/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

#ifndef __TMANAGER_STATEFUL_HELPER_H_
#define __TMANAGER_STATEFUL_HELPER_H_

#include <set>
#include <string>
#include "network/network.h"
#include "manager/tmanager.h"
#include "basics/basics.h"

namespace heron {
namespace common {
class MetricsMgrSt;
class MultiCountMetric;
}
}  // namespace heron

namespace heron {
namespace tmanager {

using std::unique_ptr;
using std::shared_ptr;

class StatefulRestorer;
class StatefulCheckpointer;

// For Heron topologies running in effectively once semantics, the tmanager
// utilizes the stateful controller to handle all the work related with
// checkpointing and restoring from checkpoints. The statful controller
// offers methods to start checkpoint/restore. It also manages the state
// to track if the checkpoint/restore is done/still in progress.
//
// For more information please refer to the stateful processing design doc at
// https://docs.google.com/document/d/1pNuE77diSrYHb7vHPuPO3DZqYdcxrhywH_f7loVryCI/edit#
// and in particular the recovery section.
class StatefulController {
 public:
  explicit StatefulController(const std::string& _topology_name,
               shared_ptr<proto::ckptmgr::StatefulConsistentCheckpoints> _ckpt,
               shared_ptr<heron::common::HeronStateMgr> _state_mgr,
               std::chrono::high_resolution_clock::time_point _tmanager_start_time,
               shared_ptr<common::MetricsMgrSt> _metrics_manager_client,
               std::function<void(const proto::ckptmgr::StatefulConsistentCheckpoints&)>
                   _ckpt_save_watcher);
  virtual ~StatefulController();
  // Start a new restore process
  void StartRestore(const StMgrMap& _stmgrs, bool _ignore_prev_checkpoints);
  // Called by tmanager when a Stmgr responds back with a RestoreTopologyStateResponse
  void HandleStMgrRestored(const std::string& _stmgr_id,
                           const std::string& _checkpoint_id,
                           int64_t _restore_txid,
                           proto::system::StatusCode _status,
                           const StMgrMap& _stmgrs);
  // Called when a new physical plan is made
  void RegisterNewPhysicalPlan(const proto::system::PhysicalPlan& _pplan);

  // Called its time to start a new checkpoint
  void StartCheckpoint(const StMgrMap& _stmgrs);

  // Called when we receive a InstanceStateStored message
  void HandleInstanceStateStored(const std::string& _checkpoint_id,
                                 const std::string& _packing_plan_id,
                                 const proto::system::Instance& _instance);

  // Check if response received from given stmgr during restore
  bool GotRestoreResponse(const std::string& _stmgr) const;

  bool RestoreInProgress() const;

 private:
  // Get the youngest ckpt id that is older than the given ckpt_id
  const std::string& GetNextInLineCheckpointId(const std::string& _ckpt_id);
  // Creates a new ckpt record adding the latest one
  shared_ptr<proto::ckptmgr::StatefulConsistentCheckpoints>
    AddNewConsistentCheckpoint(const std::string& _new_checkpoint,
                               const std::string& _packing_plan);
  // Handler when statemgr saves the new checkpoint record
  void HandleCheckpointSave(shared_ptr<proto::ckptmgr::StatefulConsistentCheckpoints> _new_ckpt,
                            proto::system::StatusCode _status);

  std::string topology_name_;
  shared_ptr<proto::ckptmgr::StatefulConsistentCheckpoints> ckpt_record_;
  shared_ptr<heron::common::HeronStateMgr> state_mgr_;
  unique_ptr<StatefulCheckpointer> checkpointer_;
  unique_ptr<StatefulRestorer> restorer_;
  shared_ptr<common::MetricsMgrSt> metrics_manager_client_;
  shared_ptr<common::MultiCountMetric> count_metrics_;
  std::function<void(const proto::ckptmgr::StatefulConsistentCheckpoints&)> ckpt_save_watcher_;
};
}  // namespace tmanager
}  // namespace heron

#endif