// Copyright 2023 Google LLC
//
// 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.
//
////////////////////////////////////////////////////////////////////////////////

#ifndef TINK_HYBRID_HPKE_PUBLIC_KEY_H_
#define TINK_HYBRID_HPKE_PUBLIC_KEY_H_

#include <cstdint>
#include <memory>
#include <string>

#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "tink/hybrid/hpke_parameters.h"
#include "tink/hybrid/hybrid_public_key.h"
#include "tink/key.h"
#include "tink/partial_key_access_token.h"
#include "tink/util/statusor.h"

namespace crypto {
namespace tink {

// Representation of the encryption function for an HPKE hybrid encryption
// primitive.
class HpkePublicKey final : public HybridPublicKey {
 public:
  // Copyable and movable.
  HpkePublicKey(const HpkePublicKey& other) = default;
  HpkePublicKey& operator=(const HpkePublicKey& other) = default;
  HpkePublicKey(HpkePublicKey&& other) = default;
  HpkePublicKey& operator=(HpkePublicKey&& other) = default;

  // Creates a new HPKE public key from `public_key_bytes`. If `parameters`
  // specify a variant that uses a prefix, then `id_requirement` is used to
  // compute this prefix.
  static absl::StatusOr<HpkePublicKey> Create(
      const HpkeParameters& parameters, absl::string_view public_key_bytes,
      absl::optional<int> id_requirement, PartialKeyAccessToken token);

  absl::string_view GetPublicKeyBytes(PartialKeyAccessToken token) const {
    return public_key_bytes_;
  }

  absl::string_view GetOutputPrefix() const override { return output_prefix_; }

  const HpkeParameters& GetParameters() const override { return parameters_; }

  absl::optional<int32_t> GetIdRequirement() const override {
    return id_requirement_;
  }

  bool operator==(const Key& other) const override;

  std::unique_ptr<Key> Clone() const override {
    return std::make_unique<HpkePublicKey>(*this);
  }

 private:
  explicit HpkePublicKey(const HpkeParameters& parameters,
                         absl::string_view public_key_bytes,
                         absl::optional<int> id_requirement,
                         absl::string_view output_prefix)
      : parameters_(parameters),
        public_key_bytes_(public_key_bytes),
        id_requirement_(id_requirement),
        output_prefix_(output_prefix) {}

  HpkeParameters parameters_;
  std::string public_key_bytes_;
  absl::optional<int> id_requirement_;
  std::string output_prefix_;
};

}  // namespace tink
}  // namespace crypto

#endif  // TINK_HYBRID_HPKE_PUBLIC_KEY_H_
