Add get_common_chats method (#303)

* Add get_common_chats method

* Return properly formatted list

* Fix small format and docstring issues

pyrogram/client/methods/users/__init__.py

@@ -18,6 +18,7 @@
 
 from .block_user import BlockUser
 from .delete_profile_photos import DeleteProfilePhotos
+from .get_common_chats import GetCommonChats
 from .get_me import GetMe
 from .get_profile_photos import GetProfilePhotos
 from .get_profile_photos_count import GetProfilePhotosCount
@@ -30,6 +31,7 @@ from .update_username import UpdateUsername
 
 class Users(
     BlockUser,
+    GetCommonChats,
     GetProfilePhotos,
     SetProfilePhoto,
     DeleteProfilePhotos,

pyrogram/client/methods/users/get_common_chats.py

@@ -0,0 +1,62 @@
+# Pyrogram - Telegram MTProto API Client Library for Python
+# Copyright (C) 2017-2019 Dan Tès <https://github.com/delivrance>
+#
+# This file is part of Pyrogram.
+#
+# Pyrogram is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Pyrogram is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
+
+from typing import Union
+
+import pyrogram
+from pyrogram.api import functions, types
+from ...ext import BaseClient
+
+
+class GetCommonChats(BaseClient):
+    def get_common_chats(self, user_id: Union[int, str]) -> list:
+        """Get the common chats you have with a user.
+
+        Parameters:
+            user_id (``int`` | ``str``):
+                Unique identifier (int) or username (str) of the target chat.
+                For your personal cloud (Saved Messages) you can simply use "me" or "self".
+                For a contact that exists in your Telegram address book you can use his phone number (str).
+
+        Returns:
+            List of :obj:`Chat`: On success, a list of the common chats is returned.
+            
+        Raises:
+            ValueError: If the user_id doesn't belong to a user.
+
+        Example:
+            .. code-block:: python
+
+                common = app.get_common_chats("haskell")
+                print(common)
+        """
+
+        peer = self.resolve_peer(user_id)
+
+        if isinstance(peer, types.InputPeerUser):
+            r = self.send(
+                functions.messages.GetCommonChats(
+                    user_id=peer,
+                    max_id=0,
+                    limit=100,
+                )
+            )
+
+            return pyrogram.List([pyrogram.Chat._parse_chat(self, x) for x in r.chats])
+        
+        raise ValueError('The user_id "{}" doesn\'t belong to a user'.format(user_id))