(function () {
'use strict';

var input = process.argv[2];
var fs = require('fs');
var nb = fs.readFileSync(input, null);

var ab = nb.buffer.slice(nb.byteOffset, nb.byteOffset + nb.byteLength);
var dv = new DataView(ab);

//
// read header
//
console.log('');
console.log('//////////////////');
console.log('//    HEADER    //');
console.log('//////////////////');
console.log('');

console.log('id (int)', dv.getUint16(0));

var flags = dv.getUint16(2, false);
console.log('header 0x', flags.toString(16));
var flagsstr = ''
	+ 'qr ' + ((flags & 0x8000) >> 15) + ', '
  + 'opcode ' + ((flags & 0x7800) >> 11) + ', '
  + 'aa ' + ((flags &  0x400) >> 10) + ', '
  + 'tc ' + ((flags &  0x200) >>  9) + ', '
  + 'rd ' + ((flags &  0x100) >>  8) + ', '
  + 'ra ' + ((flags &   0x80) >>  7) + ', '
  + 'res1 ' + ((flags &   0x40) >>  6) + ', '
  + 'res2 ' + ((flags &   0x20) >>  5) + ', '
  + 'res3 ' + ((flags &   0x10) >>  4) + ', '
  + 'rcode ' + ((flags &    0xF));
console.log('(flags: ' + flagsstr);

var qdcount = dv.getUint16(4, false);  // query count
var ancount = dv.getUint16(6, false);  // answer count
var nscount = dv.getUint16(8, false);  // authority count
var arcount = dv.getUint16(10, false); // additional count
var count;

console.log('qdcount', qdcount);
console.log('ancount', ancount);
console.log('nscount', nscount);
console.log('arcount', arcount);

function unpackQuestion(dv, total, len) {
  var qnames = [];
  var labelLen;
  while (true) {
    if (total >= len) {
      break;
    }
    labelLen = dv.getUint8(total, false); // additional count
    total += 1;
    if (!labelLen) {
      break;
    }
    if (192 === labelLen) {
      console.log('ERROR: Compression pointer found');
      console.log(dv.getUint8(total, false));
      console.log(dv.getUint8(dv.getUint8(total + 0, false), false));
      console.log(dv.getUint8(dv.getUint8(total + 1, false), false));
      console.log(dv.getUint8(dv.getUint8(total + 2, false), false));
      break;
    }
    var i;
    var label = '';
    console.log('label len', labelLen);
    for (i = 0; i < labelLen; i += 1) {
      label += String.fromCharCode(dv.getUint8(total + i, false));
    }
    total += label.length;
    console.log('label:', label);
    qnames.push(label);
  }
  // leading length and (potentially) trailing null
  console.log('QNAME (len ' + (qnames.join('.').length + 1 + (labelLen ? 0 : 1)) + '):', qnames.join('.'));
  console.log('QTYPE (len 2):', dv.getUint16(total, false));
  total += 2;
  console.log('QCLASS (len 2):', dv.getUint16(total, false));
  total += 2;

  return {
    total: total
  , qname: qnames.join('.')
  };
}

var q = { total: 12 };
function mapChar(ch) { return JSON.stringify(String.fromCharCode(ch)) + '(' + ch + ')'; }


console.log('');
console.log('//////////////////');
console.log('//   QUESTION   //');
console.log('//////////////////');
console.log('');
for (count = 0; count < qdcount; count += 1) {
  console.log('');
  console.log('Question ' + (count + 1) + ' of ' + qdcount + ' (byte index: ' + q.total + ')');
  q = unpackQuestion(dv, q.total, ab.byteLength);
  console.log('');
}

console.log('');
console.log('//////////////////');
console.log('//    ANSWER    //');
console.log('//////////////////');
console.log('');
for (count = 0; count < ancount; count += 1) {
  console.log('');
  console.log('Answer', count + 1, 'of', ancount + ' (byte index: ' + q.total + ')');
  q = unpackQuestion(dv, q.total, ab.byteLength);
  console.log('');
}


console.log('');
console.log('//////////////////');
console.log('//   AUTHORITY  //');
console.log('//////////////////');
console.log('');
for (count = 0; count < nscount; count += 1) {
  console.log('');
  console.log('Authority', count + 1, 'of', nscount + ' (byte index: ' + q.total + ')');
  q = unpackQuestion(dv, q.total, ab.byteLength);
  console.log('ttl (len 4):', dv.getUint32(q.total, false));
  q.total += 4;
  q.rdlength = dv.getUint16(q.total, false);
  console.log('rdlen (len 2):', q.rdlength);
  q.total += 2;
  console.log('rrdata (len ' + q.rdlength + '):');
  console.log([].slice.call(new Uint8Array(ab), q.total, q.total + q.rdlength).map(mapChar).join(' '));
  q.total += q.rdlength;
  console.log('');
}

console.log('');
console.log('//////////////////');
console.log('//  ADDITIONAL  //');
console.log('//////////////////');
console.log('');
for (count = 0; count < arcount; count += 1) {
  console.log('');
  console.log('Additional', count + 1, 'of', arcount + ' (byte index: ' + q.total + ')');
  q = unpackQuestion(dv, q.total, ab.byteLength);
  console.log('');
}


}());