package org.apache.maven.plugins.artifact.buildinfo;
   
   /*
    * 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.
   */
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.maven.shared.utils.StringUtils;
  import org.apache.maven.shared.utils.cli.CommandLineException;
  import org.apache.maven.shared.utils.cli.CommandLineUtils;
  import org.apache.maven.shared.utils.cli.Commandline;
  import org.apache.maven.shared.utils.cli.StreamConsumer;
  import org.apache.maven.toolchain.Toolchain;
  
  /**
   * A helper to get JDK version from a JDK toolchain.
   */
  class JdkToolchainUtil
  {
      static String getJavaVersion( Toolchain toolchain )
      {
          String version = "unknown";
          String java = toolchain.findTool( "java" );
          if ( java != null )
          {
              try
              {
                  Commandline cl = new Commandline( java + " -version" );
                  LineConsumer out = new LineConsumer(); 
                  LineConsumer err = new LineConsumer(); 
                  CommandLineUtils.executeCommandLine( cl, out, err );
                  version = StringUtils.join( err.getLines().iterator(), ":" );
                  if ( version == null )
                  {
                      version = "unable to detect...";
                  }
              }
              catch ( CommandLineException cle )
              {
                  version = cle.toString();
              }
          }
          return version;
      }
  
      private static class LineConsumer implements StreamConsumer
      {
          private List<String> lines = new ArrayList<>();
  
          @Override
          public void consumeLine( String line )
              throws IOException
          {
              lines.add( line );
          }
  
          List<String> getLines()
          {
              return lines;
          }
      }
  }