/*
 *
 * 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.replication;


import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.ServerName;

/**
 * This class is responsible for the parsing logic for a znode representing a queue.
 * It will extract the peerId if it's recovered as well as the dead region servers
 * that were part of the queue's history.
 */
@InterfaceAudience.Private
public class ReplicationQueueInfo {
  private static final Log LOG = LogFactory.getLog(ReplicationQueueInfo.class);

  private final String peerId;
  private final String peerClusterZnode;
  private boolean queueRecovered;
  // List of all the dead region servers that had this queue (if recovered)
  private List<String> deadRegionServers = new ArrayList<>();

  /**
   * The passed znode will be either the id of the peer cluster or
   * the handling story of that queue in the form of id-servername-*
   */
  public ReplicationQueueInfo(String znode) {
    this.peerClusterZnode = znode;
    String[] parts = znode.split("-", 2);
    this.queueRecovered = parts.length != 1;
    this.peerId = this.queueRecovered ?
        parts[0] : peerClusterZnode;
    if (parts.length >= 2) {
      // extract dead servers
      extractDeadServersFromZNodeString(parts[1], this.deadRegionServers);
    }
  }

  /**
   * Parse dead server names from znode string servername can contain "-" such as
   * "ip-10-46-221-101.ec2.internal", so we need skip some "-" during parsing for the following
   * cases: 2-ip-10-46-221-101.ec2.internal,52170,1364333181125-<server name>-...
   */
  private static void
      extractDeadServersFromZNodeString(String deadServerListStr, List<String> result) {

    if(deadServerListStr == null || result == null || deadServerListStr.isEmpty()) return;

    // valid server name delimiter "-" has to be after "," in a server name
    int seenCommaCnt = 0;
    int startIndex = 0;
    int len = deadServerListStr.length();

    for (int i = 0; i < len; i++) {
      switch (deadServerListStr.charAt(i)) {
      case ',':
        seenCommaCnt += 1;
        break;
      case '-':
        if(seenCommaCnt>=2) {
          if (i > startIndex) {
            String serverName = deadServerListStr.substring(startIndex, i);
            if(ServerName.isFullServerName(serverName)){
              result.add(serverName);
            } else {
              LOG.error("Found invalid server name:" + serverName);
            }
            startIndex = i + 1;
          }
          seenCommaCnt = 0;
        }
        break;
      default:
        break;
      }
    }

    // add tail
    if(startIndex < len - 1){
      String serverName = deadServerListStr.substring(startIndex, len);
      if(ServerName.isFullServerName(serverName)){
        result.add(serverName);
      } else {
        LOG.error("Found invalid server name at the end:" + serverName);
      }
    }

    LOG.debug("Found dead servers:" + result);
  }

  public List<String> getDeadRegionServers() {
    return Collections.unmodifiableList(this.deadRegionServers);
  }

  public String getPeerId() {
    return this.peerId;
  }

  public String getPeerClusterZnode() {
    return this.peerClusterZnode;
  }

  public boolean isQueueRecovered() {
    return queueRecovered;
  }
}