#ifndef muz_AUDIOENGINE_HPP
#define muz_AUDIOENGINE_HPP

#include <portaudio.h>

#include "commons.hpp"
#include "AudioConf.hpp"

namespace muz
{
  class Signal;

  MUZ_ERROR(audio_error);

  /**
   * Make sound from signals.
   * @see Signal
   **/
  class AudioEngine
  {
  public:
    explicit AudioEngine(AudioConf const& conf);
    virtual ~AudioEngine();

    /**
     * Initialize the engine opening audio device.
     **/
    void init();

    /**
     * Run the engine, making sound.
     **/
    void run();

    /**
     * Push a new signal in the signals queue.
     */
    void push_signal(std::unique_ptr<Signal> signal);

    /**
     * Pop the current signal or does nothing if the queue is empty.
     **/
    void pop_signal();

  private:
    AudioConf m_conf;
    PaStream* m_stream = nullptr;
    std::vector<std::unique_ptr<Signal>> m_sig_queue;
    std::mutex m_sig_mtx;
    std::vector<float> m_frame;

    /**
     * Throws an audio_error exception if err is an error.
     **/
    void check_error(PaError err);

    /**
     * Gives the next sample of the current signal.
     * @see Signal
     **/
    std::vector<float> next();

    /**
     * Portaudio audio callback.
     **/
    static int callback(void const* input, void* output,
                        unsigned long frames_per_buffer,
                        PaStreamCallbackTimeInfo const* time,
                        PaStreamCallbackFlags flags,
                        void* data);
  };
}

#endif