From ea57db7aad19bf90d57b8949fea69c5e66e57fa1 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Thu, 28 Jan 2021 21:05:00 +0100
Subject: [PATCH] Add comment_to parameter to more easily post comments

---
 telethon/client/messages.py   | 27 ++++++++++++++++++++++++++-
 telethon/client/uploads.py    | 18 +++++++++++++++---
 telethon/tl/custom/message.py |  6 ++++++
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/telethon/client/messages.py b/telethon/client/messages.py
index 057b9069..ba3b8532 100644
--- a/telethon/client/messages.py
+++ b/telethon/client/messages.py
@@ -577,6 +577,19 @@ class MessageMethods:
 
     # region Message sending/editing/deleting
 
+    async def _get_comment_data(
+            self: 'TelegramClient',
+            entity: 'hints.EntityLike',
+            message: 'typing.Union[int, types.Message]'
+    ):
+        r = await self(functions.messages.GetDiscussionMessageRequest(
+            peer=entity,
+            msg_id=utils.get_message_id(message)
+        ))
+        m = r.messages[0]
+        chat = next(c for c in r.chats if c.id == m.peer_id.channel_id)
+        return utils.get_input_peer(chat), m.id
+
     async def send_message(
             self: 'TelegramClient',
             entity: 'hints.EntityLike',
@@ -591,7 +604,8 @@ class MessageMethods:
             clear_draft: bool = False,
             buttons: 'hints.MarkupLike' = None,
             silent: bool = None,
-            schedule: 'hints.DateLike' = None
+            schedule: 'hints.DateLike' = None,
+            comment_to: 'typing.Union[int, types.Message]' = None
     ) -> 'types.Message':
         """
         Sends a message to the specified user, chat or channel.
@@ -672,6 +686,14 @@ class MessageMethods:
                 it will be scheduled to be automatically sent at a later
                 time.
 
+            comment_to (`int` | `Message <telethon.tl.custom.message.Message>`, optional):
+                Similar to ``reply_to``, but replies in the linked group of a
+                broadcast channel instead (effectively leaving a "comment to"
+                the specified message).
+
+                This parameter takes precedence over ``reply_to``. If there is
+                no linked chat, `telethon.errors.sgIdInvalidError` is raised.
+
         Returns
             The sent `custom.Message <telethon.tl.custom.message.Message>`.
 
@@ -740,6 +762,9 @@ class MessageMethods:
             )
 
         entity = await self.get_input_entity(entity)
+        if comment_to is not None:
+            entity, reply_to = await self._get_comment_data(entity, comment_to)
+
         if isinstance(message, types.Message):
             if buttons is None:
                 markup = message.reply_markup
diff --git a/telethon/client/uploads.py b/telethon/client/uploads.py
index 7f75842a..191f7727 100644
--- a/telethon/client/uploads.py
+++ b/telethon/client/uploads.py
@@ -114,6 +114,7 @@ class UploadMethods:
             silent: bool = None,
             supports_streaming: bool = False,
             schedule: 'hints.DateLike' = None,
+            comment_to: 'typing.Union[int, types.Message]' = None,
             **kwargs) -> 'types.Message':
         """
         Sends message with the given file to the specified entity.
@@ -260,6 +261,14 @@ class UploadMethods:
                 it will be scheduled to be automatically sent at a later
                 time.
 
+            comment_to (`int` | `Message <telethon.tl.custom.message.Message>`, optional):
+                Similar to ``reply_to``, but replies in the linked group of a
+                broadcast channel instead (effectively leaving a "comment to"
+                the specified message).
+
+                This parameter takes precedence over ``reply_to``. If there is
+                no linked chat, `telethon.errors.sgIdInvalidError` is raised.
+
         Returns
             The `Message <telethon.tl.custom.message.Message>` (or messages)
             containing the sent file, or messages if a list of them was passed.
@@ -317,6 +326,12 @@ class UploadMethods:
         if not caption:
             caption = ''
 
+        entity = await self.get_input_entity(entity)
+        if comment_to is not None:
+            entity, reply_to = await self._get_comment_data(entity, comment_to)
+        else:
+            reply_to = utils.get_message_id(reply_to
+
         # First check if the user passed an iterable, in which case
         # we may want to send grouped.
         if utils.is_list_like(file):
@@ -351,9 +366,6 @@ class UploadMethods:
 
             return result
 
-        entity = await self.get_input_entity(entity)
-        reply_to = utils.get_message_id(reply_to)
-
         if formatting_entities is not None:
             msg_entities = formatting_entities
         else:
diff --git a/telethon/tl/custom/message.py b/telethon/tl/custom/message.py
index 24b04326..c6e20b76 100644
--- a/telethon/tl/custom/message.py
+++ b/telethon/tl/custom/message.py
@@ -235,6 +235,7 @@ class _Message(ChatGetter, SenderGetter):
         self._via_bot = None
         self._via_input_bot = None
         self._action_entities = None
+        self._linked_chat = None
 
         sender_id = None
         if from_id is not None:
@@ -295,6 +296,11 @@ class _Message(ChatGetter, SenderGetter):
                 self._action_entities = [entities.get(utils.get_peer_id(
                     types.PeerChat(self.action.chat_id)))]
 
+        if self.replies and self.replies.channel_id:
+            self._linked_chat = entities.get(utils.get_peer_id(
+                    types.PeerChannel(self.replies.channel_id)))
+
+
     # endregion Initialization
 
     # region Public Properties