Add option for custom api server.

README.md

@@ -8,7 +8,7 @@
 
 Client lib for [Telegram bot api](https://core.telegram.org/bots/api). Supports **Bot API v2.3.1** (of 4th Dec 2016).
 
-##### Simple echo bot example:
+### Simple echo bot
 ```go
 package main
 
@@ -21,7 +21,8 @@ import (
 func main() {
     bot, err := micha.NewBot("<token>")
     if err != nil {
-        log.Fatal(err)
+        log.Println(err)
+        return
     }
 
     go bot.Start()
@@ -34,3 +35,42 @@ func main() {
 }
 
 ```
+
+
+### Custom [Telegram Bot API](https://github.com/tdlib/telegram-bot-api)
+```go
+package main
+
+import (
+    "log"
+
+    "github.com/onrik/micha"
+)
+
+func main() {
+    bot, err := micha.NewBot(
+        "<token>",
+        micha.WithAPIServer("http://127.0.0.1:8081"),
+    )
+    if err != nil {
+        log.Println(err)
+        return
+    }
+
+    err = bot.Logout()
+    if err != nil {
+        log.Println(err)
+        return
+    }
+
+
+    go bot.Start()
+
+    for update := range bot.Updates() {
+        if update.Message != nil {
+            bot.SendMessage(update.Message.Chat.ID, update.Message.Text, nil)
+        }
+    }
+}
+
+```

bot.go

@@ -10,8 +10,7 @@ import (
 )
 
 const (
-	API_URL      = "https://api.telegram.org/bot%s/%s"
-	FILE_API_URL = "https://api.telegram.org/file/bot%s/%s"
+	defaultAPIServer = "https://api.telegram.org"
 )
 
 type Response struct {
@@ -37,7 +36,8 @@ func NewBot(token string, opts ...Option) (*Bot, error) {
 	options := Options{
 		limit:      100,
 		timeout:    25,
-		logger:     newLogger("micha"),
+		logger:     newLogger("[micha] "),
+		apiServer:  defaultAPIServer,
 		httpClient: http.DefaultClient,
 	}
 
@@ -63,7 +63,7 @@ func NewBot(token string, opts ...Option) (*Bot, error) {
 
 // Build url for API method
 func (bot *Bot) buildURL(method string) string {
-	return fmt.Sprintf(API_URL, bot.token, method)
+	return bot.Options.apiServer + fmt.Sprintf("/bot%s/%s", bot.token, method)
 }
 
 // Decode response result to target object
@@ -230,6 +230,28 @@ func (bot *Bot) DeleteWebhook() error {
 	return bot.post("deleteWebhook", nil, nil)
 }
 
+// Logout
+// Use this method to log out from the cloud Bot API server before launching the bot locally.
+// You must log out the bot before running it locally,
+// otherwise there is no guarantee that the bot will receive updates.
+// After a successful call, you can immediately log in on a local server,
+// but will not be able to log in back to the cloud Bot API server for 10 minutes.
+func (bot *Bot) Logout() error {
+	url := defaultAPIServer + fmt.Sprintf("/bot%s/logOut", bot.token)
+	request, err := newGetRequest(url, nil)
+	if err != nil {
+		return err
+	}
+
+	response, err := bot.httpClient.Do(request)
+	if err != nil {
+		return err
+	}
+
+	_, err = handleResponse(response)
+	return err
+}
+
 // A simple method for testing your bot's auth token.
 // Returns basic information about the bot in form of a User object.
 func (bot *Bot) GetMe() (*User, error) {
@@ -558,7 +580,7 @@ func (bot *Bot) GetFile(fileID string) (*File, error) {
 
 // Return absolute url for file downloading by file path
 func (bot *Bot) DownloadFileURL(filePath string) string {
-	return fmt.Sprintf(FILE_API_URL, bot.token, filePath)
+	return bot.Options.apiServer + fmt.Sprintf("/file/bot%s/%s", bot.token, filePath)
 }
 
 // Use this method to edit text messages sent by the bot or via the bot (for inline bots).

bot_test.go

@@ -30,6 +30,7 @@ func (s *BotTestSuite) SetupSuite() {
 			limit:      100,
 			timeout:    25,
 			logger:     newLogger("micha"),
+			apiServer:  defaultAPIServer,
 			httpClient: http.DefaultClient,
 		},
 	}
@@ -129,7 +130,7 @@ func (s *BotTestSuite) TestNewBot() {
 	s.Require().NotNil(bot)
 	s.Require().Equal(25, bot.timeout)
 	s.Require().Equal(100, bot.limit)
-	s.Require().Equal(newLogger("micha"), bot.logger)
+	s.Require().Equal(newLogger("[micha] "), bot.logger)
 
 	// With options
 	logger := log.New(os.Stderr, "", log.LstdFlags)

options.go

@@ -1,9 +1,12 @@
 package micha
 
+import "strings"
+
 type Options struct {
 	limit      int
 	timeout    int
 	logger     Logger
+	apiServer  string
 	httpClient HttpClient
 }
 
@@ -39,6 +42,13 @@ func WithHttpClient(httpClient HttpClient) Option {
 	}
 }
 
+// WithAPIServer - set custom api server (https://github.com/tdlib/telegram-bot-api)
+func WithAPIServer(url string) Option {
+	return func(o *Options) {
+		o.apiServer = strings.TrimSuffix(url, "/")
+	}
+}
+
 // SendMessageOptions optional params SendMessage method
 type SendMessageOptions struct {
 	ParseMode             ParseMode   `json:"parse_mode,omitempty"`