////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2018 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Tobias Gödderz
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_GRAPH_GRAPHCACHE_H
#define ARANGOD_GRAPH_GRAPHCACHE_H

#include <velocypack/Buffer.h>
#include <chrono>
#include <utility>

#include "Aql/Query.h"
#include "Aql/VariableGenerator.h"
#include "Basics/ReadWriteLock.h"
#include "Transaction/Methods.h"
#include "Transaction/StandaloneContext.h"

namespace arangodb {
namespace graph {
class GraphCache {
 public:
  // save now() along with the graph
  using EntryType =
      std::pair<std::chrono::steady_clock::time_point, std::shared_ptr<const Graph>>;
  using CacheType = std::unordered_map<std::string, EntryType>;

  // TODO The cache saves the graph names globally, not per database!
  // This must be addressed as soon as it is activated.
  const std::shared_ptr<const Graph> getGraph(
      std::shared_ptr<transaction::Context> ctx, std::string const& name,
      std::chrono::seconds maxAge = std::chrono::seconds(60));

 private:
  basics::ReadWriteLock _lock;
  CacheType _cache;
};
}  // namespace graph
}  // namespace arangodb

#endif  // ARANGOD_GRAPH_GRAPHCACHE_H