package org.openslx.imagemaster.session;

import java.sql.SQLException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.openslx.bwlp.thrift.iface.ClientSessionData;
import org.openslx.bwlp.thrift.iface.Satellite;
import org.openslx.bwlp.thrift.iface.TAuthorizationException;
import org.openslx.bwlp.thrift.iface.TNotFoundException;
import org.openslx.bwlp.thrift.iface.UserInfo;
import org.openslx.imagemaster.db.mappers.DbSatellite;
import org.openslx.imagemaster.util.Hash;
import org.openslx.util.QuickTimer;
import org.openslx.util.QuickTimer.Task;

/**
 * Class for managing active user sessions. This class and all its function are
 * (supposed to be) thread-safe.
 */
public class SessionManager
{
	private static Logger log = LogManager.getLogger( SessionManager.class );

	// Map of currently known sessions
	private static final Map<String, Session> sessions = new LinkedHashMap<>();

	// Map of pending "access code -> session" lookups
	private static final Map<String, AccessCode> accessCodes = new ConcurrentHashMap<>();

	public static ClientSessionData addSession( Session session )
	{
		final String authToken = Hash.md5( UUID.randomUUID().toString() );
		final String sessionId = Hash.sha256( UUID.randomUUID().toString() );

		synchronized ( sessions ) {
			sessions.put( authToken, session );
			sessions.put( sessionId, session );
		}
		UserInfo ui = session.getUserInfo();
		List<Satellite> sats;
		try {
			sats = DbSatellite.getSatellites( ui );
		} catch ( SQLException e ) {
			sats = null;
		}
		return new ClientSessionData( sessionId, authToken, sats, ui );
	}

	public static ClientSessionData addSession( Session session, String accessToken )
	{
		ClientSessionData s = addSession( session );
		if ( accessToken != null ) {
			accessCodes.put( accessToken, new AccessCode( s, null ) );
		}
		return s;
	}

	public static void addAuthError( TAuthorizationException ex, String accessToken )
	{
		if ( accessToken == null )
			return;
		accessCodes.put( accessToken, new AccessCode( null, ex ) );
	}

	static {
		QuickTimer.scheduleAtFixedDelay( new Task() {
			@Override
			public void fire()
			{
				synchronized ( sessions ) {
					Iterator<Session> it = sessions.values().iterator();
					while ( it.hasNext() ) {
						final Session s = it.next();
						if ( s.timedOut() ) {
							it.remove();
						}
					}
				}
				Iterator<AccessCode> it = accessCodes.values().iterator();
				while ( it.hasNext() ) {
					final AccessCode s = it.next();
					if ( s.timedOut() ) {
						it.remove();
					}
				}
			}
		}, 123, TimeUnit.MINUTES.toMillis( 13 ) );
	}

	/**
	 * Get from userToken, known to satellite servers.
	 */
	public static Session getSessionFromToken( String token )
	{
		if ( token == null || token.length() != 32 ) {
			log.debug( "invalid token format: " + token );
			return null;
		}
		final Session session;
		synchronized ( sessions ) {
			session = sessions.get( token );
		}
		if ( session == null || session.timedOut() ) {
			return null;
		}
		return session;
	}

	/**
	 * Get from sessionId, only known by client/user and us.
	 */
	public static Session getSessionFromSessionId( String sessionId )
	{
		if ( sessionId == null || sessionId.length() != 64 ) {
			log.debug( "invalid sessionid format: " + sessionId );
			return null;
		}
		final Session session;
		synchronized ( sessions ) {
			session = sessions.get( sessionId );
		}
		if ( session == null || session.timedOut() ) {
			return null;
		}
		session.refresh();
		return session;
	}

	public static Session getSessionFromSessionIdOrToken( String sessionId )
	{
		final Session session;
		synchronized ( sessions ) {
			session = sessions.get( sessionId );
		}
		if ( session == null || session.timedOut() ) {
			return null;
		}
		return session;
	}

	public static void invalidate( String sessionId )
	{
		if ( sessionId == null || sessionId.length() != 64 ) {
			log.debug( "invalidate: invalid sessionid format: " + sessionId );
			return;
		}
		synchronized ( sessions ) {
			Session session = sessions.get( sessionId );
			if ( session != null ) {
				session.invalidate();
			}
		}
	}

	/**
	 * Get the according session data (satToken, masterToken) for given access code, which was
	 * supplied by the client earlier. This can only be done once; retrieving the session will remove
	 * the entry from the lookup table.
	 */
	public static ClientSessionData getSessionFromAccessCode( String accessCode )
			throws TNotFoundException, TAuthorizationException
	{
		AccessCode data = accessCodes.remove( accessCode );
		if ( data == null )
			throw new TNotFoundException();
		if ( data.ex != null )
			throw data.ex;
		return data.clientSession;
	}

}