// 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

//

//     https://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.

// IWYU pragma: private, include "common/value.h"

// IWYU pragma: friend "common/value.h"

#ifndef THIRD_PARTY_CEL_CPP_COMMON_VALUES_NULL_VALUE_H_

#define THIRD_PARTY_CEL_CPP_COMMON_VALUES_NULL_VALUE_H_

#include <ostream>

#include <string>

#include "absl/base/nullability.h"

#include "absl/status/status.h"

#include "absl/strings/string_view.h"

#include "common/type.h"

#include "common/value_kind.h"

#include "common/values/values.h"

#include "google/protobuf/arena.h"

#include "google/protobuf/descriptor.h"

#include "google/protobuf/io/zero_copy_stream.h"

#include "google/protobuf/message.h"

namespace cel {

class Value;

class NullValue;

// `NullValue` represents the CEL `null` value.

class NullValue final : private common_internal::ValueMixin<NullValue> {

 public:

  static constexpr ValueKind kKind = ValueKind::kNull;

  NullValue() = default;

  NullValue(const NullValue&) = default;

  NullValue(NullValue&&) = default;

  NullValue& operator=(const NullValue&) = default;

  NullValue& operator=(NullValue&&) = default;

  constexpr ValueKind kind() const { return kKind; }

  absl::string_view GetTypeName() const { return NullType::kName; }

  std::string DebugString() const { return "null"; }

  // See Value::SerializeTo().

  absl::Status SerializeTo(

      const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,

      google::protobuf::MessageFactory* absl_nonnull message_factory,

      google::protobuf::io::ZeroCopyOutputStream* absl_nonnull output) const;

  // See Value::ConvertToJson().

  absl::Status ConvertToJson(

      const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,

      google::protobuf::MessageFactory* absl_nonnull message_factory,

      google::protobuf::Message* absl_nonnull json) const;

  absl::Status Equal(const Value& other,

                     const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,

                     google::protobuf::MessageFactory* absl_nonnull message_factory,

                     google::protobuf::Arena* absl_nonnull arena,

                     Value* absl_nonnull result) const;

  using ValueMixin::Equal;

  bool IsZeroValue() const { return true; }

  friend void swap(NullValue&, NullValue&) noexcept {}

 private:

  friend class common_internal::ValueMixin<NullValue>;

};

inline bool operator==(NullValue, NullValue) { return true; }

inline bool operator!=(NullValue lhs, NullValue rhs) {

  return !operator==(lhs, rhs);

}

inline std::ostream& operator<<(std::ostream& out, const NullValue& value) {

  return out << value.DebugString();

}

}  // namespace cel

#endif  // THIRD_PARTY_CEL_CPP_COMMON_VALUES_NULL_VALUE_H_