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#include "engine/minimal_converter.h"

#include <cstddef>
#include <cstdint>
#include <memory>

#include "absl/log/check.h"
#include "absl/strings/string_view.h"
#include "absl/types/span.h"
#include "base/strings/assign.h"
#include "converter/attribute.h"
#include "converter/candidate.h"
#include "converter/converter_interface.h"
#include "converter/segments.h"
#include "request/conversion_request.h"

namespace mozc {
namespace {

bool AddAsIsCandidate(const absl::string_view key, Segments* segments) {
  if (key.empty()) {
    return false;
  }
  if (segments == nullptr) {
    return false;
  }
  segments->Clear();
  Segment* segment = segments->add_segment();
  DCHECK(segment);

  converter::Candidate* candidate = segment->push_back_candidate();
  DCHECK(candidate);
  strings::Assign(candidate->content_key, key);
  strings::Assign(candidate->content_value, key);
  strings::Assign(candidate->key, key);
  strings::Assign(candidate->value, key);
  candidate->lid = 0;
  candidate->rid = 0;
  candidate->wcost = 0;
  candidate->cost = 0;
  candidate->attributes = converter::Attribute::DEFAULT_ATTRIBUTE;

  return true;
}

bool AddAsIsCandidate(const ConversionRequest& request, Segments* segments) {
  return AddAsIsCandidate(request.key(), segments);
}

class MinimalConverter : public ConverterInterface {
 public:
  MinimalConverter() = default;

  bool StartConversion(const ConversionRequest& request,
                       Segments* segments) const override {
    return AddAsIsCandidate(request, segments);
  }

  bool StartReverseConversion(Segments* segments,
                              const absl::string_view key) const override {
    return false;
  }

  bool StartPrediction(const ConversionRequest& request,
                       Segments* segments) const override {
    return AddAsIsCandidate(request, segments);
  }

  bool StartPredictionWithPreviousSuggestion(
      const ConversionRequest& request, const Segment& previous_segment,
      Segments* segments) const override {
    return AddAsIsCandidate(request, segments);
  }

  void PrependCandidates(const ConversionRequest& request,
                         const Segment& segment,
                         Segments* segments) const override {
    segments->PrependCandidates(segment);
  }

  void FinishConversion(const ConversionRequest& request,
                        Segments* segments) const override {}

  void CancelConversion(Segments* segments) const override {}

  void ResetConversion(Segments* segments) const override {}

  void RevertConversion(Segments* segments) const override {}

  bool DeleteCandidateFromHistory(const Segments& segments,
                                  size_t segment_index,
                                  int candidate_index) const override {
    return true;
  }

  bool ReconstructHistory(
      Segments* segments,
      const absl::string_view preceding_text) const override {
    return true;
  }

  bool CommitSegmentValue(Segments* segments, size_t segment_index,
                          int candidate_index) const override {
    return true;
  }

  bool CommitPartialSuggestionSegmentValue(
      Segments* segments, size_t segment_index, int candidate_index,
      absl::string_view current_segment_key,
      absl::string_view new_segment_key) const override {
    return true;
  }

  bool FocusSegmentValue(Segments* segments, size_t segment_index,
                         int candidate_index) const override {
    return true;
  }

  bool CommitSegments(Segments* segments,
                      absl::Span<const size_t> candidate_index) const override {
    return true;
  }

  bool ResizeSegment(Segments* segments, const ConversionRequest& request,
                     size_t segment_index, int offset_length) const override {
    return true;
  }

  bool ResizeSegments(Segments* segments, const ConversionRequest& request,
                      size_t start_segment_index,
                      absl::Span<const uint8_t> new_size_array) const override {
    return true;
  }

  void CommitContext(const ConversionRequest& request) const override {}
};
}  // namespace

std::unique_ptr<ConverterInterface> CreateMinimalConverter() {
  return std::make_unique<MinimalConverter>();
}

}  // namespace mozc
