			var dashesLeft = new String('-', 48 - message.Length / 2 - message.Length % 2);
+			var dashesRight = new String('-', 48 - message.Length / 2);
+
+			return $"### {dashesLeft} {message} {dashesRight} ###";
+		}
+
+		private void InitializeSessionLogging()
+		{
+			if (Session?.AppConfig?.ServiceLogFilePath != null)
+			{
+				sessionWriter = logWriterFactory.Invoke(Session.AppConfig.ServiceLogFilePath);
+				logger.Subscribe(sessionWriter);
+				logger.LogLevel = Session.Settings.LogLevel;
+			}
+			else
+			{
+				logger.Warn("Could not initialize session writer due to missing configuration data!");
+			}
+		}
+
+		private void FinalizeSessionLogging()
+		{
+			if (sessionWriter != null)
+			{
+				logger.Unsubscribe(sessionWriter);
+				sessionWriter = null;
+			}
+		}
+	}
+}