#include <u.h>
#include <libc.h>
#include <thread.h>
#include <bio.h>
#include "collectd.h"

#define	MAXETHER	8

typedef struct Ether Ether;
struct Ether {
	char*	name;
	uvlong	n;
};

static Biobuf *
readether(Biobuf *bp, char *file, Ether *ether)
{
	char *p, *q;

	if(bp == nil){
		bp = Bopen(file, OREAD);
		if(bp == nil)
			sysfatal("couldn't open %s: %r", file);
	}
	p = Brdline(bp, '\n');
	if(p == nil){
		Bterm(bp);
		return nil;
	}
	p[Blinelen(bp)-1] = '\0';

	if(q = strchr(p, ':'))
		*q++ = '\0';
	else
		sysfatal("unexpected stats output");

	ether->name = p;
	ether->n = strtoull(q, nil, 0);

	return bp;
}

static void
submit(Channel *c, char *name, char *type, uvlong rx, uvlong tx)
{
	Packet *pp;

	pp = palloc();
	pp->host = estrdup(hostname);
	pp->interval = interval;
	pp->time = time(nil);
	pp->plugin = estrdup("interface");
	pp->pinst = estrdup(name);
	pp->type = estrdup(type);
	addcounter(pp, rx);
	addcounter(pp, tx);

	if(nbsendp(c, pp) < 1)
		pfree(pp);
}

void
interfaceproc(void *arg)
{
	Channel *c;
	int i;
	char name[NAMELEN];
	char file[NAMELEN];
	Biobuf *bp;
	Ether ether;
	uvlong in, out;
	uvlong ierrs, oerrs;

	c = arg;
	bp = nil;
	for(;;){
		snooze();

		for(i = 0; i < MAXETHER; ++i){
			snprint(name, sizeof name, "ether%d", i);
			snprint(file, sizeof file, "/net/%s/stats", name);

			/*
			 * Interfaces may be specified using
			 * non-contiguous numbers; rather than bail,
			 * we skip stats files we cannot read.
			 */
			if(access(file, AREAD) != 0)
				continue;

			ierrs = 0;
			oerrs = 0;
			while(bp = readether(bp, file, &ether)){
				if(strcmp(ether.name, "in") == 0)
					in = ether.n;

				else if(strcmp(ether.name, "out") == 0)
					out = ether.n;

				else if(strcmp(ether.name, "crc errs") == 0 ||
    				    strcmp(ether.name, "overflows") == 0 ||
				    strcmp(ether.name, "soft overflows") == 0 ||
				    strcmp(ether.name, "framing errs") == 0 ||
				    strcmp(ether.name, "buffer errs") == 0)
					ierrs += ether.n;

				else if(strcmp(ether.name, "output errs") == 0)
					oerrs += ether.n;
			}
			submit(c, name, "if_packets", in, out);
			submit(c, name, "if_errors", ierrs, oerrs);
		}
	}
}