text: //////////////////////////////////////////////////////////////////////////////
  //
  // Copyright (c) 2004-2020 musikcube team
  //
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are met:
  //
  //    * Redistributions of source code must retain the above copyright notice,
  //      this list of conditions and the following disclaimer.
  //
  //    * Redistributions in binary form must reproduce the above copyright
  //      notice, this list of conditions and the following disclaimer in the
  //      documentation and/or other materials provided with the distribution.
  //
  //    * Neither the name of the author nor the names of other contributors may
  //      be used to endorse or promote products derived from this software
  //      without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  // POSSIBILITY OF SUCH DAMAGE.
  //
  //////////////////////////////////////////////////////////////////////////////
  
  #pragma once
  
  #include <musikcore/config.h>
  #include <musikcore/audio/IStream.h>
  #include <musikcore/sdk/constants.h>
  #include <musikcore/sdk/IOutput.h>
  #include <musikcore/sdk/IBufferProvider.h>
  
  #include <sigslot/sigslot.h>
  
  #include <thread>
  #include <mutex>
  #include <condition_variable>
  #include <atomic>
  
  namespace musik { namespace core { namespace audio {
  
      struct FftContext;
  
      class Player : public musik::core::sdk::IBufferProvider {
          public:
              enum class DestroyMode: int { Drain = 0, NoDrain = 1 };
  
              struct Gain {
                  Gain() noexcept {
                      this->preamp = this->gain = this->peak = 1.0f;
                      this->peakValid = false;
                  }
                  float preamp;
                  float gain;
                  float peak;
                  bool peakValid;
              };
  
              struct EventListener {
                  virtual ~EventListener() { }
                  virtual void OnPlayerBuffered(Player* player) { }
                  virtual void OnPlayerStarted(Player* player) { }
                  virtual void OnPlayerAlmostEnded(Player* player) { }
                  virtual void OnPlayerFinished(Player* player) { }
                  virtual void OnPlayerOpenFailed(Player* player) { }
                  virtual void OnPlayerDestroying(Player* player) { }
                  virtual void OnPlayerMixPoint(Player* player, int id, double time) { }
              };
  
              static Player* Create(
                  const std::string &url,
                  std::shared_ptr<musik::core::sdk::IOutput> output,
                  DestroyMode destroyMode,
                  EventListener *listener,
                  Gain gain = Gain());
  
              virtual void OnBufferProcessed(musik::core::sdk::IBuffer *buffer);
  
              void Detach(EventListener *listener);
              void Attach(EventListener *listener);
  
              void Play();
              void Destroy();
              void Destroy(DestroyMode mode);
  
              double GetPosition();
              void SetPosition(double seconds);
              double GetDuration();
  
              void AddMixPoint(int id, double time);
  
              bool HasCapability(musik::core::sdk::Capability capability);
  
              std::string GetUrl() const { return this->url; }
  
              musik::core::sdk::StreamState GetStreamState() noexcept { return this->streamState; }
  
          private:
              friend void playerThreadLoop(Player* player);
  
              double GetPositionInternal();
  
              Player(
                  const std::string &url,
                  std::shared_ptr<musik::core::sdk::IOutput> output,
                  DestroyMode finishMode,
                  EventListener *listener,
                  Gain gain);
  
              virtual ~Player();
  
              struct MixPoint {
                  MixPoint(int id, double time) noexcept {
                      this->id = id;
                      this->time = time;
                  }
  
                  int id;
                  double time;
              };
  
              using MixPointPtr = std::shared_ptr<MixPoint>;
              using MixPointList = std::list<MixPointPtr>;
              using ListenerList = std::list<EventListener*>;
              using OutputPtr = std::shared_ptr<musik::core::sdk::IOutput>;
  
              typedef enum {
                  Idle = 0,
                  Playing = 1,
                  Quit = 2
              } InternalState;
  
              bool Exited();
              int State();
              ListenerList Listeners();
  
              std::thread* thread;
  
              OutputPtr output;
              IStreamPtr stream;
              ListenerList listeners;
              MixPointList pendingMixPoints;
              MixPointList processedMixPoints;
              MixPointList mixPointsHitTemp; /* so we don't have to keep alloc'ing it */
  
              void UpdateNextMixPointTime();
  
              std::string url;
  
              /* granular mutexes for better performance */
              std::mutex queueMutex, listenerMutex;
              std::condition_variable writeToOutputCondition;
  
              double volume;
              double nextMixPoint;
              std::atomic<double> currentPosition;
              std::atomic<double> seekToPosition;
              std::atomic<musik::core::sdk::StreamState> streamState;
              std::atomic<int> internalState;
              bool notifiedStarted;
              float* spectrum;
              DestroyMode destroyMode;
              Gain gain;
              int pendingBufferCount;
              bool threadFinished;
  
              FftContext* fftContext;
      };
  
  } } }
  