/*
 * 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.accumulo.core.client;

import static com.google.common.base.Charsets.UTF_8;

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

import org.apache.accumulo.core.Constants;
import org.apache.accumulo.core.client.ClientConfiguration.ClientProperty;
import org.apache.accumulo.core.client.impl.ConnectorImpl;
import org.apache.accumulo.core.client.impl.ServerConfigurationUtil;
import org.apache.accumulo.core.client.security.tokens.AuthenticationToken;
import org.apache.accumulo.core.client.security.tokens.PasswordToken;
import org.apache.accumulo.core.conf.AccumuloConfiguration;
import org.apache.accumulo.core.conf.DefaultConfiguration;
import org.apache.accumulo.core.metadata.RootTable;
import org.apache.accumulo.core.security.Credentials;
import org.apache.accumulo.core.util.ArgumentChecker;
import org.apache.accumulo.core.util.ByteBufferUtil;
import org.apache.accumulo.core.util.OpTimer;
import org.apache.accumulo.core.util.TextUtil;
import org.apache.accumulo.core.zookeeper.ZooUtil;
import org.apache.accumulo.fate.zookeeper.ZooCache;
import org.apache.accumulo.fate.zookeeper.ZooCacheFactory;
import org.apache.commons.configuration.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;

/**
 * <p>
 * An implementation of instance that looks in zookeeper to find information needed to connect to an instance of accumulo.
 *
 * <p>
 * The advantage of using zookeeper to obtain information about accumulo is that zookeeper is highly available, very responsive, and supports caching.
 *
 * <p>
 * Because it is possible for multiple instances of accumulo to share a single set of zookeeper servers, all constructors require an accumulo instance name.
 *
 * If you do not know the instance names then run accumulo org.apache.accumulo.server.util.ListInstances on an accumulo server.
 *
 */

public class ZooKeeperInstance implements Instance {

  private static final Logger log = Logger.getLogger(ZooKeeperInstance.class);

  private String instanceId = null;
  private String instanceName = null;

  private final ZooCache zooCache;

  private final String zooKeepers;

  private final int zooKeepersSessionTimeOut;

  private AccumuloConfiguration accumuloConf;
  private ClientConfiguration clientConf;

  /**
   *
   * @param instanceName
   *          The name of specific accumulo instance. This is set at initialization time.
   * @param zooKeepers
   *          A comma separated list of zoo keeper server locations. Each location can contain an optional port, of the format host:port.
   */
  public ZooKeeperInstance(String instanceName, String zooKeepers) {
    this(ClientConfiguration.loadDefault().withInstance(instanceName).withZkHosts(zooKeepers));
  }

  /**
   *
   * @param instanceName
   *          The name of specific accumulo instance. This is set at initialization time.
   * @param zooKeepers
   *          A comma separated list of zoo keeper server locations. Each location can contain an optional port, of the format host:port.
   * @param sessionTimeout
   *          zoo keeper session time out in milliseconds.
   * @deprecated since 1.6.0; Use {@link #ZooKeeperInstance(Configuration)} instead.
   */
  @Deprecated
  public ZooKeeperInstance(String instanceName, String zooKeepers, int sessionTimeout) {
    this(ClientConfiguration.loadDefault().withInstance(instanceName).withZkHosts(zooKeepers).withZkTimeout(sessionTimeout));
  }

  /**
   *
   * @param instanceId
   *          The UUID that identifies the accumulo instance you want to connect to.
   * @param zooKeepers
   *          A comma separated list of zoo keeper server locations. Each location can contain an optional port, of the format host:port.
   * @deprecated since 1.6.0; Use {@link #ZooKeeperInstance(Configuration)} instead.
   */
  @Deprecated
  public ZooKeeperInstance(UUID instanceId, String zooKeepers) {
    this(ClientConfiguration.loadDefault().withInstance(instanceId).withZkHosts(zooKeepers));
  }

  /**
   *
   * @param instanceId
   *          The UUID that identifies the accumulo instance you want to connect to.
   * @param zooKeepers
   *          A comma separated list of zoo keeper server locations. Each location can contain an optional port, of the format host:port.
   * @param sessionTimeout
   *          zoo keeper session time out in milliseconds.
   * @deprecated since 1.6.0; Use {@link #ZooKeeperInstance(Configuration)} instead.
   */
  @Deprecated
  public ZooKeeperInstance(UUID instanceId, String zooKeepers, int sessionTimeout) {
    this(ClientConfiguration.loadDefault().withInstance(instanceId).withZkHosts(zooKeepers).withZkTimeout(sessionTimeout));
  }

  /**
   * @param config
   *          Client configuration for specifying connection options. See {@link ClientConfiguration} which extends Configuration with convenience methods
   *          specific to Accumulo.
   * @since 1.6.0
   */
  public ZooKeeperInstance(Configuration config) {
    this(config, new ZooCacheFactory());
  }

  ZooKeeperInstance(Configuration config, ZooCacheFactory zcf) {
    ArgumentChecker.notNull(config);
    if (config instanceof ClientConfiguration) {
      this.clientConf = (ClientConfiguration) config;
    } else {
      this.clientConf = new ClientConfiguration(config);
    }
    this.instanceId = clientConf.get(ClientProperty.INSTANCE_ID);
    this.instanceName = clientConf.get(ClientProperty.INSTANCE_NAME);
    if ((instanceId == null) == (instanceName == null))
      throw new IllegalArgumentException("Expected exactly one of instanceName and instanceId to be set");
    this.zooKeepers = clientConf.get(ClientProperty.INSTANCE_ZK_HOST);
    this.zooKeepersSessionTimeOut = (int) AccumuloConfiguration.getTimeInMillis(clientConf.get(ClientProperty.INSTANCE_ZK_TIMEOUT));
    zooCache = zcf.getZooCache(zooKeepers, zooKeepersSessionTimeOut);
  }

  @Override
  public String getInstanceID() {
    if (instanceId == null) {
      // want the instance id to be stable for the life of this instance object,
      // so only get it once
      String instanceNamePath = Constants.ZROOT + Constants.ZINSTANCES + "/" + instanceName;
      byte[] iidb = zooCache.get(instanceNamePath);
      if (iidb == null) {
        throw new RuntimeException("Instance name " + instanceName
            + " does not exist in zookeeper.  Run \"accumulo org.apache.accumulo.server.util.ListInstances\" to see a list.");
      }
      instanceId = new String(iidb, UTF_8);
    }

    if (zooCache.get(Constants.ZROOT + "/" + instanceId) == null) {
      if (instanceName == null)
        throw new RuntimeException("Instance id " + instanceId + " does not exist in zookeeper");
      throw new RuntimeException("Instance id " + instanceId + " pointed to by the name " + instanceName + " does not exist in zookeeper");
    }

    return instanceId;
  }

  @Override
  public List<String> getMasterLocations() {
    String masterLocPath = ZooUtil.getRoot(this) + Constants.ZMASTER_LOCK;

    OpTimer opTimer = new OpTimer(log, Level.TRACE).start("Looking up master location in zoocache.");
    byte[] loc = ZooUtil.getLockData(zooCache, masterLocPath);
    opTimer.stop("Found master at " + (loc == null ? null : new String(loc, UTF_8)) + " in %DURATION%");

    if (loc == null) {
      return Collections.emptyList();
    }

    return Collections.singletonList(new String(loc, UTF_8));
  }

  @Override
  public String getRootTabletLocation() {
    String zRootLocPath = ZooUtil.getRoot(this) + RootTable.ZROOT_TABLET_LOCATION;

    OpTimer opTimer = new OpTimer(log, Level.TRACE).start("Looking up root tablet location in zookeeper.");
    byte[] loc = zooCache.get(zRootLocPath);
    opTimer.stop("Found root tablet at " + (loc == null ? null : new String(loc, UTF_8)) + " in %DURATION%");

    if (loc == null) {
      return null;
    }

    return new String(loc, UTF_8).split("\\|")[0];
  }

  @Override
  public String getInstanceName() {
    if (instanceName == null)
      instanceName = lookupInstanceName(zooCache, UUID.fromString(getInstanceID()));

    return instanceName;
  }

  @Override
  public String getZooKeepers() {
    return zooKeepers;
  }

  @Override
  public int getZooKeepersSessionTimeOut() {
    return zooKeepersSessionTimeOut;
  }

  @Override
  @Deprecated
  public Connector getConnector(String user, CharSequence pass) throws AccumuloException, AccumuloSecurityException {
    return getConnector(user, TextUtil.getBytes(new Text(pass.toString())));
  }

  @Override
  @Deprecated
  public Connector getConnector(String user, ByteBuffer pass) throws AccumuloException, AccumuloSecurityException {
    return getConnector(user, ByteBufferUtil.toBytes(pass));
  }

  @Override
  public Connector getConnector(String principal, AuthenticationToken token) throws AccumuloException, AccumuloSecurityException {
    return new ConnectorImpl(this, new Credentials(principal, token));
  }

  @Override
  @Deprecated
  public Connector getConnector(String principal, byte[] pass) throws AccumuloException, AccumuloSecurityException {
    return getConnector(principal, new PasswordToken(pass));
  }

  @Override
  @Deprecated
  public AccumuloConfiguration getConfiguration() {
    return ServerConfigurationUtil.convertClientConfig(accumuloConf == null ? DefaultConfiguration.getInstance() : accumuloConf, clientConf);
  }

  @Override
  @Deprecated
  public void setConfiguration(AccumuloConfiguration conf) {
    this.accumuloConf = conf;
  }

  /**
   * Given a zooCache and instanceId, look up the instance name.
   */
  public static String lookupInstanceName(ZooCache zooCache, UUID instanceId) {
    ArgumentChecker.notNull(zooCache, instanceId);
    for (String name : zooCache.getChildren(Constants.ZROOT + Constants.ZINSTANCES)) {
      String instanceNamePath = Constants.ZROOT + Constants.ZINSTANCES + "/" + name;
      byte[] bytes = zooCache.get(instanceNamePath);
      UUID iid = UUID.fromString(new String(bytes, UTF_8));
      if (iid.equals(instanceId)) {
        return name;
      }
    }
    return null;
  }
}
