/*
 * The contents of this file are subject to the Mozilla Public License Version 1.1
 * (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.mozilla.org/MPL/>.
 * 
 * Software distributed under the License is distributed on an "AS IS" basis, WITHOUT
 * WARRANTY OF ANY KIND, either express or implied. See the License for the specific
 * language governing rights and limitations under the License.
 * 
 * The Original Code is the Venice Web Communities System.
 * 
 * The Initial Developer of the Original Code is Eric J. Bowersox <erbo@silcom.com>,
 * for Silverwrist Design Studios.  Portions created by Eric J. Bowersox are
 * Copyright (C) 2001 Eric J. Bowersox/Silverwrist Design Studios.  All Rights Reserved.
 * 
 * Contributor(s): 
 */
package com.silverwrist.venice.servlets.format;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.parsers.*;
import org.apache.log4j.*;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import com.silverwrist.util.DOMElementHelper;
import com.silverwrist.util.StringUtil;
import com.silverwrist.venice.core.ConfigException;
import com.silverwrist.venice.core.UserContext;
import com.silverwrist.venice.servlets.Variables;

public class RenderConfig
{
  /*--------------------------------------------------------------------------------
   * Static data values
   *--------------------------------------------------------------------------------
   */

  protected static final String ATTR_NAME = "com.silverwrist.venice.servlets.RenderConfig";
  protected static final String CONFIG_FILE_PARAM = "render.config";

  private static Category logger = Category.getInstance(RenderConfig.class.getName());

  /*--------------------------------------------------------------------------------
   * Attributes
   *--------------------------------------------------------------------------------
   */

  private Document config;
  private String site_title;
  private boolean want_comments;
  private boolean allow_gzip;
  private String font_face;
  private String image_url;
  private String static_url;
  private String site_logo;
  private Hashtable stock_messages;

  /*--------------------------------------------------------------------------------
   * Constructor
   *--------------------------------------------------------------------------------
   */

  protected RenderConfig(String config_file) throws ConfigException
  {
    config = loadConfiguration(config_file);

    // Make sure the configuration is valid...
    Element root = config.getDocumentElement();
    if (!(root.getTagName().equals("render-config")))
    { // not the correct root tag name
      logger.fatal("config document is not a <render-config/> document (root tag: <"
		   + root.getTagName() + "/>)");
      throw new ConfigException("document is not a <render-config/> document",root);

    } // end if

    // Get the site name.
    DOMElementHelper root_h = new DOMElementHelper(root);
    site_title = root_h.getSubElementText("site-name");
    if (site_title==null)
    { // no <site-name/> section - bail out now!
      logger.fatal("config document has no <site-title/> element");
      throw new ConfigException("no <site-title/> section found in config file",root);

    } // end if

    if (logger.isDebugEnabled())
      logger.debug("Site title: " + site_title);

    Element render_sect = root_h.getSubElement("rendering");
    if (render_sect==null)
    { // no <rendering/> section - bail out now!
      logger.fatal("config document has no <rendering/> section");
      throw new ConfigException("no <rendering/> section found in config file",root);

    } // end if

    DOMElementHelper render_sect_h = new DOMElementHelper(render_sect);
    want_comments = render_sect_h.hasChildElement("html-comments");
    allow_gzip = render_sect_h.hasChildElement("gzip-output");
    if (logger.isDebugEnabled())
    { // log the read values
      logger.debug("Use HTML comments: " + String.valueOf(want_comments));
      logger.debug("Use GZIP encoding: " + String.valueOf(allow_gzip));

    } // end if

    font_face = render_sect_h.getSubElementText("font");
    if (font_face==null)
    { // no <font/> tag - bail out now!
      logger.fatal("<rendering/> section has no <font/> element");
      throw new ConfigException("no <font/> found in <rendering/> section",render_sect);

    } // end if

    if (logger.isDebugEnabled())
      logger.debug("Font face: " + font_face);

    Element paths_sect = root_h.getSubElement("paths");
    if (paths_sect==null)
    { // no <paths/> section - bail out now!
      logger.fatal("config document has no <paths/> section");
      throw new ConfigException("no <paths/> section found in config file",root);

    } // end if

    DOMElementHelper paths_sect_h = new DOMElementHelper(paths_sect);
    image_url = paths_sect_h.getSubElementText("image");
    if (image_url==null)
    { // no <image/> tag - bail out now!
      logger.fatal("<paths/> section has no <image/> element");
      throw new ConfigException("no <image/> found in <paths/> section",paths_sect);

    } // end if

    if (logger.isDebugEnabled())
      logger.debug("Image path: " + image_url);

    static_url = paths_sect_h.getSubElementText("static");
    if (static_url==null)
    { // no <static/> tag - bail out now!
      logger.fatal("<paths/> section has no <static/> element");
      throw new ConfigException("no <static/> found in <paths/> section",paths_sect);

    } // end if

    if (logger.isDebugEnabled())
      logger.debug("Static files path: " + static_url);

    site_logo = paths_sect_h.getSubElementText("site-logo");
    if (site_logo==null)
    { // no <image/> tag - bail out now!
      logger.fatal("<paths/> section has no <site-logo/> element");
      throw new ConfigException("no <site-logo/> found in <paths/> section",paths_sect);

    } // end if

    if (logger.isDebugEnabled())
      logger.debug("Site logo: " + image_url);

    Element msg_sect = root_h.getSubElement("messages");
    if (msg_sect==null)
    { // no <messages/> section - bail out now!
      logger.fatal("config document has no <messages/> section");
      throw new ConfigException("no <messages/> section found in config file",root);

    } // end if

    // Initialize the stock messages list.
    stock_messages = new Hashtable();
    NodeList msg_nodes = msg_sect.getChildNodes();
    for (int i=0; i<msg_nodes.getLength(); i++)
    { // examine all subnodes to add them to the message text
      Node msgn = msg_nodes.item(i);
      if (msgn.getNodeType()==Node.ELEMENT_NODE)
      { // add it to the hash table by its tag name
	Element msgel = (Element)msgn;
	DOMElementHelper h = new DOMElementHelper(msgel);
	String txt = h.getElementText();
	if (txt!=null)
	  stock_messages.put(msgel.getTagName(),txt.trim());

      } // end if

    } // end for

    if (logger.isDebugEnabled())
      logger.debug(stock_messages.size() + " stock messages loaded from config");

  } // end constructor

  /*--------------------------------------------------------------------------------
   * Internal functions
   *--------------------------------------------------------------------------------
   */

  private static Document loadConfiguration(String configname) throws ConfigException
  {
    try
    { // create a simple DOM parser by using the Java XML parsing API
      DocumentBuilderFactory fac = DocumentBuilderFactory.newInstance();
      fac.setNamespaceAware(false);
      fac.setValidating(false);
      DocumentBuilder parser = fac.newDocumentBuilder();

      // access the config file and parse it into our config data tree
      File configfile = new File(configname);
      Document rc = parser.parse(configfile);
      if (logger.isDebugEnabled())
	logger.debug("configuration loaded successfully");
      return rc;

    } // end try
    catch (FactoryConfigurationError e1)
    { // if the document builder factory could not be created
      logger.fatal("Parser factory configuration error: " + e1.getMessage(),e1);
      throw new ConfigException("XML parser factory could not be created - " + e1.getMessage());

    } // end catch
    catch (ParserConfigurationException e2)
    { // if the XML parser itself could not be created
      logger.fatal("Parser configuration error: " + e2.getMessage(),e2);
      throw new ConfigException("XML parser could not be created - " + e2.getMessage(),e2);

    } // end catch
    catch (SAXException e3)
    { // if the XML parser choked on our document
      if (e3 instanceof SAXParseException)
      { // we have a detailed message - make a proper exception
	SAXParseException e3a = (SAXParseException)e3;
	logger.fatal("Config file error [" + configname + ":" + e3a.getLineNumber() + ","
		     + e3a.getColumnNumber() + "]: " + e3a.getMessage(),e3a);
	throw new ConfigException("Configuration file error: " + e3a.getMessage() + " at line "
				  + e3a.getLineNumber() + ", column " + e3a.getColumnNumber(),e3a);

      } // end if
      else
      { // generic exception - just send up a simple error message
	logger.fatal("Config file error [" + configname + "]: " + e3.getMessage(),e3);
	throw new ConfigException("Configuration file error - " + e3.getMessage(),e3);

      } // end else

    } // end catch
    catch (IOException e4)
    { // error reading the config file itself off the disk
      logger.fatal("IO error reading config: " + e4.getMessage(),e4);
      throw new ConfigException("unable to read config file \"" + configname + "\" - " + e4.getMessage(),e4);

    } // end catch

  } // end loadConfiguration

  /*--------------------------------------------------------------------------------
   * External operations usable only by RenderData
   *--------------------------------------------------------------------------------
   */

  boolean useHTMLComments()
  {
    return want_comments;

  } // end useHTMLComments

  boolean isGZIPAllowed()
  {
    return allow_gzip;

  } // end isGZIPAllowed

  String getFullImagePath(String name)
  {
    StringBuffer buf = new StringBuffer();
    buf.append(image_url).append(name);
    return buf.toString();

  } // end getFullImagePath

  String getStaticFilePath(String name)
  {
    StringBuffer buf = new StringBuffer();
    buf.append(static_url).append(name);
    return buf.toString();

  } // end getStaticFilePath

  String getTitleTag(String specific)
  {
    StringBuffer buf = new StringBuffer();
    buf.append("<TITLE>").append(specific).append(" - ").append(site_title).append("</TITLE>");
    return buf.toString();

  } // end getTitleTag

  String getSiteImageTag(int hspace, int vspace)
  {
    StringBuffer buf = new StringBuffer();
    buf.append("<IMG SRC=\"").append(site_logo).append("\" ALT=\"").append(site_title);
    buf.append("\" WIDTH=140 HEIGHT=80 BORDER=0");
    if (hspace>0)
      buf.append(" HSPACE=").append(hspace);
    if (vspace>0)
      buf.append(" VSPACE=").append(vspace);
    buf.append('>');
    return buf.toString();

  } // end getSiteImageTag

  String getStdFontTag(String color, int size)
  {
    StringBuffer buf = new StringBuffer("<FONT FACE=\"");
    buf.append(font_face).append("\" SIZE=").append(size);
    if (color!=null)
      buf.append(" COLOR=\"").append(color).append("\"");
    buf.append('>');
    return buf.toString();

  } // end getStdFontTag

  String getStdBaseFontTag(int size)
  {
    StringBuffer buf = new StringBuffer("<BASEFONT FACE=\"");
    buf.append(font_face).append("\" SIZE=").append(size).append('>');
    return buf.toString();

  } // end getStdBaseFontTag

  public String getRequiredBullet()
  {
    StringBuffer buf = new StringBuffer("<FONT FACE=\"");
    buf.append(font_face).append("\" COLOR=\"red\">*</FONT>");
    return buf.toString();

  } // end getRequiredBullet

  void writeFooter(Writer out) throws IOException
  {
    out.write("<HR WIDTH=\"80%\">\n<TABLE ALIGN=CENTER BORDER=0 CELLPADDING=0 CELLSPACING=6><TR VALIGN=TOP>"
	      + "\n<TD ALIGN=RIGHT>\n");
    out.write(getStdFontTag(null,1));
    out.write(getStockMessage("footer-text"));
    out.write("</FONT>\n</TD>\n<TD ALIGN=LEFT>\n<A HREF=\"http://venice.sourceforge.net\" TARGET=\"_blank\">"
	      + "<IMG SRC=\"");
    out.write(getFullImagePath("powered-by-venice.gif"));
    out.write("\" ALT=\"Powered by Venice\" WIDTH=140 HEIGHT=80 BORDER=0 HSPACE=0 VSPACE=0></A>\n</TD>\n"
	      + "</TR></TABLE>\n");

  } // end writeFooter

  void writeContentHeader(Writer out, String primary, String secondary) throws IOException
  {
    out.write(getStdFontTag("#3333AA",5) + "<B>" + StringUtil.encodeHTML(primary) + "</B></FONT>");
    if (secondary!=null)
      out.write("&nbsp;&nbsp;" + getStdFontTag("#3333AA",3) + "<B>" + StringUtil.encodeHTML(secondary)
		+ "</B></FONT>");
    out.write("<HR ALIGN=LEFT SIZE=2 WIDTH=\"90%\" NOSHADE>\n");

  } // end writeContentHeader

  String getStockMessage(String identifier)
  {
    return (String)(stock_messages.get(identifier));

  } // end getStockMessage

  void writeStockMessage(Writer out, String identifier) throws IOException
  {
    String text = (String)(stock_messages.get(identifier));
    out.write(StringUtil.encodeHTML(text));

  } // end writeStockMessage

  /*--------------------------------------------------------------------------------
   * Static operations for use by VeniceServlet
   *--------------------------------------------------------------------------------
   */

  public static RenderConfig getRenderConfig(ServletContext ctxt) throws ServletException
  {
    // Look in the servlet attributes first.
    Object obj = ctxt.getAttribute(ATTR_NAME);
    if (obj!=null)
      return (RenderConfig)obj;

    // Get the parameter for the renderer's config file.
    String cfgfile = ctxt.getInitParameter(CONFIG_FILE_PARAM);
    logger.info("Initializing Venice rendering using config file: " + cfgfile);
    
    try
    { // create the RenderConfig object and save it to attributes.
      RenderConfig rconf = new RenderConfig(cfgfile);
      ctxt.setAttribute(ATTR_NAME,rconf);
      return rconf;

    } // end try
    catch (ConfigException e)
    { // configuration failed!  post an error message
      logger.fatal("Rendering configuration failed: " + e.getMessage(),e);
      throw new ServletException("Venice rendering configuration failed: " + e.getMessage(),e);

    } // end catch

  } // end getRenderConfig

  public static RenderData createRenderData(ServletContext ctxt, HttpServletRequest request,
					    HttpServletResponse response) throws ServletException
  {
    UserContext uc = Variables.getUserContext(ctxt,request,request.getSession(true));
    return new RenderData(getRenderConfig(ctxt),uc,request,response);

  } // end createRenderData

  public static RenderData createRenderData(ServletContext ctxt, UserContext uc, HttpServletRequest request,
					    HttpServletResponse response) throws ServletException
  {
    return new RenderData(getRenderConfig(ctxt),uc,request,response);

  } // end createRenderData

} // end class RenderConfig