/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2021 Osimis S.A., Belgium
 * Copyright (C) 2021-2021 Sebastien Jodogne, ICTEAM UCLouvain, Belgium
 *
 * This program 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 3 of
 * the License, or (at your option) any later version.
 *
 * This program 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 program. If not, see
 * <http://www.gnu.org/licenses/>.
 **/


#pragma once

#if !defined(ORTHANC_SANDBOXED)
#  error The macro ORTHANC_SANDBOXED must be defined
#endif

#if ORTHANC_SANDBOXED == 1
#  error The job engine cannot be used in sandboxed environments
#endif

#include "JobInfo.h"
#include "IJobUnserializer.h"

#include <list>
#include <set>
#include <queue>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition_variable.hpp>

namespace Orthanc
{
  // This class handles the state machine of the jobs engine
  class ORTHANC_PUBLIC JobsRegistry : public boost::noncopyable
  {
  public:
    class ORTHANC_PUBLIC IObserver : public boost::noncopyable
    {
    public:
      virtual ~IObserver()
      {
      }

      virtual void SignalJobSubmitted(const std::string& jobId) = 0;

      virtual void SignalJobSuccess(const std::string& jobId) = 0;

      virtual void SignalJobFailure(const std::string& jobId) = 0;
    };

  private:
    enum CompletedReason
    {
      CompletedReason_Success,
      CompletedReason_Failure,
      CompletedReason_Canceled
    };

    class JobHandler;

    struct PriorityComparator
    {
      bool operator() (JobHandler* const& a,
                       JobHandler* const& b) const;
    };

    typedef std::map<std::string, JobHandler*>              JobsIndex;
    typedef std::list<JobHandler*>                          CompletedJobs;
    typedef std::set<JobHandler*>                           RetryJobs;
    typedef std::priority_queue<JobHandler*,
                                std::vector<JobHandler*>,   // Could be a "std::deque"
                                PriorityComparator>         PendingJobs;

    boost::mutex               mutex_;
    JobsIndex                  jobsIndex_;
    PendingJobs                pendingJobs_;
    CompletedJobs              completedJobs_;
    RetryJobs                  retryJobs_;

    boost::condition_variable  pendingJobAvailable_;
    boost::condition_variable  someJobComplete_;
    size_t                     maxCompletedJobs_;

    IObserver*                 observer_;


#ifndef NDEBUG
    bool IsPendingJob(const JobHandler& job) const;

    bool IsCompletedJob(JobHandler& job) const;

    bool IsRetryJob(JobHandler& job) const;
#endif

    void CheckInvariants() const;

    void ForgetOldCompletedJobs();

    void SetCompletedJob(JobHandler& job,
                         bool success);

    void MarkRunningAsCompleted(JobHandler& job,
                                CompletedReason reason);

    void MarkRunningAsRetry(JobHandler& job,
                            unsigned int timeout);

    void MarkRunningAsPaused(JobHandler& job);

    bool GetStateInternal(JobState& state,
                          const std::string& id);

    void RemovePendingJob(const std::string& id);

    void RemoveRetryJob(JobHandler* handler);

    void SubmitInternal(std::string& id,
                        JobHandler* handler);

  public:
    explicit JobsRegistry(size_t maxCompletedJobs);

    JobsRegistry(IJobUnserializer& unserializer,
                 const Json::Value& s,
                 size_t maxCompletedJobs);

    ~JobsRegistry();

    void SetMaxCompletedJobs(size_t i);

    size_t GetMaxCompletedJobs();

    void ListJobs(std::set<std::string>& target);

    bool GetJobInfo(JobInfo& target,
                    const std::string& id);

    bool GetJobOutput(std::string& output,
                      MimeType& mime,
                      std::string& filename,
                      const std::string& job,
                      const std::string& key);

    void Serialize(Json::Value& target);

    void Submit(std::string& id,
                IJob* job,        // Takes ownership
                int priority);

    void Submit(IJob* job,        // Takes ownership
                int priority);

    void SubmitAndWait(Json::Value& successContent,
                       IJob* job,        // Takes ownership
                       int priority);

    bool SetPriority(const std::string& id,
                     int priority);

    bool Pause(const std::string& id);

    bool Resume(const std::string& id);

    bool Resubmit(const std::string& id);

    bool Cancel(const std::string& id);

    void ScheduleRetries();

    bool GetState(JobState& state,
                  const std::string& id);

    void SetObserver(IObserver& observer);

    void ResetObserver();

    void GetStatistics(unsigned int& pending,
                       unsigned int& running,
                       unsigned int& success,
                       unsigned int& errors);

    class ORTHANC_PUBLIC RunningJob : public boost::noncopyable
    {
    private:
      JobsRegistry&  registry_;
      JobHandler*    handler_;  // Can only be accessed if the
                                // registry mutex is locked!
      IJob*          job_;  // Will by design be in mutual exclusion,
                            // because only one RunningJob can be
                            // executed at a time on a JobHandler

      std::string    id_;
      int            priority_;
      JobState       targetState_;
      unsigned int   targetRetryTimeout_;
      bool           canceled_;

    public:
      RunningJob(JobsRegistry& registry,
                 unsigned int timeout);

      ~RunningJob();

      bool IsValid() const;

      const std::string& GetId() const;

      int GetPriority() const;

      IJob& GetJob();

      bool IsPauseScheduled();

      bool IsCancelScheduled();

      void MarkSuccess();

      void MarkFailure();

      void MarkPause();

      void MarkCanceled();

      void MarkRetry(unsigned int timeout);

      void UpdateStatus(ErrorCode code,
                        const std::string& details);
    };
  };
}