#include <gst/gst.h>
#include <glib.h>

struct paraminfo {
  gchar *name;
  GObject *obj;
  GParamSpecInt *pspec;
};

static struct paraminfo*
new_paraminfo (GstElement *obj, gchar *name)
{
  struct paraminfo *info = g_new (struct paraminfo, 1);
  info->name = name;
  info->obj = G_OBJECT (obj);
  info->pspec = G_PARAM_SPEC_INT (
    g_object_class_find_property (G_OBJECT_GET_CLASS (obj), name));
  return info;
}

static void
free_paraminfo (gpointer ptr)
{
  g_free (ptr);
}

struct appdata {
  GList *paramlist;
  GRand *rand;
  gint min,max;
};

static gboolean
bus_call (GstBus     *bus,
          GstMessage *msg,
          gpointer    data)
{
  GMainLoop *loop = (GMainLoop *) data;

  switch (GST_MESSAGE_TYPE (msg)) {

    case GST_MESSAGE_EOS:
      g_print ("End of stream\n");
      g_main_loop_quit (loop);
      break;

    case GST_MESSAGE_ERROR: {
      gchar  *debug;
      GError *error;

      gst_message_parse_error (msg, &error, &debug);
      g_free (debug);

      g_printerr ("Error: %s\n", error->message);
      g_error_free (error);

      g_main_loop_quit (loop);
      break;
    }
    default:
      break;
  }

  return TRUE;
}

static gboolean
source_tick (struct appdata *data)
{
  int randparam = g_rand_int_range (data->rand,
    0, g_list_length (data->paramlist));
  struct paraminfo *info = g_list_nth_data (data->paramlist,
    randparam);
  int randval = g_rand_int_range (data->rand,
      -10000, 10000);
      //info->pspec->minimum, info->pspec->maximum);

  g_print ("setting '%s' to '%d'\n",
    info->name, randval);
  g_object_set (info->obj,
    info->name, randval,
    NULL);

  return TRUE;
}

int
main (int   argc,
      char *argv[])
{
  GMainLoop *loop;

  GstElement *pipeline, *box;
  GstBus *bus;
  guint bus_watch_id;
  GSource *source;
  struct appdata data = {
    .paramlist = NULL,
    .rand = g_rand_new (),
  };

  /* Initialisation */
  gst_init (&argc, &argv);

  loop = g_main_loop_new (NULL, FALSE);

  /* Create gstreamer elements */
  pipeline = gst_parse_launch ("videotestsrc ! video/x-raw,width=1024,height=1024 ! "
    "videobox name=box ! fakesink",
                  NULL);

  box = gst_bin_get_by_name (GST_BIN (pipeline), "box");
  data.paramlist = g_list_append (data.paramlist, new_paraminfo (box, "left"));
  data.paramlist = g_list_append (data.paramlist, new_paraminfo (box, "right"));
  data.paramlist = g_list_append (data.paramlist, new_paraminfo (box, "top"));
  data.paramlist = g_list_append (data.paramlist, new_paraminfo (box, "bottom"));

  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
  bus_watch_id = gst_bus_add_watch (bus, bus_call, loop);
  gst_object_unref (bus);

  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  g_print ("Running...\n");

  source = g_timeout_source_new (1);
  g_source_set_callback (source, (GSourceFunc)source_tick, &data, NULL);
  g_source_attach (source, NULL);
  g_source_unref (source);

  g_main_loop_run (loop);

  g_print ("Returned, stopping playback\n");
  gst_element_set_state (pipeline, GST_STATE_NULL);

  g_print ("Deleting pipeline\n");
  gst_object_unref (GST_OBJECT (pipeline));
  g_source_remove (bus_watch_id);
  g_main_loop_unref (loop);
  g_list_free_full (data.paramlist, free_paraminfo);
  g_rand_free (data.rand);

  return 0;
}