/**
 * Copyright (C) 2013 Regents of the University of California.
 * @author: Jeff Thompson <jefft0@remap.ucla.edu>
 * See COPYING for copyright and distribution information.
 */

#include <cstdlib>
#include <sstream>
#include <iostream>
#include <time.h>
#include <stdint.h>
#include <ndn-cpp/data.hpp>
#include <ndn-cpp/security/identity/memory-identity-storage.hpp>
#include <ndn-cpp/security/identity/memory-private-key-storage.hpp>
#include <ndn-cpp/security/policy/self-verify-policy-manager.hpp>
#include <ndn-cpp/security/key-chain.hpp>
#include <ndn-cpp/sha256-with-rsa-signature.hpp>

using namespace std;
using namespace ndn;
using namespace ndn::func_lib;
#if NDN_CPP_HAVE_STD_FUNCTION
// In the std library, the placeholders are in a different namespace than boost.                                                           
using namespace func_lib::placeholders;
#endif

static uint8_t DEFAULT_PUBLIC_KEY_DER[] = {
0x30, 0x81, 0x9F, 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x81,
0x8D, 0x00, 0x30, 0x81, 0x89, 0x02, 0x81, 0x81, 0x00, 0xE1, 0x7D, 0x30, 0xA7, 0xD8, 0x28, 0xAB, 0x1B, 0x84, 0x0B, 0x17,
0x54, 0x2D, 0xCA, 0xF6, 0x20, 0x7A, 0xFD, 0x22, 0x1E, 0x08, 0x6B, 0x2A, 0x60, 0xD1, 0x6C, 0xB7, 0xF5, 0x44, 0x48, 0xBA,
0x9F, 0x3F, 0x08, 0xBC, 0xD0, 0x99, 0xDB, 0x21, 0xDD, 0x16, 0x2A, 0x77, 0x9E, 0x61, 0xAA, 0x89, 0xEE, 0xE5, 0x54, 0xD3,
0xA4, 0x7D, 0xE2, 0x30, 0xBC, 0x7A, 0xC5, 0x90, 0xD5, 0x24, 0x06, 0x7C, 0x38, 0x98, 0xBB, 0xA6, 0xF5, 0xDC, 0x43, 0x60,
0xB8, 0x45, 0xED, 0xA4, 0x8C, 0xBD, 0x9C, 0xF1, 0x26, 0xA7, 0x23, 0x44, 0x5F, 0x0E, 0x19, 0x52, 0xD7, 0x32, 0x5A, 0x75,
0xFA, 0xF5, 0x56, 0x14, 0x4F, 0x9A, 0x98, 0xAF, 0x71, 0x86, 0xB0, 0x27, 0x86, 0x85, 0xB8, 0xE2, 0xC0, 0x8B, 0xEA, 0x87,
0x17, 0x1B, 0x4D, 0xEE, 0x58, 0x5C, 0x18, 0x28, 0x29, 0x5B, 0x53, 0x95, 0xEB, 0x4A, 0x17, 0x77, 0x9F, 0x02, 0x03, 0x01,
0x00, 01  
};

static uint8_t DEFAULT_PRIVATE_KEY_DER[] = {
0x30, 0x82, 0x02, 0x5d, 0x02, 0x01, 0x00, 0x02, 0x81, 0x81, 0x00, 0xe1, 0x7d, 0x30, 0xa7, 0xd8, 0x28, 0xab, 0x1b, 0x84,
0x0b, 0x17, 0x54, 0x2d, 0xca, 0xf6, 0x20, 0x7a, 0xfd, 0x22, 0x1e, 0x08, 0x6b, 0x2a, 0x60, 0xd1, 0x6c, 0xb7, 0xf5, 0x44,
0x48, 0xba, 0x9f, 0x3f, 0x08, 0xbc, 0xd0, 0x99, 0xdb, 0x21, 0xdd, 0x16, 0x2a, 0x77, 0x9e, 0x61, 0xaa, 0x89, 0xee, 0xe5,
0x54, 0xd3, 0xa4, 0x7d, 0xe2, 0x30, 0xbc, 0x7a, 0xc5, 0x90, 0xd5, 0x24, 0x06, 0x7c, 0x38, 0x98, 0xbb, 0xa6, 0xf5, 0xdc,
0x43, 0x60, 0xb8, 0x45, 0xed, 0xa4, 0x8c, 0xbd, 0x9c, 0xf1, 0x26, 0xa7, 0x23, 0x44, 0x5f, 0x0e, 0x19, 0x52, 0xd7, 0x32,
0x5a, 0x75, 0xfa, 0xf5, 0x56, 0x14, 0x4f, 0x9a, 0x98, 0xaf, 0x71, 0x86, 0xb0, 0x27, 0x86, 0x85, 0xb8, 0xe2, 0xc0, 0x8b,
0xea, 0x87, 0x17, 0x1b, 0x4d, 0xee, 0x58, 0x5c, 0x18, 0x28, 0x29, 0x5b, 0x53, 0x95, 0xeb, 0x4a, 0x17, 0x77, 0x9f, 0x02,
0x03, 0x01, 0x00, 0x01, 0x02, 0x81, 0x80, 0x1a, 0x4b, 0xfa, 0x4f, 0xa8, 0xc2, 0xdd, 0x69, 0xa1, 0x15, 0x96, 0x0b, 0xe8,
0x27, 0x42, 0x5a, 0xf9, 0x5c, 0xea, 0x0c, 0xac, 0x98, 0xaa, 0xe1, 0x8d, 0xaa, 0xeb, 0x2d, 0x3c, 0x60, 0x6a, 0xfb, 0x45,
0x63, 0xa4, 0x79, 0x83, 0x67, 0xed, 0xe4, 0x15, 0xc0, 0xb0, 0x20, 0x95, 0x6d, 0x49, 0x16, 0xc6, 0x42, 0x05, 0x48, 0xaa,
0xb1, 0xa5, 0x53, 0x65, 0xd2, 0x02, 0x99, 0x08, 0xd1, 0x84, 0xcc, 0xf0, 0xcd, 0xea, 0x61, 0xc9, 0x39, 0x02, 0x3f, 0x87,
0x4a, 0xe5, 0xc4, 0xd2, 0x07, 0x02, 0xe1, 0x9f, 0xa0, 0x06, 0xc2, 0xcc, 0x02, 0xe7, 0xaa, 0x6c, 0x99, 0x8a, 0xf8, 0x49,
0x00, 0xf1, 0xa2, 0x8c, 0x0c, 0x8a, 0xb9, 0x4f, 0x6d, 0x73, 0x3b, 0x2c, 0xb7, 0x9f, 0x8a, 0xa6, 0x7f, 0x9b, 0x9f, 0xb7,
0xa1, 0xcc, 0x74, 0x2e, 0x8f, 0xb8, 0xb0, 0x26, 0x89, 0xd2, 0xe5, 0x66, 0xe8, 0x8e, 0xa1, 0x02, 0x41, 0x00, 0xfc, 0xe7,
0x52, 0xbc, 0x4e, 0x95, 0xb6, 0x1a, 0xb4, 0x62, 0xcc, 0xd8, 0x06, 0xe1, 0xdc, 0x7a, 0xa2, 0xb6, 0x71, 0x01, 0xaa, 0x27,
0xfc, 0x99, 0xe5, 0xf2, 0x54, 0xbb, 0xb2, 0x85, 0xe1, 0x96, 0x54, 0x2d, 0xcb, 0xba, 0x86, 0xfa, 0x80, 0xdf, 0xcf, 0x39,
0xe6, 0x74, 0xcb, 0x22, 0xce, 0x70, 0xaa, 0x10, 0x00, 0x73, 0x1d, 0x45, 0x0a, 0x39, 0x51, 0x84, 0xf5, 0x15, 0x8f, 0x37,
0x76, 0x91, 0x02, 0x41, 0x00, 0xe4, 0x3f, 0xf0, 0xf4, 0xde, 0x79, 0x77, 0x48, 0x9b, 0x9c, 0x28, 0x45, 0x26, 0x57, 0x3c,
0x71, 0x40, 0x28, 0x6a, 0xa1, 0xfe, 0xc3, 0xe5, 0x37, 0xa1, 0x03, 0xf6, 0x2d, 0xbe, 0x80, 0x64, 0x72, 0x69, 0x2e, 0x9b,
0x4d, 0xe3, 0x2e, 0x1b, 0xfe, 0xe7, 0xf9, 0x77, 0x8c, 0x18, 0x53, 0x9f, 0xe2, 0xfe, 0x00, 0xbb, 0x49, 0x20, 0x47, 0xdf,
0x01, 0x61, 0x87, 0xd6, 0xe3, 0x44, 0xb5, 0x03, 0x2f, 0x02, 0x40, 0x54, 0xec, 0x7c, 0xbc, 0xdd, 0x0a, 0xaa, 0xde, 0xe6,
0xc9, 0xf2, 0x8d, 0x6c, 0x2a, 0x35, 0xf6, 0x3c, 0x63, 0x55, 0x29, 0x40, 0xf1, 0x32, 0x82, 0x9f, 0x53, 0xb3, 0x9e, 0x5f,
0xc1, 0x53, 0x52, 0x3e, 0xac, 0x2e, 0x28, 0x51, 0xa1, 0x16, 0xdb, 0x90, 0xe3, 0x99, 0x7e, 0x88, 0xa4, 0x04, 0x7c, 0x92,
0xae, 0xd2, 0xe7, 0xd4, 0xe1, 0x55, 0x20, 0x90, 0x3e, 0x3c, 0x6a, 0x63, 0xf0, 0x34, 0xf1, 0x02, 0x41, 0x00, 0x84, 0x5a,
0x17, 0x6c, 0xc6, 0x3c, 0x84, 0xd0, 0x93, 0x7a, 0xff, 0x56, 0xe9, 0x9e, 0x98, 0x2b, 0xcb, 0x5a, 0x24, 0x4a, 0xff, 0x21,
0xb4, 0x9e, 0x87, 0x3d, 0x76, 0xd8, 0x9b, 0xa8, 0x73, 0x96, 0x6c, 0x2b, 0x5c, 0x5e, 0xd3, 0xa6, 0xff, 0x10, 0xd6, 0x8e,
0xaf, 0xa5, 0x8a, 0xcd, 0xa2, 0xde, 0xcb, 0x0e, 0xbd, 0x8a, 0xef, 0xae, 0xfd, 0x3f, 0x1d, 0xc0, 0xd8, 0xf8, 0x3b, 0xf5,
0x02, 0x7d, 0x02, 0x41, 0x00, 0x8b, 0x26, 0xd3, 0x2c, 0x7d, 0x28, 0x38, 0x92, 0xf1, 0xbf, 0x15, 0x16, 0x39, 0x50, 0xc8,
0x6d, 0x32, 0xec, 0x28, 0xf2, 0x8b, 0xd8, 0x70, 0xc5, 0xed, 0xe1, 0x7b, 0xff, 0x2d, 0x66, 0x8c, 0x86, 0x77, 0x43, 0xeb,
0xb6, 0xf6, 0x50, 0x66, 0xb0, 0x40, 0x24, 0x6a, 0xaf, 0x98, 0x21, 0x45, 0x30, 0x01, 0x59, 0xd0, 0xc3, 0xfc, 0x7b, 0xae,
0x30, 0x18, 0xeb, 0x90, 0xfb, 0x17, 0xd3, 0xce, 0xb5
};

uint8_t Data1[] = {
0x04, 0x82, // NDN Data
  0x02, 0xaa, // Signature
    0x03, 0xb2, // SignatureBits
      0x08, 0x85, 0x20, 0xea, 0xb5, 0xb0, 0x63, 0xda, 0x94, 0xe9, 0x68, 0x7a,
      0x8e, 0x65, 0x60, 0xe0, 0xc6, 0x43, 0x96, 0xd9, 0x69, 0xb4, 0x40, 0x72, 0x52, 0x00, 0x2c, 0x8e, 0x2a, 0xf5,
      0x47, 0x12, 0x59, 0x93, 0xda, 0xed, 0x82, 0xd0, 0xf8, 0xe6, 0x65, 0x09, 0x87, 0x84, 0x54, 0xc7, 0xce, 0x9a,
      0x93, 0x0d, 0x47, 0xf1, 0xf9, 0x3b, 0x98, 0x78, 0x2c, 0x22, 0x21, 0xd9, 0x2b, 0xda, 0x03, 0x30, 0x84, 0xf3,
      0xc5, 0x52, 0x64, 0x2b, 0x1d, 0xde, 0x50, 0xe0, 0xee, 0xca, 0xa2, 0x73, 0x7a, 0x93, 0x30, 0xa8, 0x47, 0x7f,
      0x6f, 0x41, 0xb0, 0xc8, 0x6e, 0x89, 0x1c, 0xcc, 0xf9, 0x01, 0x44, 0xc3, 0x08, 0xcf, 0x77, 0x47, 0xfc, 0xed,
      0x48, 0xf0, 0x4c, 0xe9, 0xc2, 0x3b, 0x7d, 0xef, 0x6e, 0xa4, 0x80, 0x40, 0x9e, 0x43, 0xb6, 0x77, 0x7a, 0x1d,
      0x51, 0xed, 0x98, 0x33, 0x93, 0xdd, 0x88, 0x01, 0x0e, 0xd3, 
    0x00, 
  0x00, 
  0xf2, 0xfa, 0x9d, 0x6e, 0x64, 0x6e, 0x00, 0xfa, 0x9d, 0x61, 0x62, 0x63, 0x00, 0x00,  // Name
  0x01, 0xa2, // SignedInfo
    0x03, 0xe2, // PublisherPublicKeyDigest
      0x02, 0x85, 0xb5, 0x50, 0x6b, 0x1a,
      0xba, 0x3d, 0xa7, 0x76, 0x1b, 0x0f, 0x8d, 0x61, 0xa4, 0xaa, 0x7e, 0x3b, 0x6d, 0x15, 0xb4, 0x26, 0xfe, 0xb5,
      0xbd, 0xa8, 0x23, 0x89, 0xac, 0xa7, 0x65, 0xa3, 0xb8, 0x1c, 
    0x00, 
    0x02, 0xba, // Timestamp
      0xb5, 0x05, 0x1d, 0xde, 0xe9, 0x5b, 0xdb, 
    0x00, 
    0x01, 0xe2, // KeyLocator
      0x01, 0xda, // Key
        0x0a, 0x95, 0x30, 0x81, 0x9f, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86,
        0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x81, 0x8d, 0x00, 0x30, 0x81, 0x89, 0x02, 0x81,
        0x81, 0x00, 0xe1, 0x7d, 0x30, 0xa7, 0xd8, 0x28, 0xab, 0x1b, 0x84, 0x0b, 0x17, 0x54, 0x2d, 0xca, 0xf6, 0x20,
        0x7a, 0xfd, 0x22, 0x1e, 0x08, 0x6b, 0x2a, 0x60, 0xd1, 0x6c, 0xb7, 0xf5, 0x44, 0x48, 0xba, 0x9f, 0x3f, 0x08,
        0xbc, 0xd0, 0x99, 0xdb, 0x21, 0xdd, 0x16, 0x2a, 0x77, 0x9e, 0x61, 0xaa, 0x89, 0xee, 0xe5, 0x54, 0xd3, 0xa4,
        0x7d, 0xe2, 0x30, 0xbc, 0x7a, 0xc5, 0x90, 0xd5, 0x24, 0x06, 0x7c, 0x38, 0x98, 0xbb, 0xa6, 0xf5, 0xdc, 0x43,
        0x60, 0xb8, 0x45, 0xed, 0xa4, 0x8c, 0xbd, 0x9c, 0xf1, 0x26, 0xa7, 0x23, 0x44, 0x5f, 0x0e, 0x19, 0x52, 0xd7,
        0x32, 0x5a, 0x75, 0xfa, 0xf5, 0x56, 0x14, 0x4f, 0x9a, 0x98, 0xaf, 0x71, 0x86, 0xb0, 0x27, 0x86, 0x85, 0xb8,
        0xe2, 0xc0, 0x8b, 0xea, 0x87, 0x17, 0x1b, 0x4d, 0xee, 0x58, 0x5c, 0x18, 0x28, 0x29, 0x5b, 0x53, 0x95, 0xeb,
        0x4a, 0x17, 0x77, 0x9f, 0x02, 0x03, 0x01, 0x00, 0x01, 
      0x00, 
    0x00, 
  0x00, 
  0x01, 0x9a, // Content
    0xc5, 0x53, 0x55, 0x43, 0x43, 0x45, 0x53, 0x53, 0x21, 
  0x00, 
0x00,
1
};

static void dumpData(const Data& data)
{
  cout << "name: " << data.getName().to_uri() << endl;
  if (data.getContent().size() > 0) {
    cout << "content (raw): ";
    for (size_t i = 0; i < data.getContent().size(); ++i)
      cout << (*data.getContent())[i];
    cout<< endl;
    cout << "content (hex): " << toHex(*data.getContent()) << endl;
  }
  else
    cout << "content: <empty>" << endl;
  
  cout << "metaInfo.timestamp: ";
  if (data.getMetaInfo().getTimestampMilliseconds() >= 0) {
    time_t seconds = data.getMetaInfo().getTimestampMilliseconds() / 1000.0;
    cout << data.getMetaInfo().getTimestampMilliseconds() << " milliseconds, UTC time: " << asctime(gmtime(&seconds));
  }
  else
    cout << "<none>" << endl;
  if (!(data.getMetaInfo().getType() < 0 || data.getMetaInfo().getType() == ndn_ContentType_DATA)) {
    cout << "metaInfo.type: ";
    if (data.getMetaInfo().getType() == ndn_ContentType_ENCR)
      cout << "ENCR" << endl;
    else if (data.getMetaInfo().getType() == ndn_ContentType_GONE)
      cout << "GONE" << endl;
    else if (data.getMetaInfo().getType() == ndn_ContentType_KEY)
      cout << "KEY" << endl;
    else if (data.getMetaInfo().getType() == ndn_ContentType_LINK)
      cout << "LINK" << endl;
    else if (data.getMetaInfo().getType() == ndn_ContentType_NACK)
      cout << "NACK" << endl;
  }
  cout << "metaInfo.freshnessSeconds: ";
  if (data.getMetaInfo().getFreshnessSeconds() >= 0)
    cout << data.getMetaInfo().getFreshnessSeconds() << endl;
  else
    cout << "<none>" << endl;
  cout << "metaInfo.finalBlockID: "
       << (data.getMetaInfo().getFinalBlockID().getValue().size() > 0 ? 
           toHex(*data.getMetaInfo().getFinalBlockID().getValue()).c_str() : "<none>") << endl;
    
  const Sha256WithRsaSignature *signature = dynamic_cast<const Sha256WithRsaSignature*>(data.getSignature());
  if (signature) {
    cout << "signature.digestAlgorithm: "
         << (signature->getDigestAlgorithm().size() > 0 ? toHex(*signature->getDigestAlgorithm()).c_str() : "default (sha-256)") << endl;
    cout << "signature.witness: "
         << (signature->getWitness().size() > 0 ? toHex(*signature->getWitness()).c_str() : "<none>") << endl;
    cout << "signature.signature: "
         << (signature->getSignature().size() > 0 ? toHex(*signature->getSignature()).c_str() : "<none>") << endl;
    cout << "signature.publisherPublicKeyDigest: "
         << (signature->getPublisherPublicKeyDigest().getPublisherPublicKeyDigest().size() > 0 ? 
           toHex(*signature->getPublisherPublicKeyDigest().getPublisherPublicKeyDigest()).c_str() : "<none>") << endl;
    cout << "signature.keyLocator: ";
    if ((int)signature->getKeyLocator().getType() >= 0) {
      if (signature->getKeyLocator().getType() == ndn_KeyLocatorType_KEY)
        cout << "Key: " << toHex(*signature->getKeyLocator().getKeyData()) << endl;
      else if (signature->getKeyLocator().getType() == ndn_KeyLocatorType_CERTIFICATE)
        cout << "Certificate: " << toHex(*signature->getKeyLocator().getKeyData()) << endl;
      else if (signature->getKeyLocator().getType() == ndn_KeyLocatorType_KEYNAME) {
        cout << "KeyName: " << signature->getKeyLocator().getKeyName().to_uri() << endl;
        cout << "signature.keyLocator: ";
        if ((int)signature->getKeyLocator().getKeyNameType() >= 0) {
          bool showKeyNameData = true;
          if (signature->getKeyLocator().getKeyNameType() == ndn_KeyNameType_PUBLISHER_PUBLIC_KEY_DIGEST)
            cout << "PublisherPublicKeyDigest: ";
          else if (signature->getKeyLocator().getKeyNameType() == ndn_KeyNameType_PUBLISHER_CERTIFICATE_DIGEST)
            cout << "PublisherCertificateDigest: ";
          else if (signature->getKeyLocator().getKeyNameType() == ndn_KeyNameType_PUBLISHER_ISSUER_KEY_DIGEST)
            cout << "PublisherIssuerKeyDigest: ";
          else if (signature->getKeyLocator().getKeyNameType() == ndn_KeyNameType_PUBLISHER_ISSUER_CERTIFICATE_DIGEST)
            cout << "PublisherIssuerCertificateDigest: ";
          else {
            cout << "<unrecognized ndn_KeyNameType " << signature->getKeyLocator().getKeyNameType() << ">" << endl;
            showKeyNameData = false;
          }
          if (showKeyNameData)
            cout << (signature->getKeyLocator().getKeyData().size() > 0 ?
                     toHex(*signature->getKeyLocator().getKeyData()).c_str() : "<none>") << endl;
        }
        else
          cout << "<no key digest>" << endl;
      }
      else
        cout << "<unrecognized ndn_KeyLocatorType " << signature->getKeyLocator().getType() << ">" << endl;
    }
    else
      cout << "<none>" << endl;
  }
}

static void onVerified(const char *prefix, const ptr_lib::shared_ptr<Data>& data)
{
  cout << prefix << " signature verification: VERIFIED" << endl;
}

static void onVerifyFailed(const char *prefix, const ptr_lib::shared_ptr<Data>& data)
{
  cout << prefix << " signature verification: FAILED" << endl;
}

int main(int argc, char** argv)
{
  try {
    ptr_lib::shared_ptr<Data> data(new Data());
    data->wireDecode(Data1, sizeof(Data1));
    cout << "Decoded Data:" << endl;
    dumpData(*data);
    
    Blob encoding = data->wireEncode();
    
    ptr_lib::shared_ptr<Data> reDecodedData(new Data());
    reDecodedData->wireDecode(*encoding);
    cout << endl << "Re-decoded Data:" << endl;
    dumpData(*reDecodedData);
  
    ptr_lib::shared_ptr<Data> freshData(new Data(Name("/ndn/abc")));
    const uint8_t freshContent[] = "SUCCESS!";
    freshData->setContent(freshContent, sizeof(freshContent) - 1);
    freshData->getMetaInfo().setTimestampMilliseconds(time(NULL) * 1000.0);
    
    ptr_lib::shared_ptr<MemoryIdentityStorage> identityStorage(new MemoryIdentityStorage());
    ptr_lib::shared_ptr<MemoryPrivateKeyStorage> privateKeyStorage(new MemoryPrivateKeyStorage());
    KeyChain keyChain
      (ptr_lib::make_shared<IdentityManager>(identityStorage, privateKeyStorage), 
       ptr_lib::make_shared<SelfVerifyPolicyManager>(identityStorage.get()));
    
    // Initialize the storage.
    Name keyName("/testname/DSK-123");
    Name certificateName = keyName.getSubName(0, keyName.size() - 1).append("KEY").append
           (keyName.get(keyName.size() - 1)).append("ID-CERT").append("0");
    identityStorage->addKey(keyName, KEY_TYPE_RSA, Blob(DEFAULT_PUBLIC_KEY_DER, sizeof(DEFAULT_PUBLIC_KEY_DER)));
    privateKeyStorage->setKeyPairForKeyName
      (keyName, DEFAULT_PUBLIC_KEY_DER, sizeof(DEFAULT_PUBLIC_KEY_DER), DEFAULT_PRIVATE_KEY_DER, sizeof(DEFAULT_PRIVATE_KEY_DER));
    
    keyChain.sign(*freshData, certificateName);
    cout << endl << "Freshly-signed Data:" << endl;
    dumpData(*freshData);
    
    keyChain.verifyData(freshData, bind(&onVerified, "Freshly-signed Data", _1), bind(&onVerifyFailed, "Freshly-signed Data", _1));
  } catch (std::exception& e) {
    cout << "exception: " << e.what() << endl;
  }
  return 0;
}