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#ifndef MOZC_REWRITER_USAGE_REWRITER_H_
#define MOZC_REWRITER_USAGE_REWRITER_H_

#include <cstdint>
#ifndef NO_USAGE_REWRITER

#include <map>
#include <string>
#include <utility>

#include "base/port.h"
#include "base/serialized_string_array.h"
#include "converter/segments.h"
#include "dictionary/dictionary_interface.h"
#include "dictionary/pos_matcher.h"
#include "rewriter/rewriter_interface.h"
#include "testing/base/public/gunit_prod.h"  // for FRIEND_TEST()

namespace mozc {

class DataManagerInterface;

class UsageRewriter : public RewriterInterface {
 public:
  UsageRewriter(const DataManagerInterface *data_manager,
                const dictionary::DictionaryInterface *dictionary);
  ~UsageRewriter() override;
  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_TEST(UsageRewriterTest, GetKanjiPrefixAndOneHiragana);

  static constexpr size_t kUsageItemByteLength = 20;

  class UsageDictItemIterator {
   public:
    UsageDictItemIterator() : ptr_(nullptr) {}
    explicit UsageDictItemIterator(const char *ptr) : ptr_(ptr) {}

    size_t usage_id() const {
      return *reinterpret_cast<const uint32_t *>(ptr_);
    }
    size_t key_index() const {
      return *reinterpret_cast<const uint32_t *>(ptr_ + 4);
    }
    size_t value_index() const {
      return *reinterpret_cast<const uint32_t *>(ptr_ + 8);
    }
    size_t conjugation_id() const {
      return *reinterpret_cast<const uint32_t *>(ptr_ + 12);
    }
    size_t meaning_index() const {
      return *reinterpret_cast<const uint32_t *>(ptr_ + 16);
    }

    UsageDictItemIterator &operator++() {
      ptr_ += kUsageItemByteLength;
      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 char *ptr_;
  };

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

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

  std::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_;
};

}  // namespace mozc

#endif  // NO_USAGE_REWRITER

#endif  // MOZC_REWRITER_USAGE_REWRITER_H_
