using System;
using System.IO;
using System.Diagnostics;
using System.Collections;
using System.Runtime.CompilerServices;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Reflection;
using System.Collections.Concurrent;
using System.Linq;
using System.Threading;
using System.Security.Cryptography.X509Certificates;
using lib.Net;
//using System.Threading.Tasks;

static public class log
{


	[Flags]
	public enum LogType
	{
		Invalid = 0,
		Trace = 1,
		Debug = 2,
		Info = 3,
		High = 4,
		Warn = 5,
		Error = 6,
		Fatal = 7,

		Time = 64,
		Raw = 65,
	}

	[Flags]
	public enum Endpoints
	{
		None = 0,

		File = 1 << 0,
		Console = 1 << 1,

		All = File | Console,
	}


	public struct LogEvent
	{
		public DateTime Time;
		public LogType LogType;
		public string Msg;
		public string Path;
		public int Line;
		public string Member;

		public string Cat;
		public object Obj;



		static ImmutableDictionary<int, string> s_shortname = ImmutableDictionary<int, string>.Empty;


		public LogEvent( LogType logType, string msg, string path, int line, string member, string cat, object obj )
		{

			//Cache the automatic category names
			// R A R E and S L O W and S A F E
			if( string.IsNullOrEmpty( cat ) )
			{
				var pathHash = path.GetHashCode();
				if( s_shortname.TryGetValue( pathHash, out var autoCat ) )
				{
					cat = autoCat;
				}
				else
				{
					var pathPieces = path.Split( '\\' );

					if( pathPieces.Length < 2 )
					{
						pathPieces = path.Split( '/' );
					}

					var lastDir = pathPieces[pathPieces.Length - 2];

					ImmutableInterlocked.AddOrUpdate( ref s_shortname, pathHash, lastDir, ( key, value ) => { return lastDir; } );

					cat = lastDir;
				}
			}

			Time = DateTime.Now;
			LogType = logType;
			Msg = msg;
			Path = path;
			Line = line;
			Member = member;
			Cat = cat;
			Obj = obj;
		}
	}
	static LogEvent CreateLogEvent( LogType logType, string msg, string cat, object obj, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		var logEvent = new LogEvent( logType, msg, path, line, member, cat, obj );

		return logEvent;
	}



	public delegate void Log_delegate( LogEvent evt );





	static public void create( string filename, Endpoints endpoints )
	{
		startup( filename, endpoints );
	}

	static public void destroy()
	{
		string msg = "==============================================================================\nLogfile shutdown at " + DateTime.Now.ToString();

		var evt = CreateLogEvent( LogType.Info, msg, "System", null );

		s_events.Enqueue( evt );

		stop();
	}


	static internal ConcurrentQueue<LogEvent> s_events = new ConcurrentQueue<LogEvent>();

	static private Thread s_thread;

	/*
	static public Log log
	{
		get
		{
			return s_log;
		}
	}
	*/

	static string s_cwd = Directory.GetCurrentDirectory();
	static int s_cwdLength = s_cwd.Length;
	static ImmutableDictionary<int, string> s_files = ImmutableDictionary<int, string>.Empty;

#region Util
	static public string whatFile( string path )
	{
		var file = "";

		var pathHash = path.GetHashCode();
		if( s_files.TryGetValue( pathHash, out var autoCat ) )
		{
			file = autoCat;
		}
		else
		{
			var pathPieces = path.Split( '\\' );

			if( pathPieces.Length < 2 )
			{
				pathPieces = path.Split( '/' );
			}

			var lastDir = pathPieces[pathPieces.Length - 1];

			ImmutableInterlocked.AddOrUpdate( ref s_files, pathHash, lastDir, ( key, value ) => { return lastDir; } );

			file = lastDir;
		}

		return file;
	}

	static public string relativePath( string fullPath )
	{
		if( fullPath.Length < s_cwdLength )
			return fullPath;

		var rel = fullPath.Substring( s_cwdLength + 1 );

		return rel;
	}

	static public string thisFilePath( [CallerFilePath] string path = "" )
	{
		return relativePath( path );
	}
#endregion // Util

#region Forwards
	static public void fatal( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Fatal, path, line, member, cat, obj );
	}

	static public void error( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Error, path, line, member, cat, obj );
	}

	static public void warn( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Warn, path, line, member, cat, obj );
	}

	static public void high( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.High, path, line, member, cat, obj );
	}

	static public void info( string msg, string cat = "", object obj = null,
	[CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Info, path, line, member, cat, obj );
	}

	static public void debug( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Debug, path, line, member, cat, obj );
	}

	static public void trace( string msg, string cat = "", object obj = null, [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		logBase( msg, LogType.Trace, path, line, member, cat, obj );
	}
	#endregion


#region Helpers
	static public void logProps( object obj, string header, LogType type = LogType.Debug, string cat = "", string prefix = "", [CallerFilePath] string path = "", [CallerLineNumber] int line = -1, [CallerMemberName] string member = "" )
	{
		var list = refl.GetAllProperties( obj.GetType() );

		lock( s_lock )
		{
			var evt = new LogEvent( type, header, path, line, member, cat, obj );
			{

				s_events.Enqueue( evt );

				foreach( var pi in list )
				{
					try
					{
						var v = pi.GetValue( obj );

						logBase( $"{prefix}{pi.Name} = {v}", type, path, line, member, cat );
					}
					catch( Exception ex )
					{
						logBase( $"Exception processing {pi.Name} {ex.Message}", LogType.Error, "log" );
					}
				}

			}
		}
	}

	//This might seem a little odd, but the intent is that usually you wont need to set notExpectedValue.
	static public void expected<T>( T value, string falseString, string trueString = "", T notExpectedValue = default( T ) )
	{
		if( !value.Equals( notExpectedValue ) )
		{
			log.debug( $"Properly got {value}{trueString}" );
		}
		else
		{
			log.warn( $"Got {notExpectedValue} instead of {value}{falseString}" );
		}
	}
#endregion


	static object s_lock = new object();

	static public LogEvent logCreateEvent( string msg, LogType type = LogType.Debug, string path = "", int line = -1, string member = "", string cat = "unk", object obj = null )
	{
		LogEvent evt = new LogEvent( type, msg, path, line, member, cat, obj );
		return evt;
	}


	static public void logBase( string msg, LogType type = LogType.Debug, string path = "", int line = -1, string member = "", string cat = "unk", object obj = null )
	{
		var evt = logCreateEvent( msg, type, path, line, member, cat );

		s_events.Enqueue( evt );
	}


	static Endpoints s_endpoints = Endpoints.Console;
	static int s_catWidth = 14;
	static int s_timeWidth = 6;

	static void startup( string filename, Endpoints endpoints )
	{
		s_startTime = DateTime.Now;

		s_cwd = Directory.GetCurrentDirectory();
		s_cwdLength = s_cwd.Length;

		s_endpoints = endpoints;

		var start = new ThreadStart( run );

		s_thread = new Thread( start );
		s_thread.Priority = ThreadPriority.BelowNormal;
		s_thread.Name = $"Logging";
		s_thread.Start();

		//TODO: Fix this so itll work without a directory.
		Directory.CreateDirectory( Path.GetDirectoryName( filename ) );

		string dir = Path.GetDirectoryName( filename );

		if( dir.Length > 0 )
		{
			Directory.CreateDirectory( dir );
		}


		s_stream = new FileStream( filename, FileMode.Append, FileAccess.Write );
		s_writer = new StreamWriter( s_stream );

		s_errorStream = new FileStream( filename + ".error", FileMode.Append, FileAccess.Write );
		s_errorWriter = new StreamWriter( s_errorStream );


		info( $"Logging in {filename}" );

		//Debug.Listeners.Add( this );

		//var evt = CreateLogEvent( LogType.Info, $"startup", "System", null );

		//s_events.Enqueue( evt );

		/*
		if( (endpoints & Endpoints.Console) == Endpoints.Console )
		{
			addDelegate(WriteToConsole);
		}
		*/



		info( $"startup" );

	}

	static bool s_running = true;

	static void run()
	{
		while( s_running )
		{
			while( s_events.TryDequeue( out var evt ) )
			{
				writeToAll( evt );
			}

			// TODO PERF Replace this with a semaphore/mutex
			Thread.Sleep( 0 );
		}
	}

	static void stop()
	{
		s_running = false;

		s_writer.Close();
		s_stream.Close();

		s_errorWriter.Close();
		s_errorStream.Close();

	}

	static public void addDelegate( Log_delegate cb )
	{
		s_delegates.Add( cb );
	}

	public static char getSymbol( LogType type )
	{
		switch( type )
		{
			case LogType.Trace: return ' ';
			case LogType.Debug: return ' ';
			case LogType.Info:  return ' ';
			case LogType.High:  return '+';
			case LogType.Warn:  return '+';
			case LogType.Error: return '*';
			case LogType.Fatal: return '*';
			     default:       return '?';
		}
	}

	private static void setConsoleColor( log.LogEvent evt )
	{
		switch( evt.LogType )
		{
			case log.LogType.Trace:
				Console.ForegroundColor = ConsoleColor.DarkGray;
				break;
			case log.LogType.Debug:
				Console.ForegroundColor = ConsoleColor.Gray;
				break;
			case log.LogType.Info:
				Console.ForegroundColor = ConsoleColor.DarkGreen;
				break;
			case log.LogType.High:
				Console.ForegroundColor = ConsoleColor.Cyan;
				break;
			case log.LogType.Warn:
				Console.ForegroundColor = ConsoleColor.Yellow;
				break;
			case log.LogType.Error:
				Console.ForegroundColor = ConsoleColor.DarkRed;
				Console.BackgroundColor = ConsoleColor.DarkGray;
				break;
			case log.LogType.Fatal:
				Console.ForegroundColor = ConsoleColor.Red;
				Console.BackgroundColor = ConsoleColor.DarkGray;
				break;

			case log.LogType.Invalid:
			case log.LogType.Time:
			case log.LogType.Raw:
				Console.ForegroundColor = ConsoleColor.Red;
				break;

		}
	}

	static private DateTime s_lastTime = DateTime.MinValue;
	static private DateTime s_startTime = DateTime.MinValue;

	static private int s_lastDisplaySeconds = -1;
	static private int s_lastSecond = -1;
	static private string s_timeHeader = " ";


	static public string msgHeader( LogEvent evt )
	{
		var span = evt.Time - s_startTime;

		char sym = getSymbol( evt.LogType );

		var truncatedCat = evt.Cat.Substring( 0, Math.Min( s_catWidth, evt.Cat.Length ) );

		var time = span.Milliseconds; // humanTime( secondSpan );

		var msgHdr = string.Format( $"{s_timeHeader}{{0,-{s_timeWidth}}} | {{1,-{s_catWidth}}}{{2}}| ", time, truncatedCat, sym );

		return msgHdr;
	}

	static public string msgFrom( LogEvent evt )
	{
		var msgHdr = msgHeader( evt );

		string finalLine = $"{msgHdr}{evt.Msg}";

		return finalLine;
	}

	static private void writeSpecialEvent( LogEvent evt )
	{
		if( ( s_endpoints & Endpoints.Console ) == Endpoints.Console )
		{
			//setConsoleColor( evt );
			//Console.WriteLine( $"{evt.Time.ToShortTimeString()}" );
			//Console.ResetColor();
		}

		foreach( Log_delegate cb in s_delegates )
		{
			cb( evt );
		}
	}

	static private void writeToAll( LogEvent evt )
	{
		try
		{
			#region Time
			var span = evt.Time - s_startTime;

			var curSeconds = (int)span.TotalSeconds;

			if( curSeconds - s_lastDisplaySeconds > 10 )
			{
				s_lastDisplaySeconds = curSeconds;

				var minuteEvt = new LogEvent( LogType.Raw, $"T I M E ==> {evt.Time.Hour.ToString("D2")}:{evt.Time.Minute.ToString("D2")}:{evt.Time.Second.ToString("D2")}.{evt.Time.Millisecond.ToString("D4")} | {evt.Time.ToShortDateString()}", "", 0, "", "lib.time", null );
				minuteEvt.Time = evt.Time;
				writeSpecialEvent( minuteEvt );
			}

			if( evt.LogType != LogType.Raw )
			{
				var curSecond = (int)span.TotalSeconds;

				if( s_lastSecond == curSecond )
				{
					s_timeHeader = " ";
				}
				else
				{
					s_timeHeader = "*";
					s_lastSecond = curSecond;
				}
			}

			#endregion


			#region Write
			var finalLine = msgFrom( evt );

			if( ( s_endpoints & Endpoints.File ) == Endpoints.File )
			{
				s_writer.WriteLine( finalLine );
			}

			if( ( s_endpoints & Endpoints.Console ) == Endpoints.Console )
			{
				setConsoleColor( evt );
				Console.WriteLine( finalLine );
				Console.ResetColor();
			}


			//Debug.WriteLine( finalLine );

			s_writer.Flush();

			foreach( Log_delegate cb in s_delegates )
			{
				cb( evt );
			}

			#endregion
		}
		catch( Exception ex )
		{
		#region Catch
			Console.WriteLine( "EXCEPTION DURING LOGGING" );
			Console.WriteLine( "EXCEPTION DURING LOGGING" );
			Console.WriteLine( "EXCEPTION DURING LOGGING" );
			Console.WriteLine( "EXCEPTION DURING LOGGING" );
			Console.WriteLine( "EXCEPTION DURING LOGGING" );
			Console.WriteLine( $"Exception {ex}" );

			Debug.WriteLine( "EXCEPTION DURING LOGGING" );
			Debug.WriteLine( "EXCEPTION DURING LOGGING" );
			Debug.WriteLine( "EXCEPTION DURING LOGGING" );
			Debug.WriteLine( "EXCEPTION DURING LOGGING" );
			Debug.WriteLine( "EXCEPTION DURING LOGGING" );
			Debug.WriteLine( $"Exception {ex}" );
		#endregion
		}

	}

	public static void WriteToConsole( LogEvent evt )
	{
		char sym = getSymbol( evt.LogType );

		var truncatedCat = evt.Cat.Substring( 0, Math.Min( 8, evt.Cat.Length ) );

		string finalLine = string.Format( "{0,-8}{1}| {2}", truncatedCat, sym, evt.Msg );

		Console.WriteLine( finalLine );
	}


	private static Stream s_stream;
	private static StreamWriter s_writer;

	private static Stream s_errorStream;
	private static StreamWriter s_errorWriter;

	private static ArrayList s_delegates = new ArrayList();

}