#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 System.Collections;
using System.Globalization;
using System.Reflection;
using System.Xml;

using log4net.Appender;
using log4net.Util;
using log4net.Core;
using log4net.ObjectRenderer;

namespace log4net.Repository.Hierarchy
{
	/// <summary>
	/// Initializes the log4net environment using an XML DOM.
	/// </summary>
	/// <remarks>
	/// <para>
	/// Configures a <see cref="Hierarchy"/> using an XML DOM.
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	/// <author>Gert Driesen</author>
	public class XmlHierarchyConfigurator
	{
		private enum ConfigUpdateMode
		{
			Merge, 
			Overwrite
		}

		#region Public Instance Constructors

		/// <summary>
		/// Construct the configurator for a hierarchy
		/// </summary>
		/// <param name="hierarchy">The hierarchy to build.</param>
		/// <remarks>
		/// <para>
		/// Initializes a new instance of the <see cref="XmlHierarchyConfigurator" /> class
		/// with the specified <see cref="Hierarchy" />.
		/// </para>
		/// </remarks>
		public XmlHierarchyConfigurator(Hierarchy hierarchy) 
		{
			m_hierarchy = hierarchy;
			m_appenderBag = new Hashtable();
		}

		#endregion Public Instance Constructors

		#region Public Instance Methods

		/// <summary>
		/// Configure the hierarchy by parsing a DOM tree of XML elements.
		/// </summary>
		/// <param name="element">The root element to parse.</param>
		/// <remarks>
		/// <para>
		/// Configure the hierarchy by parsing a DOM tree of XML elements.
		/// </para>
		/// </remarks>
		public void Configure(XmlElement element) 
		{
			if (element == null || m_hierarchy == null)
			{
				return;
			}

			string rootElementName = element.LocalName;

			if (rootElementName != CONFIGURATION_TAG)
			{
				LogLog.Error("XmlHierarchyConfigurator: Xml element is - not a <" + CONFIGURATION_TAG + "> element.");
				return;
			}

			if (!LogLog.InternalDebugging)
			{
				// Look for a debug attribute to enable internal debug
				string debugAttribute = element.GetAttribute(INTERNAL_DEBUG_ATTR);
				LogLog.Debug("XmlHierarchyConfigurator: "+INTERNAL_DEBUG_ATTR+" attribute [" + debugAttribute + "].");

				if (debugAttribute.Length>0 && debugAttribute != "null") 
				{	  
					LogLog.InternalDebugging = OptionConverter.ToBoolean(debugAttribute, true);
				}
				else 
				{
					LogLog.Debug("XmlHierarchyConfigurator: Ignoring " + INTERNAL_DEBUG_ATTR + " attribute.");
				}

				string confDebug = element.GetAttribute(CONFIG_DEBUG_ATTR);
				if (confDebug.Length>0 && confDebug != "null")
				{	  
					LogLog.Warn("XmlHierarchyConfigurator: The \"" + CONFIG_DEBUG_ATTR + "\" attribute is deprecated.");
					LogLog.Warn("XmlHierarchyConfigurator: Use the \"" + INTERNAL_DEBUG_ATTR + "\" attribute instead.");
					LogLog.InternalDebugging = OptionConverter.ToBoolean(confDebug, true);
				}
			}

			// Default mode is merge
			ConfigUpdateMode configUpdateMode = ConfigUpdateMode.Merge;

			// Look for the config update attribute
			string configUpdateModeAttribute = element.GetAttribute(CONFIG_UPDATE_MODE_ATTR);
			if (configUpdateModeAttribute != null && configUpdateModeAttribute.Length > 0)
			{
				// Parse the attribute
				try
				{
					configUpdateMode = (ConfigUpdateMode)OptionConverter.ConvertStringTo(typeof(ConfigUpdateMode), configUpdateModeAttribute);
				}
				catch
				{
					LogLog.Error("XmlHierarchyConfigurator: Invalid " + CONFIG_UPDATE_MODE_ATTR + " attribute value [" + configUpdateModeAttribute + "]");
				}
			}

			// IMPL: The IFormatProvider argument to Enum.ToString() is deprecated in .NET 2.0
			LogLog.Debug("XmlHierarchyConfigurator: Configuration update mode [" + configUpdateMode.ToString() + "].");

			// Only reset configuration if overwrite flag specified
			if (configUpdateMode == ConfigUpdateMode.Overwrite)
			{
				// Reset to original unset configuration
				m_hierarchy.ResetConfiguration();
				LogLog.Debug("XmlHierarchyConfigurator: Configuration reset before reading config.");
			}

			/* Building Appender objects, placing them in a local namespace
			   for future reference */

			/* Process all the top level elements */

			foreach (XmlNode currentNode in element.ChildNodes)
			{
				if (currentNode.NodeType == XmlNodeType.Element) 
				{
					XmlElement currentElement = (XmlElement)currentNode;

					if (currentElement.LocalName == LOGGER_TAG)
					{
						ParseLogger(currentElement);
					} 
					else if (currentElement.LocalName == CATEGORY_TAG)
					{
						// TODO: deprecated use of category
						ParseLogger(currentElement);
					} 
					else if (currentElement.LocalName == ROOT_TAG)
					{
						ParseRoot(currentElement);
					} 
					else if (currentElement.LocalName == RENDERER_TAG)
					{
						ParseRenderer(currentElement);
					}
					else if (currentElement.LocalName == APPENDER_TAG)
					{
						// We ignore appenders in this pass. They will
						// be found and loaded if they are referenced.
					}
					else
					{
						// Read the param tags and set properties on the hierarchy
						SetParameter(currentElement, m_hierarchy);
					}
				}
			}

			// Lastly set the hierarchy threshold
			string thresholdStr = element.GetAttribute(THRESHOLD_ATTR);
			LogLog.Debug("XmlHierarchyConfigurator: Hierarchy Threshold [" + thresholdStr + "]");
			if (thresholdStr.Length > 0 && thresholdStr != "null") 
			{
				Level thresholdLevel = (Level) ConvertStringTo(typeof(Level), thresholdStr);
				if (thresholdLevel != null)
				{
					m_hierarchy.Threshold = thresholdLevel;
				}
				else
				{
					LogLog.Warn("XmlHierarchyConfigurator: Unable to set hierarchy threshold using value [" + thresholdStr + "] (with acceptable conversion types)");
				}
			}

			// Done reading config
		}

		#endregion Public Instance Methods

		#region Protected Instance Methods

		/// <summary>
		/// Parse appenders by IDREF.
		/// </summary>
		/// <param name="appenderRef">The appender ref element.</param>
		/// <returns>The instance of the appender that the ref refers to.</returns>
		/// <remarks>
		/// <para>
		/// Parse an XML element that represents an appender and return 
		/// the appender.
		/// </para>
		/// </remarks>
		protected IAppender FindAppenderByReference(XmlElement appenderRef) 
		{	
			string appenderName = appenderRef.GetAttribute(REF_ATTR);

			IAppender appender = (IAppender)m_appenderBag[appenderName];
			if (appender != null) 
			{
				return appender;
			} 
			else 
			{
				// Find the element with that id
				XmlElement element = null;

				if (appenderName != null && appenderName.Length > 0)
				{
					foreach (XmlElement curAppenderElement in appenderRef.OwnerDocument.GetElementsByTagName(APPENDER_TAG))
					{
						if (curAppenderElement.GetAttribute("name") == appenderName)
						{
							element = curAppenderElement;
							break;
						}
					}
				}

				if (element == null) 
				{
					LogLog.Error("XmlHierarchyConfigurator: No appender named [" + appenderName + "] could be found."); 
					return null;
				} 
				else
				{
					appender = ParseAppender(element);
					if (appender != null)
					{
						m_appenderBag[appenderName] = appender;
					}
					return appender;
				}
			} 
		}

		/// <summary>
		/// Parses an appender element.
		/// </summary>
		/// <param name="appenderElement">The appender element.</param>
		/// <returns>The appender instance or <c>null</c> when parsing failed.</returns>
		/// <remarks>
		/// <para>
		/// Parse an XML element that represents an appender and return
		/// the appender instance.
		/// </para>
		/// </remarks>
		protected IAppender ParseAppender(XmlElement appenderElement) 
		{
			string appenderName = appenderElement.GetAttribute(NAME_ATTR);
			string typeName = appenderElement.GetAttribute(TYPE_ATTR);

			LogLog.Debug("XmlHierarchyConfigurator: Loading Appender [" + appenderName + "] type: [" + typeName + "]");
			try 
			{
				IAppender appender = (IAppender)Activator.CreateInstance(SystemInfo.GetTypeFromString(typeName, true, true));
				appender.Name = appenderName;

				foreach (XmlNode currentNode in appenderElement.ChildNodes)
				{
					/* We're only interested in Elements */
					if (currentNode.NodeType == XmlNodeType.Element) 
					{
						XmlElement currentElement = (XmlElement)currentNode;

						// Look for the appender ref tag
						if (currentElement.LocalName == APPENDER_REF_TAG)
						{
							string refName = currentElement.GetAttribute(REF_ATTR);

							IAppenderAttachable appenderContainer = appender as IAppenderAttachable;
							if (appenderContainer != null) 
							{
								LogLog.Debug("XmlHierarchyConfigurator: Attaching appender named [" + refName + "] to appender named [" + appender.Name + "].");

								IAppender referencedAppender = FindAppenderByReference(currentElement);
								if (referencedAppender != null)
								{
									appenderContainer.AddAppender(referencedAppender);
								}
							} 
							else 
							{
								LogLog.Error("XmlHierarchyConfigurator: Requesting attachment of appender named ["+refName+ "] to appender named [" + appender.Name + "] which does not implement log4net.Core.IAppenderAttachable.");
							}
						}
						else
						{
							// For all other tags we use standard set param method
							SetParameter(currentElement, appender);
						}
					}
				}

				IOptionHandler optionHandler = appender as IOptionHandler;
				if (optionHandler != null) 
				{
					optionHandler.ActivateOptions();
				}

				LogLog.Debug("XmlHierarchyConfigurator: Created Appender [" + appenderName + "]");	
				return appender;
			}
			catch (Exception ex) 
			{
				// Yes, it's ugly.  But all exceptions point to the same problem: we can't create an Appender

				LogLog.Error("XmlHierarchyConfigurator: Could not create Appender [" + appenderName + "] of type [" + typeName + "]. Reported error follows.", ex);
				return null;
			}
		}

		/// <summary>
		/// Parses a logger element.
		/// </summary>
		/// <param name="loggerElement">The logger element.</param>
		/// <remarks>
		/// <para>
		/// Parse an XML element that represents a logger.
		/// </para>
		/// </remarks>
		protected void ParseLogger(XmlElement loggerElement) 
		{