Add new methods from the API v2.1

Notes:

  Merge branch 'master' of https://github.com/HorusGoul/node-telegram-bot-api into pr/158

References:

  * PR #158: https://github.com/yagop/node-telegram-bot-api/pull/158

README.md

@@ -87,6 +87,10 @@ TelegramBot
     * [.downloadFile(fileId, downloadDir)](#TelegramBot+downloadFile) ⇒ <code>Promise</code>
     * [.onText(regexp, callback)](#TelegramBot+onText)
     * [.onReplyToMessage(chatId, messageId, callback)](#TelegramBot+onReplyToMessage)
+    * [.getChat(chatId)](#TelegramBot+getChat) ⇒ <code>Promise</code>
+    * [.getChatAdministrators(chatId)](#TelegramBot+getChatAdministrators) ⇒ <code>Promise</code>
+    * [.getChatMembersCount(chatId)](#TelegramBot+getChatMembersCount) ⇒ <code>Promise</code>
+    * [.getChatMember(chatId, userId)](#TelegramBot+getChatMember) ⇒ <code>Promise</code>
 
 <a name="new_TelegramBot_new"></a>
 
@@ -531,4 +535,53 @@ Register a reply to wait for a message response.
 | messageId | <code>Number</code> &#124; <code>String</code> | The message id to be replied. |
 | callback | <code>function</code> | Callback will be called with the reply message. |
 
+<a name="TelegramBot+getChat"></a>
+
+### telegramBot.getChat(chatId) ⇒ <code>Promise</code>
+Returns information about the chat in form of a `Chat` object.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+**See**: https://core.telegram.org/bots/api#getchat  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| chatId | <code>Number</code> &#124; <code>String</code> | Unique identifier for the target group or username of the target supergroup |
+
+<a name="TelegramBot+getChatAdministrators"></a>
+
+### telegramBot.getChatAdministrators(chatId) ⇒ <code>Promise</code>
+Returns the administrators in a chat in form of an Array of `ChatMember` objects.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+**See**: https://core.telegram.org/bots/api#getchatadministrators  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| chatId | <code>Number</code> &#124; <code>String</code> | Unique identifier for the target group or username of the target supergroup |
+
+<a name="TelegramBot+getChatMembersCount"></a>
+
+### telegramBot.getChatMembersCount(chatId) ⇒ <code>Promise</code>
+Returns the number of members in a chat in form of an `Int` object.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+**See**: https://core.telegram.org/bots/api#getchatmemberscount  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| chatId | <code>Number</code> &#124; <code>String</code> | Unique identifier for the target group or username of the target supergroup |
+
+<a name="TelegramBot+getChatMember"></a>
+
+### telegramBot.getChatMember(chatId, userId) ⇒ <code>Promise</code>
+Returns information about a member of a chat in form of a `ChatMember` object.
+
+**Kind**: instance method of <code>[TelegramBot](#TelegramBot)</code>  
+**See**: https://core.telegram.org/bots/api#getchatmember  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| chatId | <code>Number</code> &#124; <code>String</code> | Unique identifier for the target group or username of the target supergroup |
+| userId | <code>String</code> | Unique identifier of the target user |
+
 * * *

src/telegram.js

@@ -755,6 +755,60 @@ class TelegramBot extends EventEmitter {
       callback
     });
   }
+
+  /**
+   * Returns information about the chat in form of a `Chat` object.
+   * @param  {Number|String} chatId  Unique identifier for the target group or username of the target supergroup
+   * @return {Promise}
+   * @see https://core.telegram.org/bots/api#getchat
+   */
+  getChat(chatId) {
+    const form = {
+      chat_id: chatId
+    };
+    return this._request('getChat', { form });
+  }
+
+  /**
+   * Returns the administrators in a chat in form of an Array of `ChatMember` objects.
+   * @param  {Number|String} chatId  Unique identifier for the target group or username of the target supergroup
+   * @return {Promise}
+   * @see https://core.telegram.org/bots/api#getchatadministrators
+   */
+  getChatAdministrators(chatId) {
+    const form = {
+      chat_id: chatId
+    };
+    return this._request('getChatAdministrators', { form });
+  }
+
+  /**
+   * Returns the number of members in a chat in form of an `Int` object.
+   * @param  {Number|String} chatId  Unique identifier for the target group or username of the target supergroup
+   * @return {Promise}
+   * @see https://core.telegram.org/bots/api#getchatmemberscount
+   */
+  getChatMembersCount(chatId) {
+    const form = {
+      chat_id: chatId
+    };
+    return this._request('getChatMembersCount', { form });
+  }
+
+  /**
+   * Returns information about a member of a chat in form of a `ChatMember` object.
+   * @param  {Number|String} chatId  Unique identifier for the target group or username of the target supergroup
+   * @param  {String} userId  Unique identifier of the target user
+   * @return {Promise}
+   * @see https://core.telegram.org/bots/api#getchatmember
+   */
+  getChatMember(chatId, userId) {
+    const form = {
+      chat_id: chatId,
+      user_id: userId
+    };
+    return this._request('getChatMember', { form });
+  }
 }
 
 module.exports = TelegramBot;