/* Libvisual-plugins - Standard plugins for libvisual
 *
 * Copyright (C) 2012-2023 Libvisual Team
 * Copyright (C) 2004-2006 Dennis Smit <ds@nerds-incorporated.org>
 *
 * Authors: Dennis Smit <ds@nerds-incorporated.org>
 *          Chong Kai Xiong <kaixiong@codeleft.sg>
 *          Sebastian Pipping <sebastian@pipping.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <config.h>
#include <gettext.h>
#include <libvisual/libvisual.h>
#include <gst/gst.h>

typedef struct {
	GstElement *pipeline;
	GMainLoop *glib_main_loop;
	GstBuffer *buffer;
	GstElement *capsfilter;
	GstElement *sink;
	GMutex *mutex;
} GstreamerPrivate;

int act_gstreamer_init (VisPluginData *plugin);
int act_gstreamer_cleanup (VisPluginData *plugin);
int act_gstreamer_requisition (VisPluginData *plugin, int *width, int *height);
int act_gstreamer_dimension (VisPluginData *plugin, VisVideo *video, int width, int height);
int act_gstreamer_events (VisPluginData *plugin, VisEventQueue *events);
VisPalette *act_gstreamer_palette (VisPluginData *plugin);
int act_gstreamer_render (VisPluginData *plugin, VisVideo *video, VisAudio *audio);

void handle_sink_handoff (GstElement *sink, GstBuffer *buffer, GstPad *pad, GstreamerPrivate *data);
void handle_bus_error_message (GstBus *bus, GstMessage *message, GstreamerPrivate *priv);
void handle_bus_eos_message (GstBus *bus, GstMessage *message, GstreamerPrivate *priv);

VISUAL_PLUGIN_API_VERSION_VALIDATOR

const VisPluginInfo *get_plugin_info (int *count)
{
	static VisActorPlugin actor[] = {{
		.requisition = act_gstreamer_requisition,
		.palette = act_gstreamer_palette,
		.render = act_gstreamer_render,
		.vidoptions.depth = VISUAL_VIDEO_DEPTH_24BIT
	}};

	static VisPluginInfo info[] = {{
		.type = VISUAL_PLUGIN_TYPE_ACTOR,

		.plugname = "gstreamer",
		.name = "libvisual gstreamer",
		.author = N_("Dennis Smit  <synap@yourbase.nl>"),
		.version = "0.1",
		.about = N_("Libvisual gstreamer plugin"),
		.help = N_("Capable of using gstreamer to play video, or do effects using the gstreamer pipeline"),
		.license = VISUAL_PLUGIN_LICENSE_LGPL,

		.init = act_gstreamer_init,
		.cleanup = act_gstreamer_cleanup,
		.events = act_gstreamer_events,

		.plugin = VISUAL_OBJECT (&actor[0])
	}};

	*count = sizeof (info) / sizeof (*info);

	return info;
}

int act_gstreamer_init (VisPluginData *plugin)
{
	GstreamerPrivate *priv;

#if ENABLE_NLS
	bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
#endif

	priv = visual_mem_new0 (GstreamerPrivate, 1);
	visual_object_set_private (VISUAL_OBJECT (plugin), priv);

	gst_init (NULL, NULL);

	// Regarding the pipeline below:
	// - Element "filesrc" reads a video file from disk.
	// - Element "decodebin" auto-magically constructs a decoding pipeline
	//   using available decoders and demuxers via auto-plugging.
	// - Element "videoconvert" does conversion between video formats
	//   from given to wanted.
	// - Element "videoscale" does scaling from given to wanted resolution.
	// - Element "capsfilter" limits the output to the width/height/format we want.
	// - Element "fakesink" allows accessing the rendered raw pixels from C code.
	// - "name=capsfilter" and "name=sink" are needed to access these elements
	//   from within C code further down.
	// - "signal-handoffs=true" makes fakesink let use know it started using
	//   a different buffer.
	// - "sync=true" makes fakesink respect the target framerate of the video
	//   input to give the appearance of original playback speed
	//   (in contrast to serving frames as fast as possible).
	char *launch_str = g_strdup_printf ("filesrc location=%s ! decodebin ! videoconvert ! "
						"videoscale ! capsfilter name=capsfilter ! "
						"fakesink name=sink signal-handoffs=true sync=true",
						"test.mpg");

	GError *error = NULL;
	priv->pipeline = gst_parse_launch (launch_str, &error);

	if (!priv->pipeline) {
		visual_log (VISUAL_LOG_ERROR, "Failed to create pipeline: %s", error->message);
		g_error_free (error);
		g_free (launch_str);
		return FALSE;
	}

	priv->capsfilter = gst_bin_get_by_name (GST_BIN (priv->pipeline), "capsfilter");
	GstCaps *caps = gst_caps_new_simple ("video/x-raw",
						"width", G_TYPE_INT, 320,
						"height", G_TYPE_INT, 240,
						"format", G_TYPE_STRING, "BGR",
						NULL);
	g_object_set (priv->capsfilter, "caps", caps, NULL);
	gst_caps_unref (caps);

	priv->buffer = NULL;
	priv->mutex = g_slice_new0 (GMutex);
	g_mutex_init (priv->mutex);

	priv->sink = gst_bin_get_by_name (GST_BIN (priv->pipeline), "sink");
	g_signal_connect (priv->sink, "handoff", G_CALLBACK (handle_sink_handoff), priv);

	gst_element_set_state (priv->pipeline, GST_STATE_PAUSED);

	GstStateChangeReturn status = gst_element_get_state (priv->pipeline, NULL, NULL, GST_CLOCK_TIME_NONE);
	if (status != GST_STATE_CHANGE_SUCCESS) {
		visual_log (VISUAL_LOG_ERROR, "Failed to ready pipeline: %s", launch_str);
		g_free (launch_str);
		return FALSE;
	}
	g_free (launch_str);

	GstBus *bus = gst_pipeline_get_bus (GST_PIPELINE (priv->pipeline));
	g_signal_connect (bus, "message::error", G_CALLBACK (handle_bus_error_message), priv);
	g_signal_connect (bus, "message::eos", G_CALLBACK (handle_bus_eos_message), priv);
	gst_object_unref (bus);

	priv->glib_main_loop = g_main_loop_new (NULL, FALSE);

	return 0;
}

int act_gstreamer_cleanup (VisPluginData *plugin)
{
	GstreamerPrivate *priv = visual_object_get_private (VISUAL_OBJECT (plugin));

	if (priv->pipeline) {
		g_signal_handlers_disconnect_by_func (priv->sink, "handoff", handle_sink_handoff);

		GstBus *bus = gst_pipeline_get_bus (GST_PIPELINE (priv->pipeline));
		g_signal_handlers_disconnect_by_func (bus, handle_bus_error_message, priv);
		g_signal_handlers_disconnect_by_func (bus, handle_bus_eos_message, priv);
		gst_object_unref (bus);

		g_main_loop_unref (priv->glib_main_loop);

		gst_object_unref (priv->sink);
		gst_object_unref (priv->capsfilter);

		gst_element_set_state (priv->pipeline, GST_STATE_NULL);
		gst_object_unref (priv->pipeline);

		if (priv->buffer) {
			gst_buffer_unref (priv->buffer);
		}

		g_mutex_clear (priv->mutex);
		g_slice_free (GMutex, priv->mutex);
	}

	visual_mem_free (priv);

	return 0;
}

int act_gstreamer_requisition (VisPluginData *plugin, int *width, int *height)
{
	GstreamerPrivate *priv = visual_object_get_private (VISUAL_OBJECT (plugin));

	GstCaps *caps = NULL;
	g_object_get (priv->capsfilter, "caps", &caps, NULL);

	GstStructure *structure = gst_caps_get_structure (caps, 0);
	gst_structure_get (structure,
				"width", width,
				"height", height,
				NULL);
	gst_caps_unref (caps);

	return 0;
}

int act_gstreamer_dimension (VisPluginData *plugin, VisVideo *video, int width, int height)
{
	GstreamerPrivate *priv = visual_object_get_private (VISUAL_OBJECT (plugin));

	GstCaps *caps = gst_caps_new_simple ("video/x-raw",
						"width" , G_TYPE_INT, width,
						"height", G_TYPE_INT, height,
						"format", G_TYPE_STRING, "BGR",
						NULL);
	g_object_set (priv->capsfilter, "caps", caps, NULL);
	gst_caps_unref (caps);

	visual_video_set_dimension (video, width, height);

	return 0;
}

int act_gstreamer_events (VisPluginData *plugin, VisEventQueue *events)
{
	VisEvent ev;

	while (visual_event_queue_poll (events, &ev)) {
		switch (ev.type) {
			case VISUAL_EVENT_RESIZE:
				act_gstreamer_dimension (plugin, ev.event.resize.video,
						ev.event.resize.width, ev.event.resize.height);
				break;


			default:
				break;
		}
	}

	return 0;
}

VisPalette *act_gstreamer_palette (VisPluginData *plugin)
{
	return NULL;
}

int act_gstreamer_render (VisPluginData *plugin, VisVideo *video, VisAudio *audio)
{
	GstreamerPrivate *priv = visual_object_get_private (VISUAL_OBJECT (plugin));

	GstState state, pending_state;
	GstStateChangeReturn status;

	gst_element_get_state (priv->pipeline, &state, &pending_state, 0);
	if (state != GST_STATE_PLAYING && pending_state != GST_STATE_PLAYING) {
		/* Set pipeline to playing if not already done so */
		gst_element_set_state (priv->pipeline, GST_STATE_PLAYING);

		/* Check pipeline state, make sure it's already playing, or going to be set playing */
		status = gst_element_get_state (priv->pipeline, &state, &pending_state, 10 * GST_MSECOND);

		switch (status) {
			case GST_STATE_CHANGE_ASYNC:
				visual_log (VISUAL_LOG_INFO, "Waiting for pipeline to get ready (Current state: %s)",
							gst_element_state_get_name (state));
				return 0;

			case GST_STATE_CHANGE_FAILURE:
				visual_log (VISUAL_LOG_INFO, "Failed to animate pipeline");
				return 0;

			default: /* nothing */;
		}
	}

	/* Process any messages on the bus */
	g_main_context_iteration (g_main_loop_get_context (priv->glib_main_loop), FALSE);

	/* Draw if we have a buffer */
	g_mutex_lock (priv->mutex);
	if (priv->buffer) {
		// NOTE: GStreamer format "BGR" does not have any padding
		const int expected_row_pitch = video->width * (24 / 8);
		const int expected_buffer_size = expected_row_pitch * video->height;

		/* Copy buffer to video only if dimensions match, ignoring
		 * buffers received from GStreamer before their corresponding
		 * resizes were completed. */
		if (gst_buffer_get_size (priv->buffer) == expected_buffer_size) {
			GstMapInfo info;
			if (gst_buffer_map(priv->buffer, &info, GST_MAP_READ)) {
				VisVideo * const source = visual_video_new();
				visual_video_set_depth(source, VISUAL_VIDEO_DEPTH_24BIT);
				visual_video_set_dimension(source, video->width, video->height);
				visual_video_set_buffer(source, info.data);

				visual_video_depth_transform (video, source);

				visual_object_unref (VISUAL_OBJECT (source));

				gst_buffer_unmap(priv->buffer, &info);
			}
		}

		gst_buffer_unref (priv->buffer);

		priv->buffer = NULL;
	}
	g_mutex_unlock (priv->mutex);

	return 0;
}

void handle_sink_handoff (GstElement *sink, GstBuffer *buffer, GstPad *pad, GstreamerPrivate* priv)
{
	g_mutex_lock (priv->mutex);

	/* Keep the most recently received buffer alive for rendering */
	if (priv->buffer) {
		gst_buffer_unref (priv->buffer);
	}

	priv->buffer = buffer;
	gst_buffer_ref (priv->buffer);

	g_mutex_unlock (priv->mutex);
}

void handle_bus_error_message (GstBus *bus, GstMessage *message, GstreamerPrivate *priv)
{
	GError *error = NULL;
	char   *msg   = NULL;
	gst_message_parse_error (message, &error, &msg);
	visual_log (VISUAL_LOG_ERROR, "GStreamer error: %s", msg);
	g_error_free (error);
	g_free (msg);
}

void handle_bus_eos_message (GstBus *bus, GstMessage *message, GstreamerPrivate *priv)
{
	visual_log (VISUAL_LOG_INFO, "End of stream!");
}