package main

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

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

func errorOccured(e error) bool {
	return e != nil
}

func main() {
	var (
		addr          = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
		checkInterval = flag.Int("check-interval", 60, "The interval to wait between Kaifu API requests")
	)

	flag.Parse()

	visitors := prometheus.NewGauge(
		prometheus.GaugeOpts{
			Name: "visitors",
			Help: "Current number of visitors at Kaifu-Lodge",
		},
	)

	prometheus.MustRegister(visitors)

	go func() {
		for {
			fmt.Printf("Checking...\n")
			visitorNum, err := getCurrentNumberOfVisitors()

			if errorOccured(err) {
				fmt.Printf("Error while checking... %v\n", err)
			} else {
				fmt.Printf("New visitor num: %d\n", visitorNum)
				visitors.Set(float64(visitorNum))
			}
			time.Sleep(time.Duration(*checkInterval) * time.Second)
		}
	}()

	http.Handle("/metrics", promhttp.Handler())
	log.Fatal(http.ListenAndServe(*addr, nil))
}

func getCurrentNumberOfVisitors() (int32, error) {

	client := &http.Client{}
	req, err := http.NewRequest("GET", "https://clubconnector.sovd.cloud/api/anwesende/d371bf89-57e5-41d8-9989-440a061157c9-076015/1", nil)

	if errorOccured(err) {
		return 0, err
	}

	resp, err := client.Do(req)
	if errorOccured(err) {
		return 0, err
	}

	// Read Response Body
	respBody, _ := ioutil.ReadAll(resp.Body)

	var dat map[string]interface{}
	err = json.Unmarshal(respBody, &dat)

	if errorOccured(err) {
		return 0, err
	}

	visitors := int32(dat["count"].(float64))
	return visitors, nil
}