package main

import (
	"encoding/base64"
	"fmt"
	"io"
	"net/http"
	"os"
	"time"

	"github.com/charmbracelet/log"
	"github.com/go-co-op/gocron/v2"
)

const calendar_url = "https://frontdoor.spa.gla.ac.uk/spacett/download/uogtimetable.ics"

var authorization string

func main() {
	// collect guid and password
	var (
		guid     string
		password string
	)
	fmt.Print("Enter your GUID: ")
	fmt.Scan(&guid)
	fmt.Print("Enter your password: ")
	fmt.Scan(&password)
	b64 := base64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("%s:%s", guid, password)))
	authorization = fmt.Sprintf("Basic %s", b64)

	// create scheduler
	s, err := gocron.NewScheduler()
	if err != nil {
		log.Fatal(err)
	}

	j, err := s.NewJob(
		// every 24 hours
		gocron.DurationJob(
			24*time.Hour,
		),

		// fetch the calendar
		gocron.NewTask(
			func() {
				// create request
				req, err := http.NewRequest("GET", calendar_url, nil)
				if err != nil {
					log.Fatal(err)
				}
				req.Header.Set("Authorization", authorization)

				// send request
				resp, err := http.DefaultClient.Do(req)
				if err != nil {
					log.Fatal(err)
				}

				// read response
				defer resp.Body.Close()
				body, err := io.ReadAll(resp.Body)
				if err != nil {
					log.Fatal(err)
				}

				// check if authentication failed
				if resp.StatusCode == 401 {
					log.Fatal("authentication failed")
				} else {
					os.WriteFile("calendar.ics", body, 0644)
					log.Info("Written calendar to calendar.ics")
				}
			},
		),
	)
	if err != nil {
		log.Fatal(err)
	}

	// run job and start scheduler
	go j.RunNow()
	s.Start()

	// block until ready
	time.Sleep(24 * time.Hour)

	err = s.Shutdown()
	if err != nil {
		log.Fatal(err)
	}
}