/* ================================================================

  * Cewolf : Chart enabling Web Objects Framework

  * ================================================================

  *

  * Project Info:  http://cewolf.sourceforge.net

  * Project Lead:  Guido Laures (guido@laures.de);

  *

  * (C) Copyright 2002, by Guido Laures

  *

  * 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 de.laures.cewolf;

 import java.util.Enumeration;

 import java.util.HashMap;

 import java.util.Map;

 import javax.servlet.ServletConfig;

 import javax.servlet.ServletContext;

 /**

  * This class represents the configuration of the Cewolf framework.

  * It is designed as singleton and resists in application context.

  * @author glaures

  * @since 0.8

  */

 public class Configuration {

 	public static final String KEY = Configuration.class.getName();

 	private static final String DEFAULT_OVERLIB_URL = "overlib.js";

 	private static final String DEFAULT_STORAGE = "de.laures.cewolf.storage.TransientSessionStorage";

 	private String overlibURL = DEFAULT_OVERLIB_URL;

 	private boolean debugged = false;

 	private String storageClassName = DEFAULT_STORAGE;

 	private Storage storage = null;

 	private Map parameters = new HashMap();

 	/** package protected constructor triggered by servlet */

 	protected Configuration(ServletContext ctx) {

         ctx.log("configuring cewolf app..");

         ctx.setAttribute(KEY, this);

         //retrieve the init config params

         ServletConfig config = (ServletConfig) ctx.getAttribute(CewolfRenderer.INIT_CONFIG);

         if (config != null)

         {

             Enumeration initParams = config.getInitParameterNames();

             try {

                 while (initParams.hasMoreElements()) {

                     String param = (String) initParams.nextElement();

                     String value = config.getInitParameter(param);

                     if ("debug".equalsIgnoreCase(param)) {

                         debugged = Boolean.valueOf(value).booleanValue();

                     } else if ("overliburl".equalsIgnoreCase(param)) {

                         overlibURL = value;

                     } else if ("storage".equalsIgnoreCase(param)) {

                         storageClassName = value;

                     } else {

                         ctx.log(param + " parameter is ignored.");

                     }

                     parameters.put(param,value);

                 }

             } catch (Throwable t) {

                 ctx.log("Error in Cewolf config.", t);

             }            

         }

         else {

         	ctx.log("Cewolf Misconfiguration. You should add a <load-on-startup> tag "

         			+ "to your web.xml for the Cewolf rendering servlet.\n"

 					+ "A default Configuration will be used if not.");

         }

 		try {

 			initStorage(ctx);

 		} catch (CewolfException ex) {

 			ctx.log("exception during storage init from class " + storageClassName);

 			ctx.log("using " + DEFAULT_STORAGE);

 			storageClassName = DEFAULT_STORAGE;

 			try {

 				initStorage(ctx);

 			} catch(CewolfException cwex){

 				cwex.printStackTrace();

 				throw new RuntimeException(storageClassName + ".init() threw exception.");

 			}

 		}

 		ctx.log("using storage class " + storageClassName);

 		ctx.log("using overlibURL " + overlibURL);

 		ctx.log("debugging is turned " + (debugged ? "on" : "off"));

 		ctx.log("...done.");

 	}

 	private void initStorage(ServletContext ctx) throws CewolfException {

 		try {

 			storage = (Storage)Class.forName(storageClassName).newInstance();

 		} catch(Exception ex){

 			ex.printStackTrace();

 			throw new CewolfException(ex.getMessage());

 		}

 		storage.init(ctx);

 	}

 	private Configuration() {

 	}

 	/**

 	 * Factory method. If no Configuration had been initialized before, a new

 	 * one is created, stored in ctx and returned to the caller.

 	 * @param ctx the servlet context from where to retrieve the Configuration

 	 * object.

 	 * @return the config object

 	 */

 	public static Configuration getInstance(ServletContext ctx) {

 		Configuration config = null;

         config = (Configuration) ctx.getAttribute(KEY);

         if (config == null)

         {

             ctx.log("No Configuration for this context.  Initializing.");

             config = new Configuration(ctx);

             ctx.setAttribute(KEY, config);

         }

 		return config;

 	}

 	/**

 	 * Checks if debugging is configured to be turned on. Configured by

 	 * init param <code>debug</code> in web.xml.

 	 * @return <code>true</code> if a debugging is on, else <code>false</false>

 	 */

 	public boolean isDebugged() {

 		return debugged;

 	}

 	/**

 	 * Returns the location of the overlib.js relative to webapp's root.

 	 * Configured by init param <code>overliburl</code> in web.xml. Defaults to

 	 * <code>overlib.js</code>

 	 * @return String

 	 */

 	public String getOverlibURL() {

 		return overlibURL;

 	}

 	public Storage getStorage() {

 		return storage;

 	}

 	/**

 	 * Get the initialization parameters from Cewolf servlet.

 	 * @return The parameter map (String->String) values

 	 */

 	public Map getParameters() {

 		return parameters;

 	}

 }