#ifndef SYNCHRONIZED_MS_H
#define SYNCHRONIZED_MS_H

#include <casacore/ms/MeasurementSets/MeasurementSet.h>

#include <condition_variable>
#include <mutex>
#include <set>
#include <string>

namespace wsclean {

class SynchronizedMS {
 public:
  SynchronizedMS() {}

  SynchronizedMS(const std::string& filename,
                 const casacore::TableLock::LockOption lock_option =
                     casacore::TableLock::DefaultLocking)
      : _lock(std::make_shared<MSLock>(filename, lock_option)) {}

  void Reset() { _lock.reset(); }

  casacore::MeasurementSet* operator->() { return &_lock->MS(); }

  casacore::MeasurementSet& operator*() { return _lock->MS(); }

  casacore::MeasurementSet& MS() { return _lock->MS(); }

  const std::string& Filename() const { return _lock->Filename(); }

 private:
  class MSLock {
   public:
    MSLock(const std::string& filename,
           const casacore::TableLock::LockOption lock_option)
        : _filename(filename) {
      std::unique_lock<std::mutex> lock(_mutex);
      while (_openFiles.count(filename)) _condition.wait(lock);
      _openFiles.insert(filename);
      lock.unlock();

      _ms.reset(new casacore::MeasurementSet(_filename,
                                             casacore::TableLock(lock_option)));
    }

    MSLock(const MSLock&) = delete;

    MSLock(MSLock&& other) {
      // the other must already have access, so the ms can be directly claimed.
      // (unless the other was an empty object, in which case the
      //  copy will also be an empty object)
      _filename = std::move(other._filename);
      _ms = std::move(other._ms);
      other._filename = std::string();
      other._ms.reset();
    }

    ~MSLock() { release(); }

    MSLock& operator=(const MSLock&) = delete;

    MSLock& operator=(MSLock&& rhs) {
      release();

      _filename = std::move(rhs._filename);
      _ms = std::move(rhs._ms);
      return *this;
    }

    casacore::MeasurementSet& MS() { return *_ms; }

    const std::string& Filename() const { return _filename; }

   private:
    void release() {
      if (!_filename.empty()) {
        _ms.reset();
        std::lock_guard<std::mutex> lock(_mutex);
        _openFiles.erase(_filename);
        _condition.notify_all();
      }
    }

    static std::set<std::string> _openFiles;
    static std::condition_variable _condition;
    static std::mutex _mutex;

    std::string _filename;
    std::unique_ptr<casacore::MeasurementSet> _ms;
  };

  std::shared_ptr<MSLock> _lock;
};

}  // namespace wsclean

#endif
