using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;

namespace Swan.Logging {
  /// <summary>
  /// Entry-point for logging. Use this static class to register/unregister
  /// loggers instances. By default, the <c>ConsoleLogger</c> is registered.
  /// </summary>
  public static class Logger {
    /*private static readonly Object SyncLock = new Object();*/
    // [Obsolete("NEED", false)]
    private static readonly List<ILogger> Loggers = new List<ILogger>();

    // [Obsolete("NEED", false)]
    private static UInt64 _loggingSequence;

    // [Obsolete("NEED", false)]
    static Logger() {
      if(Terminal.IsConsolePresent) {
        Loggers.Add(ConsoleLogger.Instance);
      }

      if(DebugLogger.IsDebuggerAttached) {
        Loggers.Add(DebugLogger.Instance);
      }
    }

    /*#region Standard Public API

    /// <summary>
    /// Registers the logger.
    /// </summary>
    /// <typeparam name="T">The type of logger to register.</typeparam>
    /// <exception cref="InvalidOperationException">There is already a logger with that class registered.</exception>
    public static void RegisterLogger<T>() where T : ILogger {
      lock(SyncLock) {
        ILogger loggerInstance = Loggers.FirstOrDefault(x => x.GetType() == typeof(T));

        if(loggerInstance != null) {
          throw new InvalidOperationException("There is already a logger with that class registered.");
        }

        Loggers.Add(Activator.CreateInstance<T>());
      }
    }

    /// <summary>
    /// Registers the logger.
    /// </summary>
    /// <param name="logger">The logger.</param>
    public static void RegisterLogger(ILogger logger) {
      lock(SyncLock) {
        Loggers.Add(logger);
      }
    }

    /// <summary>
    /// Unregisters the logger.
    /// </summary>
    /// <param name="logger">The logger.</param>
    /// <exception cref="ArgumentOutOfRangeException">logger.</exception>
    public static void UnregisterLogger(ILogger logger) => RemoveLogger(x => x == logger);

    /// <summary>
    /// Unregisters the logger.
    /// </summary>
    /// <typeparam name="T">The type of logger to unregister.</typeparam>
    public static void UnregisterLogger<T>() => RemoveLogger(x => x.GetType() == typeof(T));

    /// <summary>
    /// Remove all the loggers.
    /// </summary>
    public static void NoLogging() {
      lock(SyncLock) {
        Loggers.Clear();
      }
    }

    #region Debug

    /// <summary>
    /// Logs a debug message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Debug(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Debug, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a debug message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Debug(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Debug, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a debug message to the console.
    /// </summary>
    /// <param name="extendedData">The exception.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Debug(this Exception extendedData, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Debug, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #region Trace

    /// <summary>
    /// Logs a trace message to the console.
    /// </summary>
    /// <param name="message">The text.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Trace(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Trace, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a trace message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Trace(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Trace, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a trace message to the console.
    /// </summary>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Trace(this Exception extendedData, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Trace, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #region Warn

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="message">The text.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Warn(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Warning, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Warn(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Warning, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Warn(this Exception extendedData, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Warning, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #region Fatal

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="message">The text.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Fatal(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Fatal, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Fatal(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Fatal, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a warning message to the console.
    /// </summary>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Fatal(this Exception extendedData, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Fatal, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #region Info

    /// <summary>
    /// Logs an info message to the console.
    /// </summary>
    /// <param name="message">The text.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Info(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Info, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs an info message to the console.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Info(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Info, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs an info message to the console.
    /// </summary>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Info(this Exception extendedData, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Info, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #region Error

    /// <summary>
    /// Logs an error message to the console's standard error.
    /// </summary>
    /// <param name="message">The text.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Error(this String message, String source = null, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Error, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs an error message to the console's standard error.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Error(this String message, Type source, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Error, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs an error message to the console's standard error.
    /// </summary>
    /// <param name="ex">The exception.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Error(this Exception ex, String source, String message, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Error, message, source, ex, callerMemberName, callerFilePath, callerLineNumber);

    #endregion

    #endregion*/

    #region Extended Public API

    /*/// <summary>
    /// Logs the specified message.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="messageType">Type of the message.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Log(this String message, String source, LogLevel messageType, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(messageType, message, source, extendedData, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs the specified message.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="source">The source.</param>
    /// <param name="messageType">Type of the message.</param>
    /// <param name="extendedData">The extended data.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Log(this String message, Type source, LogLevel messageType, Object extendedData = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(messageType, message, source?.FullName, extendedData, callerMemberName, callerFilePath, callerLineNumber);*/

    /// <summary>
    /// Logs an error message to the console's standard error.
    /// </summary>
    /// <param name="ex">The ex.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    // [Obsolete("NEED", false)]
    public static void Log(this Exception ex, String source = null, String message = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Error, message ?? ex.Message, source ?? ex.Source, ex, callerMemberName, callerFilePath, callerLineNumber);

    /*/// <summary>
    /// Logs an error message to the console's standard error.
    /// </summary>
    /// <param name="ex">The ex.</param>
    /// <param name="source">The source.</param>
    /// <param name="message">The message.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Log(this Exception ex, Type source = null, String message = null, [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) => LogMessage(LogLevel.Error, message ?? ex.Message, source?.FullName ?? ex.Source, ex, callerMemberName, callerFilePath, callerLineNumber);

    /// <summary>
    /// Logs a trace message showing all possible non-null properties of the given object
    /// This method is expensive as it uses Stringify internally.
    /// </summary>
    /// <param name="obj">The object.</param>
    /// <param name="source">The source.</param>
    /// <param name="text">The title.</param>
    /// <param name="callerMemberName">Name of the caller member. This is automatically populated.</param>
    /// <param name="callerFilePath">The caller file path. This is automatically populated.</param>
    /// <param name="callerLineNumber">The caller line number. This is automatically populated.</param>
    public static void Dump(this Object obj, String source, String text = "Object Dump", [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) {
      if(obj == null) {
        return;
      }

      String message = $"{text} ({obj.GetType()}): {Environment.NewLine}{obj.Stringify().Indent(5)}";
      LogMessage(LogLevel.Trace, message, source, obj, callerMemberName, callerFilePath, callerLineNumber);
    }

    /// <summary>
    /// Logs a trace message showing all possible non-null properties of the given object
    /// This method is expensive as it uses Stringify internally.
    /// </summary>
    /// <param name="obj">The object.</param>
    /// <param name="source">The source.</param>
    /// <param name="text">The text.</param>
    /// <param name="callerMemberName">Name of the caller member.</param>
    /// <param name="callerFilePath">The caller file path.</param>
    /// <param name="callerLineNumber">The caller line number.</param>
    public static void Dump(this Object obj, Type source, String text = "Object Dump", [CallerMemberName] String callerMemberName = "", [CallerFilePath] String callerFilePath = "", [CallerLineNumber] Int32 callerLineNumber = 0) {
      if(obj == null) {
        return;
      }

      String message = $"{text} ({obj.GetType()}): {Environment.NewLine}{obj.Stringify().Indent(5)}";
      LogMessage(LogLevel.Trace, message, source?.FullName, obj, callerMemberName, callerFilePath, callerLineNumber);
    }*/

    #endregion

    /*private static void RemoveLogger(Func<ILogger, Boolean> criteria) {
      lock(SyncLock) {
        ILogger loggerInstance = Loggers.FirstOrDefault(criteria);

        if(loggerInstance == null) {
          throw new InvalidOperationException("The logger is not registered.");
        }

        loggerInstance.Dispose();

        _ = Loggers.Remove(loggerInstance);
      }
    }*/

    // [Obsolete("NEED", false)]
    private static void LogMessage(LogLevel logLevel, String message, String sourceName, Object extendedData, String callerMemberName, String callerFilePath, Int32 callerLineNumber) {
      UInt64 sequence = _loggingSequence;
      DateTime date = DateTime.UtcNow;
      _loggingSequence++;

      String loggerMessage = String.IsNullOrWhiteSpace(message) ? String.Empty : message.RemoveControlCharsExcept('\n');

      LogMessageReceivedEventArgs eventArgs = new LogMessageReceivedEventArgs(sequence, logLevel, date, sourceName, loggerMessage, extendedData, callerMemberName, callerFilePath, callerLineNumber);

      foreach(ILogger logger in Loggers) {
        _ = Task.Run(() => {
          if(logger.LogLevel <= logLevel) {
            logger.Log(eventArgs);
          }
        });
      }
    }
  }
}