#region Copyright & License
//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed 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 log4net.ObjectRenderer;
using log4net.Core;
using log4net.Util;

namespace log4net.Repository.Hierarchy
{
	#region LoggerCreationEvent

	/// <summary>
	/// Delegate used to handle logger creation event notifications.
	/// </summary>
	/// <param name="sender">The <see cref="Hierarchy"/> in which the <see cref="Logger"/> has been created.</param>
	/// <param name="e">The <see cref="LoggerCreationEventArgs"/> event args that hold the <see cref="Logger"/> instance that has been created.</param>
	/// <remarks>
	/// <para>
	/// Delegate used to handle logger creation event notifications.
	/// </para>
	/// </remarks>
	public delegate void LoggerCreationEventHandler(object sender, LoggerCreationEventArgs e);

	/// <summary>
	/// Provides data for the <see cref="Hierarchy.LoggerCreatedEvent"/> event.
	/// </summary>
	/// <remarks>
	/// <para>
	/// A <see cref="Hierarchy.LoggerCreatedEvent"/> event is raised every time a
	/// <see cref="Logger"/> is created.
	/// </para>
	/// </remarks>
	public class LoggerCreationEventArgs : EventArgs
	{
		/// <summary>
		/// The <see cref="Logger"/> created
		/// </summary>
		private Logger m_log;

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="log">The <see cref="Logger"/> that has been created.</param>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="LoggerCreationEventArgs" /> event argument 
		/// class,with the specified <see cref="Logger"/>.
		/// </para>
		/// </remarks>
		public LoggerCreationEventArgs(Logger log)
		{
			m_log = log;
		}

		/// <summary>
		/// Gets the <see cref="Logger"/> that has been created.
		/// </summary>
		/// <value>
		/// The <see cref="Logger"/> that has been created.
		/// </value>
		/// <remarks>
		/// <para>
		/// The <see cref="Logger"/> that has been created.
		/// </para>
		/// </remarks>
		public Logger Logger
		{
			get { return m_log; }
		}
	}

	#endregion LoggerCreationEvent

	/// <summary>
	/// Hierarchical organization of loggers
	/// </summary>
	/// <remarks>
	/// <para>
	/// <i>The casual user should not have to deal with this class
	/// directly.</i>
	/// </para>
	/// <para>
	/// This class is specialized in retrieving loggers by name and
	/// also maintaining the logger hierarchy. Implements the 
	/// <see cref="ILoggerRepository"/> interface.
	/// </para>
	/// <para>
	/// The structure of the logger hierarchy is maintained by the
	/// <see cref="GetLogger(string)"/> method. The hierarchy is such that children
	/// link to their parent but parents do not have any references to their
	/// children. Moreover, loggers can be instantiated in any order, in
	/// particular descendant before ancestor.
	/// </para>
	/// <para>
	/// In case a descendant is created before a particular ancestor,
	/// then it creates a provision node for the ancestor and adds itself
	/// to the provision node. Other descendants of the same ancestor add
	/// themselves to the previously created provision node.
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	/// <author>Gert Driesen</author>
	public class Hierarchy : LoggerRepositorySkeleton, IBasicRepositoryConfigurator, IXmlRepositoryConfigurator
	{
		#region Public Events

		/// <summary>
		/// Event used to notify that a logger has been created.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Event raised when a logger is created.
		/// </para>
		/// </remarks>
		public event LoggerCreationEventHandler LoggerCreatedEvent
		{
			add { m_loggerCreatedEvent += value; }
			remove { m_loggerCreatedEvent -= value; }
		}

		#endregion Public Events

		#region Public Instance Constructors

		/// <summary>
		/// Default constructor
		/// </summary>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="Hierarchy" /> class.
		/// </para>
		/// </remarks>
		public Hierarchy() : this(new DefaultLoggerFactory())
		{
		}

		/// <summary>
		/// Construct with properties
		/// </summary>
		/// <param name="properties">The properties to pass to this repository.</param>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="Hierarchy" /> class.
		/// </para>
		/// </remarks>
		public Hierarchy(PropertiesDictionary properties) : this(properties, new DefaultLoggerFactory())
		{
		}

		/// <summary>
		/// Construct with a logger factory
		/// </summary>
		/// <param name="loggerFactory">The factory to use to create new logger instances.</param>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="Hierarchy" /> class with 
		/// the specified <see cref="ILoggerFactory" />.
		/// </para>
		/// </remarks>
		public Hierarchy(ILoggerFactory loggerFactory) : this(new PropertiesDictionary(), loggerFactory)
		{
		}

		/// <summary>
		/// Construct with properties and a logger factory
		/// </summary>
		/// <param name="properties">The properties to pass to this repository.</param>
		/// <param name="loggerFactory">The factory to use to create new logger instances.</param>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="Hierarchy" /> class with 
		/// the specified <see cref="ILoggerFactory" />.
		/// </para>
		/// </remarks>
		public Hierarchy(PropertiesDictionary properties, ILoggerFactory loggerFactory) : base(properties)
		{
			if (loggerFactory == null)
			{
				throw new ArgumentNullException("loggerFactory");
			}

			m_defaultFactory = loggerFactory;

			m_ht = System.Collections.Hashtable.Synchronized(new System.Collections.Hashtable());
		}

		#endregion Public Instance Constructors

		#region Public Instance Properties

		/// <summary>
		/// Has no appender warning been emitted
		/// </summary>
		/// <remarks>
		/// <para>
		/// Flag to indicate if we have already issued a warning
		/// about not having an appender warning.
		/// </para>
		/// </remarks>
		public bool EmittedNoAppenderWarning
		{
			get { return m_emittedNoAppenderWarning; }
			set { m_emittedNoAppenderWarning = value; }
		}

		/// <summary>
		/// Get the root of this hierarchy
		/// </summary>
		/// <remarks>
		/// <para>
		/// Get the root of this hierarchy.
		/// </para>
		/// </remarks>
		public Logger Root
		{
			get 
			{ 
				if (m_root == null)
				{
					lock(this)
					{
						if (m_root == null)
						{
							// Create the root logger
							Logger root = m_defaultFactory.CreateLogger(null);
							root.Hierarchy = this;

							// Store root
							m_root = root;
						}
					}
				}
				return m_root; 
			}
		}

		/// <summary>
		/// Gets or sets the default <see cref="ILoggerFactory" /> instance.
		/// </summary>
		/// <value>The default <see cref="ILoggerFactory" /></value>
		/// <remarks>
		/// <para>
		/// The logger factory is used to create logger instances.
		/// </para>
		/// </remarks>
		public ILoggerFactory LoggerFactory
		{
			get { return m_defaultFactory; }
			set
			{
				if (value == null)
				{
					throw new ArgumentNullException("value");
				}
				m_defaultFactory = value;
			}
		}

		#endregion Public Instance Properties

		#region Override Implementation of LoggerRepositorySkeleton

		/// <summary>
		/// Test if a logger exists
		/// </summary>
		/// <param name="name">The name of the logger to lookup</param>
		/// <returns>The Logger object with the name specified</returns>
		/// <remarks>
		/// <para>
		/// Check if the named logger exists in the hierarchy. If so return
		/// its reference, otherwise returns <c>null</c>.
		/// </para>
		/// </remarks>
		override public ILogger Exists(string name) 
		{	
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}

			return m_ht[new LoggerKey(name)] as Logger;
		}

		/// <summary>
		/// Returns all the currently defined loggers in the hierarchy as an Array
		/// </summary>
		/// <returns>All the defined loggers</returns>
		/// <remarks>
		/// <para>
		/// Returns all the currently defined loggers in the hierarchy as an Array.
		/// The root logger is <b>not</b> included in the returned
		/// enumeration.
		/// </para>
		/// </remarks>
		override public ILogger[] GetCurrentLoggers() 
		{
			// The accumulation in loggers is necessary because not all elements in
			// ht are Logger objects as there might be some ProvisionNodes
			// as well.
			System.Collections.ArrayList loggers = new System.Collections.ArrayList(m_ht.Count);
	
			// Iterate through m_ht values
			foreach(object node in m_ht.Values)
			{
				if (node is Logger) 
				{
					loggers.Add(node);
				}
			}
			return (Logger[])loggers.ToArray(typeof(Logger));
		}

		/// <summary>
		/// Return a new logger instance named as the first parameter using
		/// the default factory.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Return a new logger instance named as the first parameter using
		/// the default factory.
		/// </para>
		/// <para>
		/// If a logger of that name already exists, then it will be
		/// returned.  Otherwise, a new logger will be instantiated and
		/// then linked with its existing ancestors as well as children.
		/// </para>
		/// </remarks>
		/// <param name="name">The name of the logger to retrieve</param>
		/// <returns>The logger object with the name specified</returns>
		override public ILogger GetLogger(string name) 
		{
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}

			return GetLogger(name, m_defaultFactory);
		}

		/// <summary>
		/// Shutting down a hierarchy will <i>safely</i> close and remove
		/// all appenders in all loggers including the root logger.
		/// </summary>
		/// <remarks>