main.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api"
	"github.com/joho/godotenv"
)

func main() {
	// loadEnvironmentalVariables()

	//log to file as well as stdout
	// f, err := os.OpenFile("output.txt", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	// if err != nil {
	// 	log.Fatalf("error opening file: %v", err)
	// }
	// defer f.Close()
	// mw := io.MultiWriter(os.Stdout, f)
	// log.SetOutput(mw)

	//set up telegram info
	bot, err := tgbotapi.NewBotAPI(os.Getenv("TELEGRAM_TOKEN"))
	errCheck(err, "Failed to start telegram bot")
	log.Printf("Authorized on account %s", bot.Self.UserName)
	chatID, err := strconv.ParseInt(os.Getenv("CHAT_ID"), 10, 64)
	errCheck(err, "Failed to fetch chat ID")

	client := &http.Client{}

	//for heroku
	go func() {
		http.ListenAndServe(":"+os.Getenv("PORT"),
			http.HandlerFunc(http.NotFound))
	}()
	for {
		//fetching cookies
		log.Println("Fetching cookies")
		sessionID := fetchCookies()

		//logging in
		log.Println("Logging in")
		loginForm := url.Values{}
		loginForm.Add("txtNRIC", os.Getenv("NRIC"))
		loginForm.Add("txtPassword", os.Getenv("PASSWORD"))
		loginForm.Add("btnLogin", " ")
		req, err := http.NewRequest("POST", "http://www.bbdc.sg/bbdc/bbdc_web/header2.asp",
			strings.NewReader(loginForm.Encode()))
		errCheck(err, "Error creating log in request")
		//req.AddCookie(aspxanon)
		req.AddCookie(sessionID)
		req.AddCookie(&http.Cookie{Name: "language", Value: "en-US"})
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
		_, err = client.Do(req)
		errCheck(err, "Error logging in")

		//fetching the booking page
		log.Println("Fetching booking page")
		req, err = http.NewRequest("POST", "http://www.bbdc.sg/bbdc/b-3c-pLessonBooking1.asp",
			strings.NewReader(bookingForm().Encode()))
		//req.AddCookie(aspxanon)
		req.AddCookie(sessionID)
		req.AddCookie(&http.Cookie{Name: "language", Value: "en-US"})
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
		errCheck(err, "Error creating get bookings request")
		resp, err := client.Do(req)
		errCheck(err, "Error fetching booking slots")
		body, _ := ioutil.ReadAll(resp.Body)
		ioutil.WriteFile("booking.txt", body, 0644)

		//parse booking page to get booking dates
		//The data is hidden away in the following function call in the HTML page
		//fetched:
		//doTooltipV(event,0, "03/05/2019 (Fri)","3","11:30","13:10","BBDC");
		log.Println("Parsing booking page")
		foundSlot := false
		substrs := strings.Split(string(body), "doTooltipV(")[1:]

		for _, substr := range substrs {
			bookingData := strings.Split(substr, ",")[0:6]
			day := bookingData[2]
			// monthInt := day[5:7]
			fmt.Println("Available slots, %v", bookingData)
			alert("Available slot on "+day+" from "+bookingData[4]+" to "+bookingData[5],
				bot, chatID)
			validSlot := true
			// if (strings.Contains(day, "Sat")) && (monthInt == "09" || monthInt == "10" || monthInt == "11" || monthInt == "12") {
			// 	alert("Slot that matches condition (09, 10, 11, 12, Saturdays) on "+day+" from "+bookingData[4]+" to "+bookingData[5],
			// 		bot, chatID)
			// 	foundSlot = true
			// 	validSlot = true
			// }

			if validSlot {
				//Check if the slot found is within 10 days to determine whether to auto book
				layout := "02/01/2006"
				dayProper, err := time.Parse(layout, strings.Split(strings.Split(day, "\"")[1], " ")[0])

				errCheck(err, "Error parsing date of slot")
				daysFromNow := int(dayProper.Sub(time.Now()).Hours()/24) + 1
				daysToLookAhead, err := strconv.Atoi(os.Getenv("DAYSTOLOOKAHEAD"))
				if daysFromNow <= daysToLookAhead {
					//if the slot is today
					//note dayProper will be at midnight of the date given
					//so the current time will actually ahead of the day of the slot
					//if the slot is today, and you'll get a negative number
					log.Printf("Entered autobook segment with daysFromNow %d and slot date %s \n", daysFromNow, day)
					if dayProper.Sub(time.Now()).Hours() > 0 || os.Getenv("AUTOBOOK_TODAY") == "TRUE" {
						log.Printf("Proceeded with autobook")

						//need to get slot ID for auto-book
						//strings.Split(substr, ",") returns- "BBDC"); SetMouseOverToggleColor("cell145_2") ' onmouseout='hideTip(); SetMouseOverToggleColor("cell145_2")'><input type="checkbox" id="145_2" name="slot" value="1893904" onclick="SetCountAndToggleColor('cell145_2'
						//splitting on value= and taking the second element returns- "1893904" onclick="SetCountAndToggleColor('cell145_2'
						//then split on " and take the second element to get 1893904
						slotID := strings.Split(strings.Split(strings.Split(substr, ",")[6], "value=")[1], "\"")[1]
						log.Println("Booking slot")
						req, err = http.NewRequest("POST", "http://www.bbdc.sg/bbdc/b-3c-pLessonBookingDetails.asp",
							strings.NewReader(paymentForm(slotID).Encode()))
						//req.AddCookie(aspxanon)
						req.AddCookie(sessionID)
						req.AddCookie(&http.Cookie{Name: "language", Value: "en-US"})
						req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
						errCheck(err, "Error creating get bookings request")
						_, err = client.Do(req)
						errCheck(err, "Error creating booking slot")
						log.Println("Finished booking slot")

						alert("Auto-booked slot, "+day+" from "+bookingData[4]+" to "+bookingData[5]+"because the slot as it was within 10 days of the current date. Please visit http://www.bbdc.sg/bbweb/default.aspx to verify!", bot, chatID)
					} else {
						log.Printf("Did not proceed with autobook as time till event was %f hours away \n", dayProper.Sub(time.Now()).Hours())
					}
				} else {
					alert("Did not book slot on "+day+" from "+bookingData[4]+" to "+bookingData[5]+" because date is "+strconv.Itoa(daysFromNow)+" days away.",
						bot, chatID)
				}
			}
		}

		if foundSlot {
			alert("Finished getting slots", bot, chatID)
		} else {
			log.Println("No slots found")
		}
		r := rand.Intn(300) + 120
		s := fmt.Sprint(time.Duration(r) * time.Second)
		alert("Retrigger in: "+s, bot, chatID)
		ping()
		time.AfterFunc(30*time.Second, ping)
		time.Sleep(time.Duration(r) * time.Second)
	}
}

func ping() {
	resp, err := http.Get(os.Getenv("HEROKU_LINK"))
	fmt.Printf("%v", resp)
	errCheck(err, "Error")
	log.Println("Pinged ")
}

func alert(msg string, bot *tgbotapi.BotAPI, chatID int64) {
	telegramMsg := tgbotapi.NewMessage(chatID, msg)
	bot.Send(telegramMsg)
	log.Println("Sent message to " + strconv.FormatInt(chatID, 10) + ": " + msg)
}

func loadEnvironmentalVariables() {
	err := godotenv.Load()
	if err != nil {
		log.Print("Error loading environmental variables: ")
		log.Fatal(err.Error())
	}
}

func fetchCookies() (*http.Cookie) {
	resp, err := http.Get("http://www.bbdc.sg/bbdc/bbdc_web/newheader.asp")
	errCheck(err, "Error fetching cookies (sessionID)")
	sessionID := resp.Cookies()[0]
	return sessionID
}

func paymentForm(slotID string) url.Values {
	form := url.Values{}
	form.Add("accId", os.Getenv("ACCOUNT_ID"))
	form.Add("slot", slotID)

	return form
}

func bookingForm() url.Values {
	bookingForm := url.Values{}
	bookingForm.Add("accId", os.Getenv("ACCOUNT_ID"))
	months := strings.Split(os.Getenv("WANTED_MONTHS"), ",")

	sessions := strings.Split(os.Getenv("WANTED_SESSIONS"), ",")
	days := strings.Split(os.Getenv("WANTED_DAYS"), ",")
	for _, month := range months {
		bookingForm.Add("Month", month)
	}
	for _, session := range sessions {
		bookingForm.Add("Session", session)
	}
	for _, day := range days {
		bookingForm.Add("Day", day)
	}
	bookingForm.Add("defPLVenue", "1")
	bookingForm.Add("optVenue", "1")

	log.Printf("Looking through booking form for %s, for %s sessions, for these days %s (where 7 = Saturday etc.)", strings.Join(months, " "), strings.Join(sessions, " "), strings.Join(days, " "))

	return bookingForm
}

func errCheck(err error, msg string) {
	if err != nil {
		log.Fatal(msg + ": " + err.Error())
	}
}