/*
    * $Header: /cvsroot/jdbforms/dbforms/src/org/dbforms/dom/AbstractDOMFactoryImpl.java,v 1.1 2005/12/02 12:35:47 hkollmann Exp $
    * $Revision: 1.1 $
    * $Date: 2005/12/02 12:35:47 $
    *
    * DbForms - a Rapid Application Development Framework
    * Copyright (C) 2001 Joachim Peer <joepeer@excite.com>
    *
    * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   */
  
  package org.dbforms.dom;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.dbforms.interfaces.IDOMFactory;
  
  import org.dbforms.util.Util;
  
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.xpath.XPathEvaluator;
  
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  import java.net.URL;
  import java.net.URLConnection;
  
  /***
   * abstract class to hide the implemtation details of the various dom
   * implementations.
   * 
   * @author Henner Kollmann
   */
  public abstract class AbstractDOMFactoryImpl implements IDOMFactory {
  
  	private Log logCat = LogFactory.getLog(this.getClass().getName());
  
  	/***
  	 * Creates a string representation of the given DOMDocument
  	 * 
  	 * @param doc
  	 *            The document to transform
  	 * 
  	 * @return string representation
  	 */
  	public abstract String DOM2String(Document doc);
  
  	/***
  	 * Creates an new DOMDocument from the given string
  	 * 
  	 * @param data
  	 *            the string to parse
  	 * 
  	 * @return The new DOMDocument
  	 */
  	public abstract Document String2DOM(String data);
  
  	/***
  	 * Creates a new empty DOMDocument
  	 * 
  	 * @return An empty DOMDocument
  	 */
  	public abstract Document newDOMDocument();
  
  	/***
  	 * Reads a DOMDocument from given InputStream
  	 * 
  	 * @param in
  	 *            The InputStream to read
  	 * 
  	 * @return The new parsed DOMDocument
  	 */
  	public abstract Document read(InputStream in);
  
  	/***
  	 * Reads a DOMDocument from given url
  	 * 
  	 * @param url
  	 *            the url to read from
  	 * 
  	 * @return The new parsed DOMDocument
 	 */
 	public Document read(String url) {
 		Document doc = null;
 
 		if (!Util.isNull(url)) {
 			InputStream in = null;
 			String path = null;
 			URL u = null;
 
 			try {
 				u = new URL(url);
 				path = u.getPath();
 			} catch (Exception e) {
 				path = url;
 			}
 
 			if (u != null) {
 				try {
 					// Try to parse via URL connection
 					URLConnection con = u.openConnection();
 					con.connect();
 					in = con.getInputStream();
 				} catch (Exception e) {
 					logCat.error("read", e);
 				}
 			}
 
 			if (in == null) {
 				try {
 					in = new FileInputStream(path);
 				} catch (Exception e) {
 					logCat.error("read", e);
 				}
 			}
 
 			if (in != null) {
 				doc = read(in);
 
 				try {
 					in.close();
 				} catch (Exception e) {
 					logCat.error("read", e);
 				}
 			}
 		}
 
 		return doc;
 	}
 
 	/***
 	 * Writes a DOMElement into an OutputStream
 	 * 
 	 * @param out
 	 *            OutputStream to write into
 	 * @param root
 	 *            root element to start writing
 	 */
 	public abstract void write(OutputStream out, Element root)
 			throws IOException;
 
 	/***
 	 * Writes a DOMDocument into an OutputStream
 	 * 
 	 * @param out
 	 *            OutputStream to write into
 	 * @param doc
 	 *            doc to write
 	 */
 	public final void write(OutputStream out, Document doc) throws IOException {
 		write(out, doc.getDocumentElement());
 	}
 
 	/***
 	 * Writes an DOMDocument into a file
 	 * 
 	 * @param url
 	 *            The url to write to
 	 * @param doc
 	 *            The document to write
 	 */
 	public final void write(String url, Document doc) throws IOException {
 		write(url, doc.getDocumentElement());
 	}
 
 	/***
 	 * Writes an DOMElement into a file
 	 * 
 	 * @param url
 	 *            The url to write to
 	 * @param root
 	 *            root element to start writing
 	 */
 	public final void write(String url, Element root) throws IOException {
 		if (!Util.isNull(url) && (root != null)) {
 			OutputStream out = null;
 
 			try {
 				URL u = new URL(url);
 				URLConnection con = u.openConnection();
 				con.connect();
 				out = con.getOutputStream();
 			} catch (Exception e) {
 				logCat.error("write", e);
 			}
 
 			if (out == null) {
 				try {
 					out = new FileOutputStream(url);
 				} catch (Exception e) {
 					logCat.error("write", e);
 				}
 			}
 
 			if (out != null) {
 				write(out, root);
 				out.close();
 			} else {
 				throw new IOException("no target found to wich we can write");
 			}
 		}
 	}
 
 	/***
 	 * returns an new created XPathEvaluator
 	 * 
 	 * @return the new XPathEvaluator
 	 */
 	public abstract XPathEvaluator newXPathEvaluator();
 
 }