/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2013, Regents of the University of California
 *                     Yingdi Yu
 *
 * BSD license, See the LICENSE file for more information
 *
 * Author: Yingdi Yu <yingdi@cs.ucla.edu>
 */

#include "sync-validator.h"
#include "sync-logging.h"
#include <ndn-cpp-dev/security/certificate-cache-ttl.hpp>
#include <queue>

using namespace ndn;
using namespace std;

INIT_LOGGER ("SyncValidator");

namespace Sync {

const shared_ptr<CertificateCache> SyncValidator::DefaultCertificateCache = shared_ptr<CertificateCache>();
const shared_ptr<SecRuleRelative> SyncValidator::DefaultDataRule = shared_ptr<SecRuleRelative>();

SyncValidator::SyncValidator(const Name& prefix,
                             const IdentityCertificate& anchor,
                             shared_ptr<Face> face,
                             shared_ptr<SecRuleRelative> rule,
                             shared_ptr<CertificateCache> certificateCache, 
                             const int stepLimit)
  : Validator(face)
  , m_prefix(prefix)
  , m_anchor(anchor)
  , m_stepLimit(stepLimit)
  , m_certificateCache(certificateCache)
  , m_dataRule(rule)
{
  if(!static_cast<bool>(face))
    throw Error("Face is not set!");

  if(!static_cast<bool>(m_certificateCache))
    m_certificateCache = make_shared<CertificateCacheTtl>(m_face->ioService());

  Name certPrefix = prefix;
  certPrefix.append("intro-cert");
  m_prefixId = m_face->setInterestFilter (certPrefix, 
                                          bind(&SyncValidator::onCertInterest, this, _1, _2), 
                                          bind(&SyncValidator::onCertRegisterFailed, this, _1, _2));

  setAnchor(m_anchor);
}

void
SyncValidator::deriveTrustNodes()
{
  queue<Name> nodeQueue;

  // Clear existing trust nodes.
  m_trustedNodes.clear();

  // Add the trust anchor.
  IntroNode origin(m_anchor);
  m_trustedNodes[origin.name()] = m_anchor.getPublicKeyInfo();
  nodeQueue.push(origin.name());

  // BFS trusted nodes.
  while(!nodeQueue.empty())
    {
      // Get next trusted node to process.
      Nodes::const_iterator it = m_introNodes.find(nodeQueue.front());
      const PublicKey& publicKey = m_trustedNodes[nodeQueue.front()];

      if(it != m_introNodes.end())
        {
          // If the trusted node exists in the graph.
          IntroNode::const_iterator eeIt = it->second.introduceeBegin();
          IntroNode::const_iterator eeEnd = it->second.introduceeEnd();
          for(; eeIt != eeEnd; eeIt++)
            {
              // Check the nodes introduced by the trusted node.
              Edges::const_iterator edgeIt = m_introCerts.find(*eeIt);
              if(edgeIt != m_introCerts.end() 
                 && m_trustedNodes.find(edgeIt->second.getIntroduceeName()) == m_trustedNodes.end()
                 && verifySignature(edgeIt->second, publicKey))
                {
                  // If the introduced node can be validated, add it into trusted node set and the node queue.
                  m_trustedNodes[edgeIt->second.getIntroduceeName()] = edgeIt->second.getIntroduceeCert().getPublicKeyInfo();
                  nodeQueue.push(edgeIt->second.getIntroduceeName());
                }
            }
        }
      nodeQueue.pop();
    }
}

void
SyncValidator::checkPolicy (const Data& data, 
                            int stepCount, 
                            const OnDataValidated& onValidated, 
                            const OnDataValidationFailed& onValidationFailed,
                            std::vector<shared_ptr<ValidationRequest> >& nextSteps)
{
  if(m_stepLimit == stepCount)
    return onValidationFailed(data.shared_from_this(), 
                              "Maximum steps of validation reached: " + data.getName().toUri());

  if(m_prefix.isPrefixOf(data.getName()))
    {
      try
        {
          SignatureSha256WithRsa sig(data.getSignature());
          Name keyLocatorName = sig.getKeyLocator().getName();

          TrustNodes::const_iterator it = m_trustedNodes.find(keyLocatorName);
          if(m_trustedNodes.end() != it)
            {
              if(verifySignature(data, sig, it->second))
                return onValidated(data.shared_from_this());
              else
                return onValidationFailed(data.shared_from_this(), 
                                          "Cannot verify signature: " + data.getName().toUri());
            }
          else
            {
              Name interestName = m_prefix;
              interestName.append("intro-cert").append(keyLocatorName.wireEncode());
              Interest interest(interestName);
              interest.setInterestLifetime(500);

              OnDataValidated onKeyValidated = bind(&SyncValidator::onCertificateValidated, this, 
                                                    _1, data.shared_from_this(), onValidated, onValidationFailed);
              
              OnDataValidationFailed onKeyValidationFailed = bind(&SyncValidator::onCertificateValidationFailed, this, 
                                                                  _1, _2, data.shared_from_this(), onValidationFailed);              

              shared_ptr<ValidationRequest> nextStep = make_shared<ValidationRequest>(interest, 
                                                                                      onKeyValidated,
                                                                                      onKeyValidationFailed,
                                                                                      1,
                                                                                      stepCount + 1);
              nextSteps.push_back(nextStep);

              return;
            }
        }
      catch(SignatureSha256WithRsa::Error& e)
        {
          return onValidationFailed(data.shared_from_this(), 
                                    "Not SignatureSha256WithRsa signature: " + string(e.what()));
        }
      catch(KeyLocator::Error& e)
        {
          return onValidationFailed(data.shared_from_this(),
                                    "Key Locator is not a name: " + data.getName().toUri());
        }
    }

  if(static_cast<bool>(m_dataRule) && m_dataRule->satisfy(data))
    {
      try
        {
          SignatureSha256WithRsa sig(data.getSignature());
          Name keyLocatorName = sig.getKeyLocator().getName();
          
          TrustNodes::const_iterator it = m_trustedNodes.find(keyLocatorName);
          if(m_trustedNodes.end() != it)
            {
              if(verifySignature(data, sig, it->second))
                return onValidated(data.shared_from_this());
              else
                return onValidationFailed(data.shared_from_this(), 
                                          "Cannot verify signature: " + data.getName().toUri());
            }
          else
            return onValidationFailed(data.shared_from_this(), 
                                      "Signer cannot be trusted: " + keyLocatorName.toUri());
        }
      catch(SignatureSha256WithRsa::Error& e)
        {
          return onValidationFailed(data.shared_from_this(), 
                                    "Not SignatureSha256WithRsa signature: " + string(e.what()));
        }
      catch(KeyLocator::Error& e)
        {
          return onValidationFailed(data.shared_from_this(),
                                    "Key Locator is not a name: " + data.getName().toUri());
        }
    }
  else
    return onValidationFailed(data.shared_from_this(),
                              "No data rule or rule is not satisfied: " + data.getName().toUri());
}

void
SyncValidator::checkPolicy (const Interest& interest, 
                            int stepCount, 
                            const OnInterestValidated& onValidated, 
                            const OnInterestValidationFailed& onValidationFailed,
                            std::vector<shared_ptr<ValidationRequest> >& nextSteps)
{
  onValidationFailed(interest.shared_from_this(),  "No policy for signed interest checking");
}

void
SyncValidator::onCertificateValidated(const shared_ptr<const Data>& signCertificate, 
                                      const shared_ptr<const Data>& data, 
                                      const OnDataValidated& onValidated, 
                                      const OnDataValidationFailed& onValidationFailed)
{
  try
    {
      IntroCertificate introCert(*signCertificate);
      addParticipant(introCert);
      
      if(verifySignature(*data, introCert.getIntroduceeCert().getPublicKeyInfo()))
        return onValidated(data);
      else
        return onValidationFailed(data, 
                                  "Cannot verify signature: " + data->getName().toUri());
    }
  catch(IntroCertificate::Error& e)
    {
      return onValidationFailed(data, 
                                "Intro cert decoding error: " + string(e.what()));
    }
}

void
SyncValidator::onCertificateValidationFailed(const shared_ptr<const Data>& signCertificate, 
                                             const string& failureInfo,
                                             const shared_ptr<const Data>& data, 
                                             const OnDataValidationFailed& onValidationFailed)
{
  onValidationFailed(data, failureInfo);
}

void
SyncValidator::onCertInterest(const Name& prefix, const Interest& interest)
{
  Name name = interest.getName(); 
  Edges::const_iterator it = m_introCerts.begin();
  for(; it != m_introCerts.end(); it++)
    {
      if(name.isPrefixOf(it->first))
        {
          m_face->put(it->second);
          return;
        }
    }
}

void
SyncValidator::onCertRegisterFailed(const Name& prefix, const string& msg)
{
  _LOG_DEBUG("SyncValidator::onCertRegisterFailed: " << msg);
}

} // namespace Sync