/*
 * Copyright 1999-2001,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.struts.webapp.example;


import java.util.Locale;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import org.apache.struts.util.MessageResources;
import org.apache.struts.util.ModuleException;
import org.apache.commons.beanutils.PropertyUtils;


/**
 * Implementation of <strong>Action</strong> that validates a user logon.
 *
 * @author Craig R. McClanahan
 * @version $Rev: 54936 $ $Date: 2004-10-16 18:57:09 +0100 (Sat, 16 Oct 2004) $
 */

public final class LogonAction extends Action {


    // ----------------------------------------------------- Instance Variables


    /**
     * The <code>Log</code> instance for this application.
     */
    private Log log =
        LogFactory.getLog("org.apache.struts.webapp.Example");


    // --------------------------------------------------------- Public Methods


    /**
     * Process the specified HTTP request, and create the corresponding HTTP
     * response (or forward to another web component that will create it).
     * Return an <code>ActionForward</code> instance describing where and how
     * control should be forwarded, or <code>null</code> if the response has
     * already been completed.
     *
     * @param mapping The ActionMapping used to select this instance
     * @param form The optional ActionForm bean for this request (if any)
     * @param request The HTTP request we are processing
     * @param response The HTTP response we are creating
     *
     * @exception Exception if business logic throws an exception
     */
    public ActionForward execute(ActionMapping mapping,
				 ActionForm form,
				 HttpServletRequest request,
				 HttpServletResponse response)
	throws Exception {

	// Extract attributes we will need
	Locale locale = getLocale(request);
	MessageResources messages = getResources(request);
	User user = null;

	// Validate the request parameters specified by the user
	ActionErrors errors = new ActionErrors();
	String username = (String)
            PropertyUtils.getSimpleProperty(form, "username");
        String password = (String)
            PropertyUtils.getSimpleProperty(form, "password");
	UserDatabase database = (UserDatabase)
	  servlet.getServletContext().getAttribute(Constants.DATABASE_KEY);
	if (database == null)
            errors.add(ActionErrors.GLOBAL_ERROR,
                       new ActionError("error.database.missing"));
	else {
	    user = getUser(database, username);
	    if ((user != null) && !user.getPassword().equals(password))
		user = null;
	    if (user == null)
                errors.add(ActionErrors.GLOBAL_ERROR,
                           new ActionError("error.password.mismatch"));
	}

	// Report any errors we have discovered back to the original form
	if (!errors.isEmpty()) {
	    saveErrors(request, errors);
            return (mapping.getInputForward());
	}

	// Save our logged-in user in the session
	HttpSession session = request.getSession();
	session.setAttribute(Constants.USER_KEY, user);
        if (log.isDebugEnabled()) {
            log.debug("LogonAction: User '" + user.getUsername() +
                      "' logged on in session " + session.getId());
        }

        // Remove the obsolete form bean
	if (mapping.getAttribute() != null) {
            if ("request".equals(mapping.getScope()))
                request.removeAttribute(mapping.getAttribute());
            else
                session.removeAttribute(mapping.getAttribute());
        }

	// Forward control to the specified success URI
	return (mapping.findForward("success"));

    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Look up the user, throwing an exception to simulate business logic
     * rule exceptions.
     *
     * @param database Database in which to look up the user
     * @param username Username specified on the logon form
     *
     * @exception AppException if a business logic rule is violated
     */
    public User getUser(UserDatabase database, String username)
        throws ModuleException {

        // Force an ArithmeticException which can be handled explicitly
        if ("arithmetic".equals(username)) {
            throw new ArithmeticException();
        }

        // Force an application-specific exception which can be handled
        if ("expired".equals(username)) {
            throw new ExpiredPasswordException(username);
        }

        // Look up and return the specified user
        return ((User) database.findUser(username));

    }


}
