/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
/**
 * Copyright (C) 2013 Regents of the University of California.
 * @author: Yingdi Yu <yingdi@cs.ucla.edu>
 * @author: Jeff Thompson <jefft0@remap.ucla.edu>
 * See COPYING for copyright and distribution information.
 */

#include "common.hpp"

#include "validator.hpp"
#include "../util/logging.hpp"
#include "../util/crypto.hpp"

#include <cryptopp/rsa.h>
#include <cryptopp/files.h>
#include <cryptopp/hex.h>


using namespace std;

INIT_LOGGER("ndn.Validator");

namespace ndn {

const shared_ptr<Face> Validator::DefaultFace = shared_ptr<Face>();

Validator::Validator(shared_ptr<Face> face /* = DefaultFace */)                   
  : m_face(face)
{}

void
Validator::validate(const Interest& interest, 
                    const OnInterestValidated &onValidated, 
                    const OnInterestValidationFailed &onValidationFailed,
                    int stepCount)
{
  vector<shared_ptr<ValidationRequest> > nextSteps;
  checkPolicy(interest, stepCount, onValidated, onValidationFailed, nextSteps);
  
  if (!nextSteps.empty())
    {
      if(!static_cast<bool>(m_face))
        throw Error("Face should be set prior to verify method to call");
      
      vector<shared_ptr<ValidationRequest> >::const_iterator it = nextSteps.begin();
      OnFailure onFailure = bind(onValidationFailed, interest.shared_from_this(), _1);
      for(; it != nextSteps.end(); it++)
        m_face->expressInterest((*it)->m_interest,
                                bind(&Validator::onData, this, _1, _2, *it), 
                                bind(&Validator::onTimeout, 
                                     this, _1, (*it)->m_retry, 
                                     onFailure, 
                                     *it));
    }
  else
    {
      //If there is no nextStep, that means InterestPolicy has already been able to verify the Interest.
      //No more further processes.
    }
}

void
Validator::validate(const Data& data, 
                    const OnDataValidated &onValidated, 
                    const OnDataValidationFailed &onValidationFailed,
                    int stepCount)
{
  vector<shared_ptr<ValidationRequest> > nextSteps;
  checkPolicy(data, stepCount, onValidated, onValidationFailed, nextSteps);

  if (!nextSteps.empty())
    {
      if(!static_cast<bool>(m_face))
        throw Error("Face should be set prior to verify method to call");

      vector<shared_ptr<ValidationRequest> >::const_iterator it = nextSteps.begin();
      OnFailure onFailure = bind(onValidationFailed, data.shared_from_this(), _1);
      for(; it != nextSteps.end(); it++)
        m_face->expressInterest((*it)->m_interest,
                                bind(&Validator::onData, this, _1, _2, *it), 
                                bind(&Validator::onTimeout, 
                                     this, _1, (*it)->m_retry, 
                                     onFailure,
                                     *it));
    }
  else
    {
      //If there is no nextStep, that means InterestPolicy has already been able to verify the Interest.
      //No more further processes.
    }
}

void
Validator::onData(const Interest& interest, 
                  Data& data, 
                  const shared_ptr<ValidationRequest>& nextStep)
{
  validate(data, nextStep->m_onValidated, nextStep->m_onDataValidated, nextStep->m_stepCount);
}

void
Validator::onTimeout(const Interest& interest, 
                     int retry, 
                     const OnFailure &onFailure, 
                     const shared_ptr<ValidationRequest>& nextStep)
{
  if (retry > 0)
    // Issue the same expressInterest except decrement retry.
    m_face->expressInterest(interest, 
                            bind(&Validator::onData, this, _1, _2, nextStep), 
                            bind(&Validator::onTimeout, this, _1, retry - 1, onFailure, nextStep));
  else
    onFailure("Cannot fetch cert: " + interest.getName().toUri());
}

bool
Validator::verifySignature(const Data& data, const PublicKey& key)
{
  try
    {
      switch(data.getSignature().getType()){
      case Signature::Sha256WithRsa:
        {
          SignatureSha256WithRsa sigSha256Rsa(data.getSignature());
          return verifySignature(data, sigSha256Rsa, key);
        }
      default:
        {
          _LOG_DEBUG("verifySignature: Unknown signature type: " << data.getSignature().getType());
          return false;
        }
      }
    }
  catch(Signature::Error &e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
  return false;
}

bool
Validator::verifySignature(const Interest& interest, const PublicKey& key)
{
  const Name &interestName = interest.getName();

  if(interestName.size() < 2)
    return false;

  try
    {
      const Block& nameBlock = interestName.wireEncode();

      Signature sig(interestName[-2].blockFromValue(), 
                    interestName[-1].blockFromValue());

      switch(sig.getType()){
      case Signature::Sha256WithRsa:
        {
          SignatureSha256WithRsa sigSha256Rsa(sig);

          return verifySignature(nameBlock.value(), 
                                 nameBlock.value_size() - interestName[-1].size(), 
                                 sigSha256Rsa, key);
        }
      default:
        {
          _LOG_DEBUG("verifySignature: Unknown signature type: " << sig.getType());
          return false;
        }
      }
    }
  catch(Signature::Error &e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
  catch(Block::Error &e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
  return false;
}

bool
Validator::verifySignature(const Buffer& data, const Signature& sig, const PublicKey& key)
{
  try
    {
      switch(sig.getType()){
      case Signature::Sha256WithRsa:
        {
          SignatureSha256WithRsa sigSha256Rsa(sig);
          return verifySignature(data, sigSha256Rsa, key);
        }
      default:
        {
          _LOG_DEBUG("verifySignature: Unknown signature type: " << sig.getType());
          return false;
        }
      }
    }
  catch(Signature::Error &e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
  return false;
}

bool
Validator::verifySignature(const uint8_t* buf, const size_t size, const SignatureSha256WithRsa& sig, const PublicKey& key)
{
  try
    {
      using namespace CryptoPP;

      RSA::PublicKey publicKey;
      ByteQueue queue;

      queue.Put(reinterpret_cast<const byte*>(key.get().buf()), key.get().size());
      publicKey.Load(queue);

      RSASS<PKCS1v15, SHA256>::Verifier verifier (publicKey);
      return verifier.VerifyMessage(buf, size, sig.getValue().value(), sig.getValue().value_size());
    }
  catch(CryptoPP::Exception& e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
}

bool
Validator::verifySignature(const uint8_t* buf, const size_t size, const SignatureSha256& sig)
{
  try
    {
      ConstBufferPtr buffer = crypto::sha256(buf, size);
      const Block& sigValue = sig.getValue();

      if(static_cast<bool>(buffer) 
         && buffer->size() == sigValue.value_size()
         && buffer->size() == crypto::SHA256_DIGEST_SIZE)
        {

          const uint8_t* p1 = buffer->buf();
          const uint8_t* p2 = sigValue.value();

          for(size_t i = 0; i < crypto::SHA256_DIGEST_SIZE; i++)
            if(p1[i] != p2[i]) 
              return false;
          return true;
        }
      else
        return false;
    }
  catch(CryptoPP::Exception& e)
    {
      _LOG_DEBUG("verifySignature: " << e.what());
      return false;
    }
}

} // namespace ndn