/**
 * Copyright (C) 2013 Regents of the University of California.
 * @author: Jeff Thompson <jefft0@remap.ucla.edu>
 * @author: Yingdi Yu <yingdi@cs.ucla.edu>
 * @author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 * See COPYING for copyright and distribution information.
 */

#include "asn_ext.hpp"
#include "../../util/time.hpp"

#include <boost/format.hpp>
#include <boost/lexical_cast.hpp>

using namespace CryptoPP;

namespace ndn {

size_t
DEREncodeGeneralTime(CryptoPP::BufferedTransformation &bt, const time::system_clock::TimePoint& time)
{
  std::string str = time::toIsoString(time);
  // For example, 20131226T232254
  // 20131226T232254.100000
  BOOST_ASSERT(str.size() >= 15);
  std::string asn1time = str.substr(0, 8) + str.substr(9,6) + "Z";

  bt.Put(GENERALIZED_TIME);
  size_t lengthBytes = DERLengthEncode(bt, asn1time.size());
  bt.Put(reinterpret_cast<const uint8_t*>(asn1time.c_str()), asn1time.size());
  return 1+lengthBytes+asn1time.size();
}

void
BERDecodeTime(CryptoPP::BufferedTransformation &bt, time::system_clock::TimePoint& time)
{
  byte b;
  if (!bt.Get(b) || (b != GENERALIZED_TIME && b != UTC_TIME))
    BERDecodeError();

  size_t bc;
  if (!BERLengthDecode(bt, bc))
    BERDecodeError();

  SecByteBlock time_str(bc);
  if (bc != bt.Get(time_str, bc))
    BERDecodeError();

  std::string str;
  str.assign (time_str.begin(), time_str.end());
  
  if (b == UTC_TIME) {
    if (boost::lexical_cast<int>(str.substr(0,2)) < 50)
      str = "20" + str;
    else
      str = "19" + str;
  }
 
  time = time::fromIsoString(str.substr(0, 8) + "T" + str.substr(8, 6));
}

} // namespace ndn