content: package hip.ch7.shortestpath;
  
  
  import hip.util.Cli;
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.io.LineIterator;
  import org.apache.commons.lang.StringUtils;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.Text;
  import org.apache.hadoop.mapreduce.Counter;
  import org.apache.hadoop.mapreduce.CounterGroup;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
  import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;
  import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
  import org.apache.hadoop.util.Tool;
  import org.apache.hadoop.util.ToolRunner;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.Iterator;
  
  public final class Main extends Configured implements Tool {
  
    /**
     * Main entry point for the example.
     *
     * @param args arguments
     * @throws Exception when something goes wrong
     */
    public static void main(final String[] args) throws Exception {
      int res = ToolRunner.run(new Configuration(), new Main(), args);
      System.exit(res);
    }
  
    /**
     * The MapReduce driver - setup and launch the job.
     *
     * @param args the command-line arguments
     * @return the process exit code
     * @throws Exception if something goes wrong
     */
    public int run(final String[] args) throws Exception {
  
      Cli cli = Cli.builder().setArgs(args).addOptions(Options.values()).build();
      int result = cli.runCmd();
  
      if (result != 0) {
        return result;
      }
  
      String startNode = cli.getArgValueAsString(Options.START);
      String targetNode = cli.getArgValueAsString(Options.END);
      Path inputPath = new Path(cli.getArgValueAsString(Options.INPUT));
      Path outputPath = new Path(cli.getArgValueAsString(Options.OUTPUT));
  
      iterate(super.getConf(), startNode, targetNode, inputPath, outputPath);
  
      return 0;
    }
  
    public static final String TARGET_NODE = "shortestpath.targetnode";
  
    public static void iterate(Configuration conf, String startNode, String targetNode,
                               Path input, Path outputPath)
        throws Exception {
  
      Path inputPath = new Path(outputPath, "input.txt");
  
      createInputFile(conf, input, inputPath, startNode);
  
      int iter = 1;
  
      while (true) {
  
        Path jobOutputPath =
            new Path(outputPath, String.valueOf(iter));
  
        System.out.println("======================================");
        System.out.println("=  Iteration:    " + iter);
        System.out.println("=  Input path:   " + inputPath);
        System.out.println("=  Output path:  " + jobOutputPath);
        System.out.println("======================================");
  
        if (findShortestPath(conf, inputPath, jobOutputPath, startNode, targetNode)) {
          break;
        }
        inputPath = jobOutputPath;
        iter++;
      }
    }
  
    public static void createInputFile(Configuration conf, Path file, Path targetFile,
                                       String startNode)
        throws IOException {
      FileSystem fs = file.getFileSystem(conf);
  
      OutputStream os = fs.create(targetFile);
      LineIterator iter = org.apache.commons.io.IOUtils
          .lineIterator(fs.open(file), "UTF8");
      while (iter.hasNext()) {
        String line = iter.nextLine();
  
        String[] parts = StringUtils.split(line);
        int distance = Node.INFINITE;
        if (startNode.equals(parts[0])) {
          distance = 0;
        }
        IOUtils.write(parts[0] + '\t' + String.valueOf(distance) + "\t\t",
            os);
        IOUtils.write(StringUtils.join(parts, '\t', 1, parts.length), os);
        IOUtils.write("\n", os);
      }
  
      os.close();
    }
  
    public static boolean findShortestPath(Configuration conf, Path inputPath,
                                           Path outputPath, String startNode,
                                           String targetNode)
        throws Exception {
      conf.set(TARGET_NODE, targetNode);
  
      Job job = new Job(conf);
      job.setJarByClass(Main.class);
      job.setMapperClass(Map.class);
      job.setReducerClass(Reduce.class);
  
      job.setInputFormatClass(KeyValueTextInputFormat.class);
  
      job.setMapOutputKeyClass(Text.class);
      job.setMapOutputValueClass(Text.class);
  
      FileInputFormat.setInputPaths(job, inputPath);
      FileOutputFormat.setOutputPath(job, outputPath);
  
      if (!job.waitForCompletion(true)) {
        throw new Exception("Job failed");
      }
  
      Counter counter = job.getCounters()
          .findCounter(Reduce.PathCounter.TARGET_NODE_DISTANCE_COMPUTED);
  
      if (counter != null && counter.getValue() > 0) {
        CounterGroup group = job.getCounters().getGroup(Reduce.PathCounter.PATH.toString());
        Iterator<Counter> iter = group.iterator();
        iter.hasNext();
        String path = iter.next().getName();
        System.out.println("==========================================");
        System.out.println("= Shortest path found, details as follows.");
        System.out.println("= ");
        System.out.println("= Start node:  " + startNode);
        System.out.println("= End node:    " + targetNode);
        System.out.println("= Hops:        " + counter.getValue());
        System.out.println("= Path:        " + path);
        System.out.println("==========================================");
        return true;
      }
      return false;
    }
  
    public enum Options implements Cli.ArgGetter {
      START(Cli.ArgBuilder.builder().hasArgument(true).required(true).description("Start person")),
      END(Cli.ArgBuilder.builder().hasArgument(true).required(true).description("End person")),
      INPUT(Cli.ArgBuilder.builder().hasArgument(true).required(true).description("Input file or directory")),
      OUTPUT(Cli.ArgBuilder.builder().hasArgument(true).required(true).description("HDFS output directory"));
      private final Cli.ArgInfo argInfo;
  
      Options(final Cli.ArgBuilder builder) {
        this.argInfo = builder.setArgName(name()).build();
      }
  
      @Override
      public Cli.ArgInfo getArgInfo() {
        return argInfo;
      }
    }
  
  }
  