package emissary.util;
   
   import org.apache.commons.codec.binary.Hex;
   import org.apache.commons.io.IOUtils;
   
   import java.io.DataInputStream;
   import java.io.IOException;
   import java.io.InputStream;
   import java.nio.file.Files;
  import java.nio.file.Paths;
  
  /**
   * Pretend to be Emacs hexl mode
   */
  public class Hexl {
  
      static final int CHARS_PER_LINE = 16;
      static final int COUNTER_SIZE = 4;
      static final String printable = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()_+|~-=\\`{}[]:;<>?,./'\"";
  
      /**
       * Unformatted hex string
       */
      public static String toUnformattedHexString(byte[] data) {
          return Hex.encodeHexString(data);
      }
  
  
      /**
       * Print out the whole byte array as hex
       */
      public static String toHexString(byte[] data) {
          return toHexString(data, data.length);
      }
  
      /**
       * Print out a portion of the data as a hexdump for debugging
       * 
       * @param limit how many bytes of data to print starting from 0
       */
      @SuppressWarnings("PMD.UselessParentheses")
      public static String toHexString(byte[] data, int limit) {
  
          StringBuilder output = new StringBuilder(2048);
  
          int stop = data.length;
  
          if (limit < stop) {
              stop = limit;
          }
  
          int lineCount = 0;
  
          byte[] rhs = new byte[CHARS_PER_LINE];
  
          int j = 0;
  
          for (int i = 0; i < stop; i++, j++) {
  
  
              // end a line
              if (j >= CHARS_PER_LINE) {
                  output.append("  ").append(new String(rhs));
                  output.append(System.getProperty("line.separator", "\n"));
                  j = 0;
                  lineCount++;
              }
  
              // start a new line
              if (j == 0) {
                  String s = Integer.toHexString(lineCount);
                  int pad = COUNTER_SIZE - s.length();
                  while (pad-- > 0) {
                      output.append("0");
                  }
                  output.append(s);
                  output.append(": ");
              }
  
              String s = Integer.toHexString(data[i] & 0xff);
              if (s.length() < 2) {
                  output.append("0").append(s);
              } else {
                  output.append(s);
              }
  
              // Group hex entries
              if (j % 2 != 0) {
                  output.append(" ");
              }
  
              // Build the rhs
              if (printable.indexOf(data[i]) > -1) {
                  rhs[j] = data[i];
              } else {
                  rhs[j] = (byte) '.';
              }
          }
  
         int pad = ((CHARS_PER_LINE * 2) + (CHARS_PER_LINE / 2) + 1) - ((j * 2) + (j / 2) - 1);
         while (pad-- > 0) {
             output.append(" ");
         }
         while (j < CHARS_PER_LINE) {
             rhs[j++] = (byte) ' ';
         }
         output.append(new String(rhs));
 
         return output.toString();
     }
 
     /** This class is not meant to be instantiated. */
     private Hexl() {}
 
     @SuppressWarnings("SystemOut")
     public static void main(String[] argv) {
 
         if (argv.length < 1) {
             System.err.println("usage: java emissary.util.Hexl datafile1 datafile2 ...");
             return;
         }
 
         byte[] theContent;
 
         for (int i = 0; i < argv.length; i++) {
 
             try (InputStream theFile = Files.newInputStream(Paths.get(argv[i]));
                     DataInputStream theStream = new DataInputStream(theFile)) {
                 theContent = IOUtils.toByteArray(theStream);
             } catch (IOException e) {
                 System.err.println("Error reading from " + argv[i]);
                 continue;
             }
 
             System.out.println("File " + argv[i]);
             System.out.println(toHexString(theContent));
         }
     }
 }