// SPDX-License-Identifier: BSD-3-Clause
// SPDX-FileCopyrightText: 2020-2023 The Monero Project

#pragma once

#include <string>
#include <vector>

#include <gcrypt.h>

#include <span.h>

#include "s_expression.h"

namespace openpgp
{

enum algorithm : uint8_t
{
  rsa = 1,
};

class public_key_rsa
{
public:
  public_key_rsa(s_expression expression, size_t bits);

  size_t bits() const;
  const gcry_sexp_t &get() const;

private:
  s_expression m_expression;
  size_t m_bits;
};

class public_key_block : public std::vector<public_key_rsa>
{
public:
  public_key_block(const std::string &armored);
  public_key_block(const epee::span<const uint8_t> buffer);

  std::string user_id() const;

private:
  std::string m_user_id;
};

class signature_rsa
{
public:
  enum type : uint8_t
  {
    binary_document = 0,
    canonical_text_document = 1,
  };

  signature_rsa(
    uint8_t algorithm,
    std::pair<uint8_t, uint8_t> hash_leftmost_bytes,
    uint8_t hash_algorithm,
    const std::vector<uint8_t> &hashed_data,
    type type,
    s_expression signature,
    uint8_t version);

  static signature_rsa from_armored(const std::string &armored_signed_message);
  static signature_rsa from_base64(const std::string &base64);
  static signature_rsa from_buffer(const epee::span<const uint8_t> input);

  bool verify(const epee::span<const uint8_t> message, const public_key_rsa &public_key) const;

private:
  s_expression hash_message(const epee::span<const uint8_t> message, size_t public_key_bits) const;
  std::vector<uint8_t> hash_asn_object_id() const;
  s_expression hash_bytes(const epee::span<const uint8_t> message, size_t public_key_bits) const;

  static std::vector<uint8_t> format_hashed_appendix(
    uint8_t algorithm,
    uint8_t hash_algorithm,
    const std::vector<uint8_t> &hashed_data,
    uint8_t type,
    uint8_t version);

private:
  uint8_t m_hash_algorithm;
  std::pair<uint8_t, uint8_t> m_hash_leftmost_bytes;
  std::vector<uint8_t> m_hashed_appendix;
  s_expression m_signature;
  type m_type;
};

class message_armored
{
public:
  message_armored(const std::string &message_armored);

  operator epee::span<const uint8_t>() const;

private:
  std::string m_message;
};

} // namespace openpgp