// testpipeline.c
// create a dummy pipeline to view the camera feed
//

#include <gst/gst.h>

GMainLoop *main_loop;

static gboolean my_bus_callback (GstBus *bus, GstMessage *msg, gpointer data) {
	switch (GST_MESSAGE_TYPE (msg)) {
		case GST_MESSAGE_ERROR: {
			GError *err;
			gchar *debug;

			gst_message_parse_error (msg, &err, &debug);
			g_print ("Error: %s\n", err->message);
			g_error_free (err);
			g_free (debug);

			g_main_loop_quit (main_loop);
			break;
		}
	}

	return TRUE;
}

GstElement *__video_tee;

gboolean build_video_source (GstElement *pipeline) {
	// build the pipeline that goes from source to tee
	g_debug ("Building video source ...");
	GstElement *bin = gst_bin_new ("video-source");

	GstElement *src = gst_element_factory_make ("v4l2src", NULL);
	GstElement *caps = gst_element_factory_make ("capsfilter", NULL);
	GstElement *col = gst_element_factory_make ("ffmpegcolorspace", NULL);

	if (!src || !caps || !col) {
		g_warning ("Failed to create one of the elements for basic video source.");

		gst_object_unref (bin);

		gst_object_unref (src);
		gst_object_unref (caps);
		gst_object_unref (col);

		return FALSE;
	}

	GstCaps *c = gst_caps_new_simple ("video/x-raw-yuv",
						"width", G_TYPE_INT, 640,
						"height", G_TYPE_INT, 480,
						"framerate", GST_TYPE_FRACTION, 30, 1,
						NULL);

	g_object_set (G_OBJECT (caps), "caps", c, NULL);
	gst_caps_unref (c);

	g_debug ("Attaching source elements ...");
	gst_bin_add_many (GST_BIN(bin), src, caps, col, NULL);
	if (!gst_element_link_many (src, caps, col, NULL)) {
		g_warning ("Failed to link video source elements.");

		gst_object_unref (bin);
		return FALSE;
	}

	GstPad *colspace_src = gst_element_get_static_pad (col, "src");
	g_assert (colspace_src);

	// create our ghost pad for the outside world
	GstPad *gp = gst_ghost_pad_new ("src", colspace_src);
	if (!gp) {
		g_warning ("Failed to create ghost pad for video source.");

		gst_object_unref (colspace_src);
		gst_object_unref (bin);
	}

	gst_object_unref (colspace_src);

	// Now create our tee
	__video_tee = gst_element_factory_make ("tee", NULL);
	if (!__video_tee) {
		g_warning ("Failed to create splitter tee.");

		gst_object_unref (bin);
		return FALSE;
	}

	GstPad *tee_sink = gst_element_get_static_pad (__video_tee, "sink");
	if (!tee_sink) {
		g_warning ("Failed to query video splitter tee for sink pad.");

		gst_object_unref (bin);
		return FALSE;
	}

	gst_bin_add_many (GST_BIN(pipeline), bin, __video_tee, NULL);
	if (GST_PAD_LINK_FAILED (gst_pad_link (gp, tee_sink))) {
		g_warning ("Failed to attach video source to splitter tee.");

		gst_bin_remove_many (GST_BIN (pipeline), bin, __video_tee, NULL);
		gst_object_unref (bin);
		gst_object_unref (__video_tee);

		return FALSE;
	}

	return TRUE;
}

gboolean attach_video_view (GstElement *pipeline) {
	g_debug ("Attaching video view ...");

	GstElement *view_bin = gst_bin_new ("view-bin");

	GstElement *sink = gst_element_factory_make ("xvimagesink", NULL);
	GstElement *col = gst_element_factory_make ("ffmpegcolorspace", NULL);
	GstElement *queue = gst_element_factory_make ("queue", NULL);

	if (!sink || !col || !queue) {
		g_warning ("Failed to create basic viewer elements.");

		gst_object_unref (sink);
		gst_object_unref (col);
		gst_object_unref (queue);

		return FALSE;
	}

	gst_bin_add_many (GST_BIN (view_bin), queue, col, sink, NULL);
	if (!gst_element_link_many (queue, col, sink, NULL)) {
		g_warning ("Failed to link viewer elements.");

		gst_object_unref (view_bin);
		return FALSE;
	}

	gst_bin_add_many (GST_BIN (pipeline), view_bin, NULL);

	GstPad *queue_sink = gst_element_get_static_pad (queue, "sink");
	g_assert (queue_sink != NULL);

	GstPad *gp = gst_ghost_pad_new ("src", queue_sink);
	gst_object_unref (queue_sink);

	// Now request a new pad from the tee
	GstPad *tee_src = gst_element_get_request_pad (__video_tee, "src%d");
	g_assert (tee_src);

	if (GST_PAD_LINK_FAILED (gst_pad_link (tee_src, gp))) {
		g_warning ("Failed to link tee source to viewer pipeline");

		return FALSE;
	}

	// otherwise we're good!
}

int main (int argc, char *argv[]) {
	// make a dummy pipeline and run it
	//
	g_debug ("Starting up ...");
	main_loop = g_main_loop_new (NULL, FALSE);

	gst_init (&argc, &argv);

	g_debug ("Building pipeline ...");
	GstElement *pipeline = gst_pipeline_new ("mypipeline");

	if (!build_video_source (pipeline)) {
		g_warning ("Failed to build video source.");

		gst_object_unref (pipeline);
		return -1;
	}

	if (!attach_video_view (pipeline)) {
		g_warning ("Failed to build video viewer.");

		gst_object_unref (pipeline);
		return -1;
	}

	g_debug ("Attaching hooks to pipeline ...");
	GstBus *bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
	gst_bus_add_watch (bus, my_bus_callback, NULL);
	gst_object_unref (bus);


	g_debug ("Done building pipeline.  Starting up ...");
	gst_element_set_state (pipeline, GST_STATE_PLAYING);

	g_debug ("Starting main loop ..");
	g_main_loop_run (main_loop);

	gst_element_set_state (pipeline, GST_STATE_NULL);
	gst_object_unref (pipeline);
	g_main_loop_unref (main_loop);

	return 0;
}