[polling,webhook] Add methods controlling polling, webhook

Feature:

  For finer control over bot's polling and web-hook, the
  following methods have been added:

  * TelegramBot#isPolling()
  * TelegramBot#openWebHook()
  * TelegramBot#closeWebHook()
  * TelegramBot#hasOpenWebHook()

  Please read README.md for more information on the
  new methods.

README.md

@@ -73,6 +73,10 @@ TelegramBot
     * [new TelegramBot(token, [options])](#new_TelegramBot_new)
     * [.initPolling()](#TelegramBot+initPolling)
     * [.stopPolling()](#TelegramBot+stopPolling) ⇒ <code>Promise</code>
+    * [.isPolling()](#TelegramBot+isPolling) ⇒ <code>Boolean</code>
+    * [.openWebHook()](#TelegramBot+openWebHook)
+    * [.closeWebHook()](#TelegramBot+closeWebHook) ⇒ <code>Promise</code>
+    * [.hasOpenWebHook()](#TelegramBot+hasOpenWebHook) ⇒ <code>Boolean</code>
     * [.getMe()](#TelegramBot+getMe) ⇒ <code>Promise</code>
     * [.setWebHook(url, [cert])](#TelegramBot+setWebHook)
     * [.getUpdates([timeout], [limit], [offset])](#TelegramBot+getUpdates) ⇒ <code>Promise</code>
@@ -147,6 +151,32 @@ Stops polling after the last polling request resolves
 
 **Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
 **Returns**: <code>Promise</code> - promise Promise, of last polling request  
+<a name="TelegramBot+isPolling"></a>
+
+### telegramBot.isPolling() ⇒ <code>Boolean</code>
+Return true if polling. Otherwise, false.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+<a name="TelegramBot+openWebHook"></a>
+
+### telegramBot.openWebHook()
+Open webhook
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+<a name="TelegramBot+closeWebHook"></a>
+
+### telegramBot.closeWebHook() ⇒ <code>Promise</code>
+Close webhook after closing all current connections
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+**Returns**: <code>Promise</code> - promise  
+<a name="TelegramBot+hasOpenWebHook"></a>
+
+### telegramBot.hasOpenWebHook() ⇒ <code>Boolean</code>
+Return true if using webhook and it is open i.e. accepts connections.
+Otherwise, false.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
 <a name="TelegramBot+getMe"></a>
 
 ### telegramBot.getMe() ⇒ <code>Promise</code>

src/telegram.js

@@ -70,7 +70,7 @@ class TelegramBot extends EventEmitter {
     if (options.webHook) {
       const autoOpen = options.webHook.autoOpen;
       if (typeof autoOpen === 'undefined' || autoOpen === true) {
-        this._WebHook = new TelegramBotWebHook(token, options.webHook, this.processUpdate.bind(this));
+        this.openWebHook();
       }
     }
   }
@@ -325,6 +325,46 @@ class TelegramBot extends EventEmitter {
     return polling.stopPolling();
   }
 
+  /**
+   * Return true if polling. Otherwise, false.
+   * @return {Boolean}
+   */
+  isPolling() {
+    return !!this._polling;
+  }
+
+  /**
+   * Open webhook
+   */
+  openWebHook() {
+    if (this._webHook) {
+      return;
+    }
+    this._webHook = new TelegramBotWebHook(this.token, this.options.webHook, this._processUpdate.bind(this));
+  }
+
+  /**
+   * Close webhook after closing all current connections
+   * @return {Promise} promise
+   */
+  closeWebHook() {
+    if (!this._webHook) {
+      return Promise.resolve();
+    }
+    const webHook = this._webHook;
+    delete this._webHook;
+    return webHook.close();
+  }
+
+  /**
+   * Return true if using webhook and it is open i.e. accepts connections.
+   * Otherwise, false.
+   * @return {Boolean}
+   */
+  hasOpenWebHook() {
+    return !!this._webHook;
+  }
+
   /**
    * Returns basic information about the bot in form of a `User` object.
    * @return {Promise}

src/telegramWebHook.js

@@ -3,6 +3,7 @@ const https = require('https');
 const http = require('http');
 const fs = require('fs');
 const bl = require('bl');
+const Promise = require('bluebird');
 
 
 class TelegramBotWebHook {
@@ -98,6 +99,19 @@ class TelegramBotWebHook {
     }
   }
 
+  /**
+   * Close the webHook
+   * @return {Promise}
+   */
+  close() {
+    const self = this;
+    return new Promise(function closePromise(resolve, reject) {
+      self._webServer.close(function closeCb(error) {
+        if (error) return reject(error);
+        return resolve();
+      });
+    });
+  }
 }
 
 module.exports = TelegramBotWebHook;