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#ifndef MOZC_REWRITER_USAGE_REWRITER_H_
#define MOZC_REWRITER_USAGE_REWRITER_H_

#ifndef NO_USAGE_REWRITER
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <new>
#include <string>
#include <utility>

#include "absl/container/flat_hash_map.h"
#include "absl/strings/string_view.h"
#include "base/container/serialized_string_array.h"
#include "converter/candidate.h"
#include "converter/segments.h"
#include "data_manager/data_manager.h"
#include "dictionary/dictionary_interface.h"
#include "dictionary/pos_matcher.h"
#include "request/conversion_request.h"
#include "rewriter/rewriter_interface.h"

namespace mozc {

class UsageRewriter : public RewriterInterface {
 public:
  UsageRewriter(const DataManager& data_manager,
                const dictionary::DictionaryInterface& dictionary);
  ~UsageRewriter() override = default;
  bool Rewrite(const ConversionRequest& request,
               Segments* segments) const override;

  // better to show usage when user type "tab" key.
  int capability(const ConversionRequest& request) const override {
    return CONVERSION | PREDICTION;
  }

 private:
  friend class UsageRewriterTestPeer;

  static constexpr size_t kUsageItemSize = 5;

  class UsageDictItemIterator {
   public:
    using iterator_cateogry = std::input_iterator_tag;
    using value_type = size_t;

    UsageDictItemIterator() : ptr_(nullptr) {}
    explicit UsageDictItemIterator(const char* ptr)
        : ptr_(std::launder(reinterpret_cast<const uint32_t*>(ptr))) {}

    size_t usage_id() const { return *ptr_; }
    size_t key_index() const { return *(ptr_ + 1); }
    size_t value_index() const { return *(ptr_ + 2); }
    size_t conjugation_id() const { return *(ptr_ + 3); }
    size_t meaning_index() const { return *(ptr_ + 4); }

    UsageDictItemIterator& operator++() {
      ptr_ += kUsageItemSize;
      return *this;
    }

    bool IsValid() const { return ptr_ != nullptr; }

    friend bool operator==(UsageDictItemIterator x, UsageDictItemIterator y) {
      return x.ptr_ == y.ptr_;
    }

    friend bool operator!=(UsageDictItemIterator x, UsageDictItemIterator y) {
      return x.ptr_ != y.ptr_;
    }

   private:
    const uint32_t* ptr_;
  };

  using StrPair = std::pair<std::string, std::string>;
  static std::string GetKanjiPrefixAndOneHiragana(absl::string_view word);

  UsageDictItemIterator LookupUnmatchedUsageHeuristically(
      const converter::Candidate& candidate) const;
  UsageDictItemIterator LookupUsage(
      const converter::Candidate& candidate) const;

  absl::flat_hash_map<StrPair, UsageDictItemIterator> key_value_usageitem_map_;
  const dictionary::PosMatcher pos_matcher_;
  const dictionary::DictionaryInterface* dictionary_;
  const uint32_t* base_conjugation_suffix_;
  SerializedStringArray string_array_;

 private:
  friend class UsageRewriterPeer;
};

}  // namespace mozc

#endif  // NO_USAGE_REWRITER

#endif  // MOZC_REWRITER_USAGE_REWRITER_H_
