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#ifndef MOZC_PREDICTION_PREDICTOR_H_
#define MOZC_PREDICTION_PREDICTOR_H_

#include <memory>
#include <string>

#include "absl/strings/string_view.h"
#include "converter/converter_interface.h"
#include "converter/segments.h"
#include "prediction/predictor_interface.h"
#include "request/conversion_request.h"

namespace mozc::prediction {

class BasePredictor : public PredictorInterface {
 public:
  // Initializes the composite of predictor with given sub-predictors.
  BasePredictor(std::unique_ptr<PredictorInterface> dictionary_predictor,
                std::unique_ptr<PredictorInterface> user_history_predictor,
                const ConverterInterface &converter);

  // Hook(s) for all mutable operations.
  void Finish(const ConversionRequest &request, Segments *segments) override;

  // Reverts the last Finish operation.
  void Revert(Segments *segments) override;

  // Clears all history data of UserHistoryPredictor.
  bool ClearAllHistory() override;

  // Clears unused history data of UserHistoryPredictor.
  bool ClearUnusedHistory() override;

  // Clears a specific user history data of UserHistoryPredictor.
  bool ClearHistoryEntry(absl::string_view key,
                         absl::string_view value) override;

  // Syncs user history.
  bool Sync() override;

  // Reloads user history.
  bool Reload() override;

  // Waits for syncer to complete.
  bool Wait() override;

  // The following interfaces are implemented in derived classes.
  // const string &GetPredictorName() const = 0;
  // bool PredictForRequest(const ConversionRequest &request,
  //                        Segments *segments) const = 0;

 protected:
  std::unique_ptr<PredictorInterface> dictionary_predictor_;
  std::unique_ptr<PredictorInterface> user_history_predictor_;

 private:
  void PopulateReadingOfCommittedCandidateIfMissing(Segments *segments) const;

  const ConverterInterface &converter_;
};

// TODO(team): The name should be DesktopPredictor
class DefaultPredictor : public BasePredictor {
 public:
  static std::unique_ptr<PredictorInterface> CreateDefaultPredictor(
      std::unique_ptr<PredictorInterface> dictionary_predictor,
      std::unique_ptr<PredictorInterface> user_history_predictor,
      const ConverterInterface &converter);

  DefaultPredictor(std::unique_ptr<PredictorInterface> dictionary_predictor,
                   std::unique_ptr<PredictorInterface> user_history_predictor,
                   const ConverterInterface &converter);
  ~DefaultPredictor() override;

  [[nodiscard]] bool PredictForRequest(const ConversionRequest &request,
                                       Segments *segments) const override;

  absl::string_view GetPredictorName() const override {
    return predictor_name_;
  }

 private:
  const std::string predictor_name_;
};

class MobilePredictor : public BasePredictor {
 public:
  static std::unique_ptr<PredictorInterface> CreateMobilePredictor(
      std::unique_ptr<PredictorInterface> dictionary_predictor,
      std::unique_ptr<PredictorInterface> user_history_predictor,
      const ConverterInterface &converter);

  MobilePredictor(std::unique_ptr<PredictorInterface> dictionary_predictor,
                  std::unique_ptr<PredictorInterface> user_history_predictor,
                  const ConverterInterface &converter);
  ~MobilePredictor() override;

  [[nodiscard]] bool PredictForRequest(const ConversionRequest &request,
                                       Segments *segments) const override;

  absl::string_view GetPredictorName() const override {
    return predictor_name_;
  }

  static ConversionRequest GetRequestForPredict(
      const ConversionRequest &request, const Segments &segments);

 private:
  const std::string predictor_name_;
};

}  // namespace mozc::prediction

#endif  // MOZC_PREDICTION_PREDICTOR_H_
