Session Management

public interface Session extends Attributes {
    // Session identification
    String getId();
    Context getContext();
    
    // Timing information
    long getCreationTime();
    long getLastAccessedTime();
    
    // Session lifecycle
    void setMaxInactiveInterval(int interval);
    int getMaxInactiveInterval();
    void invalidate();
    boolean isNew();
    boolean isValid();
    
    // Attribute management (from Attributes interface)
    Object getAttribute(String name);
    void setAttribute(String name, Object value);
    void removeAttribute(String name);
    Set<String> getAttributeNameSet();
    void clearAttributes();
}

public class SessionDemoHandler extends Handler.Abstract {
    
    @Override
    public boolean handle(Request request, Response response, Callback callback) 
            throws Exception {
        
        // Get existing session or create new one
        Session session = request.getSession(true);
        
        // Check if this is a new session
        if (session.isNew()) {
            System.out.println("New session created: " + session.getId());
            session.setAttribute("createdAt", Instant.now());
        }
        
        // Update visit count
        Integer visitCount = (Integer) session.getAttribute("visitCount");
        if (visitCount == null) {
            visitCount = 0;
        }
        visitCount++;
        session.setAttribute("visitCount", visitCount);
        
        // Update last visit time
        session.setAttribute("lastVisit", Instant.now());
        
        // Set session timeout (30 minutes)
        session.setMaxInactiveInterval(30 * 60);
        
        // Generate response with session info
        response.setStatus(200);
        response.getHeaders().put("Content-Type", "application/json");
        
        String json = createSessionInfoJson(session);
        response.write(true, ByteBuffer.wrap(json.getBytes()), callback);
        
        return true;
    }
    
    private String createSessionInfoJson(Session session) {
        Map<String, Object> sessionInfo = new HashMap<>();
        sessionInfo.put("sessionId", session.getId());
        sessionInfo.put("isNew", session.isNew());
        sessionInfo.put("creationTime", session.getCreationTime());
        sessionInfo.put("lastAccessedTime", session.getLastAccessedTime());
        sessionInfo.put("maxInactiveInterval", session.getMaxInactiveInterval());
        
        // Add session attributes
        Map<String, Object> attributes = new HashMap<>();
        for (String name : session.getAttributeNameSet()) {
            Object value = session.getAttribute(name);
            if (value instanceof Serializable) {
                attributes.put(name, value.toString());
            }
        }
        sessionInfo.put("attributes", attributes);
        
        // Convert to JSON (simplified)
        return toJson(sessionInfo);
    }
    
    private String toJson(Map<String, Object> map) {
        // Simplified JSON conversion
        StringBuilder json = new StringBuilder("{");
        boolean first = true;
        for (Map.Entry<String, Object> entry : map.entrySet()) {
            if (!first) json.append(",");
            json.append("\"").append(entry.getKey()).append("\":");
            json.append("\"").append(entry.getValue()).append("\"");
            first = false;
        }
        json.append("}");
        return json.toString();
    }
}

public class SessionHandler extends Handler.Wrapper {
    // Session configuration
    public SessionCache getSessionCache();
    public void setSessionCache(SessionCache sessionCache);
    public SessionDataStore getSessionDataStore();
    public void setSessionDataStore(SessionDataStore sessionDataStore);
    
    // Session ID configuration
    public SessionIdManager getSessionIdManager();
    public void setSessionIdManager(SessionIdManager sessionIdManager);
    
    // Cookie configuration
    public SessionCookieConfig getSessionCookieConfig();
    public void setSessionCookieConfig(SessionCookieConfig config);
    
    // Timeout configuration
    public int getMaxInactiveInterval();
    public void setMaxInactiveInterval(int maxInactiveInterval);
    
    // Session tracking modes
    public Set<SessionTrackingMode> getEffectiveSessionTrackingModes();
    public void setSessionTrackingModes(Set<SessionTrackingMode> sessionTrackingModes);
    
    // Session lifecycle
    public Session newSession(Request request);
    public void complete(Session session);
}

public class SessionConfiguration {
    
    public void configureSession(Server server) {
        // Create session handler
        SessionHandler sessionHandler = new SessionHandler();
        
        // Configure session timeout (30 minutes)
        sessionHandler.setMaxInactiveInterval(30 * 60);
        
        // Configure session cookie
        SessionCookieConfig cookieConfig = sessionHandler.getSessionCookieConfig();
        cookieConfig.setName("JSESSIONID");
        cookieConfig.setPath("/");
        cookieConfig.setHttpOnly(true);
        cookieConfig.setSecure(true);  // HTTPS only
        cookieConfig.setMaxAge(24 * 60 * 60); // 24 hours
        
        // Set session tracking mode
        Set<SessionTrackingMode> trackingModes = EnumSet.of(SessionTrackingMode.COOKIE);
        sessionHandler.setSessionTrackingModes(trackingModes);
        
        // Set application handler as child
        sessionHandler.setHandler(new ApplicationHandler());
        
        server.setHandler(sessionHandler);
    }
}

public class DatabaseSessionDataStore extends AbstractSessionDataStore {
    private final DataSource dataSource;
    
    public DatabaseSessionDataStore(DataSource dataSource) {
        this.dataSource = dataSource;
    }
    
    @Override
    public SessionData doLoad(String id) throws Exception {
        try (Connection conn = dataSource.getConnection()) {
            String sql = "SELECT * FROM sessions WHERE session_id = ?";
            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
                stmt.setString(1, id);
                try (ResultSet rs = stmt.executeQuery()) {
                    if (rs.next()) {
                        return deserializeSessionData(rs);
                    }
                }
            }
        }
        return null;
    }
    
    @Override
    public boolean doStore(String id, SessionData data, long lastSaveTime) throws Exception {
        try (Connection conn = dataSource.getConnection()) {
            String sql = "INSERT INTO sessions (session_id, creation_time, last_access_time, " +
                        "max_inactive_interval, attributes) VALUES (?, ?, ?, ?, ?) " +
                        "ON DUPLICATE KEY UPDATE last_access_time = ?, attributes = ?";
            
            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
                stmt.setString(1, id);
                stmt.setLong(2, data.getCreated());
                stmt.setLong(3, data.getLastAccessed());
                stmt.setInt(4, data.getMaxInactiveInterval());
                stmt.setBytes(5, serializeAttributes(data.getAttributes()));
                stmt.setLong(6, data.getLastAccessed());
                stmt.setBytes(7, serializeAttributes(data.getAttributes()));
                
                return stmt.executeUpdate() > 0;
            }
        }
    }
    
    @Override
    public boolean doDelete(String id) throws Exception {
        try (Connection conn = dataSource.getConnection()) {
            String sql = "DELETE FROM sessions WHERE session_id = ?";
            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
                stmt.setString(1, id);
                return stmt.executeUpdate() > 0;
            }
        }
    }
    
    @Override
    public Set<String> doCheckExpired(Set<String> candidates, long time) throws Exception {
        Set<String> expired = new HashSet<>();
        
        try (Connection conn = dataSource.getConnection()) {
            String sql = "SELECT session_id FROM sessions WHERE " +
                        "last_access_time + (max_inactive_interval * 1000) < ?";
            
            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
                stmt.setLong(1, time);
                try (ResultSet rs = stmt.executeQuery()) {
                    while (rs.next()) {
                        expired.add(rs.getString("session_id"));
                    }
                }
            }
        }
        
        return expired;
    }
    
    @Override
    public Set<String> doGetExpired(long time) throws Exception {
        return doCheckExpired(Collections.emptySet(), time);
    }
    
    @Override
    public void doCleanOrphans(long time) throws Exception {
        try (Connection conn = dataSource.getConnection()) {
            String sql = "DELETE FROM sessions WHERE " +
                        "last_access_time + (max_inactive_interval * 1000) < ?";
            
            try (PreparedStatement stmt = conn.prepareStatement(sql)) {
                stmt.setLong(1, time);
                int deleted = stmt.executeUpdate();
                System.out.println("Cleaned " + deleted + " orphaned sessions");
            }
        }
    }
    
    private SessionData deserializeSessionData(ResultSet rs) throws SQLException {
        SessionData data = new SessionData(
            rs.getString("session_id"),
            "/", // context path
            "localhost", // virtual host
            rs.getLong("creation_time"),
            rs.getLong("last_access_time"),
            rs.getLong("last_access_time"),
            rs.getInt("max_inactive_interval")
        );
        
        // Deserialize attributes
        byte[] attributeBytes = rs.getBytes("attributes");
        if (attributeBytes != null) {
            Map<String, Object> attributes = deserializeAttributes(attributeBytes);
            data.putAllAttributes(attributes);
        }
        
        return data;
    }
    
    private byte[] serializeAttributes(Map<String, Object> attributes) {
        // Implement serialization (e.g., using Java serialization or JSON)
        try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
             ObjectOutputStream oos = new ObjectOutputStream(baos)) {
            oos.writeObject(attributes);
            return baos.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException("Failed to serialize session attributes", e);
        }
    }
    
    private Map<String, Object> deserializeAttributes(byte[] data) {
        // Implement deserialization
        try (ByteArrayInputStream bais = new ByteArrayInputStream(data);
             ObjectInputStream ois = new ObjectInputStream(bais)) {
            return (Map<String, Object>) ois.readObject();
        } catch (IOException | ClassNotFoundException e) {
            throw new RuntimeException("Failed to deserialize session attributes", e);
        }
    }
}

public class SessionCacheConfiguration {
    
    public SessionHandler createSessionHandler(DataSource dataSource) {
        SessionHandler sessionHandler = new SessionHandler();
        
        // Create session ID manager
        DefaultSessionIdManager sessionIdManager = new DefaultSessionIdManager(server);
        sessionIdManager.setWorkerName("node1");
        sessionHandler.setSessionIdManager(sessionIdManager);
        
        // Create session data store
        DatabaseSessionDataStore sessionDataStore = new DatabaseSessionDataStore(dataSource);
        sessionDataStore.setGracePeriodSec(3600); // 1 hour grace period
        sessionDataStore.setSavePeriodSec(0);     // Save on every change
        
        // Create session cache
        DefaultSessionCache sessionCache = new DefaultSessionCache(sessionHandler);
        sessionCache.setSessionDataStore(sessionDataStore);
        sessionCache.setEvictionPolicy(SessionCache.NEVER_EVICT);
        sessionCache.setSaveOnCreate(true);
        sessionCache.setSaveOnInactiveEviction(true);
        sessionCache.setRemoveUnloadableSessions(true);
        
        sessionHandler.setSessionCache(sessionCache);
        
        return sessionHandler;
    }
}

public class SecureSessionHandler extends SessionHandler {
    
    @Override
    protected void doStart() throws Exception {
        super.doStart();
        
        // Configure secure session cookie
        SessionCookieConfig cookieConfig = getSessionCookieConfig();
        cookieConfig.setSecure(true);      // HTTPS only
        cookieConfig.setHttpOnly(true);    // No JavaScript access
        cookieConfig.setSameSite(SameSite.STRICT); // CSRF protection
        
        // Use random session ID generation
        SessionIdManager idManager = getSessionIdManager();
        if (idManager instanceof DefaultSessionIdManager) {
            DefaultSessionIdManager defaultIdManager = (DefaultSessionIdManager) idManager;
            defaultIdManager.setWorkerName(null); // Use random worker name
        }
    }
    
    @Override
    public Session newSession(Request request) {
        Session session = super.newSession(request);
        
        // Add security attributes
        session.setAttribute("remoteAddr", 
            request.getConnectionMetaData().getRemoteSocketAddress());
        session.setAttribute("userAgent", request.getHeaders().get("User-Agent"));
        
        return session;
    }
    
    @Override
    protected void sessionInactivityTimer(Session session) {
        // Log session timeout for security monitoring
        System.out.println("Session timeout: " + session.getId() + 
                          " from " + session.getAttribute("remoteAddr"));
        super.sessionInactivityTimer(session);
    }
}

public class SessionValidationHandler extends Handler.Wrapper {
    
    @Override
    public boolean handle(Request request, Response response, Callback callback) 
            throws Exception {
        
        Session session = request.getSession(false);
        if (session != null && !isValidSession(session, request)) {
            // Invalid session, invalidate and create new
            session.invalidate();
            session = request.getSession(true);
        }
        
        return super.handle(request, response, callback);
    }
    
    private boolean isValidSession(Session session, Request request) {
        // Check if session is from same IP address
        String sessionAddr = (String) session.getAttribute("remoteAddr");
        String currentAddr = request.getConnectionMetaData().getRemoteSocketAddress().toString();
        
        if (sessionAddr != null && !sessionAddr.equals(currentAddr)) {
            System.err.println("Session hijack attempt detected: " + session.getId());
            return false;
        }
        
        // Check user agent
        String sessionUserAgent = (String) session.getAttribute("userAgent");
        String currentUserAgent = request.getHeaders().get("User-Agent");
        
        if (sessionUserAgent != null && !sessionUserAgent.equals(currentUserAgent)) {
            System.err.println("User agent mismatch for session: " + session.getId());
            return false;
        }
        
        return true;
    }
}

public class ClusteredSessionConfiguration {
    
    public void configureClusteredSessions(Server server, String[] nodes) {
        // Create shared session ID manager
        DefaultSessionIdManager sessionIdManager = new DefaultSessionIdManager(server);
        sessionIdManager.setWorkerName(getNodeName());
        server.addBean(sessionIdManager);
        
        // Create clustered session data store
        ClusteredSessionDataStore dataStore = new ClusteredSessionDataStore(nodes);
        
        // Configure session handler
        SessionHandler sessionHandler = new SessionHandler();
        sessionHandler.setSessionIdManager(sessionIdManager);
        
        // Create session cache with clustering support
        DefaultSessionCache sessionCache = new DefaultSessionCache(sessionHandler);
        sessionCache.setSessionDataStore(dataStore);
        sessionCache.setEvictionPolicy(SessionCache.EVICT_ON_SESSION_EXIT);
        
        sessionHandler.setSessionCache(sessionCache);
        
        // Set application handler
        sessionHandler.setHandler(new ApplicationHandler());
        server.setHandler(sessionHandler);
    }
    
    private String getNodeName() {
        // Generate unique node identifier
        return "node-" + System.currentTimeMillis();
    }
}

public class SessionStatisticsHandler extends Handler.Wrapper {
    private final AtomicLong sessionsCreated = new AtomicLong();
    private final AtomicLong sessionsDestroyed = new AtomicLong();
    private final AtomicLong sessionsTimeout = new AtomicLong();
    private final Map<String, Long> sessionStartTimes = new ConcurrentHashMap<>();
    
    @Override
    public boolean handle(Request request, Response response, Callback callback) 
            throws Exception {
        
        Session session = request.getSession(false);
        if (session != null) {
            if (session.isNew()) {
                sessionsCreated.incrementAndGet();
                sessionStartTimes.put(session.getId(), System.currentTimeMillis());
                
                // Add session listener
                session.setAttribute("statisticsHandler", this);
            }
        }
        
        return super.handle(request, response, callback);
    }
    
    public void onSessionDestroyed(String sessionId) {
        sessionsDestroyed.incrementAndGet();
        sessionStartTimes.remove(sessionId);
    }
    
    public void onSessionTimeout(String sessionId) {
        sessionsTimeout.incrementAndGet();
        sessionStartTimes.remove(sessionId);
    }
    
    public long getSessionsCreated() {
        return sessionsCreated.get();
    }
    
    public long getSessionsDestroyed() {
        return sessionsDestroyed.get();
    }
    
    public long getSessionsTimeout() {
        return sessionsTimeout.get();
    }
    
    public long getActiveSessions() {
        return sessionsCreated.get() - sessionsDestroyed.get();
    }
    
    public double getAverageSessionDuration() {
        long totalDuration = 0;
        long count = 0;
        
        for (Long startTime : sessionStartTimes.values()) {
            totalDuration += System.currentTimeMillis() - startTime;
            count++;
        }
        
        return count > 0 ? (double) totalDuration / count : 0.0;
    }
}