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

 * 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;

	}

}