package org.openslx.imagemaster.server;

import java.nio.ByteBuffer;
import java.util.List;

import org.apache.thrift.TException;
import org.openslx.imagemaster.db.DbImage;
import org.openslx.imagemaster.db.DbSatellite;
import org.openslx.imagemaster.serverconnection.ImageProcessor;
import org.openslx.imagemaster.serversession.ServerAuthenticator;
import org.openslx.imagemaster.serversession.ServerSession;
import org.openslx.imagemaster.serversession.ServerSessionManager;
import org.openslx.imagemaster.serversession.ServerUser;
import org.openslx.imagemaster.session.Authenticator;
import org.openslx.imagemaster.session.Session;
import org.openslx.imagemaster.session.SessionManager;
import org.openslx.imagemaster.session.User;
import org.openslx.imagemaster.thrift.iface.AuthenticationError;
import org.openslx.imagemaster.thrift.iface.AuthenticationException;
import org.openslx.imagemaster.thrift.iface.AuthorizationError;
import org.openslx.imagemaster.thrift.iface.AuthorizationException;
import org.openslx.imagemaster.thrift.iface.DownloadInfos;
import org.openslx.imagemaster.thrift.iface.ImageData;
import org.openslx.imagemaster.thrift.iface.ImageDataError;
import org.openslx.imagemaster.thrift.iface.ImageDataException;
import org.openslx.imagemaster.thrift.iface.InvalidTokenException;
import org.openslx.imagemaster.thrift.iface.ServerAuthenticationError;
import org.openslx.imagemaster.thrift.iface.ServerAuthenticationException;
import org.openslx.imagemaster.thrift.iface.ServerSessionData;
import org.openslx.imagemaster.thrift.iface.SessionData;
import org.openslx.imagemaster.thrift.iface.UploadException;
import org.openslx.imagemaster.thrift.iface.UploadInfos;
import org.openslx.imagemaster.thrift.iface.UserInfo;

/**
 * API Server This is where all the requests from the outside arrive. We don't
 * handle them directly in the Thrift handlers, as we might be adding other APIs
 * later, like JSON/SOAP/REST/HTTP/XML or some other stuff. They'd all just
 * interface with this static class here. Note that we use the exceptions from
 * the thrift interface that you can simply catch in any other API handler and
 * eg. transform into error codes, if the API doesn't support exceptions.
 * 
 * This will be accessed from multiple threads, so use synchronization when
 * needed (or in doubt)
 */
public class ApiServer
{

	/**
	 * Request for authentication
	 * 
	 * @param login The user's login in the form "user@organization.com"
	 * @param password user's password
	 * @return SessionData struct with session id/token iff login successful
	 * @throws AuthenticationException if login not successful
	 */
	public static SessionData authenticate( String login, String password )
			throws AuthenticationException
	{
		if ( login == null || password == null ) {
			throw new AuthenticationException(
					AuthenticationError.INVALID_CREDENTIALS,
					"Empty username or password!" );
		}
		final User user = Authenticator.authenticate( login, password );

		final Session session = new Session( user );
		return SessionManager.addSession( session );
	}

	/**
	 * Request information about user for given token
	 * 
	 * @param token a user's token
	 * @return UserInfo struct for given token's user
	 * @throws InvalidTokenException if no user matches the given token
	 */
	public static UserInfo getUserFromToken( String token )
			throws InvalidTokenException
	{
		final Session session = SessionManager.getSession( token );
		if ( session == null )
			throw new InvalidTokenException();
		return new UserInfo( session.getUserId(), session.getFirstName(),
				session.getLastName(), session.getEMail() );
	}

	public static UploadInfos submitImage( String serverSessionId, ImageData imageDescription, List<Integer> crcSums )
			throws AuthorizationException, ImageDataException, UploadException
	{
		// first check session of server
		if ( ServerSessionManager.getSession( serverSessionId ) == null ) {
			throw new AuthorizationException( AuthorizationError.NOT_AUTHENTICATED, "No valid serverSessioId" );
		}
		// then let the image processor decide what to do
		return ImageProcessor.getUploadInfos( serverSessionId, imageDescription, crcSums );
	}

	public static DownloadInfos getImage( String uuid, String serverSessionId, List<Integer> requestedBlocks ) throws AuthorizationException, ImageDataException
	{
		// first check session of server
		if ( ServerSessionManager.getSession( serverSessionId ) == null ) {
			throw new AuthorizationException( AuthorizationError.NOT_AUTHENTICATED, "No valid serverSessionId" );
		}

		if ( !DbImage.exists( uuid ) ) {
			throw new ImageDataException( ImageDataError.UNKNOWN_IMAGE, "UUID is not known by this server." );
		}

		// then let the image processor decide what to do
		return ImageProcessor.getDownloadInfos( serverSessionId, uuid, requestedBlocks );
	}

	/**
	 * Start the server authentication of a uni/hs satellite server.
	 * 
	 * @param organization the organization that the server belongs to
	 * @return a random string that needs to be encrypted with the private
	 *         key of the requesting satellite server
	 * @throws ServerAuthenticationException when organization is invalid/unknown
	 */
	public static String startServerAuthentication( String organization )
			throws ServerAuthenticationException
	{
		if ( organization == null || organization.isEmpty() ) {
			throw new ServerAuthenticationException( ServerAuthenticationError.INVALID_ORGANIZATION, "Empty organization" );
		}
		if ( DbSatellite.fromOrganization( organization ) == null ) {
			throw new ServerAuthenticationException( ServerAuthenticationError.INVALID_ORGANIZATION, "Unknown organization" );
		}
		return ServerAuthenticator.startServerAuthentication( organization );
	}

	/**
	 * Authenticate the uni/hs satellite server with the encrypted string.
	 * 
	 * @param organization the organization that the server belongs to
	 * @param challengeResponse the encrypted string
	 * @return session data iff the authentication was successful
	 * @throws AuthenticationException
	 * @throws TException
	 */
	public static ServerSessionData serverAuthenticate( String organization,
			ByteBuffer challengeResponse ) throws ServerAuthenticationException,
			TException
	{
		if ( organization == null || challengeResponse == null ) {
			throw new ServerAuthenticationException( ServerAuthenticationError.INVALID_ORGANIZATION, "Empty organization or challengeResponse" );
		}
		DbSatellite satellite = DbSatellite.fromOrganization( organization );
		if ( satellite == null ) {
			throw new ServerAuthenticationException( ServerAuthenticationError.INVALID_ORGANIZATION, "Unknown organization" );
		}
		final ServerUser serverUser = ServerAuthenticator.serverAuthenticate(
				organization, satellite.getAddress(), challengeResponse );

		final ServerSession session = new ServerSession( serverUser );
		return ServerSessionManager.addSession( session );
	}

	public static boolean isServerAuthenticated( String serverSessionId )
	{
		return ( ServerSessionManager.getSession( serverSessionId ) != null );
	}
}