/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.avro.ipc;

import java.io.IOException;
import java.util.Map;
import java.net.SocketAddress;
import java.nio.channels.SocketChannel;
import javax.security.sasl.Sasl;
import javax.security.sasl.SaslServer;
import javax.security.sasl.SaslException;
import javax.security.auth.callback.CallbackHandler;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** A {@link Server} that uses {@link javax.security.sasl} for authentication
 * and encryption. */
public class SaslSocketServer extends SocketServer {
  private static final Logger LOG = LoggerFactory.getLogger(SaslServer.class);

  private static abstract class SaslServerFactory {
    protected abstract SaslServer getServer() throws SaslException;
  }

  private SaslServerFactory factory;

  /** Create using SASL's anonymous (<a
   * href="http://www.ietf.org/rfc/rfc2245.txt">RFC 2245) mechanism. */
  public SaslSocketServer(Responder responder, SocketAddress addr)
    throws IOException {
    this(responder, addr,
         new SaslServerFactory() {
           public SaslServer getServer() { return new AnonymousServer(); }
         });
  }

  /** Create using the specified {@link SaslServer} parameters. */
  public SaslSocketServer(Responder responder, SocketAddress addr,
                          final String mechanism, final String protocol,
                          final String serverName, final Map<String,?> props,
                          final CallbackHandler cbh) throws IOException {
    this(responder, addr,
         new SaslServerFactory() {
           public SaslServer getServer() throws SaslException {
             return Sasl.createSaslServer(mechanism, protocol, serverName,
                                          props, cbh);
           }
         });
  }

  private SaslSocketServer(Responder responder, SocketAddress addr,
                           SaslServerFactory factory) throws IOException {
    super(responder, addr);
    this.factory = factory;
  }

  @Override protected Transceiver getTransceiver(SocketChannel channel)
    throws IOException {
    return new SaslSocketTransceiver(channel, factory.getServer());
  }

  private static class AnonymousServer implements SaslServer {
    private String user;
    public String getMechanismName() { return "ANONYMOUS"; }
    public byte[] evaluateResponse(byte[] response) throws SaslException {
      try {
        this.user = new String(response, "UTF-8");
      } catch (IOException e) {
        throw new SaslException(e.toString());
      }
      return null;
    }
    public boolean isComplete() { return user != null; }
    public String getAuthorizationID() { return user; }
    public byte[] unwrap(byte[] incoming, int offset, int len) {
      throw new UnsupportedOperationException();
    }
    public byte[] wrap(byte[] outgoing, int offset, int len) {
      throw new UnsupportedOperationException();
    }
    public Object getNegotiatedProperty(String propName) { return null; }
    public void dispose() {}
  }

}