/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2017-2020, Regents of the University of California.
 *
 * This file is part of ndncert, a certificate management system based on NDN.
 *
 * ndncert is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation, either
 * version 3 of the License, or (at your option) any later version.
 *
 * ndncert is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 * You should have received copies of the GNU General Public License along with
 * ndncert, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndncert authors and contributors.
 */

#include "requester.hpp"
#include "challenge-module.hpp"
#include "crypto-support/enc-tlv.hpp"
#include "protocol-detail/challenge.hpp"
#include "protocol-detail/error.hpp"
#include "protocol-detail/info.hpp"
#include "protocol-detail/new-renew-revoke.hpp"
#include "protocol-detail/probe.hpp"
#include <ndn-cxx/security/signing-helpers.hpp>
#include <ndn-cxx/security/transform/base64-encode.hpp>
#include <ndn-cxx/security/transform/buffer-source.hpp>
#include <ndn-cxx/security/transform/stream-sink.hpp>
#include <ndn-cxx/security/verification-helpers.hpp>
#include <ndn-cxx/util/io.hpp>
#include <ndn-cxx/util/random.hpp>

namespace ndn {
namespace ndncert {

_LOG_INIT(ndncert.client);

RequesterState::RequesterState(security::v2::KeyChain& keyChain, const CaProfile& caItem, RequestType requestType)
  : m_caItem(caItem)
  , m_keyChain(keyChain)
  , m_type(requestType)
{
}

shared_ptr<Interest>
Requester::genCaProfileInterest(const Name& caName)
{
  Name interestName = caName;
  if (readString(caName.at(-1)) != "CA")
    interestName.append("CA");
  interestName.append("INFO");
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(true);
  interest->setCanBePrefix(false);
  return interest;
}

boost::optional<CaProfile>
Requester::onCaProfileResponse(const Data& reply)
{
  auto caItem = INFO::decodeDataContent(reply.getContent());
  if (!security::verifySignature(reply, *caItem.m_cert)) {
    _LOG_ERROR("Cannot verify replied Data packet signature.");
    return boost::none;
  }
  return caItem;
}

shared_ptr<Interest>
Requester::genProbeInterest(const CaProfile& ca, std::vector<std::tuple<std::string, std::string>>&& probeInfo)
{
  Name interestName = ca.m_caPrefix;
  interestName.append("CA").append("PROBE");
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(true);
  interest->setCanBePrefix(false);
  interest->setApplicationParameters(PROBE::encodeApplicationParameters(std::move(probeInfo)));
  return interest;
}

void
Requester::onProbeResponse(const Data& reply, const CaProfile& ca,
                           std::vector<Name>& identityNames, std::vector<Name>& otherCas)
{
  if (!security::verifySignature(reply, *ca.m_cert)) {
    _LOG_ERROR("Cannot verify replied Data packet signature.");
    return;
  }
  processIfError(reply);
  PROBE::decodeDataContent(reply.getContent(), identityNames, otherCas);
}

shared_ptr<Interest>
Requester::genNewInterest(RequesterState& state, const Name& identityName,
                          const time::system_clock::TimePoint& notBefore,
                          const time::system_clock::TimePoint& notAfter)
{
  if (!state.m_caItem.m_caPrefix.isPrefixOf(identityName)) {
    return nullptr;
  }
  if (identityName.empty()) {
    NDN_LOG_TRACE("Randomly create a new name because identityName is empty and the param is empty.");
    state.m_identityName = state.m_caItem.m_caPrefix;
    state.m_identityName.append(std::to_string(random::generateSecureWord64()));
  }
  else {
    state.m_identityName = identityName;
  }

  // generate a newly key pair or use an existing key
  const auto& pib = state.m_keyChain.getPib();
  security::pib::Identity identity;
  try {
    identity = pib.getIdentity(state.m_identityName);
  }
  catch (const security::Pib::Error& e) {
    identity = state.m_keyChain.createIdentity(state.m_identityName);
    state.m_isNewlyCreatedIdentity = true;
    state.m_isNewlyCreatedKey = true;
  }
  try {
    state.m_keyPair = identity.getDefaultKey();
  }
  catch (const security::Pib::Error& e) {
    state.m_keyPair = state.m_keyChain.createKey(identity);
    state.m_isNewlyCreatedKey = true;
  }
  auto& keyName = state.m_keyPair.getName();

  // generate certificate request
  security::v2::Certificate certRequest;
  certRequest.setName(Name(keyName).append("cert-request").appendVersion());
  certRequest.setContentType(tlv::ContentType_Key);
  certRequest.setContent(state.m_keyPair.getPublicKey().data(), state.m_keyPair.getPublicKey().size());
  SignatureInfo signatureInfo;
  signatureInfo.setValidityPeriod(security::ValidityPeriod(notBefore, notAfter));
  state.m_keyChain.sign(certRequest, signingByKey(keyName).setSignatureInfo(signatureInfo));

  // generate Interest packet
  Name interestName = state.m_caItem.m_caPrefix;
  interestName.append("CA").append("NEW");
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(true);
  interest->setCanBePrefix(false);
  interest->setApplicationParameters(
      NEW_RENEW_REVOKE::encodeApplicationParameters(RequestType::NEW, state.m_ecdh.getBase64PubKey(), certRequest));

  // sign the Interest packet
  state.m_keyChain.sign(*interest, signingByKey(keyName));
  return interest;
}

shared_ptr<Interest>
Requester::genRevokeInterest(RequesterState& state, const security::v2::Certificate& certificate)
{
  if (!state.m_caItem.m_caPrefix.isPrefixOf(certificate.getName())) {
    return nullptr;
  }
  // generate Interest packet
  Name interestName = state.m_caItem.m_caPrefix;
  interestName.append("CA").append("REVOKE");
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(true);
  interest->setCanBePrefix(false);
  interest->setApplicationParameters(
      NEW_RENEW_REVOKE::encodeApplicationParameters(RequestType::REVOKE, state.m_ecdh.getBase64PubKey(), certificate));
  return interest;
}

std::list<std::string>
Requester::onNewRenewRevokeResponse(RequesterState& state, const Data& reply)
{
  if (!security::verifySignature(reply, *state.m_caItem.m_cert)) {
    _LOG_ERROR("Cannot verify replied Data packet signature.");
    return std::list<std::string>();
  }
  processIfError(reply);

  auto contentTLV = reply.getContent();
  contentTLV.parse();

  // ECDH
  const auto& peerKeyBase64Str = readString(contentTLV.get(tlv_ecdh_pub));
  const auto& saltStr = readString(contentTLV.get(tlv_salt));
  uint64_t saltInt = std::stoull(saltStr);
  state.m_ecdh.deriveSecret(peerKeyBase64Str);

  // HKDF
  hkdf(state.m_ecdh.context->sharedSecret, state.m_ecdh.context->sharedSecretLen,
       (uint8_t*)&saltInt, sizeof(saltInt), state.m_aesKey, sizeof(state.m_aesKey));

  // update state
  state.m_status = static_cast<Status>(readNonNegativeInteger(contentTLV.get(tlv_status)));
  state.m_requestId = readString(contentTLV.get(tlv_request_id));
  std::list<std::string> challengeList;
  for (auto const& element : contentTLV.elements()) {
    if (element.type() == tlv_challenge) {
      challengeList.push_back(readString(element));
    }
  }
  return challengeList;
}

std::vector<std::tuple<std::string, std::string>>
Requester::selectOrContinueChallenge(RequesterState& state, const std::string& challengeSelected)
{
  auto challenge = ChallengeModule::createChallengeModule(challengeSelected);
  if (challenge == nullptr) {
    BOOST_THROW_EXCEPTION(std::runtime_error("The challenge selected is not supported by your current version of NDNCERT."));
  }
  state.m_challengeType = challengeSelected;
  return challenge->getRequestedParameterList(state.m_status, state.m_challengeStatus);
}

shared_ptr<Interest>
Requester::genChallengeInterest(const RequesterState& state,
                                std::vector<std::tuple<std::string, std::string>>&& parameters)
{
  if (state.m_challengeType == "") {
    BOOST_THROW_EXCEPTION(std::runtime_error("The challenge has not been selected."));
  }
  auto challenge = ChallengeModule::createChallengeModule(state.m_challengeType);
  if (challenge == nullptr) {
    BOOST_THROW_EXCEPTION(std::runtime_error("The challenge selected is not supported by your current version of NDNCERT."));
  }
  auto challengeParams = challenge->genChallengeRequestTLV(state.m_status, state.m_challengeStatus, std::move(parameters));

  Name interestName = state.m_caItem.m_caPrefix;
  interestName.append("CA").append("CHALLENGE").append(state.m_requestId);
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(true);
  interest->setCanBePrefix(false);

  // encrypt the Interest parameters
  auto paramBlock = encodeBlockWithAesGcm128(tlv::ApplicationParameters, state.m_aesKey,
                                             challengeParams.value(), challengeParams.value_size(),
                                             (const uint8_t*)"test", strlen("test"));
  interest->setApplicationParameters(paramBlock);
  state.m_keyChain.sign(*interest, signingByKey(state.m_keyPair.getName()));
  return interest;
}

void
Requester::onChallengeResponse(RequesterState& state, const Data& reply)
{
  if (!security::verifySignature(reply, *state.m_caItem.m_cert)) {
    _LOG_ERROR("Cannot verify replied Data packet signature.");
    return;
  }
  processIfError(reply);
  auto result = decodeBlockWithAesGcm128(reply.getContent(), state.m_aesKey, (const uint8_t*)"test", strlen("test"));
  Block contentTLV = makeBinaryBlock(tlv_encrypted_payload, result.data(), result.size());
  contentTLV.parse();

  // update state
  state.m_status = static_cast<Status>(readNonNegativeInteger(contentTLV.get(tlv_status)));
  state.m_challengeStatus = readString(contentTLV.get(tlv_challenge_status));
  state.m_remainingTries = readNonNegativeInteger(contentTLV.get(tlv_remaining_tries));
  state.m_freshBefore = time::system_clock::now() +
                  time::seconds(readNonNegativeInteger(contentTLV.get(tlv_remaining_time)));

  if (contentTLV.find(tlv_issued_cert_name) != contentTLV.elements_end()) {
    Block issuedCertNameBlock = contentTLV.get(tlv_issued_cert_name);
    issuedCertNameBlock.parse();
    state.m_issuedCertName.wireDecode(issuedCertNameBlock.get(tlv::Name));
  }
}

shared_ptr<Interest>
Requester::genCertFetchInterest(const RequesterState& state)
{
  Name interestName = state.m_issuedCertName;
  auto interest = make_shared<Interest>(interestName);
  interest->setMustBeFresh(false);
  interest->setCanBePrefix(false);
  return interest;
}

shared_ptr<security::v2::Certificate>
Requester::onCertFetchResponse(const Data& reply)
{
  try {
    return std::make_shared<security::v2::Certificate>(reply.getContent().blockFromValue());
  }
  catch (const std::exception& e) {
    _LOG_ERROR("Cannot parse replied certificate ");
    return nullptr;
  }
}

void
Requester::endSession(RequesterState& state)
{
  if (state.m_status == Status::SUCCESS || state.m_status == Status::ENDED) {
    return;
  }
  if (state.m_isNewlyCreatedIdentity) {
    // put the identity into the if scope is because it may cause an error
    // outside since when endSession is called, identity may not have been created yet.
    auto identity = state.m_keyChain.getPib().getIdentity(state.m_identityName);
    state.m_keyChain.deleteIdentity(identity);
  }
  else if (state.m_isNewlyCreatedKey) {
    auto identity = state.m_keyChain.getPib().getIdentity(state.m_identityName);
    state.m_keyChain.deleteKey(identity, state.m_keyPair);
  }
  state.m_status = Status::ENDED;
}

void
Requester::processIfError(const Data& data)
{
  auto errorInfo = ErrorTLV::decodefromDataContent(data.getContent());
  if (std::get<0>(errorInfo) == ErrorCode::NO_ERROR) {
    return;
  }
  BOOST_THROW_EXCEPTION(std::runtime_error("Error info replied from the CA with Error code: " +
                                           errorCodeToString(std::get<0>(errorInfo)) +
                                           " and Error Info: " + std::get<1>(errorInfo)));
}

}  // namespace ndncert
}  // namespace ndn