refactor code

Change-Id: Ia2bc49ed8742d79000fd59f7e95fa9b957573c54
diff --git a/core/db.hpp b/core/db.hpp
new file mode 100644
index 0000000..503b562
--- /dev/null
+++ b/core/db.hpp
@@ -0,0 +1,84 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California
+ *
+ * This file is part of NSL (NDN Signature Logger).
+ * See AUTHORS.md for complete list of NSL authors and contributors.
+ *
+ * NSL is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NSL 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NSL, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of nsl authors and contributors.
+ */
+
+#ifndef NSL_CORE_DB_HPP
+#define NSL_CORE_DB_HPP
+
+#include "common.hpp"
+#include "leaf.hpp"
+#include "util/non-negative-integer.hpp"
+#include <vector>
+
+struct sqlite3;
+
+namespace nsl {
+
+class Db : noncopyable
+{
+public:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+public:
+  void
+  open(const std::string& dbDir);
+
+  bool
+  insertSubTreeData(size_t level, const NonNegativeInteger& seqNo,
+                    const Data& data,
+                    bool isFull = true,
+                    const NonNegativeInteger& nextLeafSeqNo = 0);
+
+  shared_ptr<Data>
+  getSubTreeData(size_t level, const NonNegativeInteger& seqNo);
+
+  std::vector<shared_ptr<Data>>
+  getPendingSubTrees();
+
+  bool
+  insertLeafData(const Leaf& leaf);
+
+  bool
+  insertLeafData(const Leaf& leaf, const Data& data);
+
+  std::pair<shared_ptr<Leaf>, shared_ptr<Data>>
+  getLeaf(const NonNegativeInteger& seqNo);
+
+NSL_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
+  const NonNegativeInteger&
+  getMaxLeafSeq();
+
+private:
+  sqlite3* m_db;
+
+  NonNegativeInteger m_nextLeafSeqNo;
+};
+
+} // namespace nsl
+
+#endif // NSL_CORE_DB_HPP