#ifndef FRAMEGRABBER_H
#define FRAMEGRABBER_H

#include <atomic>
#include <list>
#include <string>

#include <gst/gst.h>
#include <gst/app/gstappsrc.h>

#include "GlmToolkit.h"

class FrameBuffer;



/**
 * @brief The FrameGrabber class defines the base class for all recorders
 * used to save images or videos from a frame buffer.
 *
 * Every subclass shall at least implement init() and terminate()
 *
 * The FrameGrabbing manager calls addFrame() for all its grabbers.
 */
class FrameGrabber
{
    friend class FrameGrabbing;

    uint64_t id_;

public:
    FrameGrabber();
    virtual ~FrameGrabber();

    inline uint64_t id() const { return id_; }

    virtual void stop();
    virtual std::string info() const;
    virtual double duration() const;
    virtual bool finished() const;
    virtual bool busy() const;

protected:

    // only FrameGrabbing manager can add frame
    virtual void addFrame(GstBuffer *buffer, GstCaps *caps, float dt);

    // only addFrame method shall call those
    virtual void init(GstCaps *caps) = 0;
    virtual void terminate() = 0;

    // thread-safe testing termination
    std::atomic<bool> finished_;
    std::atomic<bool> active_;
    std::atomic<bool> accept_buffer_;

    // gstreamer pipeline
    GstElement   *pipeline_;
    GstAppSrc    *src_;
    GstCaps      *caps_;
    GstClockTime timeframe_;
    GstClockTime timestamp_;
    GstClockTime frame_duration_;

    // gstreamer callbacks
    static void callback_need_data (GstAppSrc *, guint, gpointer user_data);
    static void callback_enough_data (GstAppSrc *, gpointer user_data);

};

/**
 * @brief The FrameGrabbing class manages all frame grabbers
 *
 * Session calls grabFrame after each render
 *
 */
class FrameGrabbing
{
    friend class Session;

    // Private Constructor
    FrameGrabbing();
    FrameGrabbing(FrameGrabbing const& copy);            // Not Implemented
    FrameGrabbing& operator=(FrameGrabbing const& copy); // Not Implemented

public:

    static FrameGrabbing& manager()
    {
        // The only instance
        static FrameGrabbing _instance;
        return _instance;
    }
    ~FrameGrabbing();

    inline uint width() const { return width_; }
    inline uint height() const { return height_; }

    void add(FrameGrabber *rec);
    FrameGrabber *front();
    FrameGrabber *get(uint64_t id);
    void stopAll();
    void clearAll();

protected:

    // only for friend Session
    void grabFrame(FrameBuffer *frame_buffer, float dt);

private:
    std::list<FrameGrabber *> grabbers_;
    guint pbo_[2];
    guint pbo_index_;
    guint pbo_next_index_;
    guint size_;
    guint width_;
    guint height_;
    bool  use_alpha_;
    GstCaps *caps_;
};



#endif // FRAMEGRABBER_H