#include "gst/gstbin.h"
#include "gst/gstbus.h"
#include "gst/gstclock.h"
#include "gst/gstelement.h"
#include "gst/gstelementfactory.h"
#include "gst/gstmessage.h"
#include "gst/gstobject.h"
#include "gst/gstpipeline.h"
#include "gst/gstutils.h"
#include <gst/gst.h>

typedef struct _CustomData {
  GstElement *pipeline;
  GstElement *source;
} CustomData;

int main(int argc, char *argv[]) {
  GstBus *bus;
  GstMessage *msg;
  GstElement *video_queue;
  GstElement *video_convert;
  GstElement *video_sink;
  CustomData data;
  GstStateChangeReturn ret;
  gboolean terminate = FALSE;
  
  gst_init(&argc, &argv);
  data.source = gst_element_factory_make("v4l2src", "source");
  video_queue = gst_element_factory_make("queue", "video_queue");
  video_convert = gst_element_factory_make("videoconvert", "video_convert");
  video_sink = gst_element_factory_make("autovideosink", "video_sink");
  data.pipeline = gst_pipeline_new("media-pipeline");

  if (!data.source || !video_queue || !video_convert || !video_sink || !data.pipeline) {
    g_printerr("Couldn't create all elements.\n");
    return -1;
  }
  g_object_set(data.source, "device", "/dev/video2", NULL);
  
  gst_bin_add_many(GST_BIN(data.pipeline), data.source, video_queue, video_convert, video_sink, NULL);
  if (!gst_element_link_many(data.source, video_queue, video_convert, video_sink, NULL)) {
    g_printerr("Couldn't link stream elements.\n");
    gst_object_unref(data.pipeline);
    return -1;
  }

  ret = gst_element_set_state(data.pipeline, GST_STATE_PLAYING);
  if (ret == GST_STATE_CHANGE_FAILURE) {
    g_printerr("Failed to start playing.\n");
    return -1;
  }
  
  bus = gst_element_get_bus(data.pipeline);
  do {
    msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_STATE_CHANGED | GST_MESSAGE_ERROR | GST_MESSAGE_EOS);

    switch (GST_MESSAGE_TYPE(msg)) {
    case GST_MESSAGE_ERROR: {
      GError *err;
      gchar *debug_info;
      gst_message_parse_error(msg, &err, &debug_info);
      g_printerr("Error received from element %s: %s\n", GST_ELEMENT_NAME(msg->src), err->message);
      g_printerr("Debug info: %s\n", debug_info ? debug_info : "none");

      g_error_free(err);
      g_free(debug_info);
      terminate = TRUE;
      break;
    }
    case GST_MESSAGE_EOS:
      g_print("End-of-stream reached.\n");
      terminate = TRUE;
      break;
    case GST_MESSAGE_STATE_CHANGED:
      if (GST_MESSAGE_SRC(msg) == GST_OBJECT(data.pipeline)) {
	GstState old_state, new_state, pending_state;
	gst_message_parse_state_changed(msg, &old_state, &new_state, &pending_state);
	g_print("Changed from state %d to state %d\n", old_state, new_state);
      }
      break;
    default:
      break;
    }
    
  }while (!terminate);

  gst_object_unref(bus);
  gst_element_set_state(data.pipeline, GST_STATE_NULL);
  gst_object_unref(data.pipeline);
  
  return 0;
}