// Copyright 2015 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// +build !nonetdev

package collector

import (
	"errors"
	"fmt"
	"strconv"

	"github.com/prometheus/client_golang/prometheus"
)

/*
#cgo CFLAGS: -D_IFI_OQDROPS
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
#include <net/if.h>
*/
import "C"

type netDevCollector struct {
	subsystem   string
	metricDescs map[string]*prometheus.Desc
}

func init() {
	Factories["netdev"] = NewNetDevCollector
}

// Takes a prometheus registry and returns a new Collector exposing
// Network device stats.
func NewNetDevCollector() (Collector, error) {
	return &netDevCollector{
		subsystem:   "network",
		metricDescs: map[string]*prometheus.Desc{},
	}, nil
}

func (c *netDevCollector) Update(ch chan<- prometheus.Metric) (err error) {
	netDev, err := getNetDevStats()
	if err != nil {
		return fmt.Errorf("couldn't get netstats: %s", err)
	}
	for dev, devStats := range netDev {
		for key, value := range devStats {
			desc, ok := c.metricDescs[key]
			if !ok {
				desc = prometheus.NewDesc(
					prometheus.BuildFQName(Namespace, c.subsystem, key),
					fmt.Sprintf("%s from getifaddrs().", key),
					[]string{"device"},
					nil,
				)
				c.metricDescs[key] = desc
			}
			v, err := strconv.ParseFloat(value, 64)
			if err != nil {
				return fmt.Errorf("invalid value %s in netstats: %s", value, err)
			}
			ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, v, dev)
		}
	}
	return nil
}

func getNetDevStats() (map[string]map[string]string, error) {
	netDev := map[string]map[string]string{}

	var ifap, ifa *C.struct_ifaddrs
	if C.getifaddrs(&ifap) == -1 {
		return nil, errors.New("getifaddrs() failed")
	}
	defer C.freeifaddrs(ifap)

	for ifa = ifap; ifa != nil; ifa = ifa.ifa_next {
		if ifa.ifa_addr.sa_family == C.AF_LINK {
			devStats := map[string]string{}
			data := (*C.struct_if_data)(ifa.ifa_data)

			devStats["receive_packets"] = strconv.Itoa(int(data.ifi_ipackets))
			devStats["transmit_packets"] = strconv.Itoa(int(data.ifi_opackets))
			devStats["receive_errs"] = strconv.Itoa(int(data.ifi_ierrors))
			devStats["transmit_errs"] = strconv.Itoa(int(data.ifi_oerrors))
			devStats["receive_bytes"] = strconv.Itoa(int(data.ifi_ibytes))
			devStats["transmit_bytes"] = strconv.Itoa(int(data.ifi_obytes))
			devStats["receive_multicast"] = strconv.Itoa(int(data.ifi_imcasts))
			devStats["transmit_multicast"] = strconv.Itoa(int(data.ifi_omcasts))
			devStats["receive_drop"] = strconv.Itoa(int(data.ifi_iqdrops))
			devStats["transmit_drop"] = strconv.Itoa(int(data.ifi_oqdrops))
			netDev[C.GoString(ifa.ifa_name)] = devStats
		}
	}

	return netDev, nil
}