/*
 * Copyright (c) 2017-2019 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <hicn/transport/core/name.h>
#include <hicn/transport/core/payload_type.h>
#include <hicn/transport/errors/malformed_packet_exception.h>
#include <hicn/transport/portability/portability.h>
#include <hicn/transport/auth/crypto_hasher.h>
#include <hicn/transport/auth/crypto_suite.h>
#include <hicn/transport/auth/key_id.h>
#include <hicn/transport/utils/branch_prediction.h>
#include <hicn/transport/utils/log.h>
#include <hicn/transport/utils/membuf.h>
#include <hicn/transport/utils/object_pool.h>

namespace transport {
namespace core {

/*
 * Basic IP packet, modelled as circular chain of buffers:
 * Header = H
 * Payload = P
 *
 * H_0 --> H_1 --> H_2 --> P_0 --> P_1 --> P_2
 *  \_______________________________________|
 */

class Packet : public utils::MemBuf,
               public std::enable_shared_from_this<Packet> {
  friend class auth::Signer;
  friend class auth::Verifier;

 public:
  using Ptr = std::shared_ptr<Packet>;
  using MemBufPtr = std::shared_ptr<utils::MemBuf>;
  using Format = hicn_format_t;
  static constexpr size_t default_mtu = 1500;

  /**
   * Create new IP packet. Here we allocate just the header,
   * the eventual payload will be added by prepending the payload buffer
   * to the buffer chain whose the fist buffer is the header itself.
   */
  Packet(Format format = HF_INET6_TCP, std::size_t additional_header_size = 0);

  /**
   * Create new IP packet using raw buffer.
   */

  /* Copy buffer */
  Packet(CopyBufferOp, const uint8_t *buffer, std::size_t size);
  /* Wrap buffer */
  Packet(WrapBufferOp, uint8_t *buffer, std::size_t length, std::size_t size);
  /* Create new using pre-allocated buffer */
  Packet(CreateOp, uint8_t *buffer, std::size_t length, std::size_t size,
         Format format = HF_INET6_TCP, std::size_t additional_header_size = 0);
  /* Move MemBuf */
  Packet(MemBuf &&buffer);

  Packet(Packet &&other);

  /*
   * Copy constructor and assignemnt operators.
   */
  Packet(const Packet &other);
  Packet &operator=(const Packet &other);

  friend bool operator==(const Packet &l_packet, const Packet &r_packet);

  virtual ~Packet();

  static std::size_t getHeaderSizeFromFormat(Format format,
                                             std::size_t signature_size = 0) {
    std::size_t header_length;
    hicn_packet_get_header_length_from_format(format, &header_length);
    int is_ah = _is_ah(format);
    return is_ah * (header_length + signature_size) + (!is_ah) * header_length;
  }

  static std::size_t getHeaderSizeFromBuffer(Format format,
                                             const uint8_t *buffer);

  static std::size_t getPayloadSizeFromBuffer(Format format,
                                              const uint8_t *buffer);

  static bool isInterest(const uint8_t *buffer);

  bool isInterest();

  static Format getFormatFromBuffer(const uint8_t *buffer, std::size_t length) {
    Format format = HF_UNSPEC;
    hicn_packet_get_format((const hicn_header_t *)buffer, &format);
    return format;
  }

  void reset() {
    clear();
    packet_start_ = reinterpret_cast<hicn_header_t *>(writableData());
    header_offset_ = 0;
    format_ = HF_UNSPEC;
    payload_type_ = PayloadType::UNSPECIFIED;
    name_.clear();

    if (isChained()) {
      separateChain(next(), prev());
    }
  }

  void setFormat(Packet::Format format = HF_INET6_TCP,
                 std::size_t additional_header_size = 0);

  std::size_t payloadSize() const;

  std::size_t headerSize() const;

  std::shared_ptr<utils::MemBuf> acquireMemBufReference();

  virtual const Name &getName() const = 0;

  virtual Name &getWritableName() = 0;

  virtual void setName(const Name &name) = 0;

  virtual void setName(Name &&name) = 0;

  virtual void setLifetime(uint32_t lifetime) = 0;

  virtual uint32_t getLifetime() const = 0;

  Packet &appendPayload(const uint8_t *buffer, std::size_t length);

  Packet &appendPayload(std::unique_ptr<utils::MemBuf> &&payload);

  std::unique_ptr<utils::MemBuf> getPayload() const;

  Packet &updateLength(std::size_t length = 0);

  PayloadType getPayloadType() const;

  Packet &setPayloadType(PayloadType payload_type);

  Format getFormat() const;

  void dump() const;

  static void dump(uint8_t *buffer, std::size_t length);

  virtual void setLocator(const ip_address_t &locator) = 0;

  virtual ip_address_t getLocator() const = 0;

  /**
   * @brief Set signature timestamp, in milliseconds.
   */
  void setSignatureTimestamp(const uint64_t &timestamp_milliseconds);

  uint64_t getSignatureTimestamp() const;

  void setValidationAlgorithm(const auth::CryptoSuite &validation_algorithm);

  auth::CryptoSuite getValidationAlgorithm() const;

  void setKeyId(const auth::KeyId &key_id);

  auth::KeyId getKeyId() const;

  virtual auth::CryptoHash computeDigest(auth::CryptoHashType algorithm) const;

  void setChecksum() {
    uint16_t partial_csum =
        csum(data() + HICN_V6_TCP_HDRLEN, length() - HICN_V6_TCP_HDRLEN, 0);

    for (utils::MemBuf *current = next(); current != this;
         current = current->next()) {
      partial_csum = csum(current->data(), current->length(), ~partial_csum);
    }

    if (hicn_packet_compute_header_checksum(format_, packet_start_,
                                            partial_csum) < 0) {
      throw errors::MalformedPacketException();
    }
  }

  bool checkIntegrity() const;

  Packet &setSyn();
  Packet &resetSyn();
  bool testSyn() const;
  Packet &setAck();
  Packet &resetAck();
  bool testAck() const;
  Packet &setRst();
  Packet &resetRst();
  bool testRst() const;
  Packet &setFin();
  Packet &resetFin();
  bool testFin() const;
  Packet &resetFlags();
  std::string printFlags() const;

  Packet &setSrcPort(uint16_t srcPort);
  Packet &setDstPort(uint16_t dstPort);
  uint16_t getSrcPort() const;
  uint16_t getDstPort() const;

  Packet &setTTL(uint8_t hops);
  uint8_t getTTL() const;

 private:
  virtual void resetForHash() = 0;
  void setSignatureSize(std::size_t size_bytes);
  void prependPayload(const uint8_t **buffer, std::size_t *size);

  bool authenticationHeader() const { return _is_ah(format_); }

  std::size_t getSignatureSize() const {
    size_t size_bytes;
    int ret =
        hicn_packet_get_signature_size(format_, packet_start_, &size_bytes);

    if (ret < 0) {
      throw errors::RuntimeException("Packet without Authentication Header.");
    }

    return size_bytes;
  }

  uint8_t *getSignature() const;

 protected:
  hicn_header_t *packet_start_;
  std::size_t header_offset_;
  mutable Format format_;
  Name name_;
  mutable PayloadType payload_type_;
  static const core::Name base_name;
};

}  // end namespace core

}  // end namespace transport