//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once

#include "td/telegram/SecureStorage.h"

#include "td/utils/as.h"
#include "td/utils/common.h"
#include "td/utils/crypto.h"
#include "td/utils/logging.h"
#include "td/utils/Random.h"
#include "td/utils/Slice.h"
#include "td/utils/StringBuilder.h"
#include "td/utils/tl_helpers.h"
#include "td/utils/UInt.h"

namespace td {

struct FileEncryptionKey {
  enum class Type : int32 { None, Secret, Secure };
  FileEncryptionKey() = default;
  FileEncryptionKey(Slice key, Slice iv) : key_iv_(key.size() + iv.size(), '\0'), type_(Type::Secret) {
    if (key.size() != 32 || iv.size() != 32) {
      LOG(ERROR) << "Wrong key/iv sizes: " << key.size() << " " << iv.size();
      type_ = Type::None;
      return;
    }
    CHECK(key_iv_.size() == 64);
    MutableSlice(key_iv_).copy_from(key);
    MutableSlice(key_iv_).substr(key.size()).copy_from(iv);
  }

  explicit FileEncryptionKey(const secure_storage::Secret &secret) : type_(Type::Secure) {
    key_iv_ = secret.as_slice().str();
  }

  bool is_secret() const {
    return type_ == Type::Secret;
  }
  bool is_secure() const {
    return type_ == Type::Secure;
  }

  static FileEncryptionKey create() {
    FileEncryptionKey res;
    res.key_iv_.resize(64);
    Random::secure_bytes(res.key_iv_);
    res.type_ = Type::Secret;
    return res;
  }
  static FileEncryptionKey create_secure_key() {
    return FileEncryptionKey(secure_storage::Secret::create_new());
  }

  const UInt256 &key() const {
    CHECK(is_secret());
    CHECK(key_iv_.size() == 64);
    return *reinterpret_cast<const UInt256 *>(key_iv_.data());
  }
  Slice key_slice() const {
    CHECK(is_secret());
    CHECK(key_iv_.size() == 64);
    return Slice(key_iv_.data(), 32);
  }
  secure_storage::Secret secret() const {
    CHECK(is_secure());
    return secure_storage::Secret::create(Slice(key_iv_).truncate(32)).move_as_ok();
  }

  bool has_value_hash() const {
    CHECK(is_secure());
    return key_iv_.size() > secure_storage::Secret::size();
  }

  void set_value_hash(const secure_storage::ValueHash &value_hash) {
    key_iv_.resize(secure_storage::Secret::size() + value_hash.as_slice().size());
    MutableSlice(key_iv_).remove_prefix(secure_storage::Secret::size()).copy_from(value_hash.as_slice());
  }

  secure_storage::ValueHash value_hash() const {
    CHECK(has_value_hash());
    return secure_storage::ValueHash::create(Slice(key_iv_).remove_prefix(secure_storage::Secret::size())).move_as_ok();
  }

  UInt256 &mutable_iv() {
    CHECK(is_secret());
    CHECK(key_iv_.size() == 64);
    return *reinterpret_cast<UInt256 *>(&key_iv_[0] + 32);
  }
  Slice iv_slice() const {
    CHECK(is_secret());
    CHECK(key_iv_.size() == 64);
    return Slice(key_iv_.data() + 32, 32);
  }

  int32 calc_fingerprint() const {
    CHECK(is_secret());
    char buf[16];
    md5(key_iv_, {buf, sizeof(buf)});
    return as<int32>(buf) ^ as<int32>(buf + 4);
  }

  bool empty() const {
    return key_iv_.empty();
  }
  size_t size() const {
    return key_iv_.size();
  }

  template <class StorerT>
  void store(StorerT &storer) const {
    td::store(key_iv_, storer);
  }
  template <class ParserT>
  void parse(Type type, ParserT &parser) {
    td::parse(key_iv_, parser);
    if (key_iv_.empty()) {
      type_ = Type::None;
    } else {
      if (type_ == Type::Secure) {
        if (key_iv_.size() != 64) {
          LOG(ERROR) << "Have wrong key size " << key_iv_.size();
        }
      }
      type_ = type;
    }
  }

  string key_iv_;  // TODO wrong alignment is possible
  Type type_ = Type::None;
};

inline bool operator==(const FileEncryptionKey &lhs, const FileEncryptionKey &rhs) {
  return lhs.key_iv_ == rhs.key_iv_;
}

inline bool operator!=(const FileEncryptionKey &lhs, const FileEncryptionKey &rhs) {
  return !(lhs == rhs);
}

inline StringBuilder &operator<<(StringBuilder &string_builder, const FileEncryptionKey &key) {
  if (key.is_secret()) {
    return string_builder << "SecretKey{" << key.size() << "}";
  }
  if (key.is_secret()) {
    return string_builder << "SecureKey{" << key.size() << "}";
  }
  return string_builder << "NoKey{}";
}

}  // namespace td