AuthenticatedViewerProvider.java

/**
 *  Copyright 2011 Colin Alworth
 * 
 *  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 com.acme.gwt.server;

import javax.persistence.EntityManager;

import com.acme.gwt.data.TvViewer;
import com.google.inject.Inject;
import com.google.inject.Provider;

/**
 * Stores the current user. Currently it keeps a ref to the user object, but this might cause 
 * issues, in which case it will probably just keep the id, and get the user each time it is asked.
 * 
 * Any other auth logic or tracking can go here as well, and it might be wise to push the login
 * code here too, or at least let this class deal with it, so that something like OpenID can be
 * wired in easily.
 * 
 * As it is now, this MUST be correctly scoped in whatever container it is used in.
 * 
 * @author colin
 *
 */
public class AuthenticatedViewerProvider implements Provider<TvViewer> {
	private Provider<EntityManager> emProvider;

	// instead of this, ask for generic session provider, where the session just holds an ID
	// with which to find the current viewer. Servlet impl will just be session scoped
	private Provider<SessionProvider> session;

	@Inject
	public AuthenticatedViewerProvider(Provider<EntityManager> emp,
			Provider<SessionProvider> sessionProvider) {
		this.emProvider = emp;
		this.session = sessionProvider;
	}

	@Override
	public TvViewer get() {
		return session.get().get() == null ? null : emProvider.get().find(
				TvViewer.class, session.get().get());
	}
	public void setCurrentViewer(TvViewer viewer) {
		session.get().setActiveViewerId(viewer == null ? null : viewer.getId());
	}

	public interface SessionProvider extends Provider<Long> {
		void setActiveViewerId(Long viewerId);
	}
}