main.go

package main

import (
	"log"
	"net/http"
	"bytes"
	"os"
	"time"
	"io/ioutil"
	"encoding/json"

	"github.com/joho/godotenv"
	"gopkg.in/telegram-bot-api.v4"

	"github.com/snowypowers/sgweatherbot/poller"
	"github.com/snowypowers/sgweatherbot/store"

)


var nlpToken, botToken, webLink, apiKey string
var client = &http.Client{Timeout: time.Second * 10}

type context struct{
	poller *poller.Poller
	reply chan tgbotapi.MessageConfig
}

func main() {
	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	botToken = os.Getenv("BOT_TOKEN")
	webLink = os.Getenv("WEBSITE_LINK")
	apiKey = os.Getenv("DATA_API_KEY")
	nlpToken = os.Getenv("NLP_TOKEN")

	//Poller
	p := poller.NewPoller(client)
	wf2 := poller.Subscription{
		"wf2",
		"https://api.data.gov.sg/v1/environment/2-hour-weather-forecast",
		apiKey,
		300}
	wf2Close := p.Listen(wf2)

	//Bot
	bot, err := tgbotapi.NewBotAPIWithClient(botToken, client)
	if err != nil {
		log.Fatal(err)
	}
	bot.Debug = true
	log.Printf("Authorized on account %s", bot.Self.UserName)

	_, err = bot.SetWebhook(tgbotapi.NewWebhookWithCert(webLink+bot.Token, "cert.pem"))
	if err != nil {
		log.Fatal(err)
	}
	updates := bot.ListenForWebhook("/" + bot.Token)
	//Website
	http.Handle("/", http.FileServer(http.Dir("./website")))

	go http.ListenAndServeTLS("0.0.0.0:8443", "cert.pem", "key.pem", nil)

	//Cmd Handling
	reply := make(chan tgbotapi.MessageConfig)
	ctx := context{p, reply}

	for {
		select {
			case u:= <-updates:
				go processUpdate(u, ctx)
			case r := <-reply:
				bot.Send(r)
		}
	}

	//Teardown
	close(wf2Close)
}

func processUpdate(update tgbotapi.Update, ctx context) {
	//Command Parsing
	cmd := update.Message.Command()
	args := update.Message.CommandArguments()
	var msg tgbotapi.MessageConfig
	switch cmd {
		case "w", "weather", "wf2":
			msg = processWf2(update, ctx.poller.ValueByName("wf2"), args)
		case "start":
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, "Hello!\nI am Teru!\n I provide 2 hour nowcasts of the weather in Singapore!This data is provided by NEA.\n To get the weather at a certain area, type /w <area name>.\nType /help for instructions!")
		case "help":
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, "Use command /w to get the weather forecast for the next 2 hours")
		case "about":
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, "Data retrieved from NEA. Conversations powered by API.ai, Coded in Go.")
		case "":
			//No cmds. Forward req to API.AI
			msg = processNLP(update)
		default:
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, "huh?")
	}
	ctx.reply <- msg
}

func processNLP(update tgbotapi.Update) tgbotapi.MessageConfig {
	req := constructNLPReq(update)
	res, err := client.Do(req)
	if err != nil {
		log.Panic(err)
	}
	defer res.Body.Close()
	bs, err := ioutil.ReadAll(res.Body)
	var resBody nlpResponse
	if err := json.Unmarshal(bs, &resBody); err != nil {
		log.Println(err)
	}
	return nlpRespToMsg(update, resBody)
}

func constructNLPReq(update tgbotapi.Update) *http.Request {
	nlpBody := nlpRequest{update.Message.Text, string(update.Message.Chat.ID), "en", 20170101}
	body, err := json.Marshal(nlpBody)
	req, err := http.NewRequest("POST", "https://api.api.ai/v1/query", bytes.NewBuffer(body))
	if err != nil {
		log.Panic(err)
	}
	req.Header.Set("Authorization", "Bearer " + nlpToken)
	req.Header.Set("Content-Type", "application/json")
	return req
}

func nlpRespToMsg(update tgbotapi.Update, res nlpResponse) tgbotapi.MessageConfig {
	log.Printf("NLP RESP: %v+", res)
	msg := tgbotapi.NewMessage(update.Message.Chat.ID, res.Result.Speech)
	return msg
}

func processWf2(update tgbotapi.Update, data []byte, args string) tgbotapi.MessageConfig {
	d := store.ParseWf2(data)
	a := store.ParseArea(args)
	log.Printf("args: %s", a)
	var msg tgbotapi.MessageConfig
	switch(a) {
		case "All":
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, printAllWf2(d))
		case "North", "South", "East", "West", "Central":
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, printAreaWf2(d, a))
		case "":
			if args == "" {
				msg = tgbotapi.NewMessage(update.Message.Chat.ID, "Choose a region or type in the area name after /w. \nFor example, /w Bedok.")
				msg.ReplyMarkup = wf2FullKb
			} else {
				msg = tgbotapi.NewMessage(update.Message.Chat.ID, "Sorry, did you spell the area wrongly?")
			}
		default:
			f := d.Forecasts[a]
			msg = tgbotapi.NewMessage(update.Message.Chat.ID, "The weather at " + a + " is " + f)
	}
	return msg
}

func printAllWf2(w store.WF2Update) string {
	s := "Weather for " + w.Timestamp.Format("Mon Jan 2 03:04 PM ") + " \n"
	for k,v:= range w.Forecasts {
		s += k + ": " + v + "\n"
	}
	return s
}

func printAreaWf2(w store.WF2Update, area string) string {
	s := "The 2 hour Nowcast for " + area + " at " + w.Timestamp.Format("Mon Jan 2 03:04 PM ") + " \n"
	for _,v := range regions[area] {
		s += v + ": " + w.Forecasts[v] + "\n"
	}
	return s
}