CurrentUser.java

package util.security;

import static util.security.SessionParameters.LOCALE;
import static util.security.SessionParameters.USERNAME;

import java.util.Locale;
import java.util.UUID;

import models.User;

import org.apache.commons.lang3.LocaleUtils;

import play.cache.Cache;
import play.i18n.Lang;
import play.libs.F.Option;
import play.mvc.Http.Context;
import play.mvc.Http.Session;
import services.UserService;

public final class CurrentUser {

	private static final String SESSION_KEY = "SESSION_ID";

	private CurrentUser() {
		throw new AssertionError();
	}

	// --- USER ---

	public static boolean isAuthenticated() {
		return getCurrentSession().isDefined()
				&& (getSessionParameter(USERNAME) != null);
	}

	public static void setUser(User user) {
		setSessionParameter(USERNAME, user.username);
		Cache.set(USERNAME.getKey(), user);
		if (user.preferredLocale != null) {
			setPreferredLocale(user.preferredLocale);
		}
	}

	public static Option<User> currentUser() {
		if (!isAuthenticated()) {
			return Option.None();
		}

		// Fetch current user.
		Option<User> optUser;
		User user = (User) Cache.get(USERNAME.getKey());
		if (user == null) {
			optUser = UserService.findByUsername(getSessionParameter(USERNAME));
			if (optUser.isDefined()) {
				Cache.set(USERNAME.getKey(), optUser.get());
			}
		} else {
			optUser = Option.Some(user);
		}

		// If current user was not found, session cookie might be outdated.
		// Clear session.
		if (!optUser.isDefined()) {
			logout();
		}

		return optUser;
	}

	// --- LOCALE ---

	public static void setPreferredLocale(Locale locale) {
		if (locale == null) {
			removeSessionParameter(LOCALE);
		} else {
			setSessionParameter(LOCALE, locale.toString());
			Context.current().changeLang(locale.getLanguage());
		}
	}

	public static Option<Locale> preferredLocale() {
		Locale locale = null;
		if (isAuthenticated() && currentUser().isDefined()) {
			User user = currentUser().get();
			locale = user.preferredLocale;
		}
		if ((locale == null) && sessionContainsParameter(LOCALE)) {
			locale = LocaleUtils.toLocale(getSessionParameter(LOCALE));
		}
		if ((locale == null) && (Context.current != null)) {
			locale = Context.current().lang().toLocale();
		}
		return Option.Some(locale);
	}

	public static Option<Lang> preferredLang() {
		if (preferredLocale().isDefined()) {
			return Option.Some(new Lang(new play.api.i18n.Lang(
					preferredLocale().get().getLanguage(), preferredLocale()
							.get().getCountry())));
		}
		return Option.None();
	}

	// --- UTIL ---

	public static void logout() {
		if (getCurrentSession().isDefined()) {
			Session session = getCurrentSession().get();
			if (isAuthenticated()) {
				removeSessionParameter(USERNAME);
			}
			session.clear();
		}
		Cache.remove(USERNAME.getKey());
	}

	static String sessionId() {
		if (!getCurrentSession().isDefined()) {
			return null;
		}
		if (getCurrentSession().get().containsKey(SESSION_KEY)) {
			return getCurrentSession().get().get(SESSION_KEY);
		}

		// Create new session.
		getCurrentSession().get().clear();
		String sessionId = UUID.randomUUID().toString();
		getCurrentSession().get().put(SESSION_KEY, sessionId);
		return sessionId();
	}

	private static String getSessionParameter(SessionParameters parameter) {
		return getCurrentSession().isDefined() ? getCurrentSession().get().get(
				parameter.getKey()) : null;
	}

	private static void setSessionParameter(SessionParameters parameter,
			String value) {
		if (getCurrentSession().isDefined()) {
			getCurrentSession().get().put(parameter.getKey(), value);
		}
	}

	private static void removeSessionParameter(SessionParameters parameter) {
		if (getCurrentSession().isDefined()) {
			getCurrentSession().get().remove(parameter.getKey());
		}
	}

	private static boolean sessionContainsParameter(SessionParameters parameter) {
		return getCurrentSession().isDefined() ? getCurrentSession().get()
				.containsKey(parameter.getKey()) : false;
	}

	private static Option<Session> getCurrentSession() {
		return Context.current.get() == null ? Option.<Session> None() : Option
				.Some(Context.current().session());
	}

}