using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Diagnostics;

using System.IO;

using System.Reflection;

using System.Text;

using Delta.Utilities.Helpers;

using Delta.Utilities.Profiling;

using NUnit.Framework;



namespace Delta.Utilities

{

	/// <summary>

	/// Log, handles all the message logging and storing the messages in an

	/// extra file which helps for later tracking and fixing bugs. Some extra

	/// functionality is provided by Delta.Engine, which sets up the log server

	/// to send log messages to a log server if specified in the application

	/// settings. Usually logging happens to the console and a log file.

	/// </summary>

	public class Log : IDisposable

	{

		#region Constants

		/// <summary>

		/// The text encoding format for all our logs.

		/// </summary>

		private static readonly Encoding TextFormat = Encoding.UTF8;



		/// <summary>

		/// The default extension for all our log files. Note 2011-04-06: Changed

		/// to .txt to make it easier to open by end users (.log is not longer

		/// used and has no special behavior anymore).

		/// </summary>

		private const string FileExtension = "txt";



		/// <summary>

		/// The maximum file size for a log file is 10 MB, if we go above that

		/// (e.g. if too much info is written every frame), then we cut the file

		/// in half (5 MB) and append from there. This way we have both the

		/// first 5 MB of the application run and the last log entries as well.

		/// </summary>

		private const int MaxLogFileSize = 10 * 1024 * 1024;



		/// <summary>

		/// The maximum size for log archive files is 20 MB, if we go above that,

		/// we will remove data from the beginning before appending new stuff at

		/// the end (the FileHelper.AppendTextToFile handles this all for us).

		/// </summary>

		private const int MaxArchiveLogFileSize = 20 * 1024 * 1024;



		/// <summary>

		/// Default log name. Currently set to Engine in case something is logged

		/// in DynamicBase or Factory, will be overwritten in Application.Start!

		/// </summary>

		internal const string DefaultLogName = "Engine";



		/// <summary>

		/// Helper to figure out when this application was started. This is

		/// not really the application start time because we will use the time

		/// the Log class is first accessed, but since we do that pretty much

		/// always at the application start (just to set the ProgramName, etc.)

		/// it will be the correct time. Used for the LogHeader!

		/// </summary>

		private static readonly DateTime applicationStartTime = DateTime.Now;



		/// <summary>

		/// Only remember the last 8 logged messages for CheckDuplicateMessage!

		/// </summary>

		private static readonly Queue<string> lastLoggedMessages = new Queue<string>(8);



		/// <summary>

		/// Maximum of Console.WriteLines we allow because of poor WriteLine

		/// performance in debug mode with debugging window open in Visual Studio!

		/// </summary>

		private const int MaxConsoleWritesPerSecond = 10;



		/// <summary>

		/// Only remember the last 10 Console.WriteLines, skip all lines than 10

		/// console writes, completely cut of any Console.WriteLines then. This

		/// way we should not lose more than 10*5ms = 50ms per second. See unit

		/// test below: 6ms for 30 characters writing to an attached debug window.

		/// </summary>

		private static readonly Queue<long> lastConsoleWriteTimes =

			new Queue<long>(MaxConsoleWritesPerSecond);

		#endregion



		#region Delegates

		/// <summary>

		/// The log delegate is used for other classes to attach to all log events

		/// that happen (both Log.Info and Log.Warning calls, but not Log.Test).

		/// It provides an already formated log text string and it used for example

		/// in the Delta.Engine.Application class to add Log Server features.

		/// </summary>

		/// <param name="message">Message</param>

		public delegate void LogDelegate(string message);

		#endregion



		#region Equals (Static)

		/// <summary>

		/// Equals, just trying to hide it.

		/// </summary>

		/// <param name="objA">Object A</param>

		/// <param name="objB">Object B</param>

		[EditorBrowsable(EditorBrowsableState.Never)]

		public new static bool Equals(object objA, object objB)

		{

			return object.Equals(objA, objB);

		}

		#endregion



		#region ReferenceEquals (Static)

		/// <summary>

		/// ReferenceEquals, just trying to hide it.

		/// </summary>

		/// <param name="objA">Object A</param>

		/// <param name="objB">Object B</param>

		[EditorBrowsable(EditorBrowsableState.Never)]

		public new static bool ReferenceEquals(object objA, object objB)

		{

			return object.ReferenceEquals(objA, objB);

		}

		#endregion



		#region ShowCurrentLogInTextEditor (Static)

		/// <summary>

		/// Show current log in text editor

		/// </summary>

		public static void ShowCurrentLogInTextEditor()

		{

			if (currentLogInstance != null &&

			    File.Exists(currentLogInstance.Filename))

			{

				try

				{

					if (CheckIfLogWasCreatedFromNunitTestRunner() == false)

					{

						Process.Start(currentLogInstance.Filename);

					}

				}

				catch (Exception ex)

				{

					Debug.WriteLine(

						"Failed to open log file in text editor: " + ex.Message);

				}

			} // if

		}

		#endregion



		#region Test (Static)

		/// <summary>

		/// Verbose log information that is usually only used for unit tests.

		/// Can be disabled in release mode and should be used only for tests

		/// anyway. This is not sent to the DeltaEngine.net server and not even

		/// put into the log file, just to the console for the debugging

		/// console or the TestRunner or TestDriven.net output window!

		/// Please note that we will skip logging the same message over and over

		/// again because it is REALLY slow in VisualStudio (@see "ToConsole()").

		/// If you really want to log everything out and do not care about

		/// performance, just use Console.WriteLine yourself (e.g. when just

		/// quickly testing if a click event happens). With Log.Test you can even

		/// spam millions of messages per second, most of them will be skipped.

		/// </summary>

		/// <param name="message">Message</param>

		public static void Test(string message)

		{

			Test(message, false);

		}



		/// <summary>

		/// Test

		/// </summary>

		/// <param name="message">Message</param>

		/// <param name="skipRepeatingMessages">

		/// If 'true', messages which are repeating will be skipped (recommended

		/// for looping calls like in render oder updating) to avoid log spamming.

		/// </param>

		public static void Test(string message, bool skipRepeatingMessages)

		{

			// Format the message with a time stamp and pass it to the console only.

			ToConsole(FormatMessage(message), skipRepeatingMessages);

		}

		#endregion



		#region Info (Static)

		/// <summary>

		/// This method logs general information to the log file, to the console,

		/// if available to the screen, and finally to the DeltaEngine.net server.

		/// These kind of messages are usually for figuring stuff out that is

		/// working, but sometimes we need some additional details. On a normal

		/// release program run we should still have zero log messages!

		/// </summary>

		/// <param name="message">Message to show in the log and console</param>

		public static void Info(string message)

		{

			Instance.WriteInfo(message, true);

		}



		/// <summary>

		/// This method logs general information to the log file, to the console,

		/// if available to the screen, and finally to the DeltaEngine.net server.

		/// These kind of messages are usually for figuring stuff out that is

		/// working, but sometimes we need some additional details. On a normal

		/// release program run we should still have zero log messages!

		/// </summary>

		/// <param name="message">Message to show in the log and console</param>

		/// <param name="checkForDuplicates">Check if this message already was

		/// logged in the last 10 messages, then skip it to prevent log spam.

		/// This is on by default.

		/// </param>

		public static void Info(string message, bool checkForDuplicates)

		{

			Instance.WriteInfo(message, checkForDuplicates);

		}

		#endregion



		#region Warning (Static)

		/// <summary>

		/// Outputs a warning, which usually indicates something went really

		/// wrong. It could be a required file was missing, an exception occurred

		/// and was caught. Sometimes even a dynamic class initialization failed

		/// and we provided some fallback, but we want to warn about the initial

		/// failure. Non recoverable errors should throw an exception and will end

		/// up in Application.HandleUnhandledExceptions (which will still use this

		/// method to put the error to the log, but then will abort the

		/// application). A programmer or user can sometimes ignore warnings and

		/// still continue working without the application crashing, but it might

		/// not behave correctly. Note: Warnings always have a stack trace!

		/// </summary>

		/// <param name="message">Message</param>

		public static void Warning(string message)

		{

			// Note: Same code as in the other Warning overload. This is done to

			// prevent bloating the callstack more because we show it for warnings!

			// Helpers to display warnings in Scene.Draw!

			if (logTimer != null)

			{

				LastWarningTime =

					//too precise/slow: (float)logTimer.ElapsedMilliseconds / 1000.0f;

					//(float)logTimer.CachedMilliseconds / 1000.0f;

					logTimer.ElapsedMilliseconds;

			}

			if (String.IsNullOrEmpty(message) == false)

			{

				LastWarningMessage =

					// Only take the first line of the warning

					message.SplitMultiLineText()[0];

			}



			// The default is to display each warning with a stack trace.

			Instance.WriteWarning(message, true);

		}



		/// <summary>

		/// Outputs a warning, which usually indicates something went really

		/// wrong. It could be a required file was missing, an exception occurred

		/// and was caught. Sometimes even a dynamic class initialization failed

		/// and we provided some fallback, but we want to warn about the initial

		/// failure. Non recoverable errors should throw an exception and will end

		/// up in Application.HandleUnhandledExceptions (which will still use this

		/// method to put the error to the log, but then will abort the

		/// application). A programmer or user can sometimes ignore warnings and

		/// still continue working without the application crashing, but it might

		/// not behave correctly. Note: Warnings always have a stack trace!

		/// </summary>

		/// <param name="message">Message</param>

		/// <param name="showStackTrace">Show Stack Trace</param>

		public static void Warning(string message, bool showStackTrace)

		{

			// Helpers to display warnings in Scene.Draw!

			if (logTimer != null)

			{

				LastWarningTime =

					//too precise/slow: (float)logTimer.ElapsedMilliseconds / 1000.0f;

					//(float)logTimer.CachedMilliseconds / 1000.0f;

					logTimer.ElapsedMilliseconds;

			}

			if (String.IsNullOrEmpty(message) == false)

			{

				LastWarningMessage =

					// Only take the first line of the warning

					message.SplitMultiLineText()[0];

			}



			// And normally process the warning.

			Instance.WriteWarning(message, showStackTrace);

		}

		#endregion



		#region InvalidVersionWarning (Static)

		/// <summary>

		/// Logs a warning because of an invalid data version.

		/// </summary>

		/// <param name="className">Class name</param>

		/// <param name="dataVersion">Data version</param>

		/// <param name="maxSupportedVersion">Maximum supported version</param>

		public static void InvalidVersionWarning(string className,

			int dataVersion, int maxSupportedVersion)

		{

			Warning(

				"The version '" + dataVersion + "' of the '" + className +

				"' data is currently not supported, the max. possible version is '" +

				maxSupportedVersion + "'. Please make sure that the data is correct.");

		}

		#endregion



		#region Close (Static)

		/// <summary>

		/// Close log, will disconnect from the Log server and even open up the

		/// log file in editor in debug mode (if a log was generated at all).

		/// </summary>

		public static void Close()

		{

			// Write out the last console message if we had to discard it earlier

			// in ToConsole because of Console.WriteLine spam, which is very slow!

			if (String.IsNullOrEmpty(lastDiscardedConsoleMessage) == false)

			{

				Console.WriteLine(lastDiscardedConsoleMessage);

				lastDiscardedConsoleMessage = "";

			}



			// Open log in editor at shutdown, but only in debug mode :) This should

			// force us NOT to have any log output (then this won't happen).

			// First handle Engine.txt we want to show it!

			if (remToLaunchEngineLogAtEndOfProgram != "" &&

			    File.Exists(remToLaunchEngineLogAtEndOfProgram))

			{

				try

				{

					if (CheckIfLogWasCreatedFromNunitTestRunner() == false)

					{

						Process.Start(remToLaunchEngineLogAtEndOfProgram);

					}

				}

				catch (Exception ex)

				{

					Console.WriteLine(

						"Failed to open engine log file in text editor: " + ex.Message);

				}

				remToLaunchEngineLogAtEndOfProgram = "";

			} // if



			// Note: There could be an Setting to disable this launching log file

			// feature, but for now we want to show it always in debug mode to the

			// programmer (we do not want any logging at all in a functional app)!

			if (currentLogInstance != null &&

			    FileHelper.Exists(currentLogInstance.Filename))

			{

				// Always close the log file first (if we can and it is still open)!

				if (currentLogInstance.logFile != null &&

				    currentLogInstance.logFile.BaseStream.CanWrite)

				{

					try

					{

						currentLogInstance.logFile.Close();

					}

					catch (ObjectDisposedException)

					{

						// Ignore this, it can happen when this is called via the

						// destructor, which happens if we don't call Close explicitly.

					}

				} // if

				currentLogInstance.logFile = null;



				// Show current log in text editor

				ShowCurrentLogInTextEditor();



				// Make sure the log instance is now gone!

				currentLogInstance = null;

			} // if

		}

		#endregion



		#region LogHappened (Static)

		/// <summary>

		/// You can attach delegates to LogHappened to get notified whenever a

		/// log message is happening (usually should only happen for testing or

		/// when something goes wrong and a log warning is put out). Used

		/// in the Delta.Engine.Application class to add Log Server features.

		/// </summary>

		public static LogDelegate LogHappened;

		#endregion



		#region LastWarningMessage (Static)

		/// <summary>

		/// Last warning message we want to display in Scene.Draw, usually not

		/// used, only if something bad happened. Set here, used there.

		/// </summary>

		public static string LastWarningMessage = "";

		#endregion



		#region LastWarningTime (Static)

		/// <summary>

		/// Helpers to display warnings in Scene.Draw, will be reduced there.

		/// Set here, used there (thus public access is needed).

		/// </summary>

		public static long LastWarningTime = -10;

		#endregion



		#region LogName (Static)

		/// <summary>

		/// Current log name, initially "Engine" until Application.Start is

		/// called, then it will be the current game, unit test or tool name.

		/// </summary>

		public static string LogName

		{

			get

			{

				return logName;

			}

			internal set

			{

				// Check if the new value is valid

				if (String.IsNullOrEmpty(value))

				{

					throw new ArgumentNullException(

						"Invalid ProgramName for the log filename, please set a valid " +

						"program name!");

				}



				// No change? Then just quit here (no need to do all the checking)

				if (logName == value)

				{

					return;

				}



				// If we have already created a log file, we need to close it and

				// create a new log file. This happens in case we had initialization

				// log warnings (in the engine usually because loading content,

				// rendering and game logic is all delayed until the app has started).

				if (currentLogInstance != null &&

				    currentLogInstance.logFile != null)

				{

					// Close the old log file.

					if (currentLogInstance.logFile.BaseStream != null)

					{

						currentLogInstance.logFile.Close();

					}

					currentLogInstance.logFile = null;



					// In debug mode we launch the log file that has been created

					// because there most likely are warnings or information the

					// programmer wants to know about (we have a zero logging policy)

					remToLaunchEngineLogAtEndOfProgram = currentLogInstance.Filename;

				}



				// Set the new programName, if a log is needed, it will be created!

				logName = value;



				// Make sure the name does not contain any invalid characters

				StringHelper.RemoveAnyForbiddenLettersForFilename(ref logName);



				// Because our programName has changed, we need to check if we

				// should archive the programName.log file!

				if (currentLogInstance != null)

				{

					currentLogInstance.ArchiveLogFile();

				}

			}

		}

		#endregion



		#region ExtraHardwareInfo (Static)

		/// <summary>

		/// Platform modules have the ability to add extra hardware information

		/// we use the DeviceHardware class to show more information about the

		/// </summary>

		public static string ExtraHardwareInfo = "";

		#endregion



		#region Filename (Public)

		/// <summary>

		/// Returns the complete file name of the current log file.

		/// </summary>

		public string Filename

		{

			get

			{

				return Path.Combine(

					Path.Combine(DirectoryHelper.GetBaseDirectory(), Directory),

					LogName + "." + FileExtension);

			}

		}

		#endregion



		#region ArchivedLogFilename (Public)

		/// <summary>

		/// Archived log filename

		/// </summary>

		public string ArchivedLogFilename

		{

			get

			{

				return Path.Combine(

					Path.Combine(DirectoryHelper.GetBaseDirectory(), Directory),

					LogName + "-Archive." + FileExtension);

			}

		}

		#endregion



		#region Internal



		#region Directory (Internal)

		/// <summary>

		/// By default no log directory is used, all logs end up in the application

		/// directory (named by the program or unit test that was started).

		/// Note: This is just a directory, no filename should be specified here.

		/// Also note that this must be set before the actual logging happens,

		/// so in case you first have some log warnings and then load the settings

		/// the initial log directory is not set.

		/// </summary>

		internal static string Directory = "";

		#endregion



		#region LogHeader (Internal)

		/// <summary>

		/// The header information of our log.

		/// </summary>

		internal static string LogHeader

		{

			get

			{

				Version programVersion = new Version(1, 0);

				try

				{

					var programAssembly = Assembly.GetEntryAssembly();

					// If getting the programAssembly is not possible (e.g. in the

					// SampleBrowser it will return null), then use the current one.

					if (programAssembly == null)

					{

						programAssembly = Assembly.GetCallingAssembly();

					}

					programVersion = programAssembly.GetName().Version;

				}

					// Ignore if this does not work (e.g. unit test)

				catch

				{

				}



				return

					"Program: " + LogName + " v" + programVersion +

					Environment.NewLine +

					"Modules: " + loadedModules +

					Environment.NewLine +

					"Start Time: " + applicationStartTime.GetIsoDateTime() +

					Environment.NewLine +

					"Platform: " + GetPlatformInfo() + ExtraHardwareInfo +

					Environment.NewLine +

					"User: " + Environment.UserName +

					" (" + Environment.MachineName + ")" +

					Environment.NewLine;

			}

		}

		#endregion



		#region loadedModules (Internal)

		/// <summary>

		/// This is also set in DynamicBase and will obviously only report

		/// the loaded modules if they have been set (Graphics, Sound, Video).

		/// </summary>

		internal static string loadedModules = "None";

		#endregion



		#region logTimer (Internal)

		/// <summary>

		/// Use timer to have more accurate timing (uses PerformanceCounters

		/// internally and can return accurate millisecond values for many million

		/// years due the use of long integer values). Usually setup in the Time

		/// class, but if that is not used or was not called before logging

		/// happens we will initialize this on our own with a simple

		/// StopwatchTimeSource and update it ourself.

		/// </summary>

		internal static BaseTimeSource logTimer;

		#endregion



		#region allowDuplicateLogChecking (Internal)

		/// <summary>

		/// By default Allow Duplicate Log Checking. This speeds up console writing

		/// by a lot (skips messages if too much is going on, making logging

		/// 10-100x faster). It also checks for duplicate messages written into

		/// the log file (keeping the log file much smaller).

		/// <para />

		/// But it can be useful if you really want every single log message in

		/// the console and log file including duplicates, then disable this

		/// feature (via Application Settings or by setting this to false).

		/// </summary>

		internal static bool allowDuplicateLogChecking = true;

		#endregion



		#endregion



		#region Private



		#region logName (Private)

		/// <summary>

		/// Current log name, will be "Engine" until Application.Start is

		/// called, then it will be the current game, unit test or tool name.

		/// </summary>

		private static string logName = DefaultLogName;

		#endregion



		#region remToLaunchEngineLogAtEndOfProgram (Private)

		/// <summary>

		/// Extra helper to show even the Engine.txt file when closing the

		/// program in case there were Engine warnings we need to know about!

		/// </summary>

		private static string remToLaunchEngineLogAtEndOfProgram = "";

		#endregion



		#region isLogFileCreatable (Private)

		/// <summary>

		/// Can the log file be created, helps us to remember if we have already

		/// tried to create a log file and was it successful.

		/// </summary>

		private bool isLogFileCreatable;

		#endregion



		#region remOurSetupLogTimer (Private)

		/// <summary>

		/// Helper to remember which timer we have setup (if we have done so at

		/// all). If this is null or not equal to logTimer than the engine has

		/// changed this and is now started. It is save to use the retrying

		/// connection feature of the Client class if so because Close is

		/// called by force when the application quits (otherwise not).

		/// </summary>

		private static BaseTimeSource remOurSetupLogTimer;

		#endregion



		#region logFile (Private)

		/// <summary>

		/// The handle to our (local) log file.

		/// </summary>

		private StreamWriter logFile;

		#endregion



		#region currentLogInstance (Private)

		/// <summary>

		/// Current log instance.

		/// </summary>

		private static Log currentLogInstance;

		#endregion



		/// <summary>

		/// Remember if the log creation in Instance was done from a test runner.

		/// </summary>

		private static bool rememberLogWasCreatedFromNunitTestRunner = false;

		/// <summary>

		/// Helper method to find out if the log instance was created by the NUnit

		/// test runner or by ReSharpers Unit Test Sessions. This is important

		/// because if the log class is being disposed by a finalizer (e.g. from

		/// WPF) and we need to show the log file in a text editor it will crash

		/// with an System.Runtime.InteropServices.InvalidComObjectException: COM

		/// object that has been separated from its underlying RCW cannot be used.

		/// We can prevent this from happening by setting this to true in the

		/// Instance property. Since we see the output in the test runner anyway

		/// opening the text editor is not important anyway.

		/// </summary>

		private static bool CheckIfLogWasCreatedFromNunitTestRunner()

		{

			if (rememberLogWasCreatedFromNunitTestRunner)

			{

				return true;

			}



			// Check if we are coming from NUnit or ReSharper test runner. Note: If

			// we only get a Finalize stack frame (4 calls long) this won't work!

			foreach (StackFrame frame in new StackTrace().GetFrames())

			{

				Type frameClass = frame.GetMethod().DeclaringType;

				if (frameClass.Name.StartsWith("NUnit") ||

					frameClass.Name.StartsWith("ReSharper"))

				{

					rememberLogWasCreatedFromNunitTestRunner = true;

					return true;

				}

			}



			// Otherwise nothing was found, return false

			return false;

		}



		#region Instance (Private)

		/// <summary>

		/// Current log instance we are using, if there is no instance, we will

		/// create one with the current program name (defaults to Engine.txt).

		/// </summary>

		private static Log Instance

		{

			get

			{

				// Got no log instance yet? Then create it ourselves.

				if (currentLogInstance == null)

				{

					currentLogInstance = new Log();

					CheckIfLogWasCreatedFromNunitTestRunner();

				}

				// But usually it is set in the constructor anyway!

				return currentLogInstance;

			}

		}

		#endregion



		#region lastDiscardedConsoleMessage (Private)

		/// <summary>

		/// Remember the last discarded console message. Show it when the app

		/// quits. It often contains interesting information about performance.

		/// </summary>

		private static string lastDiscardedConsoleMessage = "";

		#endregion



		#endregion



		#region Constructors

		/// <summary>

		/// Create log

		/// </summary>

		public Log()

		{

			// Start our own time counting if it has not been setup yet, usually

			// the Time module from the Delta project should have set this up!

			if (logTimer == null)

			{

				remOurSetupLogTimer = logTimer = new StopwatchTimeSource();

			}



			// We assume always that we can create a log file. For some platforms

			// application directory, so do not create a log file there (just use

			// LogService).

			isLogFileCreatable = true;



			// From now on static methods can use this log instance :)

			currentLogInstance = this;



			// Archive always the last log file (if exists) to have a completely

			// fresh new log for every new session

			ArchiveLogFile();

		}

		#endregion



		#region Destructor

		/// <summary>

		/// ~Log destructor, just calls Dispose, which calls Close.

		/// Note: Not often helpful because this is only called when everything

		/// else was killed and this only cleans up after all threads and objects

		/// are gone anyway.

		/// </summary>

		~Log()

		{

			Dispose();

		}

		#endregion



		#region IDisposable Members

		/// <summary>

		/// Dispose, just calls Close to make sure we dispose stuff if the

		/// application is quitting (either forcefully or normally via

		/// Application.Quit).

		/// </summary>

		public void Dispose()

		{

			Close();

		}

		#endregion



		#region ArchiveLogFile (Public)

		/// <summary>

		/// Archives a log file to an existing log-file-archive or creates a new

		/// log-file-archive, if the archive-file doesn't exist yet. However in any

		/// case the current log file will be deleted after processing to the

		/// archive. This is used for in the LogService too.

		/// </summary>

		public void ArchiveLogFile()

		{

			// Log file that should be archived is Filename (current log file)

			// Filename of the (new/existing) log-archive: ArchivedLogFilename

			// We only need to archive an existing log file

			if (FileHelper.Exists(Filename) == false)

			{

				return;

			}



			// Grab all the logged text from last session log for adding that to the

			// log archive file

			string appendLogText = FileHelper.GetText(Filename);



			// If the archive file already exists

			if (FileHelper.Exists(ArchivedLogFilename))

			{

				// Add some empty lines

				appendLogText = Environment.NewLine +

				                Environment.NewLine +

				                // Before the real text to separate this in log sessions

				                appendLogText;

			}



			try

			{

				// Finally we write this to the archive file. This file will be created

				// automatically if it does not exist yet (only for the first time)

				FileHelper.AppendTextToFile(ArchivedLogFilename, appendLogText,

					// If the existing data is more than 20 MB already, remove data from

					// the beginning and then append the appendLogText.

					MaxArchiveLogFileSize);

			}

			catch

			{

				// We should not use Info or Warning here, the log file has not

				// been deleted yet, so only warn in the console if appending failed.

				Console.WriteLine("Warning: Appending to the log archive failed: " +

				                  ArchivedLogFilename);

			}



			// And delete the original file

			FileHelper.SafeDelete(Filename);

		}

		#endregion



		#region Methods (Private)



		#region GetPlatformInfo

		/// <summary>

		/// Get platform info helper method for LogHeader to output some useful

		/// information about the currently running platform (especially nice for

		/// the log server, which shows this info in the logs too).

		/// </summary>

		private static string GetPlatformInfo()

		{

			string platform = "Windows";



			// Add some extra information about the environment (might not be

			// complete on all platforms, but on Windows this shows good stuff)

			platform +=

				", " + Environment.ProcessorCount + " CPU Cores, " +

				// This functionality is only available on Windows!

				(Environment.Is64BitProcess

				 	? "64 bit"

				 	: Environment.Is64BitOperatingSystem

				 	  	? "32 bit (on 64 bit OS)"

				 	  	: "32 bit") + ", " +

				// This shows lots of detailed information about the OS version,

				// e.g. Windows NT 6.1.7600.0 means Windows 7, 7600 is the SP!

				Environment.OSVersion.VersionString.

					Replace("Microsoft ", "").

					Replace("Windows NT 6.1.", "Windows 7 v").

					Replace("Windows NT 6.0.", "Windows Vista v");



			return platform;

		}

		#endregion



		#region CreateLogFile

		/// <summary>

		/// Create log file

		/// </summary>

		/// <param name="logFilename">Log filename</param>

		private bool CreateLogFile(string logFilename)

		{

			#region Validation

			if (String.IsNullOrEmpty(logFilename))

			{

				// If the filename is not valid, this is a fatal exception error!

				throw new ArgumentException("Sorry, can't create a log file without " +

				                            "a valid filename.", "logFilename");

			}



			if (isLogFileCreatable == false)

			{

				// Build error message and write it into the console at least

				string errorMessage = FormatMessage(

					"Sorry, can't create a log file, because an earlier try failed " +

					"already. Maybe you haven't the right to create files here?");

				Console.WriteLine(errorMessage);

				// If we can't create a log file, then log it to the log server

				if (LogHappened != null)

				{

					LogHappened(errorMessage);

				}

				return false;

			}

			#endregion



			try

			{

				// We always create a new log file (the old one will be archived

				// automatically at the program start)

				FileStream logFileStream = FileHelper.Open(logFilename,

					FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite);

				// for the log text we use here the 8-bit unicode

				logFile = new StreamWriter(logFileStream, TextFormat);



				// Activate the "Auto Flush" (to be always "up-to-date" for reading)

				logFile.AutoFlush = true;



				// and start the log file with the header

				logFile.WriteLine(LogHeader);

			}

			catch (Exception ex)

			{

				isLogFileCreatable = false;

				logFile = null;



				// Build error message and write it into the console at least

				string errorMessage = FormatMessage(

					"Sorry, can't create a log file because: " + ex);

				Console.WriteLine(errorMessage);

				// And finally send it to the log server (if connected and possible)!

				if (LogHappened != null)

				{

					LogHappened(errorMessage);

				}

			}



			return logFile != null;

		}

		#endregion



		#region CheckDuplicateMessage

		/// <summary>

		/// Returns true if we should skip this message in case we are logging it

		/// over and over again (prevent log spam). Make sure to call this BEFORE

		/// adding the time stamp, which most likely will make every message

		/// unique and prevents us from detecting log spam.

		/// </summary>

		/// <param name="message">Message</param>

		private static bool CheckDuplicateMessage(string message)

		{

			if (allowDuplicateLogChecking == false)

			{

				return false;

			}



			// We need to keep this thread safe!

			lock (lastLoggedMessages)

			{

				// Was this logged before? Note: This will need some performance, more

				// if we need to check many messages, so keep lastLoggedMessages low.

				if (lastLoggedMessages.Contains(message))

				{

					// Then abort, do not log it again, it costs too much performance!

					return true;

				}



				// Else add it to our queue and check for it next time (and log it).

				lastLoggedMessages.Enqueue(message);

			}



			return false;

		}

		#endregion



		#region ToFile

		/// <summary>

		/// To file

		/// </summary>

		/// <param name="message">Message</param>

		private void ToFile(string message)

		{

			// If we don't have a log file created yet

			if ((logFile == null ||

			     logFile.BaseStream == null) &&

			    isLogFileCreatable)

			{

				// Then just try to do it now

				CreateLogFile(Filename);

			}



			// Obviously only log if we have a logFile

			if (logFile != null)

			{

				// Keep this thread safe!

				lock (logFile)

				{

					// First just write to the log file

					logFile.WriteLine(message);



					// Is the log file still above 10 MB now?

					if (logFile.BaseStream.Length > MaxLogFileSize)

					{

						try

						{

							// Remove the last 5 MB and start from there again!

							// For that just close the file, copy half the content to a new

							// file and then open that file again to continue logging!

							logFile.Close();

							string[] logLines = FileHelper.GetLines(Filename);

							// Create new log file with half the size

							FileStream logFileStream = FileHelper.Open(Filename,

								FileMode.Truncate, FileAccess.Write, FileShare.ReadWrite);

							// for the log text we use here the 8-bit unicode

							logFile = new StreamWriter(logFileStream, TextFormat);

							// Activate AutoFlush to be always up-to-date for reading

							logFile.AutoFlush = true;

							// and dump out half of the previous log lines!

							for (int line = 0; line < logLines.Length / 2; line++)

							{

								logFile.WriteLine(logLines[line]);

							}



							// Add a note that the file was too big and 5 MB of log data

							// was removed!

							logFile.WriteLine("");

							logFile.WriteLine("****************************");

							logFile.WriteLine("Log file was exceeding " +

							                  StringHelper.WriteKbMbGbNumber(MaxLogFileSize) +

							                  ", the " +

							                  "last " +

							                  StringHelper.WriteKbMbGbNumber(MaxLogFileSize / 2) +

							                  " were removed and logging will continue here!");

							logFile.WriteLine("****************************");

							logFile.WriteLine("");

							// And log again what we last tried to log

							logFile.WriteLine(message);

						}

						catch (Exception ex)

						{

							// Note: We cannot display a dialog here, no assembly, we can

							// only spam into the log, which won't be open anyway for that

							// much logging (its too slow in Visual Studio).

							ToConsole("Failed to resize log file, it won't log anymore: " +

							          ex, true);

							isLogFileCreatable = false;

							logFile = null;

						}

					}

				}

			}

		}

		#endregion



		#region ToConsole

		/// <summary>

		/// Print to console, which is horribly slow in Visual Studio, but still

		/// very useful for debugging. Instead of logging everything to the

		/// console we gonna limit the amount of console writing. Usually we

		/// should have less than 10 message lines per second (we don't want to

		/// throw any warnings, informational logs or even test messages in

		/// a normal application run, it should have zero logging!)

		/// For additional details about bad performance of Debug.WriteLine see:

		/// http://rdn-consulting.com/blog/2008/05/28/net-consolewriteline-performance-issues/

		/// Also see the below unit test, which is horribly slow: 6ms for 30 chars

		/// </summary>

		/// <param name="message">Message</param>

		/// <param name="checkForDuplicates">Check for Duplicates</param>

		private static void ToConsole(string message, bool checkForDuplicates)

		{

			// First check if we have already logged more than 10 messages in the

			// last second, skip any new console writes until a second has passed.

			if (allowDuplicateLogChecking &&

			    checkForDuplicates &&

			    logTimer != null)

			{

				long thisTime = logTimer.ElapsedMilliseconds;

				if (lastConsoleWriteTimes.Count == MaxConsoleWritesPerSecond)

				{

					long longestTime = lastConsoleWriteTimes.Peek();

					// Abort if less than 1000ms have passed since 10 console writes ago

					if (thisTime - longestTime < 1000)

					{

						// Remember this message in case the application quits now, it

						// would be really useful to show the last message, it often

						// contains interesting information about performance, etc.

						lastDiscardedConsoleMessage = message;

						return;

					}

				}



				// Add current logging time at the end of the queue

				lastConsoleWriteTimes.Enqueue(thisTime);

				// And kill the lastDiscardedLogMessage, we are logging now!

				lastDiscardedConsoleMessage = "";

			}



			// Just pass the message directly to the IDE console. This is still slow

			// as hell, especially if debugging with the debug window open.

			// Might be a little faster with Debug.WriteLine, but we won't see it

			// in release mode. Also useful for whatever is listing at the console.

			Console.WriteLine(message);

		}

		#endregion



		#region FormatMessage

		/// <summary>

		/// Format message for use with the log methods (log server, file, console)

		/// </summary>

		/// <param name="rawMessage">Raw message</param>

		private static string FormatMessage(string rawMessage)

		{

			// Make sure the instance has been created, otherwise we have no timer!

			if (Instance != null &&

				logTimer == null)

			{

				return rawMessage;

			}



			// Note: In threading situations this can sometimes crash ..

			try

			{

				return logTimer.ToTimeString(' ', rawMessage);

			}

			catch

			{

				return rawMessage;

			}

		}

		#endregion



		#region WriteInfo

		/// <summary>

		/// Write information string to the log, the console and to the

		/// DeltaEngin.net server. For details see the static Info method.

		/// </summary>

		/// <param name="message">Message to show in the log and console</param>

		/// <param name="checkForDuplicates">Check if this message already was

		/// logged in the last 10 messages, then skip it to prevent log spam.

		/// This is on by default.

		/// </param>

		private void WriteInfo(string message, bool checkForDuplicates)

		{

			// Skip message if we just logging it over and over again (log spam)

			if (message == null ||

			    (checkForDuplicates &&

			     CheckDuplicateMessage(message)))

			{

				return;

			}



			// Format the message with a time stamp and whatever is needed

			string formattedMessage = FormatMessage(message);

			// Log the formatted message to the console first

			ToConsole(formattedMessage, checkForDuplicates);

			try

			{

				// Also send the message to all attached handlers like the log server

				if (LogHappened != null)

				{

					LogHappened(formattedMessage);

				}

				// And then finally to the current log file

				ToFile(formattedMessage);

			}

			catch (Exception ex)

			{

				// Note: The formattedMessage text was just put into the console!

				Console.WriteLine("Failed to log this info to file: " + ex);

			}

		}

		#endregion



		#region WriteWarning

		/// <summary>

		/// Warning, thought for logging "light errors" which can be handled itself

		/// by the application. For details see the static Warning method!

		/// </summary>

		/// <param name="message">Warning to show in the log and console</param>

		/// <param name="showStackTrace">Show Stack Trace</param>

		private void WriteWarning(string message, bool showStackTrace)

		{

			string[] messageLines = message.SplitMultiLineText();

			message = "";

			bool gotAlreadyStackTrace = false;

			foreach (string line in messageLines)

			{

				// .NET exception stack traces are always formated this way

				if (line.Trim().StartsWith("at ") ||

					line.Trim().StartsWith("bei ") ||

					line.Contains(" Delta."))

				{

					// Fix exception trace by putting file:line at front (to allow

					// clicking on it in VS).



					// First ignore the lines starting with TestRunner or VS process

					// starting stuff (see below):

					if (line.Contains(new[]

					{

						"System.RuntimeMethodHandle", "System.Reflection",

						"TestDriven", "System.Threading", "System.AppDomain",

						"System.Activator", "System.Runtime", "System.Windows.",

						"Delta.Utilities.Testing", "Microsoft.VisualStudio.HostingProcess",

						// Also exclude NUnit, xUnit and ReSharper stack traces

						"NUnit.Core.", "xUnit.", "JetBrains.ReSharper.",

					}))

					{

						continue;

					}



					// Okay, now split up the 5 parts: at method in file line

					string result = line.Trim();

					string trimmedLine = StringHelper.RemoveFirstWord(result);

					string[] methodAndRest = trimmedLine.Split(" in ");

					if (methodAndRest.Length == 2)

					{

						string[] fileAndLine = methodAndRest[1].Split(":line ");

						if (fileAndLine.Length == 2)

						{

							result = fileAndLine[0] + "(" + fileAndLine[1] + ",1): at " +

							         methodAndRest[0];

						}

					}

					// Output result (reformatted stack trace line)

					message +=

						(message.Length > 0

						 	? "\n"

						 	: "") + "\t" + result;



					gotAlreadyStackTrace = true;

				}

				else

				{

					message +=

						(message.Length > 0

						 	? "\n"

						 	: "") + line;

				}

			}



			if (gotAlreadyStackTrace == false &&

			    showStackTrace)

			{

				// Always show a callstack for warnings to help figure out who called

				// this method and it might (not always of course) help :) But remove

				// the first callstack line (just Log.Warning, we know that we are

				// here). Also remove the last 12 lines for generic

				// TestDriven.TestRunner or Launcher stuff:

				// System.RuntimeMethodHandle._InvokeMethodFast(...)

				// System.RuntimeMethodHandle.InvokeMethodFast(...)

				// System.Reflection.RuntimeMethodInfo.Invoke(...)

				// System.Reflection.RuntimeMethodInfo.Invoke(...)

				// System.Reflection.MethodBase.Invoke(...)

				// TestDriven.AdHoc.TestRunner.AdHocTestRunner.runAdHoc(...)

				// TestDriven.AdHoc.TestRunner.AdHocTestRunner.Run(...)

				// TestDriven.TestRunner.AdaptorTestRunner.Run(...)

				// TestDriven.TestRunner.ThreadTestRunner.Runner.Run()

				// System.Threading.ThreadHelper.ThreadStart_Context(...)

				// System.Threading.ExecutionContext.Run(...)

				// System.Threading.ThreadHelper.ThreadStart()



				// true for file and line info!

				StackTrace trace = new StackTrace(true);

				// This code is from Tools\TestRunner\UnitTestManager.cs:479

				StackFrame[] frames = trace.GetFrames();

				int frameNumber = 0;

				string callstackLines = "";

				foreach (var frame in frames)

				{

					frameNumber++;



					// Ignore the first two lines: this method and its caller

					// Log.Warning, both are not very exciting and always the same.

					if (frameNumber <= 2)

					{

						continue;

					}

					

					var method = frame.GetMethod();

					// Also exclude TestRunner code and boring invoking stuff

					if (method.DeclaringType.FullName.Contains(new[]

					{

						"System.RuntimeMethodHandle", "System.Reflection",

						"TestDriven", "System.Threading", "System.AppDomain",

						"System.Activator", "System.Runtime", "Delta.Utilities.Testing",

						"Microsoft.VisualStudio.HostingProcess", "System.Windows.",

						"MS.Win32.", "MS.Internal.",

						// Also exclude NUnit, xUnit and ReSharper stack traces

						"NUnit.Core.", "xUnit.", "JetBrains.ReSharper.",

					}))

					{

						continue;

					}

					

					// Try to get parameters with detailed value info

					string parametersText = "";

					var parameters = method.GetParameters();

					foreach (var parameter in parameters)

					{

						parametersText +=

							(parametersText.Length > 0

							 	? ", "

							 	: "") +

							parameter.ParameterType + " " + parameter.Name;

					}



					// Try to get filename with line and column information

					string filenameAndLine =

						frame.GetFileName() + "(" +

						frame.GetFileLineNumber() + "," +

						frame.GetFileColumnNumber() + "): ";

					// But cut it if we do not have it (e.g. system classes)

					if (filenameAndLine == "(0,0): ")

					{

						filenameAndLine = "";

					}



					callstackLines +=

						"\t" +

						// This is not working, projectPath is relative to the assembly

						// we are investigating, but not the project VS is running

						// sometimes

						//FileHelper.GetRelativeContentFilePath(

						//frame.GetFileName(), projectPath) + "(" +

						filenameAndLine +

						// Class and name should be useful enough :)

						"at " + method.DeclaringType + "." + method.Name +

						"(" + parametersText + ")\n";



					// Abort in release mode for TypeListManager warnings!

				} // foreach



				if (String.IsNullOrEmpty(callstackLines) == false)

				{

					message += "\n" + callstackLines;

				}

			} // if



			// Skip message if we just logging it over and over again (log spam)

			// Note: This will only skip messages that have been written exactly

			// in this same way (full warning with stack trace).

			if (CheckDuplicateMessage(message))

			{

				return;

			}



			// Format the message with a time stamp and whatever is needed

			string formattedMessage = FormatMessage(

				// Only add "Warning: " if this is not already a fatal error.

				message.StartsWith("Error: ")

					? message

					: "Warning: " + message);

			// Log the formatted message to the console first

			ToConsole(formattedMessage, true);

			try

			{

				// Also send the message to all attached handlers like the log server

				if (LogHappened != null)

				{

					LogHappened(formattedMessage);

				}

				// And then finally to the current log file

				ToFile(formattedMessage);

			}

			catch (Exception ex)

			{

				// Note: The formattedMessage text was just put into the console!

				Console.WriteLine("Failed to log this warning to file: " + ex);

			}

		}

		#endregion



		#endregion



		/// <summary>

		/// Tests

		/// </summary>

		[NUnit.Framework.Category("LongRunning")]

		internal class LogTests

		{

			#region TestLogging (Static)

			/// <summary>

			/// Test logging

			/// </summary>

			[Test]

			public static void TestLogging()

			{

				Info("Just some boring info line...");



				// Open the text editor and make sure the log is sent to the server.

				// Note: If we can connect to the log server quick enough this line

				// is not required, but if we timeout or the connection is slow, this

				// is much better and consistent to test. Also good for opening editor!

				Close();

			}

			#endregion



			#region TestConsoleLog (Static)

			/// <summary>

			/// Test console log

			/// </summary>

			[Test]

			public static void TestConsoleLog()

			{

				// Just printing to the console to see how a log would looks like

				Console.WriteLine(Log.LogHeader);

				Test("Just some boring test line...");

				Console.WriteLine("Current directory: " +

				                  System.IO.Directory.GetCurrentDirectory());

				//Console.WriteLine("Does " + Log.Instance.Filename + " exists: " +

				//	File.Exists(Log.Instance.Filename));

			}

			#endregion



			#region ConsoleWriteLinePerformance (Static)

			/// <summary>

			/// ConsoleWriteLinePerformance

			/// </summary>

			[Test]

			public static void ConsoleWriteLinePerformance()

			{

				// Simple Log.Test performance test

				Stopwatch timer = new Stopwatch();

				timer.Start();



				// Note: Makes no difference if using 1000 messages with 1 line each or

				// 100 messages with 10 lines, both take 5.8s to execute, which is

				// ridiculous. Per line that is 6ms for 30 characters, wtf?

				const int NumOfWriteLines = 1000;

				for (int i = 0; i < NumOfWriteLines; i++)

				{

					Test("Hi ho " + i);

				}

				// Note: About 6-7 times faster with shorter string (less than 1s): 

				//Console.WriteLine("Just");

				//Console.WriteLine("Just some boring test line...");

				// Note: Same speed if doing 100 messages with 10 lines each:

				//Console.WriteLine("Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...\n"+

				//	"Just some boring test line...");



				time…