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#ifndef MOZC_ENGINE_ENGINE_H_
#define MOZC_ENGINE_ENGINE_H_

#include <memory>
#include <string>
#include <vector>

#include "converter/connector.h"
#include "converter/converter.h"
#include "converter/immutable_converter_interface.h"
#include "converter/segmenter.h"
#include "data_manager/data_manager_interface.h"
#include "dictionary/dictionary_interface.h"
#include "dictionary/pos_group.h"
#include "dictionary/pos_matcher.h"
#include "dictionary/suppression_dictionary.h"
#include "dictionary/user_dictionary.h"
#include "engine/engine_interface.h"
#include "engine/user_data_manager_interface.h"
#include "prediction/predictor_interface.h"
#include "prediction/rescorer_interface.h"
#include "prediction/suggestion_filter.h"
#include "rewriter/rewriter_interface.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"

namespace mozc {

// Builds and manages a set of modules that are necessary for conversion engine.
class Engine : public EngineInterface {
 public:
  // There are two types of engine: desktop and mobile.  The differences are the
  // underlying prediction engine (DesktopPredictor or MobilePredictor) and
  // learning preference (to learn content word or not).  See Init() for the
  // details of implementation.

  // Creates an instance with desktop configuration from a data manager.  The
  // ownership of data manager is passed to the engine instance.
  static absl::StatusOr<std::unique_ptr<Engine>> CreateDesktopEngine(
      std::unique_ptr<const DataManagerInterface> data_manager);

  // Helper function for the above factory, where data manager is instantiated
  // by a default constructor.  Intended to be used for OssDataManager etc.
  template <typename DataManagerType>
  static absl::StatusOr<std::unique_ptr<Engine>> CreateDesktopEngineHelper() {
    return CreateDesktopEngine(std::make_unique<const DataManagerType>());
  }

  // Creates an instance with mobile configuration from a data manager.  The
  // ownership of data manager is passed to the engine instance.
  static absl::StatusOr<std::unique_ptr<Engine>> CreateMobileEngine(
      std::unique_ptr<const DataManagerInterface> data_manager);

  // Helper function for the above factory, where data manager is instantiated
  // by a default constructor.  Intended to be used for OssDataManager etc.
  template <typename DataManagerType>
  static absl::StatusOr<std::unique_ptr<Engine>> CreateMobileEngineHelper() {
    return CreateMobileEngine(std::make_unique<const DataManagerType>());
  }

  Engine() = default;
  Engine(const Engine &) = delete;
  Engine &operator=(const Engine &) = delete;

  ConverterImpl *GetConverter() const override { return converter_.get(); }
  prediction::PredictorInterface *GetPredictor() const override {
    return predictor_;
  }
  dictionary::SuppressionDictionary *GetSuppressionDictionary() override {
    return suppression_dictionary_.get();
  }

  bool Reload() override;

  bool ReloadAndWait() override;

  UserDataManagerInterface *GetUserDataManager() override {
    return user_data_manager_.get();
  }

  absl::string_view GetDataVersion() const override {
    return data_manager_->GetDataVersion();
  }

  const DataManagerInterface *GetDataManager() const override {
    return data_manager_.get();
  }

  std::vector<std::string> GetPosList() const override {
    return user_dictionary_->GetPosList();
  }

 private:
  // Initializes the object by the given data manager and is_mobile flag.
  // The is_mobile flag is used to select DefaultPredictor and MobilePredictor.
  absl::Status Init(std::unique_ptr<const DataManagerInterface> data_manager,
                    bool is_mobile);

  std::unique_ptr<const DataManagerInterface> data_manager_;
  std::unique_ptr<const dictionary::PosMatcher> pos_matcher_;
  std::unique_ptr<dictionary::SuppressionDictionary> suppression_dictionary_;
  Connector connector_;
  std::unique_ptr<const Segmenter> segmenter_;
  std::unique_ptr<dictionary::UserDictionary> user_dictionary_;
  std::unique_ptr<dictionary::DictionaryInterface> suffix_dictionary_;
  std::unique_ptr<dictionary::DictionaryInterface> dictionary_;
  std::unique_ptr<const dictionary::PosGroup> pos_group_;
  std::unique_ptr<ImmutableConverterInterface> immutable_converter_;
  SuggestionFilter suggestion_filter_;

  // TODO(noriyukit): Currently predictor and rewriter are created by this class
  // but owned by converter_. Since this class creates these two, it'd be better
  // if Engine class owns these two instances.
  prediction::PredictorInterface *predictor_ = nullptr;
  RewriterInterface *rewriter_ = nullptr;

  std::unique_ptr<ConverterImpl> converter_;
  std::unique_ptr<UserDataManagerInterface> user_data_manager_;
  std::unique_ptr<const prediction::RescorerInterface> rescorer_;
};

}  // namespace mozc

#endif  // MOZC_ENGINE_ENGINE_H_
