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#ifndef MOZC_SYNC_USER_DICTIONARY_SYNC_UTIL_H_
#define MOZC_SYNC_USER_DICTIONARY_SYNC_UTIL_H_

#include <string>
#include <vector>
#include "base/base.h"
#include "prediction/user_history_predictor.pb.h"

namespace mozc {

class UserHistoryStorage;

namespace sync {

class ClockTimerInterface;

class UserHistorySyncUtil {
 public:
  typedef user_history_predictor::UserHistory UserHistory;
  typedef user_history_predictor::UserHistory::Entry Entry;
  typedef user_history_predictor::UserHistory::NextEntry NextEntry;
  typedef user_history_predictor::UserHistory::Entry::EntryType EntryType;

  // Create |update| from |history|. It basically
  // aggreagate entries which are accessed after |last_access_time|.
  static bool CreateUpdate(const UserHistory &history,
                           uint64 last_access_time,
                           UserHistory *update);

  // Merge |entry| to |new_entry|.
  static bool MergeEntry(const Entry &entry, Entry *new_entry);

  // Merge a sequence of updates to the current |history|.
  static bool MergeUpdates(
      const vector<const UserHistory *> &updates,
      UserHistory *hitory);

  // Add random updates to |history|.
  // Used for unittesting.
  static void AddRandomUpdates(UserHistory *history,
                               ClockTimerInterface *clock_timer);

 private:
  UserHistorySyncUtil() {}
  ~UserHistorySyncUtil() {}
};
}  // sync
}  // mozc

#endif  // MOZC_SYNC_USER_DICTIONARY_SYNC_UTIL_H_