/**
 * 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.hadoop.hbase;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.ipc.RemoteException;

/**
 * Subclass if the server knows the region is now on another server.
 * This allows the client to call the new region server without calling the master.
 */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class RegionMovedException extends NotServingRegionException {
  private static final Log LOG = LogFactory.getLog(RegionMovedException.class);
  private static final long serialVersionUID = -7232903522310558396L;

  private final String hostname;
  private final int port;
  private final long locationSeqNum;

  private static final String HOST_FIELD = "hostname=";
  private static final String PORT_FIELD = "port=";
  private static final String LOCATIONSEQNUM_FIELD = "locationSeqNum=";

  public RegionMovedException(final String hostname, final int port,
    final long locationSeqNum) {
    super();
    this.hostname = hostname;
    this.port = port;
    this.locationSeqNum = locationSeqNum;
  }

  public String getHostname() {
    return hostname;
  }

  public int getPort() {
    return port;
  }

  public long getLocationSeqNum() {
    return locationSeqNum;
  }

  /**
   * For hadoop.ipc internal call. Do NOT use.
   * We have to parse the hostname to recreate the exception.
   * The input is the one generated by {@link #getMessage()}
   */
  public RegionMovedException(String s) {
    int posHostname = s.indexOf(HOST_FIELD) + HOST_FIELD.length();
    int posPort = s.indexOf(PORT_FIELD) + PORT_FIELD.length();
    int posSeqNum = s.indexOf(LOCATIONSEQNUM_FIELD) + LOCATIONSEQNUM_FIELD.length();

    String tmpHostname = null;
    int tmpPort = -1;
    long tmpSeqNum = HConstants.NO_SEQNUM;
    try {
      // TODO: this whole thing is extremely brittle.
      tmpHostname = s.substring(posHostname, s.indexOf(' ', posHostname));
      tmpPort = Integer.parseInt(s.substring(posPort, s.indexOf('.', posPort)));
      tmpSeqNum = Long.parseLong(s.substring(posSeqNum, s.indexOf('.', posSeqNum)));
    } catch (Exception ignored) {
      LOG.warn("Can't parse the hostname and the port from this string: " + s + ", continuing");
    }

    hostname = tmpHostname;
    port = tmpPort;
    locationSeqNum = tmpSeqNum;
  }

  @Override
  public String getMessage() {
    // TODO: deserialization above depends on this. That is bad, but also means this
    // should be modified carefully.
    return "Region moved to: " + HOST_FIELD + hostname + " " + PORT_FIELD + port + ". As of "
      + LOCATIONSEQNUM_FIELD + locationSeqNum + ".";
  }

  /**
   * Look for a RegionMovedException in the exception:
   *  - hadoop.ipc wrapped exceptions
   *  - nested exceptions
   * Returns null if we didn't find the exception or if it was not readable.
   */
  public static RegionMovedException find(Object exception) {
    if (exception == null || !(exception instanceof Throwable)){
      return null;
    }

    Throwable cur = (Throwable)exception;
    RegionMovedException res = null;

    while (res == null && cur != null) {
      if (cur instanceof RegionMovedException) {
        res = (RegionMovedException) cur;
      } else {
        if (cur instanceof RemoteException) {
          RemoteException re = (RemoteException) cur;
          Exception e = re.unwrapRemoteException(RegionMovedException.class);
          if (e == null){
            e = re.unwrapRemoteException();
          }
          // unwrapRemoteException can return the exception given as a parameter when it cannot
          //  unwrap it. In this case, there is no need to look further
          // noinspection ObjectEquality
          if (e != re){
            res =  find(e);
          }
        }
        cur = cur.getCause();
      }
    }

    if (res != null && (res.getPort() < 0 || res.getHostname() == null)){
      // We failed to parse the exception. Let's act as we don't find the exception.
      return null;
    } else {
      return res;
    }
  }
}