Message handling: Listen(), AddListener(), Listener

api.go

@@ -0,0 +1,78 @@
+package telebot
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+)
+
+func api_getMe(token string) (User, error) {
+	request := "https://api.telegram.org/bot" + token + "/getMe"
+
+	resp, err := http.Get(request)
+	if err != nil {
+		return User{}, err
+	}
+
+	defer resp.Body.Close()
+	me_json, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return User{}, err
+	}
+
+	var bot_info struct {
+		Ok          bool
+		Result      User
+		Description string
+	}
+
+	err = json.Unmarshal(me_json, &bot_info)
+	if err != nil {
+		return User{}, err
+	}
+
+	if bot_info.Ok {
+		return bot_info.Result, nil
+	} else {
+		return User{}, AuthError{bot_info.Description}
+	}
+}
+
+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
+
+	resp, err := http.Get(request)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+	updates_json, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	var updates_recieved struct {
+		Ok          bool
+		Result      []Update
+		Description string
+	}
+
+	err = json.Unmarshal(updates_json, &updates_recieved)
+
+	if !updates_recieved.Ok {
+		log.Println(FetchError{updates_recieved.Description})
+		return FetchError{updates_recieved.Description}
+	}
+
+	for _, update := range updates_recieved.Result {
+		updates <- update
+	}
+
+	return nil
+}

bot.go

@@ -0,0 +1,44 @@
+package telebot
+
+import (
+	"time"
+)
+
+type Bot struct {
+	Token string
+
+	// Bot as `User` on API level.
+	Identity User
+
+	listeners []Listener
+}
+
+type Listener func(*Bot, Message)
+
+func (b *Bot) Listen(interval time.Duration) {
+	updates := make(chan Update, 1000)
+	var latest_update int
+
+	pulse := time.NewTicker(interval)
+	go func() {
+		for range pulse.C {
+			go api_getUpdates(b.Token,
+				latest_update+1,
+				updates)
+		}
+	}()
+
+	for update := range updates {
+		if update.Id > latest_update {
+			latest_update = update.Id
+		}
+
+		for _, ear := range b.listeners {
+			go ear(b, update.Payload)
+		}
+	}
+}
+
+func (b *Bot) AddListener(ear Listener) {
+	b.listeners = append(b.listeners, ear)
+}

errors.go

@@ -5,6 +5,14 @@ type AuthError struct {
 	Payload string
 }
 
+type FetchError struct {
+	Payload string
+}
+
 func (e AuthError) Error() string {
 	return "AuthError: " + e.Payload
 }
+
+func (e FetchError) Error() string {
+	return "FetchError: " + e.Payload
+}

message.go

@@ -0,0 +1,9 @@
+package telebot
+
+type Message struct {
+	Id       int    `json:"message_id"`
+	Sender   User   `json:"from"`
+	Unixtime int    `json:"date"`
+	Text     string `json:"text"`
+	// TBA: `chat`
+}

telebot.go

@@ -2,51 +2,15 @@
 // with Telegram bots.
 package telebot
 
-import (
-	"encoding/json"
-	"io/ioutil"
-	"net/http"
-)
-
-type Bot struct {
-	Token string
-
-	// Bot as `User` on API level.
-	Identity User
-}
-
 // Attempts to construct a Bot with `token` given.
 func Create(token string) (Bot, error) {
-	request := "https://api.telegram.org/bot" + token + "/getMe"
-
-	resp, err := http.Get(request)
-	if err != nil {
-		return Bot{}, err
-	}
-
-	defer resp.Body.Close()
-	me_json, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		return Bot{}, err
-	}
-
-	var bot_info struct {
-		Ok          bool
-		Result      User
-		Description string
-	}
-
-	err = json.Unmarshal(me_json, &bot_info)
+	user, err := api_getMe(token)
 	if err != nil {
 		return Bot{}, err
 	}
 
-	if bot_info.Ok {
-		return Bot{
-			Token:    token,
-			Identity: bot_info.Result,
-		}, nil
-	} else {
-		return Bot{}, AuthError{bot_info.Description}
-	}
+	return Bot{
+		Token:    token,
+		Identity: user,
+	}, nil
 }

telebot_test.go

@@ -1,6 +1,10 @@
 package telebot
 
-import "testing"
+import (
+	"log"
+	"testing"
+	"time"
+)
 
 const TESTING_TOKEN = "107177593:AAHBJfF3nv3pZXVjXpoowVhv_KSGw56s8zo"
 
@@ -10,3 +14,22 @@ func TestCreate(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestListen(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	bot, err := Create(TESTING_TOKEN)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bot.AddListener(func(bot *Bot, message Message) {
+		log.Printf("Recieved a message \"%s\" from user \"%s\"\n",
+			message.Text, message.Sender.Username)
+	})
+
+	log.Println("Listening...")
+	bot.Listen(1 * time.Second)
+}

update.go

@@ -0,0 +1,6 @@
+package telebot
+
+type Update struct {
+	Id      int     `json:"update_id"`
+	Payload Message `json:"message"`
+}