/**
    * 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.util;
  
  import org.apache.commons.logging.LogFactory;
  import java.io.PrintStream;
  import java.io.PrintWriter;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.lang.StringUtils;
  import org.apache.hadoop.hbase.Version;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  
  /**
   * This class finds the Version information for HBase.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public class VersionInfo {
    private static final Log LOG = LogFactory.getLog(VersionInfo.class.getName());
  
    // If between two dots there is not a number, we regard it as a very large number so it is
    // higher than any numbers in the version.
    private static int VERY_LARGE_NUMBER = 100000;
  
    /**
     * Get the hbase version.
     * @return the hbase version string, eg. "0.6.3-dev"
     */
    public static String getVersion() {
      return Version.version;
    }
  
    /**
     * Get the subversion revision number for the root directory
     * @return the revision number, eg. "451451"
     */
    public static String getRevision() {
      return Version.revision;
    }
  
    /**
     * The date that hbase was compiled.
     * @return the compilation date in unix date format
     */
    public static String getDate() {
      return Version.date;
    }
  
    /**
     * The user that compiled hbase.
     * @return the username of the user
     */
    public static String getUser() {
      return Version.user;
    }
  
    /**
     * Get the subversion URL for the root hbase directory.
     * @return the url
     */
    public static String getUrl() {
      return Version.url;
    }
  
    static String[] versionReport() {
      return new String[] {
        "HBase " + getVersion(),
        "Source code repository " + getUrl() + " revision=" + getRevision(),
        "Compiled by " + getUser() + " on " + getDate(),
        "From source with checksum " + getSrcChecksum()
        };
    }
  
    /**
     * Get the checksum of the source files from which Hadoop was compiled.
     * @return a string that uniquely identifies the source
     **/
    public static String getSrcChecksum() {
      return Version.srcChecksum;
    }
  
   public static void writeTo(PrintWriter out) {
     for (String line : versionReport()) {
       out.println(line);
     }
   }
 
   public static void writeTo(PrintStream out) {
     for (String line : versionReport()) {
       out.println(line);
     }
   }
 
   public static void logVersion() {
     for (String line : versionReport()) {
       LOG.info(line);
     }
   }
 
   public static int compareVersion(String v1, String v2) {
     //fast compare equals first
     if (v1.equals(v2)) {
       return 0;
     }
     String[] v1Comps = getVersionComponents(v1);
     String[] v2Comps = getVersionComponents(v2);
 
     int length = Math.max(v1Comps.length, v2Comps.length);
     for (int i = 0; i < length; i++) {
       Integer va = i < v1Comps.length ? Integer.parseInt(v1Comps[i]) : 0;
       Integer vb = i < v2Comps.length ? Integer.parseInt(v2Comps[i]) : 0;
       int compare = va.compareTo(vb);
       if (compare != 0) {
         return compare;
       }
     }
     return 0;
   }
 
   /**
    * Returns the version components as String objects
    * Examples: "1.2.3" returns ["1", "2", "3"], "4.5.6-SNAPSHOT" returns ["4", "5", "6", "-1"]
    * "4.5.6-beta" returns ["4", "5", "6", "-2"], "4.5.6-alpha" returns ["4", "5", "6", "-3"]
    * "4.5.6-UNKNOW" returns ["4", "5", "6", "-4"]
    * @return the components of the version string
    */
   private static String[] getVersionComponents(final String version) {
     assert(version != null);
     String[] strComps = version.split("[\\.-]");
     assert(strComps.length > 0);
 
     String[] comps = new String[strComps.length];
     for (int i = 0; i < strComps.length; ++i) {
       if (StringUtils.isEmpty(strComps[i])) {
         comps[i] = String.valueOf(VERY_LARGE_NUMBER);
       } else if (StringUtils.isNumeric(strComps[i])) {
         comps[i] = strComps[i];
       } else {
         if("SNAPSHOT".equals(strComps[i])) {
           comps[i] = "-1";
         } else if("beta".equals(strComps[i])) {
           comps[i] = "-2";
         } else if("alpha".equals(strComps[i])) {
           comps[i] = "-3";
         } else {
           comps[i] = "-4";
         }
       }
     }
     return comps;
   }
 
   public static void main(String[] args) {
     writeTo(System.out);
   }
 }