Working code

telegram-bot-carparks/.gitignore

@@ -1,2 +1,3 @@
 kafka-connect-rest
-data/connectors
+data/connectors
+go/telegram_token.go

telegram-bot-carparks/go/ksqldb_pull.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"net/http"
 	"strings"
@@ -40,9 +41,17 @@ func checkSpaces(c string) (emptyPlaces float64, pctFull float64, err error) {
 	var CURRENT_EMPTY_PLACES float64
 	var PCT_FULL float64
 	err = json.Unmarshal(body, &m)
+	switch len(m) {
+	case 0:
+		// This shouldn't happen…
+		return 0, 0, fmt.Errorf("No results (not even a header row) returned from lookup")
+	case 1:
+		// len 1 means we just got a header, no rows
+		return 0, 0, fmt.Errorf("No result found")
+	default:
+		CURRENT_EMPTY_PLACES = m[1].Row.Columns[0].(float64)
+		PCT_FULL = m[1].Row.Columns[1].(float64)
+		return CURRENT_EMPTY_PLACES, PCT_FULL, nil
+	}
 
-	CURRENT_EMPTY_PLACES = m[1].Row.Columns[0].(float64)
-	PCT_FULL = m[1].Row.Columns[1].(float64)
-
-	return CURRENT_EMPTY_PLACES, PCT_FULL, nil
 }

telegram-bot-carparks/go/ksqldb_push.go

@@ -10,7 +10,8 @@ import (
 	"time"
 )
 
-func alertSpaces(c int) (err error) {
+func alertSpaces(a chan<- string, c int) (e error) {
+	defer close(a)
 
 	// Prepare the request
 	url := "http://localhost:8088/query"
@@ -58,14 +59,17 @@ func alertSpaces(c int) (err error) {
 			// {"row":{"columns":["Burnett St",1595373720000,122,117]}},
 			//   becomes
 			// {"row":{"columns":["Burnett St",1595373720000,122,117]}}
+			//
+			// Pretty sure instead of `ReadBytes` above I should be using
+			// Scanner (https://golang.org/pkg/bufio/#Scanner) to split on ASCII 44 10 13 (,CRLF)
 			lb = lb[:len(lb)-2]
 
 			// Convert the JSON to Go object
 			if strings.Contains(string(lb), "row") {
 				// Looks like a Row, let's process it!
 				err = json.Unmarshal(lb, &r)
 				if err != nil {
-					fmt.Printf("Error decoding JSON %v (%v)\n", string(lb), err)
+					return fmt.Errorf("error decoding JSON %v (%v)\n", string(lb), err)
 				} else {
 					if r.Row.Columns != nil {
 						CARPARK = r.Row.Columns[0].(string)
@@ -74,8 +78,8 @@ func alertSpaces(c int) (err error) {
 						CAPACITY = r.Row.Columns[3].(float64)
 						// Handle the timestamp
 						t := int64(DATA_TS)
-						ts := time.Unix(t/1000, 0)
-						fmt.Printf("Carpark %v at %v has %v spaces available (capacity %v)\n", CARPARK, ts, CURRENT_EMPTY_PLACES, CAPACITY)
+						ts := time.Unix(t/1000, 0).Format(time.RFC822)
+						a <- fmt.Sprintf("✨ 🎉  🚗 The %v carpark has %v spaces available (capacity %v)\n(data as of %v)", CARPARK, CURRENT_EMPTY_PLACES, CAPACITY, ts)
 					}
 				}
 			} else {

telegram-bot-carparks/go/main.go

@@ -1,6 +1,12 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"log"
+	"strconv"
+
+	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api"
+)
 
 // These are split up as when reading the chunked
 // response we need to be able to assert the Row only
@@ -30,12 +36,85 @@ type ksqlDBMessage []struct {
 
 func main() {
 
-	c := "Broadway"
-	if p, f, e := checkSpaces(c); e == nil {
-		fmt.Printf("Car park %v is %.2f%% full (%v spaces available)\n\n", c, f, p)
-	} else {
-		fmt.Printf("There was an error calling `checkSpaces`.\n%v\n\n", e)
+	var resp string
+	var chatID int64
+
+	// Authorise and create bot instance
+	bot, err := tgbotapi.NewBotAPI(TELEGRAM_API_TOKEN)
+	if err != nil {
+		log.Panic(err)
 	}
-	alertSpaces(100)
+	log.Printf("Authorized on account %s", bot.Self.UserName)
+
+	// TODO: Check that the bot is set up for `alert` command
+	// and add it if not.
+	// Currently hardcoded in setup process, but outline function
+	// has been added. Need to change it to take existing commands,
+	// and add the new one (rather than overwrite)
+
+	// Subscribe to updates
+	u := tgbotapi.NewUpdate(0)
+	u.Timeout = 60
+	updates, err := bot.GetUpdatesChan(u)
+
+	// Process any messages that we're sent as they arrive
+	for update := range updates {
+		if update.Message == nil { // ignore any non-Message Updates
+			continue
+		}
+
+		chatID = update.Message.Chat.ID
+		t := update.Message.Text
+		log.Printf("[%s] %s (command: %v)", update.Message.From.UserName, t, update.Message.IsCommand())
 
+		if update.Message.IsCommand() {
+			// Handle commands
+			switch update.Message.Command() {
+			case "alert":
+				threshold := update.Message.CommandArguments()
+				if th, e := strconv.Atoi(threshold); e == nil {
+					// Use a Go Routine to invoke the population
+					// of the alert channel and handling the returned
+					// alerts
+					go func() {
+						ac := make(chan string)
+						go alertSpaces(ac, th)
+						msg := tgbotapi.NewMessage(chatID, fmt.Sprintf("👍 Successfully created alert to be sent whenever more than %v spaces are available", th))
+						if _, e := bot.Send(msg); e != nil {
+							fmt.Printf("Error sending message to telegram.\nMessage: %v\nError: %v", msg, e)
+						}
+
+						for a := range ac {
+							msg := tgbotapi.NewMessage(chatID, a)
+							if _, e := bot.Send(msg); e != nil {
+								fmt.Printf("Error sending message to telegram.\nMessage: %v\nError: %v", msg, e)
+							}
+						}
+					}()
+				} else {
+					msg := tgbotapi.NewMessage(chatID, "Non-integer value specified for `/alert`")
+					if _, e := bot.Send(msg); e != nil {
+						fmt.Printf("Error sending message to telegram.\nMessage: %v\nError: %v", msg, e)
+					}
+
+				}
+
+			default:
+				bot.Send(tgbotapi.NewMessage(chatID, "🤔 Command not recognised."))
+			}
+		} else {
+			// We've got a carpark status request
+			if p, f, e := checkSpaces(t); e == nil {
+				resp = fmt.Sprintf("ℹ️ 🚗 Car park %v is %.2f%% full (%v spaces available)\n\n", t, f, p)
+			} else {
+				resp = fmt.Sprintf("⚠️ There was an error calling `checkSpaces` for %v:\n\n%v\n\n", t, e)
+			}
+			msg := tgbotapi.NewMessage(chatID, resp)
+
+			if _, e := bot.Send(msg); e != nil {
+				fmt.Printf("Error sending message to telegram.\nMessage: %v\nError: %v", msg, e)
+			}
+		}
+
+	}
 }

telegram-bot-carparks/go/set_command.go

@@ -0,0 +1,33 @@
+
+func setCommand(a string) {
+
+	// curl --location --request GET 'https://api.telegram.org/botMY_TOKEN/setMyCommands' \
+	// --header 'Content-Type: application/json' \
+	// --data-raw '{
+	// 	"commands": [
+	// 		{
+	// 			"command": "Alert",
+	// 			"description": "Define an alert to be sent if a carpark becomes available with greater than the defined number of spaces"
+	// 		}
+	// 	]
+	// }'
+
+	url := "https://api.telegram.org/bot" + a + "/setMyCommands"
+	method := "GET"
+
+	payload := strings.NewReader("{\"commands\": [    {        \"command\": \"Alert\",        \"description\": \"Define an alert to be sent if a carpark becomes available with greater than the defined number of spaces\"    }]}")
+
+	client := &http.Client{}
+	req, err := http.NewRequest(method, url, payload)
+
+	if err != nil {
+		fmt.Println(err)
+	}
+	req.Header.Add("Content-Type", "application/json")
+
+	res, err := client.Do(req)
+	defer res.Body.Close()
+	body, err := ioutil.ReadAll(res.Body)
+
+	fmt.Println(string(body))
+}