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// A class handling the converter on the session layer.

#ifndef MOZC_SESSION_SESSION_CONVERTER_INTERFACE_H_
#define MOZC_SESSION_SESSION_CONVERTER_INTERFACE_H_

#include <string>

#include "base/port.h"
#include "converter/segments.h"
#include "transliteration/transliteration.h"

namespace mozc {
class ConverterInterface;

namespace commands {
class Context;
class Output;
class Request;
}

namespace composer {
class Composer;
}

namespace session {
class CandidateList;

struct ConversionPreferences {
  bool use_history;
  int max_history_size;

  // This is a flag to check if the converter should return the suggestion
  // or not. Indeed, the design is actually twisted, because clients should
  // be able to avoid the invocation of SessionConverter::Suggest, if they'd
  // like. However, The current SessionConverter's architecture is too
  // complicated and has too many limitations to ensure the full state
  // transition. In order to support "skipping suggestion" for the performance
  // without current client's breakage in short period, this flag is
  // introduced.
  // TODO(hidehiko,komatsu): Remove this flag, when the full SessionConverter
  //   refactoring is done and gets safer for future development/extensions.
  bool request_suggestion;
};

// Do not forget to update SessionConverter::SetOperationPreferences()
// when update this struct.
struct OperationPreferences {
  bool use_cascading_window;
  string candidate_shortcuts;
  OperationPreferences() {
#ifdef OS_LINUX
    // TODO(komatsu): Move this logic to the client code.
    use_cascading_window = false;
#else
    use_cascading_window = true;
#endif
  }
};

// Class handling ConverterInterface with a session state.  This class
// support stateful operations related with the converter.
class SessionConverterInterface {
 public:
  SessionConverterInterface() {}
  virtual ~SessionConverterInterface() {}

  // Update OperationPreferences.
  virtual void SetOperationPreferences(const OperationPreferences &preferences)
      = 0;

  typedef int States;
  enum State {
    NO_STATE = 0,
    COMPOSITION = 1,
    SUGGESTION = 2,
    PREDICTION = 4,
    CONVERSION = 8,
  };

  // Check if the current state is in the state bitmap.
  virtual bool CheckState(States) const = 0;

  // Indicate if the conversion session is active or not.  In general,
  // Convert functions make it active and Cancel, Reset and Commit
  // functions make it deactive.
  virtual bool IsActive() const = 0;

  // Return the default conversion preferences to be used for custom
  // conversion.
  virtual const ConversionPreferences &conversion_preferences() const = 0;

  // Gets the selected candidate. If no candidate is selected, returns NULL.
  virtual const Segment::Candidate *
  GetSelectedCandidateOfFocusedSegment() const = 0;

  // Send a conversion request to the converter.
  virtual bool Convert(const composer::Composer &composer) = 0;
  virtual bool ConvertWithPreferences(
      const composer::Composer &composer,
      const ConversionPreferences &preferences) = 0;

  // Get reading text (e.g. from "猫" to "ねこ").
  virtual bool GetReadingText(const string &str, string *reading) = 0;

  // Send a transliteration request to the converter.
  virtual bool ConvertToTransliteration(
      const composer::Composer &composer,
      transliteration::TransliterationType type) = 0;

  // Convert the current composition to half-width characters.
  // NOTE(komatsu): This function might be merged to ConvertToTransliteration.
  virtual bool ConvertToHalfWidth(const composer::Composer &composer) = 0;

  // Switch the composition to Hiragana, full-width Katakana or
  // half-width Katakana by rotation.
  virtual bool SwitchKanaType(const composer::Composer &composer) = 0;

  // Send a suggestion request to the converter.
  virtual bool Suggest(const composer::Composer &composer) = 0;
  virtual bool SuggestWithPreferences(
      const composer::Composer &composer,
      const ConversionPreferences &preferences) = 0;

  // Send a prediction request to the converter.
  virtual bool Predict(const composer::Composer &composer) = 0;
  virtual bool PredictWithPreferences(
      const composer::Composer &composer,
      const ConversionPreferences &preferences) = 0;

  // Send a prediction request to the converter.
  // The result is added at the tail of existing candidate list as "suggestion"
  // candidates.
  virtual bool ExpandSuggestion(const composer::Composer &composer) = 0;
  virtual bool ExpandSuggestionWithPreferences(
      const composer::Composer &composer,
      const ConversionPreferences &preferences) = 0;

  // Clear conversion segments, but keep the context.
  virtual void Cancel() = 0;

  // Clear conversion segments and the context.
  virtual void Reset() = 0;

  // Fix the conversion with the current status.
  virtual void Commit(const composer::Composer &composer,
                      const commands::Context &context) = 0;

  // Fix the suggestion candidate.  True is returned if the selected
  // candidate is successfully committed.
  virtual bool CommitSuggestionByIndex(
      size_t index,
      const composer::Composer &composer,
      const commands::Context &context,
      size_t *committed_key_size) = 0;

  // Select a candidate and commit the selected candidate.  True is
  // returned if the selected candidate is successfully committed.
  virtual bool CommitSuggestionById(
      int id,
      const composer::Composer &composer,
      const commands::Context &context,
      size_t *committed_key_size) = 0;

  // Fix only the conversion of the first segment, and keep the rest.
  // The caller should delete characters from composer based on returned
  // |committed_key_size|.
  virtual void CommitFirstSegment(const composer::Composer &composer,
                                  const commands::Context &context,
                                  size_t *committed_key_size) = 0;

  // Fix only the [0, focused] conversion segments, and keep the rest.
  // The caller should delete characters from composer based on returned
  // |committed_key_size|.
  virtual void CommitHeadToFocusedSegments(
      const composer::Composer &composer,
      const commands::Context &context,
      size_t *committed_key_size) = 0;

  // Commit the preedit string represented by Composer.
  virtual void CommitPreedit(const composer::Composer &composer,
                             const commands::Context &context) = 0;

  // Commit prefix of the preedit string represented by Composer.
  // The caller should delete characters from composer based on returned
  // |commited_size|.
  virtual void CommitHead(size_t count,
                          const composer::Composer &composer,
                          size_t *commited_size) = 0;

  // Revert the last "Commit" operation
  virtual void Revert() = 0;

  // Move the focus of segments.
  virtual void SegmentFocusRight() = 0;
  virtual void SegmentFocusLast() = 0;
  virtual void SegmentFocusLeft() = 0;
  virtual void SegmentFocusLeftEdge() = 0;

  // Resize the focused segment.
  virtual void SegmentWidthExpand(const composer::Composer &composer) = 0;
  virtual void SegmentWidthShrink(const composer::Composer &composer) = 0;

  // Move the focus of candidates.
  virtual void CandidateNext(const composer::Composer &composer) = 0;
  virtual void CandidateNextPage() = 0;
  virtual void CandidatePrev() = 0;
  virtual void CandidatePrevPage() = 0;
  // Move the focus to the candidate represented by the id.
  virtual void CandidateMoveToId(
      int id, const composer::Composer &composer) = 0;
  // Move the focus to the index from the beginning of the current page.
  virtual void CandidateMoveToPageIndex(size_t index) = 0;
  // Move the focus to the candidate represented by the shortcut.  If
  // the shortcut is not bound with any candidate, false is returned.
  virtual bool CandidateMoveToShortcut(char shortcut) = 0;

  // Operation for the candidate list.
  virtual void SetCandidateListVisible(bool visible) = 0;

  // Fill protocol buffers and update internal status.
  virtual void PopOutput(
      const composer::Composer &composer, commands::Output *output) = 0;

  // Fill protocol buffers
  virtual void FillOutput(
      const composer::Composer &composer,
      commands::Output *output) const = 0;

  // Set setting by the request.
  // Currently this is especially for SessionConverter.
  virtual void SetRequest(const commands::Request *request) = 0;

  // Update the internal state by the context.
  virtual void OnStartComposition(const commands::Context &context) = 0;

  // Clone instance.
  // Callee object doesn't have the ownership of the cloned instance.
  virtual SessionConverterInterface *Clone() const = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(SessionConverterInterface);
};

}  // namespace session
}  // namespace mozc

#endif  // MOZC_SESSION_SESSION_CONVERTER_INTERFACE_H_