// Copyright 2010-2021, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef MOZC_REWRITER_USER_SEGMENT_HISTORY_REWRITER_H_
#define MOZC_REWRITER_USER_SEGMENT_HISTORY_REWRITER_H_

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <vector>

#include "converter/segments.h"
#include "dictionary/pos_group.h"
#include "dictionary/pos_matcher.h"
#include "request/conversion_request.h"
#include "rewriter/rewriter_interface.h"
#include "storage/lru_storage.h"
#include "absl/strings/string_view.h"

namespace mozc {

class UserSegmentHistoryRewriter : public RewriterInterface {
 public:
  UserSegmentHistoryRewriter(const dictionary::PosMatcher *pos_matcher,
                             const dictionary::PosGroup *pos_group);

  bool Rewrite(const ConversionRequest &request,
               Segments *segments) const override;

  void Finish(const ConversionRequest &request, Segments *segments) override;
  bool Sync() override;
  bool Reload() override;
  void Clear() override;

 private:
  struct Score {
    constexpr void Update(const Score other) {
      score = std::max(score, other.score);
      last_access_time = std::max(last_access_time, other.last_access_time);
    }

    friend constexpr bool operator>(const Score a, const Score b) {
      if (a.score == b.score) {
        return a.last_access_time > b.last_access_time;
      }
      return a.score > b.score;
    }

    uint32_t score, last_access_time;
  };

  struct ScoreCandidate : public Score {
    ScoreCandidate(const Score s, const Segment::Candidate *candidate)
        : Score(s), candidate(candidate) {}

    const Segment::Candidate *candidate;
  };

  bool IsAvailable(const ConversionRequest &request,
                   const Segments &segments) const;
  Score GetScore(const Segments &segments, size_t segment_index,
                 int candidate_index) const;
  bool Replaceable(const Segment::Candidate &lhs,
                   const Segment::Candidate &rhs) const;
  void RememberFirstCandidate(const Segments &segments, size_t segment_index);
  void RememberNumberPreference(const Segment &segment);
  bool RewriteNumber(Segment *segment) const;
  bool ShouldRewrite(const Segment &segment, size_t *max_candidates_size) const;
  void InsertTriggerKey(const Segment &segment);
  bool IsPunctuation(const Segment &seg,
                     const Segment::Candidate &candidate) const;
  bool SortCandidates(const std::vector<ScoreCandidate> &sorted_scores,
                      Segment *segment) const;
  Score Fetch(absl::string_view key, uint32_t weight) const;
  void Insert(absl::string_view key, bool force);

  std::unique_ptr<storage::LruStorage> storage_;
  const dictionary::PosMatcher *pos_matcher_;
  const dictionary::PosGroup *pos_group_;
};

}  // namespace mozc

#endif  // MOZC_REWRITER_USER_SEGMENT_HISTORY_REWRITER_H_
