XPath reader-writer

using System;
using System.Xml;

namespace XPathXmlStore
{
	/// <summary>
	/// Reads & writes data in xml file with XPath that doesn't exists yet.
	/// </summary>
	public class XPathStore
	{
		protected System.Xml.XmlDocument doc;
		protected string sXmlFileName;

		public XPathStore()
		{
			doc = new XmlDocument();
			sXmlFileName = "..\\..\\settings.xml";
			LoadSettings();
		}

		public void LoadSettings()
		{
			bool bReadOK = false;

			try
			{
				// load the XML from file
				doc.Load(sXmlFileName);
				Console.WriteLine ("\nSETTINGS RELOADED" );
				bReadOK = true;
			}
			catch (Exception e)
			{
				Console.WriteLine ("Exception: {0}", e.ToString());
			}

			if(!bReadOK)
			{
				doc.CreateComment("<?xml version=\"1.0\" ?>");
				Console.WriteLine ("\nCREATED NEW" );
			}
		}

		public void SaveSettings()
		{
			try{	doc.Save(sXmlFileName);
					Console.WriteLine ("SETTINGS SAVED");}
			catch (Exception e)	{	Console.WriteLine ("Exception: {0}", e.ToString()); 	}
		}


		/// <summary>
		/// Get a xml node from xPath, if it doesn,t exists create it.
		///
		/// __________ EXAMPLES ____________
		///  FdisSettings/User[@Name="FDIS_DTO"]/@AutoHide
		///  FdisSettings/User[@Name="FDIS_DTO"]/ReportFilter/Report[@Name="Afvoermeldingen per Categorie"]/@ReloadThisSettings
		/// </summary>
		/// <param name="sXPath"></param>
		/// <returns></returns>
		public System.Xml.XmlNode QueryCreatNode( string sXPath )
		{
			Console.WriteLine ("Query xml document with Xpath={0}", sXPath );
			XmlNode		node = null;

			try
			{	
				XmlNodeList list = doc.SelectNodes( sXPath );
				if( list.Count==1 )
					return list.Item(0);		// The easy way (The node exists)
				else if( list.Count==0 )
				{
					Console.WriteLine ("	ACTION) create XPath to node");

					// Parses XPath in separate parts.
					bool	bParsingRandomText	= false;
					int		nXpathPartStart		= -1;
		
					for( int i=0; i<sXPath.Length; i++ )
					{
						if( !bParsingRandomText												&&
							( (sXPath[i]=='/' || sXPath[i]=='\0') || i==sXPath.Length-1 )	&&
							nXpathPartStart!=-1													)
						{
							if( i==sXPath.Length-1 )
								i++;					// Include last caracter

							// handle this XPath part
							node = QueryCreateNode( node, sXPath.Substring( nXpathPartStart, i-nXpathPartStart ) );

							nXpathPartStart = -1;
						}
						else if( sXPath[i]=='\"' )
							bParsingRandomText = !bParsingRandomText;	//  After '"' every character is possible, even '/'
						else if( nXpathPartStart==-1 )
							nXpathPartStart = i;
					}
				}
				else 
				{
					// ERROR (only one node expected)
					Console.WriteLine ("ERROR   Xpath:{0}  returns {1} nodes\n	Change XPath or XML so it returns ony one node", sXPath, list.Count );
				}
			}
			catch(Exception e)
			{	
				Console.WriteLine ("Exception: {0}", e.ToString()); 	
				return null;
			}

			return node;
		}


		// Create the required node for XPath
		protected System.Xml.XmlNode QueryCreateNode( System.Xml.XmlNode node, string sXPathPart )
		{
			if( node==null )
				node = doc;
			Console.WriteLine ("	HANDLE XPathPart) current node={0}    XPath={1}", node.Name, sXPathPart );

			//------------------------------------------------------------------------------------
			// Step 1)	Handle select part
			int	nNodeStart = -1;
			int nAttrStart = -1;
			int nLoc = 0;

			for( ; nLoc<sXPathPart.Length; nLoc++ )
			{
				if( nAttrStart==-1 && nNodeStart==-1 )
				{
					if(sXPathPart[nLoc]=='@')
						nAttrStart = nLoc+1;
					else
						nNodeStart = nLoc;
				}

				if( sXPathPart[nLoc]=='[' || nLoc==sXPathPart.Length-1 )
					break;
			}
			if( nLoc==sXPathPart.Length-1 )
				nLoc++;					// Include last caracter


			if( nNodeStart!=-1 )
			{	
				Console.WriteLine ("		ACTION) query node={0}   with XPath={1}", sXPathPart.Substring(nNodeStart,nLoc-nNodeStart), sXPathPart) ;
	
				// Query child Node
				XmlNodeList NodeList = node.SelectNodes( sXPathPart );
				if( NodeList.Count==1 )
					return  NodeList.Item(0);
				else if( NodeList.Count==0 )
				{
					Console.WriteLine ("		ACTION) create node={0}", sXPathPart.Substring(nNodeStart,nLoc-nNodeStart) );
					node = node.AppendChild( doc.CreateElement( sXPathPart.Substring(nNodeStart,nLoc-nNodeStart) ) );
				}
				else 
					Console.WriteLine ("ERROR   XpathPart:{0}  returns {1} nodes\n	Change XPath or XML so it returns ony one node", sXPathPart, NodeList.Count );
			}
			else if( nAttrStart!=-1 )
			{
				// Get Attribute
				Console.WriteLine ("		ACTION) Query node={0} for  Attribute={1}", node.Name, sXPathPart.Substring(nAttrStart,nLoc-nAttrStart) );
				XmlAttributeCollection  AttrCol = node.Attributes;
				node = AttrCol.GetNamedItem( sXPathPart.Substring(nAttrStart,nLoc-nAttrStart) );
				if( node==null )
				{
					Console.WriteLine ("		ACTION) create attibute={0}", sXPathPart.Substring(nAttrStart,nLoc-nAttrStart) );
					node = AttrCol.SetNamedItem( doc.CreateAttribute( sXPathPart.Substring(nAttrStart,nLoc-nAttrStart) ) );
				}
			}


			//------------------------------------------------------------------------------------
			// Step 2)	Handle filter parts
			int nAttrNameStart = -1;
			int nAttrTextStart = -1;

			for( ; nLoc<sXPathPart.Length; nLoc++ )
			{
				if( sXPathPart[nLoc]=='@' )
					nAttrNameStart = nLoc+1;
				else if( sXPathPart[nLoc]=='\"' )
				{
					if( nAttrTextStart==-1 )
						nAttrTextStart = nLoc+1;
					else
					{
						Console.WriteLine ("		ACTION) query node={0} for attribute={1}", node.Name, sXPathPart.Substring(nAttrNameStart, nAttrTextStart-nAttrNameStart-2 ) );
						XmlNode attrNode = node.Attributes.GetNamedItem( sXPathPart.Substring(nAttrNameStart, nLoc-nAttrNameStart) );
						if( attrNode==null )
						{
							Console.WriteLine ("		ACTION) create attibute={0}", sXPathPart.Substring(nAttrNameStart, nAttrTextStart-nAttrNameStart-2) );
							attrNode = doc.CreateAttribute( sXPathPart.Substring(nAttrNameStart, nAttrTextStart-nAttrNameStart-2) );
							attrNode.Value = sXPathPart.Substring(nAttrTextStart, nLoc-nAttrTextStart);
							node.Attributes.SetNamedItem( attrNode );
						}

						nAttrNameStart = -1;
						nAttrTextStart = -1;
					}
				}
				else if( sXPathPart[nLoc]==']' )
					break;
			}

			return node;
		}
	}
}