// vi:ts=4:sts=4:sw=4:noet:tw=72
//
// covid-exporter
//
// Copyright (c) 2021 Andreas Neue <an@dnix.de>

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"

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

type CovidRecord struct {
	Updated                int
	Country                string
	CountryInfo            interface{}
	Cases                  int
	TodayCases             int
	Deaths                 int
	TodayDeaths            int
	Recovered              int
	TodayRecovered         int
	Active                 int
	Critical               int
	CasesPerOneMillion     float32
	DeathsPerOneMillion    float32
	Tests                  int
	TestsPerOneMillion     int
	Population             int
	Continent              string
	OneCasePerPeople       int
	OneDeathPerPeople      int
	OneTestPerPeople       int
	ActivePerOneMillion    float32
	RecoveredPerOneMillion float32
	CriticalPerOneMillion  float32
}

var (
	gaugeCases      *prometheus.GaugeVec
	gaugeActive     *prometheus.GaugeVec
	gaugeCritical   *prometheus.GaugeVec
	gaugePopulation *prometheus.GaugeVec
)

func main() {
	url := "https://corona.lmao.ninja/v3/covid-19/countries"

	go getCovidStats(url)
	serveMetrics()
}

func getCovidStats(url string) {
	for {
		resp, err := http.Get(url)
		if err != nil {
			fmt.Printf("%v\n", err)
			continue
		}
		defer resp.Body.Close()
		data, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			fmt.Printf("%v\n", err)
			continue
		}
		var cr []CovidRecord
		err = json.Unmarshal(data, &cr)
		if err != nil {
			fmt.Printf("%v\n", err)
			continue
		}
		for i := range cr {
			gaugeCases.WithLabelValues(cr[i].Country).Set(float64(cr[i].Cases))
			gaugeActive.WithLabelValues(cr[i].Country).Set(float64(cr[i].Active))
			gaugeCritical.WithLabelValues(cr[i].Country).Set(float64(cr[i].Critical))
			gaugePopulation.WithLabelValues(cr[i].Country).Set(float64(cr[i].Population))
		}
		time.Sleep(15 * time.Minute)
	}
}

func serveMetrics() {
	gaugeCases = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Name: "covid_cases",
			Help: "Covid-19 cases",
		},
		[]string{
			"country",
		},
	)
	prometheus.MustRegister(gaugeCases)
	gaugeActive = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Name: "covid_active",
			Help: "Covid-19 active cases",
		},
		[]string{
			"country",
		},
	)
	prometheus.MustRegister(gaugeActive)
	gaugeCritical = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Name: "covid_critical",
			Help: "Covid-19 critical cases",
		},
		[]string{
			"country",
		},
	)
	prometheus.MustRegister(gaugeCritical)
	gaugePopulation = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Name: "covid_population",
			Help: "Population",
		},
		[]string{
			"country",
		},
	)
	prometheus.MustRegister(gaugePopulation)

	http.Handle("/metrics", promhttp.Handler())
	http.ListenAndServe("0.0.0.0:9099", nil)
}