/*
  Copyright(C) 2011-2016 Brazil

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#pragma once

#include "cursor.hpp"
#include "vector.hpp"

namespace grn {
namespace dat {

class Trie;

class GRN_DAT_API KeyCursor : public Cursor {
 public:
  KeyCursor();
  ~KeyCursor();

  void open(const Trie &trie,
            const String &min_str,
            const String &max_str,
            UInt32 offset = 0,
            UInt32 limit = MAX_UINT32,
            UInt32 flags = 0);

  void close() override;

  const Key &next() override;

  UInt32 offset() const override {
    return offset_;
  }
  UInt32 limit() const override {
    return limit_;
  }
  UInt32 flags() const override {
    return flags_;
  }

 private:
  const Trie *trie_;
  UInt32 offset_;
  UInt32 limit_;
  UInt32 flags_;

  Vector<UInt32> buf_;
  UInt32 count_;
  UInt32 max_count_;
  bool finished_;
  UInt8 *end_buf_;
  String end_str_;

  KeyCursor(const Trie &trie,
            UInt32 offset, UInt32 limit, UInt32 flags);

  UInt32 fix_flags(UInt32 flags) const;
  void init(const String &min_str, const String &max_str);
  void ascending_init(const String &min_str, const String &max_str);
  void descending_init(const String &min_str, const String &max_str);
  void swap(KeyCursor *cursor);

  const Key &ascending_next();
  const Key &descending_next();

  static const UInt32 POST_ORDER_FLAG = 0x80000000U;

  // Disallows copy and assignment.
  KeyCursor(const KeyCursor &);
  KeyCursor &operator=(const KeyCursor &);
};

}  // namespace dat
}  // namespace grn
