////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS 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 Kaveh Vahedipour
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_CONSENSUS_JOB_H
#define ARANGOD_CONSENSUS_JOB_H 1

#include "Agent.h"
#include "Node.h"
#include "Supervision.h"

#include <velocypack/Iterator.h>
#include <velocypack/Slice.h>
#include <velocypack/velocypack-aliases.h>

#include <string>

namespace arangodb {
namespace consensus {

enum JOB_STATUS {TODO, PENDING, FINISHED, FAILED, NOTFOUND};
const std::vector<std::string> pos({"/Target/ToDo/", "/Target/Pending/",
      "/Target/Finished/", "/Target/Failed/"});

static std::string const pendingPrefix  = "/Target/Pending/";
static std::string const failedPrefix   = "/Target/Failed/";
static std::string const finishedPrefix = "/Target/Finished/";
static std::string const toDoPrefix     = "/Target/ToDo/";
static std::string const cleanedPrefix  = "Target/CleanedServers";
static std::string const planColPrefix  = "/Plan/Collections/";
static std::string const curColPrefix   = "/Current/Collections/";
static std::string const blockedServersPrefix = "/Supervision/DBServers/";
static std::string const blockedShardsPrefix = "/Supervision/Shards/";
static std::string const serverStatePrefix = "/Sync/ServerStates/";
static std::string const planVersion    = "/Plan/Version";

inline arangodb::consensus::write_ret_t transact (
  Agent* _agent, Builder const& transaction, bool waitForCommit = true) {
  
  query_t envelope = std::make_shared<Builder>();

  try {
    envelope->openArray();
    envelope->add(transaction.slice());
    envelope->close();
  } catch (std::exception const& e) {
    LOG_TOPIC(ERR, Logger::AGENCY) << "Supervision failed to build transaction.";
    LOG_TOPIC(ERR, Logger::AGENCY) << e.what() << " " << __FILE__ << __LINE__;
  }
  
  LOG_TOPIC(DEBUG, Logger::AGENCY) << envelope->toJson();
  auto ret = _agent->write(envelope);
  if (waitForCommit && !ret.indices.empty()) {
    auto maximum = *std::max_element(ret.indices.begin(), ret.indices.end());
    if (maximum > 0) {  // some baby has worked
      _agent->waitFor(maximum);
    }
  }
  return ret;
  
}


struct JobResult {
  JobResult() {}
};

struct JobCallback {
  JobCallback() {}
  virtual ~JobCallback(){};
  virtual bool operator()(JobResult*) = 0;
};

struct Job {
  
  Job(Node const& snapshot, Agent* agent, std::string const& jobId,
      std::string const& creator, std::string const& agencyPrefix) :
    _snapshot(snapshot), _agent(agent), _jobId(jobId), _creator(creator),
    _agencyPrefix(agencyPrefix), _jb(nullptr) {}
  
  virtual ~Job() {}
  
  virtual JOB_STATUS exists() const {
  
    Node const& target = _snapshot("/Target");
  
    if        (target.exists(std::string("/ToDo/")     + _jobId).size() == 2) {
      return TODO;
    } else if (target.exists(std::string("/Pending/")  + _jobId).size() == 2) {
      return PENDING;
    } else if (target.exists(std::string("/Finished/") + _jobId).size() == 2) {
      return FINISHED;
    }  else if (target.exists(std::string("/Failed/")  + _jobId).size() == 2) {
      return FAILED;
    }

    return NOTFOUND;
  
  }
  
  virtual bool finish(std::string const& type, bool success = true,
                      std::string const& reason = std::string()) const {

    Builder pending, finished;
  
    // Get todo entry
    pending.openArray();
    if (_snapshot.exists(pendingPrefix + _jobId).size() == 3) {
      _snapshot(pendingPrefix + _jobId).toBuilder(pending);
    } else if (_snapshot.exists(toDoPrefix + _jobId).size() == 3) {
      _snapshot(toDoPrefix + _jobId).toBuilder(pending);
    } else {
      LOG_TOPIC(DEBUG, Logger::AGENCY)
        << "Nothing in pending to finish up for job " << _jobId;
      return false;
    }
    pending.close();
  
    // Prepare peding entry, block toserver
    finished.openArray();
  
    // --- Add finished
    finished.openObject();
    finished.add(_agencyPrefix + (success ? finishedPrefix : failedPrefix)
                 + _jobId, VPackValue(VPackValueType::Object));
    finished.add("timeFinished",
                 VPackValue(timepointToString(std::chrono::system_clock::now())));
    for (auto const& obj : VPackObjectIterator(pending.slice()[0])) {
      finished.add(obj.key.copyString(), obj.value);
    }
    if (!reason.empty()) {
      finished.add("reason", VPackValue(reason));
    }
    finished.close();
  
    // --- Delete pending
    finished.add(_agencyPrefix + pendingPrefix + _jobId,
                 VPackValue(VPackValueType::Object));
    finished.add("op", VPackValue("delete"));
    finished.close();

    // --- Delete todo
    finished.add(_agencyPrefix + toDoPrefix + _jobId,
                 VPackValue(VPackValueType::Object));
    finished.add("op", VPackValue("delete"));
    finished.close();

    // --- Remove block if specified
    if (type != "") {
      finished.add(_agencyPrefix + "/Supervision/" + type,
                   VPackValue(VPackValueType::Object));
      finished.add("op", VPackValue("delete"));
      finished.close();
    }
    
    // --- Need precond? 
    finished.close(); finished.close();
  
    write_ret_t res = transact(_agent, finished);
  
    if (res.accepted && res.indices.size()==1 && res.indices[0]) {
      return true;
    }

    return false;
  
  }
  
  virtual JOB_STATUS status () = 0;
  
  virtual bool create () = 0;
  
  virtual bool start() = 0;
  
  Node const _snapshot;
  Agent* _agent;
  std::string _jobId;
  std::string _creator;
  std::string _agencyPrefix;

  std::shared_ptr<Builder> _jb;

};

}}

#endif