// +build !noprometheus

package instrument

import (
	"time"

	log "github.com/cihub/seelog"

	"net/http"

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

const (
	promAddr = ":9123"
)

type promInst struct {
	visits *prometheus.CounterVec
	reqDur *prometheus.HistogramVec
}

func Init() Instrument {
	go promHandle()

	visits := prometheus.NewCounterVec(
		prometheus.CounterOpts{
			Name: "trantor_visits_total",
			Help: "Number of visits.",
		},
		[]string{"section", "id", "search", "fmt"},
	)
	reqDur := prometheus.NewHistogramVec(
		prometheus.HistogramOpts{
			Name: "trantor_request_duration_seconds",
			Help: "Duration of the request in seconds.",
		},
		[]string{"section"},
	)

	prometheus.MustRegister(visits)
	prometheus.MustRegister(reqDur)

	return &promInst{
		visits: visits,
		reqDur: reqDur,
	}
}

func promHandle() {
	server := http.Server{
		Addr:    promAddr,
		Handler: promhttp.Handler(),
	}
	log.Error(server.ListenAndServe())
}

func (in promInst) Visit(section string, id string, search string, fmt string) {
	in.visits.WithLabelValues(section, id, search, fmt).Inc()
}

func (in promInst) Duration(section string, duration time.Duration) {
	in.reqDur.WithLabelValues(section).Observe(duration.Seconds())
}