package main

import (
	"encoding/json"
	"io"
	"log"
	"net/http"
	"pleroma_stats_exporter/config"
	"time"

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

type metrics struct {
	InstancesCount prometheus.Gauge
	FollowersCount prometheus.Gauge
}

func SetMetricsOpts(reg prometheus.Registerer) *metrics {
	metricsOpts := &metrics{
		InstancesCount: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Name: "pleroma_instances_count",
				Help: "Количество инстансов",
			},
		),
		FollowersCount: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Name: "pleroma_user_followers",
				Help: "Количество подписчиков",
			},
		),
	}
	reg.MustRegister(metricsOpts.InstancesCount)
	reg.MustRegister(metricsOpts.FollowersCount)
	return metricsOpts
}

func getJson(url string) string {
	resp, err := http.Get(url)
	if err != nil {
		log.Println(err)
	}
	defer resp.Body.Close()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Println(err)
	}
	return string(body)
}

func unmJson(jsonString string) map[string]any {
	decodedJson := map[string]any{}
	err := json.Unmarshal([]byte(jsonString), &decodedJson)
	if err != nil {
		log.Println(err)
	}
	return decodedJson
}

func updateMetrics(instanceMetrics *metrics, confFile config.InstanceVars) {
	instanceStat := unmJson(getJson("https://" + confFile.Target.Instance + "/api/v1/instance"))["stats"]
	instanceCount := instanceStat.(map[string]interface{})
	userFollowers := unmJson(getJson("https://" + confFile.Target.Instance + "/api/v1/accounts/" + confFile.Target.UserID))["followers_count"]
	instanceMetrics.InstancesCount.Set(instanceCount["domain_count"].(float64))
	instanceMetrics.FollowersCount.Set(userFollowers.(float64))
}

func main() {
	confFile := config.UnmYamlConfig("config.yaml")

	reg := prometheus.NewRegistry()
	instanceMetrics := SetMetricsOpts(reg)

	go func() {
		for {
			updateMetrics(instanceMetrics, confFile)
			time.Sleep(5 * time.Minute)
		}
	}()

	http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{Registry: reg}))
	log.Fatal(http.ListenAndServe(confFile.Exporter.Listen+":"+confFile.Exporter.Port, nil))
}