// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) 2020 Michael Crute <mike@crute.us>. All rights reserved.
//
// Use of this source code is governed by a license that can be found in the
// LICENSE file.

package main

import (
	"flag"
	"fmt"
	"log"
	"net/http"
	_ "net/http/pprof"
	"os"
	"strconv"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/prometheus/common/version"

	"code.crute.me/pomonaconsulting/six_monitoring/six"
)

const (
	namespace = "sixstatus"
	exporter  = "six_status_exporter"
)

var (
	up = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "", "up"),
		"Was the SIX query successful?",
		nil, nil,
	)
	rsPrefixCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "route_server", "prefix_count"),
		"Number of prefixes advertised to a route server.",
		[]string{"ipversion", "mtu", "server"}, nil,
	)
	rsErrorCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "route_server", "error_count"),
		"Number of errors reported by a route server.",
		[]string{"ipversion", "mtu", "server"}, nil,
	)
	rsTransitErrorCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "route_server", "transit_error_count"),
		"Number of transit errors reported by a route server.",
		[]string{"ipversion", "mtu", "server"}, nil,
	)
	irrPrefixCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "irr", "prefix_count"),
		"Number of prefixes resolved from IRR records.",
		[]string{"ipversion"}, nil,
	)
	irrASNCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "irr", "asn_count"),
		"Number of ASNs resolved from IRR records.",
		[]string{"ipversion"}, nil,
	)
	irrAsSetPrefixCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "irr", "as_set_prefix_count"),
		"Number of prefixes in the AS-SET resolved from IRR records.",
		[]string{"ipversion"}, nil,
	)
	pdbPrefixCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "peeringdb", "prefix_count"),
		"Number of prefixes configured in PeeringDB.",
		[]string{"ipversion"}, nil,
	)
	roaCount = prometheus.NewDesc(
		prometheus.BuildFQName(namespace, "", "roa_count"),
		"Number of resolved ROA records.",
		nil, nil,
	)
)

type SIXCollector struct {
	ASN int
}

var _ prometheus.Collector = (*SIXCollector)(nil)

func (c *SIXCollector) Describe(ch chan<- *prometheus.Desc) {
	ch <- up
	ch <- rsPrefixCount
	ch <- rsErrorCount
	ch <- rsTransitErrorCount
	ch <- irrPrefixCount
	ch <- irrASNCount
	ch <- irrAsSetPrefixCount
	ch <- pdbPrefixCount
	ch <- roaCount
}

func routeServerMetrics(rs *six.RouteServer, ch chan<- prometheus.Metric) {
	ch <- prometheus.MustNewConstMetric(
		rsPrefixCount, prometheus.GaugeValue, float64(rs.IPv4.Prefixes),
		"4", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsErrorCount, prometheus.GaugeValue, float64(rs.IPv4.Errors),
		"4", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsTransitErrorCount, prometheus.GaugeValue, float64(rs.IPv4.TransitErrors),
		"4", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsPrefixCount, prometheus.GaugeValue, float64(rs.IPv6.Prefixes),
		"6", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsErrorCount, prometheus.GaugeValue, float64(rs.IPv6.Errors),
		"6", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsTransitErrorCount, prometheus.GaugeValue, float64(rs.IPv6.TransitErrors),
		"6", "1500", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsPrefixCount, prometheus.GaugeValue, float64(rs.IPv4Jumbo.Prefixes),
		"4", "9000", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsErrorCount, prometheus.GaugeValue, float64(rs.IPv4Jumbo.Errors),
		"4", "9000", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsTransitErrorCount, prometheus.GaugeValue, float64(rs.IPv4Jumbo.TransitErrors),
		"4", "9000", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsPrefixCount, prometheus.GaugeValue, float64(rs.IPv6Jumbo.Prefixes),
		"6", "9000", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsErrorCount, prometheus.GaugeValue, float64(rs.IPv6Jumbo.Errors),
		"6", "9000", string(strconv.Itoa(rs.Number)),
	)
	ch <- prometheus.MustNewConstMetric(
		rsTransitErrorCount, prometheus.GaugeValue, float64(rs.IPv6Jumbo.TransitErrors),
		"6", "9000", string(strconv.Itoa(rs.Number)),
	)
}

func (c *SIXCollector) Collect(ch chan<- prometheus.Metric) {
	sp, err := six.FetchParseSIXCSV()
	if err != nil {
		log.Printf("error: Fetching and parsing CSV: %s", err)
		ch <- prometheus.MustNewConstMetric(up, prometheus.GaugeValue, 0)
		return
	}

	ps, ok := sp.GetParticipantByASN(c.ASN)
	if !ok {
		log.Printf("error: No participant for ASN: %d", c.ASN)
		ch <- prometheus.MustNewConstMetric(up, prometheus.GaugeValue, 0)
		return
	}

	p := ps[0]

	ch <- prometheus.MustNewConstMetric(up, prometheus.GaugeValue, 1)

	// ipversion, mtu, server

	if p.RouteServer2 != nil {
		routeServerMetrics(p.RouteServer2, ch)
	}

	if p.RouteServer3 != nil {
		routeServerMetrics(p.RouteServer3, ch)
	}

	ch <- prometheus.MustNewConstMetric(
		irrPrefixCount, prometheus.GaugeValue, float64(p.IRRv4.PrefixCount),
		"4",
	)
	ch <- prometheus.MustNewConstMetric(
		irrASNCount, prometheus.GaugeValue, float64(p.IRRv4.ASNCount),
		"4",
	)
	ch <- prometheus.MustNewConstMetric(
		irrAsSetPrefixCount, prometheus.GaugeValue, float64(p.IRRv4.ASSetCount),
		"4",
	)
	ch <- prometheus.MustNewConstMetric(
		pdbPrefixCount, prometheus.GaugeValue, float64(p.PeeringDBPrefixCountv4),
		"4",
	)
	ch <- prometheus.MustNewConstMetric(
		irrPrefixCount, prometheus.GaugeValue, float64(p.IRRv6.PrefixCount),
		"6",
	)
	ch <- prometheus.MustNewConstMetric(
		irrASNCount, prometheus.GaugeValue, float64(p.IRRv6.ASNCount),
		"6",
	)
	ch <- prometheus.MustNewConstMetric(
		irrAsSetPrefixCount, prometheus.GaugeValue, float64(p.IRRv6.ASSetCount),
		"6",
	)
	ch <- prometheus.MustNewConstMetric(
		pdbPrefixCount, prometheus.GaugeValue, float64(p.PeeringDBPrefixCountv6),
		"6",
	)

	ch <- prometheus.MustNewConstMetric(roaCount, prometheus.GaugeValue, float64(p.ROACount))
}

func main() {
	var (
		showVersion   = flag.Bool("version", false, "Print version information.")
		listenAddress = flag.String("web.listen-address", ":9119", "Address to listen on for web interface and telemetry.")
	)
	flag.Parse()

	if len(os.Args) != 2 {
		fmt.Fprintf(os.Stdout, "usage: %s <ASN>\n", os.Args[0])
		os.Exit(1)
	}

	asn, err := strconv.Atoi(os.Args[1])
	if err != nil {
		fmt.Fprintln(os.Stdout, "invalid ASN, must be numeric")
		fmt.Fprintf(os.Stdout, "usage: %s <ASN>\n", os.Args[0])
		os.Exit(1)
	}

	if *showVersion {
		fmt.Fprintln(os.Stdout, version.Print(exporter))
		os.Exit(0)
	}
	log.Println("Starting", exporter, version.Info())
	log.Println("Build context", version.BuildContext())

	prometheus.MustRegister(version.NewCollector(exporter), &SIXCollector{asn})

	log.Println("Starting Server: ", *listenAddress)
	http.Handle("/metrics", promhttp.Handler())
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(`<html>
             <head><title>SIX Status Exporter</title></head><body>
             <h1>SIX Status Exporter</h1>
             <p><a href="/metrics">Metrics</a></p>
             </body></html>`))
	})
	log.Fatal(http.ListenAndServe(*listenAddress, nil))
}