#include <config.h>
#include <glib.h>
#include <time.h>

#include "netspeed.h"

enum { N_STATES = 4 };

struct _NetSpeed
{
	LoadGraph *graph;
	gulong states[N_STATES];
	size_t cur;
};

NetSpeed* netspeed_new(LoadGraph *g)
{
	NetSpeed *ns = g_new0(NetSpeed, 1);
	ns->graph = g;
	return ns;
}

void netspeed_delete(NetSpeed *ns)
{
	g_free(ns);
}

void netspeed_add(NetSpeed *ns, gulong tx)
{
	ns->cur = (ns->cur + 1) % N_STATES;
	ns->states[ns->cur] = tx;
}

/* Something very similar to g_format_size() but for rates.
 * This should give the same display as in g-s-m */
static char*
format_rate_for_display(guint rate)
{
	char* bytes = g_format_size(rate);
	return g_strdup_printf(_("%s/s"), bytes);
}

char* netspeed_get(NetSpeed *ns)
{
	gulong older, newer;
	guint rate;

	newer = ns->states[ns->cur];
	older = ns->states[(ns->cur + 1) % N_STATES];

	if ((older != 0) && (newer > older))
		rate = (newer - older) * 1000 / ((N_STATES - 1) * ns->graph->speed);
	else
	        /* We end up here if we haven't got enough data yet or the
		   network interface has jumped back (or there has never
		   been any activity on any interface). A value of 0 is
		   likely to be accurate, but if it is wrong it will be
		   clearly wrong. In any event, it should fix itself in a
		   few seconds. */
	        rate = 0;

	return format_rate_for_display(rate);
}