Sending messages: basic functionality

api.go

@@ -4,8 +4,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
-	"log"
 	"net/http"
+	"net/url"
+	"strconv"
 )
 
 func api_getMe(token string) (User, error) {
@@ -40,9 +41,7 @@ func api_getMe(token string) (User, error) {
 	}
 }
 
-func api_getUpdates(token string,
-	offset int,
-	updates chan<- Update) error {
+func api_getUpdates(token string, offset int, updates chan<- Update) error {
 	command := fmt.Sprintf("getUpdates?offset=%d", offset)
 	request := "https://api.telegram.org/bot" + token + "/" + command
 
@@ -64,9 +63,11 @@ func api_getUpdates(token string,
 	}
 
 	err = json.Unmarshal(updates_json, &updates_recieved)
+	if err != nil {
+		return err
+	}
 
 	if !updates_recieved.Ok {
-		log.Println(FetchError{updates_recieved.Description})
 		return FetchError{updates_recieved.Description}
 	}
 
@@ -76,3 +77,40 @@ func api_getUpdates(token string,
 
 	return nil
 }
+
+func api_sendMessage(token string, recipient User, text string) error {
+	resource := "https://api.telegram.org/bot" + token + "/sendMessage"
+
+	params := url.Values{}
+	params.Set("chat_id", strconv.FormatInt(int64(recipient.Id), 10))
+	params.Set("text", text)
+
+	request := resource + "?" + params.Encode()
+
+	resp, err := http.Get(request)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+	response_json, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	var response_recieved struct {
+		Ok          bool
+		Description string
+	}
+
+	err = json.Unmarshal(response_json, &response_recieved)
+	if err != nil {
+		return err
+	}
+
+	if !response_recieved.Ok {
+		return SendError{response_recieved.Description}
+	}
+
+	return nil
+}

bot.go

@@ -42,3 +42,7 @@ func (b *Bot) Listen(interval time.Duration) {
 func (b *Bot) AddListener(ear Listener) {
 	b.listeners = append(b.listeners, ear)
 }
+
+func (b *Bot) SendMessage(recipient User, message string) {
+	go api_sendMessage(b.Token, recipient, message)
+}

errors.go

@@ -9,6 +9,10 @@ type FetchError struct {
 	Payload string
 }
 
+type SendError struct {
+	Payload string
+}
+
 func (e AuthError) Error() string {
 	return "AuthError: " + e.Payload
 }
@@ -16,3 +20,7 @@ func (e AuthError) Error() string {
 func (e FetchError) Error() string {
 	return "FetchError: " + e.Payload
 }
+
+func (e SendError) Error() string {
+	return "SendError: " + e.Payload
+}

telebot_test.go

@@ -26,8 +26,10 @@ func TestListen(t *testing.T) {
 	}
 
 	bot.AddListener(func(bot *Bot, message Message) {
-		log.Printf("Recieved a message \"%s\" from user \"%s\"\n",
-			message.Text, message.Sender.Username)
+		if message.Text == "/hi" {
+			bot.SendMessage(message.Sender,
+				"Hello, "+message.Sender.FirstName+"!")
+		}
 	})
 
 	log.Println("Listening...")

user.go

@@ -5,4 +5,9 @@ type User struct {
 	FirstName string `json:"first_name"`
 	LastName  string `json:"last_name"`
 	Username  string
+
+	// In case of group chat, Title will indicate
+	// whether it's a chat or user: if Title is empty
+	// it's a user, otherwise it's not.
+	Title string
 }