/*
 * Copyright 2005 the original author or authors.
 * 
 * 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.wamblee.security.tapestry;

import java.security.AccessController;

import javax.security.auth.Subject;

import org.apache.log4j.Logger;
import org.apache.tapestry.event.PageEvent;
import org.apache.tapestry.event.PageValidateListener;
import org.apache.tapestry.html.BasePage;
import org.wamblee.general.BeanFactory;
import org.wamblee.general.BeanKernel;
import org.wamblee.security.authorization.AuthorizationService;
import org.wamblee.security.authorization.ReadOperation;

/**
 * Base class for pages that require a user to be authenticated for the 
 * page to be viewed. 
 */
public class ProtectedPage extends BasePage implements PageValidateListener {
    
    private static final Logger LOGGER = Logger.getLogger(ProtectedPage.class);
    
    private AuthorizationService _service; 
    
    /**
     * Validates if a user is authenticated. 
     */
	public void pageValidate(PageEvent aPageEvent) {
        Subject subject =  Subject.getSubject(AccessController.getContext()); 
        if ( subject == null ) {   
            throw new RuntimeException("User not logged in, security not configured correctly, or there is a programming error.");
		} 
        BeanFactory factory = BeanKernel.getBeanFactory(); 
        
        // Check whether we have access to the current page. 
        _service = factory.find(AuthorizationService.class); 
        if ( !_service.isAllowed(this, new ReadOperation())) { 
            throw new RuntimeException("Access denied to '" + getPageName() + "' for '" + subject + "'");
        }
	}
}