#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using log4net.Appender;
using log4net.Core;
using log4net.Repository;

namespace log4net
{
  /// <summary>
  /// This class is used by client applications to request logger instances.
  /// </summary>
  /// <remarks>
  /// <para>
  /// This class has static methods that are used by a client to request
  /// a logger instance. The <see cref="M:GetLogger(string)"/> method is 
  /// used to retrieve a logger.
  /// </para>
  /// <para>
  /// See the <see cref="ILog"/> interface for more details.
  /// </para>
  /// </remarks>
  /// <example>Simple example of logging messages
  /// <code lang="C#">
  /// ILog log = LogManager.GetLogger("application-log");
  /// 
  /// log.Info("Application Start");
  /// log.Debug("This is a debug message");
  /// 
  /// if (log.IsDebugEnabled)
  /// {
  ///    log.Debug("This is another debug message");
  /// }
  /// </code>
  /// </example>
  /// <threadsafety static="true" instance="true" />
  /// <seealso cref="ILog"/>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public static class LogManager
  {
    /// <overloads>Returns the named logger if it exists.</overloads>
    /// <summary>
    /// Returns the named logger if it exists.
    /// </summary>
    /// <remarks>
    /// <para>
    /// If the named logger exists (in the default repository) then it
    /// returns a reference to the logger, otherwise it returns <c>null</c>.
    /// </para>
    /// </remarks>
    /// <param name="name">The fully qualified logger name to look for.</param>
    /// <returns>The logger found, or <c>null</c> if no logger could be found.</returns>
    public static ILog? Exists(string name)
    {
      return Exists(Assembly.GetCallingAssembly(), name);
    }

    /// <overloads>Get the currently defined loggers.</overloads>
    /// <summary>
    /// Returns all the currently defined loggers in the default repository.
    /// </summary>
    /// <remarks>
    /// <para>The root logger is <b>not</b> included in the returned array.</para>
    /// </remarks>
    /// <returns>All the defined loggers.</returns>
    public static ILog[] GetCurrentLoggers()
    {
      return GetCurrentLoggers(Assembly.GetCallingAssembly());
    }

    /// <overloads>Get or create a logger.</overloads>
    /// <summary>
    /// Retrieves or creates a named logger.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Retrieves a logger named as the <paramref name="name"/>
    /// parameter. If the named logger already exists, then the
    /// existing instance will be returned. Otherwise, a new instance is
    /// created.
    /// </para>
    /// <para>By default, loggers do not have a set level but inherit
    /// it from the hierarchy. This is one of the central features of
    /// log4net.
    /// </para>
    /// </remarks>
    /// <param name="name">The name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(string name)
    {
      return GetLogger(Assembly.GetCallingAssembly(), name);
    }

    /// <summary>
    /// Returns the named logger if it exists.
    /// </summary>
    /// <remarks>
    /// <para>
    /// If the named logger exists (in the specified repository) then it
    /// returns a reference to the logger, otherwise it returns
    /// <c>null</c>.
    /// </para>
    /// </remarks>
    /// <param name="repository">The repository to lookup in.</param>
    /// <param name="name">The fully qualified logger name to look for.</param>
    /// <returns>
    /// The logger found, or <c>null</c> if the logger doesn't exist in the specified 
    /// repository.
    /// </returns>
    public static ILog? Exists(string repository, string name)
    {
      return WrapLogger(LoggerManager.Exists(repository, name));
    }

    /// <summary>
    /// Returns the named logger if it exists.
    /// </summary>
    /// <remarks>
    /// <para>
    /// If the named logger exists (in the repository for the specified assembly) then it
    /// returns a reference to the logger, otherwise it returns
    /// <c>null</c>.
    /// </para>
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    /// <param name="name">The fully qualified logger name to look for.</param>
    /// <returns>
    /// The logger, or <c>null</c> if the logger doesn't exist in the specified
    /// assembly's repository.
    /// </returns>
    public static ILog? Exists(Assembly repositoryAssembly, string name)
    {
      return WrapLogger(LoggerManager.Exists(repositoryAssembly, name));
    }

    /// <summary>
    /// Returns all the currently defined loggers in the specified repository.
    /// </summary>
    /// <param name="repository">The repository to lookup in.</param>
    /// <remarks>
    /// The root logger is <b>not</b> included in the returned array.
    /// </remarks>
    /// <returns>All the defined loggers.</returns>
    public static ILog[] GetCurrentLoggers(string repository)
    {
      return WrapLoggers(LoggerManager.GetCurrentLoggers(repository));
    }

    /// <summary>
    /// Returns all the currently defined loggers in the specified assembly's repository.
    /// </summary>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    /// <remarks>
    /// The root logger is <b>not</b> included in the returned array.
    /// </remarks>
    /// <returns>All the defined loggers.</returns>
    public static ILog[] GetCurrentLoggers(Assembly repositoryAssembly)
    {
      return WrapLoggers(LoggerManager.GetCurrentLoggers(repositoryAssembly));
    }

    /// <summary>
    /// Retrieves or creates a named logger.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Retrieve a logger named as the <paramref name="name"/>
    /// parameter. If the named logger already exists, then the
    /// existing instance will be returned. Otherwise, a new instance is
    /// created.
    /// </para>
    /// <para>
    /// By default, loggers do not have a set level but inherit
    /// it from the hierarchy. This is one of the central features of
    /// log4net.
    /// </para>
    /// </remarks>
    /// <param name="repository">The repository to lookup in.</param>
    /// <param name="name">The name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(string repository, string name)
    {
      return WrapLogger(LoggerManager.GetLogger(repository, name))!;
    }

    /// <summary>
    /// Retrieves or creates a named logger.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Retrieve a logger named as the <paramref name="name"/>
    /// parameter. If the named logger already exists, then the
    /// existing instance will be returned. Otherwise, a new instance is
    /// created.
    /// </para>
    /// <para>
    /// By default, loggers do not have a set level but inherit
    /// it from the hierarchy. This is one of the central features of
    /// log4net.
    /// </para>
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    /// <param name="name">The name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(Assembly repositoryAssembly, string name)
    {
      return WrapLogger(LoggerManager.GetLogger(repositoryAssembly, name))!;
    }

    /// <summary>
    /// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
    /// </summary>
    /// <remarks>
    /// Get the logger for the fully qualified name of the type specified.
    /// </remarks>
    /// <param name="type">The full name of <paramref name="type"/> will be used as the name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(Type type)
    {
      return GetLogger(Assembly.GetCallingAssembly(), type.FullName!);
    }

    /// <summary>
    /// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
    /// </summary>
    /// <remarks>
    /// Gets the logger for the fully qualified name of the type specified.
    /// </remarks>
    /// <param name="repository">The repository to lookup in.</param>
    /// <param name="type">The full name of <paramref name="type"/> will be used as the name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(string repository, Type type)
    {
      return WrapLogger(LoggerManager.GetLogger(repository, type))!;
    }

    /// <summary>
    /// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
    /// </summary>
    /// <remarks>
    /// Gets the logger for the fully qualified name of the type specified.
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    /// <param name="type">The full name of <paramref name="type"/> will be used as the name of the logger to retrieve.</param>
    /// <returns>The logger with the name specified.</returns>
    public static ILog GetLogger(Assembly repositoryAssembly, Type type)
    {
      return WrapLogger(LoggerManager.GetLogger(repositoryAssembly, type))!;
    }

    /// <summary>
    /// Shuts down the log4net system.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Calling this method will <b>safely</b> close and remove all
    /// appenders in all the loggers including root contained in all the
    /// default repositories.
    /// </para>
    /// <para>
    /// Some appenders need to be closed before the application exists. 
    /// Otherwise, pending logging events might be lost.
    /// </para>
    /// <para>The <c>shutdown</c> method is careful to close nested
    /// appenders before closing regular appenders. This allows
    /// configurations where a regular appender is attached to a logger
    /// and again to a nested appender.
    /// </para>
    /// </remarks>
    public static void Shutdown()
    {
      LoggerManager.Shutdown();
    }

    /// <overloads>Shutdown a logger repository.</overloads>
    /// <summary>
    /// Shuts down the default repository.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Calling this method will <b>safely</b> close and remove all
    /// appenders in all the loggers including root contained in the
    /// default repository.
    /// </para>
    /// <para>Some appenders need to be closed before the application exists. 
    /// Otherwise, pending logging events might be lost.
    /// </para>
    /// <para>The <c>shutdown</c> method is careful to close nested
    /// appenders before closing regular appenders. This allows
    /// configurations where a regular appender is attached to a logger
    /// and again to a nested appender.
    /// </para>
    /// </remarks>
    public static void ShutdownRepository()
    {
      ShutdownRepository(Assembly.GetCallingAssembly());
    }

    /// <summary>
    /// Shuts down the repository for the repository specified.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Calling this method will <b>safely</b> close and remove all
    /// appenders in all the loggers including root contained in the
    /// <paramref name="repository"/> specified.
    /// </para>
    /// <para>
    /// Some appenders need to be closed before the application exists. 
    /// Otherwise, pending logging events might be lost.
    /// </para>
    /// <para>The <c>shutdown</c> method is careful to close nested
    /// appenders before closing regular appenders. This allows
    /// configurations where a regular appender is attached to a logger
    /// and again to a nested appender.
    /// </para>
    /// </remarks>
    /// <param name="repository">The repository to shut down.</param>
    public static void ShutdownRepository(string repository)
    {
      LoggerManager.ShutdownRepository(repository);
    }

    /// <summary>
    /// Shuts down the repository specified.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Calling this method will <b>safely</b> close and remove all
    /// appenders in all the loggers including root contained in the
    /// repository. The repository is looked up using
    /// the <paramref name="repositoryAssembly"/> specified.
    /// </para>
    /// <para>
    /// Some appenders need to be closed before the application exists. 
    /// Otherwise, pending logging events might be lost.
    /// </para>
    /// <para>
    /// The <c>shutdown</c> method is careful to close nested
    /// appenders before closing regular appenders. This allows
    /// configurations where a regular appender is attached to a logger
    /// and again to a nested appender.
    /// </para>
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    public static void ShutdownRepository(Assembly repositoryAssembly)
    {
      LoggerManager.ShutdownRepository(repositoryAssembly);
    }

    /// <overloads>Reset the configuration of a repository</overloads>
    /// <summary>
    /// Resets all values contained in this repository instance to their defaults.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Resets all values contained in the repository instance to their
    /// defaults.  This removes all appenders from all loggers, sets
    /// the level of all non-root loggers to <c>null</c>,
    /// sets their additivity flag to <c>true</c> and sets the level
    /// of the root logger to <see cref="Level.Debug"/>. Moreover,
    /// message disabling is set to its default "off" value.
    /// </para>    
    /// </remarks>
    public static void ResetConfiguration()
    {
      ResetConfiguration(Assembly.GetCallingAssembly());
    }

    /// <summary>
    /// Resets all values contained in this repository instance to their defaults.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Reset all values contained in the repository instance to their
    /// defaults.  This removes all appenders from all loggers, sets
    /// the level of all non-root loggers to <c>null</c>,
    /// sets their additivity flag to <c>true</c> and sets the level
    /// of the root logger to <see cref="Level.Debug"/>. Moreover,
    /// message disabling is set to its default "off" value.
    /// </para>    
    /// </remarks>
    /// <param name="repository">The repository to reset.</param>
    public static void ResetConfiguration(string repository)
    {
      LoggerManager.ResetConfiguration(repository);
    }

    /// <summary>
    /// Resets all values contained in this repository instance to their defaults.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Reset all values contained in the repository instance to their
    /// defaults.  This removes all appenders from all loggers, sets
    /// the level of all non-root loggers to <c>null</c>,
    /// sets their additivity flag to <c>true</c> and sets the level
    /// of the root logger to <see cref="Level.Debug"/>. Moreover,
    /// message disabling is set to its default "off" value.
    /// </para>    
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository to reset.</param>
    public static void ResetConfiguration(Assembly repositoryAssembly)
    {
      LoggerManager.ResetConfiguration(repositoryAssembly);
    }

    /// <overloads>Get a logger repository.</overloads>
    /// <summary>
    /// Returns the default <see cref="ILoggerRepository"/> instance.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Gets the <see cref="ILoggerRepository"/> for the repository specified
    /// by the callers assembly (<see cref="M:Assembly.GetCallingAssembly()"/>).
    /// </para>
    /// </remarks>
    /// <returns>The <see cref="ILoggerRepository"/> instance for the default repository.</returns>
    public static ILoggerRepository GetRepository()
    {
      return GetRepository(Assembly.GetCallingAssembly());
    }

    /// <summary>
    /// Returns the default <see cref="ILoggerRepository"/> instance.
    /// </summary>
    /// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
    /// <remarks>
    /// <para>
    /// Gets the <see cref="ILoggerRepository"/> for the repository specified
    /// by the <paramref name="repository"/> argument.
    /// </para>
    /// </remarks>
    /// <param name="repository">The repository to lookup in.</param>
    public static ILoggerRepository GetRepository(string repository)
    {
      return LoggerManager.GetRepository(repository);
    }

    /// <summary>
    /// Returns the default <see cref="ILoggerRepository"/> instance.
    /// </summary>
    /// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
    /// <remarks>
    /// <para>
    /// Gets the <see cref="ILoggerRepository"/> for the repository specified
    /// by the <paramref name="repositoryAssembly"/> argument.
    /// </para>
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to look up the repository.</param>
    public static ILoggerRepository GetRepository(Assembly repositoryAssembly)
    {
      return LoggerManager.GetRepository(repositoryAssembly);
    }

    /// <overloads>Create a logger repository.</overloads>
    /// <summary>
    /// Creates a repository with the specified repository type.
    /// </summary>
    /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
    /// and has a no arg constructor. An instance of this type will be created to act
    /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
    /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
    /// <remarks>
    /// <para>
    /// The <see cref="ILoggerRepository"/> created will be associated with the repository
    /// specified such that a call to <see cref="M:GetRepository()"/> will return 
    /// the same repository instance.
    /// </para>
    /// </remarks>
    public static ILoggerRepository CreateRepository(Type repositoryType)
    {
      return CreateRepository(Assembly.GetCallingAssembly(), repositoryType);
    }

    /// <summary>
    /// Creates a repository with the specified name.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Creates the default type of <see cref="ILoggerRepository"/> which is a
    /// <see cref="log4net.Repository.Hierarchy.Hierarchy"/> object.
    /// </para>
    /// <para>
    /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
    /// An <see cref="Exception"/> will be thrown if the repository already exists.
    /// </para>
    /// </remarks>
    /// <param name="repository">The name of the repository, this must be unique amongst repositories.</param>
    /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
    /// <exception cref="LogException">The specified repository already exists.</exception>
    public static ILoggerRepository CreateRepository(string repository)
    {
      return LoggerManager.CreateRepository(repository);
    }

    /// <summary>
    /// Creates a repository with the specified name and repository type.
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
    /// An <see cref="Exception"/> will be thrown if the repository already exists.
    /// </para>
    /// </remarks>
    /// <param name="repository">The name of the repository, this must be unique to the repository.</param>
    /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
    /// and has a no arg constructor. An instance of this type will be created to act
    /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
    /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
    /// <exception cref="LogException">The specified repository already exists.</exception>
    public static ILoggerRepository CreateRepository(string repository, Type repositoryType)
    {
      return LoggerManager.CreateRepository(repository, repositoryType);
    }

    /// <summary>
    /// Creates a repository for the specified assembly and repository type.
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <see cref="ILoggerRepository"/> created will be associated with the repository
    /// specified such that a call to <see cref="M:GetRepository(Assembly)"/> with the
    /// same assembly specified will return the same repository instance.
    /// </para>
    /// </remarks>
    /// <param name="repositoryAssembly">The assembly to use to get the name of the repository.</param>
    /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
    /// and has a no arg constructor. An instance of this type will be created to act
    /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
    /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
    public static ILoggerRepository CreateRepository(Assembly repositoryAssembly, Type repositoryType)
    {
      return LoggerManager.CreateRepository(repositoryAssembly, repositoryType);
    }

    /// <summary>
    /// Gets the list of currently defined repositories.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Get an array of all the <see cref="ILoggerRepository"/> objects that have been created.
    /// </para>
    /// </remarks>
    /// <returns>An array of all the known <see cref="ILoggerRepository"/> objects.</returns>
    public static ILoggerRepository[] GetAllRepositories()
    {
      return LoggerManager.GetAllRepositories();
    }

    /// <summary>
    /// Flushes logging events buffered in all configured appenders in the default repository.
    /// </summary>
    /// <param name="millisecondsTimeout">The maximum time in milliseconds to wait for logging events from asynchronous appenders to be flushed.</param>
    /// <returns><c>True</c> if all logging events were flushed successfully, else <c>false</c>.</returns>
    public static bool Flush(int millisecondsTimeout)
    {
      if (LoggerManager.GetRepository(Assembly.GetCallingAssembly()) is not IFlushable flushableRepository)
      {
        return false;
      }

      return flushableRepository.Flush(millisecondsTimeout);
    }

    /// <summary>
    /// Looks up the wrapper object for the logger specified.
    /// </summary>
    /// <param name="logger">The logger to get the wrapper for.</param>
    /// <returns>The wrapper for the logger specified.</returns>
    [return: NotNullIfNotNull("logger")]
    private static ILog? WrapLogger(ILogger? logger)
    {
      return (ILog?)s_wrapperMap.GetWrapper(logger);
    }

    /// <summary>
    /// Looks up the wrapper objects for the loggers specified.
    /// </summary>
    /// <param name="loggers">The loggers to get the wrappers for.</param>
    /// <returns>The wrapper objects for the loggers specified.</returns>
    private static ILog[] WrapLoggers(ILogger[] loggers)
    {
      var results = new ILog[loggers.Length];
      for (int i = 0; i < loggers.Length; i++)
      {
        results[i] = WrapLogger(loggers[i]);
      }
      return results;
    }

    /// <summary>
    /// Create the <see cref="ILoggerWrapper"/> objects used by
    /// this manager.
    /// </summary>
    /// <param name="logger">The logger to wrap.</param>
    /// <returns>The wrapper for the logger specified.</returns>
    private static ILoggerWrapper WrapperCreationHandler(ILogger logger)
    {
      return new LogImpl(logger);
    }

    /// <summary>
    /// The wrapper map to use to hold the <see cref="LogImpl"/> objects.
    /// </summary>
    private static readonly WrapperMap s_wrapperMap = new(WrapperCreationHandler);
  }
}