/**
 * 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 backtype.storm.security.auth;

import java.io.IOException;
import java.net.Socket;
import java.security.Principal;
import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;

import javax.security.auth.Subject;
import javax.security.auth.login.Configuration;
import javax.security.sasl.SaslServer;

import backtype.storm.utils.ExtendedThreadPoolExecutor;
import org.apache.thrift.TException;
import org.apache.thrift.TProcessor;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.server.TServer;
import org.apache.thrift.server.TThreadPoolServer;
import org.apache.thrift.transport.TSaslServerTransport;
import org.apache.thrift.transport.TServerSocket;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;
import org.apache.thrift.transport.TTransportFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import backtype.storm.security.auth.ThriftConnectionType;

/**
 * Base class for SASL authentication plugin.
 */
public abstract class SaslTransportPlugin implements ITransportPlugin {
    protected ThriftConnectionType type;
    protected Map storm_conf;
    protected Configuration login_conf;
    private static final Logger LOG = LoggerFactory.getLogger(SaslTransportPlugin.class);

    @Override
    public void prepare(ThriftConnectionType type, Map storm_conf, Configuration login_conf) {
        this.type = type;
        this.storm_conf = storm_conf;
        this.login_conf = login_conf;
    }

    @Override
    public TServer getServer(TProcessor processor) throws IOException, TTransportException {
        int port = type.getPort(storm_conf);
        TTransportFactory serverTransportFactory = getServerTransportFactory();
        TServerSocket serverTransport = new TServerSocket(port);
        int numWorkerThreads = type.getNumThreads(storm_conf);
        Integer queueSize = type.getQueueSize(storm_conf);

        TThreadPoolServer.Args server_args =
                new TThreadPoolServer.Args(serverTransport).processor(new TUGIWrapProcessor(processor)).minWorkerThreads(numWorkerThreads)
                        .maxWorkerThreads(numWorkerThreads).protocolFactory(new TBinaryProtocol.Factory(false, true));

        if (serverTransportFactory != null) {
            server_args.transportFactory(serverTransportFactory);
        }
        BlockingQueue workQueue = new SynchronousQueue();
        if (queueSize != null) {
            workQueue = new ArrayBlockingQueue(queueSize);
        }
        ThreadPoolExecutor executorService = new ExtendedThreadPoolExecutor(numWorkerThreads, numWorkerThreads, 60, TimeUnit.SECONDS, workQueue);
        server_args.executorService(executorService);
        return new TThreadPoolServer(server_args);
    }

    /**
     * All subclass must implement this method
     * 
     * @return
     * @throws IOException
     */
    protected abstract TTransportFactory getServerTransportFactory() throws IOException;

    /**
     * Processor that pulls the SaslServer object out of the transport, and assumes the remote user's UGI before calling through to the original processor.
     * 
     * This is used on the server side to set the UGI for each specific call.
     */
    private class TUGIWrapProcessor implements TProcessor {
        final TProcessor wrapped;

        TUGIWrapProcessor(TProcessor wrapped) {
            this.wrapped = wrapped;
        }

        public boolean process(final TProtocol inProt, final TProtocol outProt) throws TException {
            // populating request context
            ReqContext req_context = ReqContext.context();

            TTransport trans = inProt.getTransport();
            // Sasl transport
            TSaslServerTransport saslTrans = (TSaslServerTransport) trans;
            // remote address
            TSocket tsocket = (TSocket) saslTrans.getUnderlyingTransport();
            Socket socket = tsocket.getSocket();
            req_context.setRemoteAddress(socket.getInetAddress());

            // remote subject
            SaslServer saslServer = saslTrans.getSaslServer();
            String authId = saslServer.getAuthorizationID();
            Subject remoteUser = new Subject();
            remoteUser.getPrincipals().add(new User(authId));
            req_context.setSubject(remoteUser);

            // invoke service handler
            return wrapped.process(inProt, outProt);
        }
    }

    public static class User implements Principal {
        private final String name;

        public User(String name) {
            this.name = name;
        }

        /**
         * Get the full name of the user.
         */
        public String getName() {
            return name;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            } else if (o == null || getClass() != o.getClass()) {
                return false;
            } else {
                return (name.equals(((User) o).name));
            }
        }

        @Override
        public int hashCode() {
            return name.hashCode();
        }

        @Override
        public String toString() {
            return name;
        }
    }
}