#include <iostream>
#include <iomanip>
#include <cmath>

#include <gst/gst.h>

#ifndef FPS
#define FPS 30
#endif

using namespace std;

namespace
{
	constexpr size_t g_fps { FPS };
	constexpr GstClockTime g_frame_reference_duration { static_cast<GstClockTime>(round(static_cast<long double>(GST_SECOND) / g_fps)) };

	GstPadProbeReturn on_source_buffer(GstPad* pad, GstPadProbeInfo* info, gpointer user_data)
	{
		GstBuffer* const buf = GST_BUFFER(info->data);

		const GstClockTime current_time { buf->pts };
		static GstClockTime prev_time { current_time };

		static size_t counter { };
		static GstClockTime prev_avg_print_time { current_time };
		static GstClockTime avg_buffer { current_time };

		const GstClockTime duration { current_time - prev_time };
		prev_time = current_time;

		if (counter + 1)
			avg_buffer = (avg_buffer * counter + duration) / (counter + 1);

		++counter;

		if (current_time - prev_avg_print_time > 10 * GST_SECOND)
		{
			cout << "average duration: " << avg_buffer << " (" << showpos << static_cast<long>(avg_buffer) - static_cast<long>(g_frame_reference_duration) << ')' << " ns" << endl;
			prev_avg_print_time = current_time;
		}

		return GST_PAD_PROBE_OK;
	}
}

int main (int argc, char *argv[])
{
	/* Initialize GStreamer */
	gst_init(&argc, &argv);

	GstElement* const pipeline { gst_pipeline_new("nvarguscamerasrc-framerate-issue-test") };
	GstElement* const source { gst_element_factory_make("nvarguscamerasrc", "source") };
	GstElement* const capsfilter { gst_element_factory_make("capsfilter", "capsfilter") };
	GstElement* const sink { gst_element_factory_make("fakesink", "sink") };

	gst_bin_add_many(GST_BIN(pipeline),
		source,
		capsfilter,
		sink,
		nullptr);

	{
		GstCaps* const input_caps
		{
			gst_caps_new_simple("video/x-raw",
				"width", G_TYPE_INT, 1280,
				"height", G_TYPE_INT, 720,
				"framerate", GST_TYPE_FRACTION, g_fps, 1,
				nullptr)
		};

		GstCapsFeatures* const memory_features { gst_caps_features_new("memory:NVMM", nullptr) };
		gst_caps_set_features(input_caps, 0, memory_features);
		g_object_set(capsfilter, "caps", input_caps, nullptr);
	}

	gst_element_link_many(source,
		capsfilter,
		sink,
		nullptr);

	GstPad* const src_pad { gst_element_get_static_pad(source, "src") };

	gst_pad_add_probe(src_pad, GST_PAD_PROBE_TYPE_BUFFER, on_source_buffer, nullptr, nullptr);

	gst_object_unref(src_pad);

	gst_element_set_state(pipeline, GST_STATE_PLAYING);

    GMainLoop* const main_loop { g_main_loop_new(nullptr, false) };
	g_main_loop_run(main_loop);

	g_main_loop_unref(main_loop);

	return 0;
}