/*
 * Copyright 2014-2016 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 sample;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.springframework.session.Session;
import org.springframework.session.SessionRepository;
import org.springframework.session.web.http.HttpSessionManager;

public class UserAccountsFilter implements Filter {

	public void init(FilterConfig filterConfig) throws ServletException {
	}

	@SuppressWarnings("unchecked")
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest httpRequest = (HttpServletRequest) request;

		// tag::HttpSessionManager[]
		HttpSessionManager sessionManager = (HttpSessionManager) httpRequest
				.getAttribute(HttpSessionManager.class.getName());
		// end::HttpSessionManager[]
		SessionRepository<Session> repo = (SessionRepository<Session>) httpRequest
				.getAttribute(SessionRepository.class.getName());

		String currentSessionAlias = sessionManager.getCurrentSessionAlias(httpRequest);
		Map<String, String> sessionIds = sessionManager.getSessionIds(httpRequest);
		String unauthenticatedAlias = null;

		String contextPath = httpRequest.getContextPath();
		List<Account> accounts = new ArrayList<Account>();
		Account currentAccount = null;
		for (Map.Entry<String, String> entry : sessionIds.entrySet()) {
			String alias = entry.getKey();
			String sessionId = entry.getValue();

			Session session = repo.getSession(sessionId);
			if (session == null) {
				continue;
			}

			String username = session.getAttribute("username");
			if (username == null) {
				unauthenticatedAlias = alias;
				continue;
			}

			String logoutUrl = sessionManager.encodeURL("./logout", alias);
			String switchAccountUrl = sessionManager.encodeURL("./", alias);
			Account account = new Account(username, logoutUrl, switchAccountUrl);
			if (currentSessionAlias.equals(alias)) {
				currentAccount = account;
			}
			else {
				accounts.add(account);
			}
		}

		// tag::addAccountUrl[]
		String addAlias = unauthenticatedAlias == null ? // <1>
				sessionManager.getNewSessionAlias(httpRequest)
				: // <2>
				unauthenticatedAlias; // <3>
		String addAccountUrl = sessionManager.encodeURL(contextPath, addAlias); // <4>
		// end::addAccountUrl[]

		httpRequest.setAttribute("currentAccount", currentAccount);
		httpRequest.setAttribute("addAccountUrl", addAccountUrl);
		httpRequest.setAttribute("accounts", accounts);

		chain.doFilter(request, response);
	}

	public void destroy() {
	}

}
