// Licensed to the Apache Software Foundation (ASF) under one
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// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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 <unordered_map>
#include <vector>

#include "arrow/util/concurrent_map.h"

#include "parquet/encryption/kms_client.h"
#include "parquet/platform.h"

namespace parquet::encryption {

/// This class supports local wrapping mode, master keys will be fetched from the KMS
/// server and used to encrypt other keys (data encryption keys or key encryption keys).
class PARQUET_EXPORT LocalWrapKmsClient : public KmsClient {
 public:
  static constexpr const char kLocalWrapNoKeyVersion[] = "NO_VERSION";

  explicit LocalWrapKmsClient(const KmsConnectionConfig& kms_connection_config);

  std::string WrapKey(const std::string& key_bytes,
                      const std::string& master_key_identifier) override;

  std::string UnwrapKey(const std::string& wrapped_key,
                        const std::string& master_key_identifier) override;

 protected:
  /// Get master key from the remote KMS server.
  /// Note: this function might be called by multiple threads
  virtual std::string GetMasterKeyFromServer(
      const std::string& master_key_identifier) = 0;

 private:
  /// KMS systems wrap keys by encrypting them by master keys, and attaching additional
  /// information (such as the version number of the masker key) to the result of
  /// encryption. The master key version is required in  key rotation. Currently, the
  /// local wrapping mode does not support key rotation (because not all KMS systems allow
  /// to fetch a master key by its ID and version number). Still, the local wrapping mode
  /// adds a placeholder for the master key version, that will enable support for key
  /// rotation in this mode in the future, with appropriate KMS systems. This will also
  /// enable backward compatibility, where future readers will be able to extract master
  /// key version in the files written by the current code.
  ///
  /// LocalKeyWrap class writes (and reads) the "key wrap" as a flat json with the
  /// following fields:
  /// 1. "masterKeyVersion" - a String, with the master key version. In the current
  /// version, only one value is allowed - "NO_VERSION".
  /// 2. "encryptedKey" - a String, with the key encrypted by the master key
  /// (base64-encoded).
  class LocalKeyWrap {
   public:
    static constexpr const char kLocalWrapKeyVersionField[] = "masterKeyVersion";
    static constexpr const char kLocalWrapEncryptedKeyField[] = "encryptedKey";

    LocalKeyWrap(std::string master_key_version, std::string encrypted_encoded_key);

    static std::string CreateSerialized(const std::string& encrypted_encoded_key);

    static LocalKeyWrap Parse(const std::string& wrapped_key);

    const std::string& master_key_version() const { return master_key_version_; }

    const std::string& encrypted_encoded_key() const { return encrypted_encoded_key_; }

   private:
    std::string encrypted_encoded_key_;
    std::string master_key_version_;
  };

  std::string GetKeyFromServer(const std::string& key_identifier);

 protected:
  KmsConnectionConfig kms_connection_config_;
  ::arrow::util::ConcurrentMap<std::string, std::string> master_key_cache_;
};

}  // namespace parquet::encryption