#include <gst/gst.h>

static GstPad *audiosrc_blockpad;
static GstElement *videosrc, *videosink, *pipeline, *textoverlay, *audiosrc, *audiosink;

static GstPadProbeReturn pad_probe_videosrc_cb(GstPad * videosrc_pad, GstPadProbeInfo * info, gpointer user_data){

    /* unlink videotestsrc from ximagesink */
    gst_element_set_state(videosink, GST_STATE_NULL);
    gst_bin_remove(GST_BIN(pipeline), videosink);

    /* adding the textoverlay */
    textoverlay = gst_element_factory_make("textoverlay", NULL);
    g_object_set(G_OBJECT (textoverlay), "text", "Hello World!", NULL);
    gst_bin_add_many(GST_BIN(pipeline), textoverlay, videosink, NULL);

    /* inserting the text overlay */
    gst_element_link_many(videosrc, textoverlay, videosink, NULL);

    gst_element_set_state(textoverlay, GST_STATE_PLAYING);
    gst_element_set_state(videosink, GST_STATE_PLAYING);

    //gst_debug_set_threshold_from_string ("*:5", TRUE);

    return GST_PAD_PROBE_REMOVE;
}

static GstPadProbeReturn pad_probe_cb (GstPad * pad, GstPadProbeInfo * info, gpointer user_data){

    /* remove audio */
    gst_element_set_state(audiosink, GST_STATE_NULL);
    gst_bin_remove(GST_BIN(pipeline), audiosink);

    gst_pad_add_probe (gst_element_get_static_pad(videosrc, "src"), GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM, pad_probe_videosrc_cb, user_data, NULL);

    GST_DEBUG_BIN_TO_DOT_FILE (GST_BIN (pipeline), GST_DEBUG_GRAPH_SHOW_ALL ,"usecase2-b");

    return GST_PAD_PROBE_OK;
}

static gboolean timeout_cb (gpointer user_data){

    GST_DEBUG_BIN_TO_DOT_FILE (GST_BIN (pipeline), GST_DEBUG_GRAPH_SHOW_ALL ,"usecase2-a");

    gst_pad_add_probe (audiosrc_blockpad, GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM, pad_probe_cb, user_data, NULL);
    return FALSE;
}

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

    /* init GStreamer */
    gst_init (&argc, &argv);
    loop = g_main_loop_new (NULL, FALSE);

    videosrc = gst_element_factory_make("videotestsrc", NULL);
    videosink = gst_element_factory_make("ximagesink", NULL);

    audiosrc = gst_element_factory_make("audiotestsrc", NULL);
    audiosink = gst_element_factory_make("pulsesink", NULL);
    /* We must set provide-clock to FALSE, otherwise, ximagesink loses its clock and freezes */
    g_object_set(G_OBJECT (audiosink), "provide-clock", FALSE, NULL);

    audiosrc_blockpad = gst_element_get_static_pad(audiosrc, "src");

    pipeline = gst_pipeline_new("pipeline");

    gst_bin_add_many(GST_BIN(pipeline), audiosink, audiosrc, videosrc, videosink, NULL);

    gst_element_link_many(videosrc, videosink, NULL);
    gst_element_link_many(audiosrc, audiosink, NULL);

    gst_element_set_state(pipeline, GST_STATE_PLAYING);


    g_timeout_add_seconds (5, timeout_cb, loop);

    g_main_loop_run (loop);

    gst_element_set_state (pipeline, GST_STATE_NULL);

    gst_object_unref (pipeline);

    return 0;
}