Implement `TextChannel.follow()`

discord/channel.py

@@ -33,7 +33,7 @@ from .enums import ChannelType, try_enum
 from .mixins import Hashable
 from . import utils
 from .asset import Asset
-from .errors import ClientException, NoMoreItems
+from .errors import ClientException, NoMoreItems, InvalidArgument
 from .webhook import Webhook
 
 __all__ = (
@@ -455,6 +455,46 @@ class TextChannel(discord.abc.Messageable, discord.abc.GuildChannel, Hashable):
         data = await self._state.http.create_webhook(self.id, name=str(name), avatar=avatar, reason=reason)
         return Webhook.from_state(data, state=self._state)
 
+    async def follow(self, *, destination):
+        """
+        Follows a channel using a webhook.
+
+        Only news channels can be followed.
+
+        .. note::
+
+            The webhook returned will not provide a token to do webhook
+            actions, as Discord does not provide it.
+
+        .. versionadded:: 1.3.0
+
+        Parameters
+        -----------
+        destination: :class:`TextChannel`
+            The channel you would like to follow from.
+
+        Raises
+        -------
+        HTTPException
+            Following the channel failed.
+        Forbidden
+            You do not have the permissions to create a webhook.
+
+        Returns
+        --------
+        :class:`Webhook`
+            The created webhook.
+        """
+
+        if not self.is_news():
+            raise ClientException('The channel must be a news channel.')
+
+        if not isinstance(destination, TextChannel):
+            raise InvalidArgument('Expected TextChannel received {0.__name__}'.format(type(destination)))
+
+        data = await self._state.http.follow_webhook(self.id, webhook_channel_id=destination.id)
+        return Webhook._as_follower(data, channel=destination, user=self._state.user)
+
 class VoiceChannel(discord.abc.Connectable, discord.abc.GuildChannel, Hashable):
     """Represents a Discord guild voice channel.
 

discord/http.py

@@ -564,6 +564,12 @@ class HTTPClient:
     def get_webhook(self, webhook_id):
         return self.request(Route('GET', '/webhooks/{webhook_id}', webhook_id=webhook_id))
 
+    def follow_webhook(self, channel_id, webhook_channel_id):
+        payload = {
+            'webhook_channel_id': str(webhook_channel_id)
+        }
+        return self.request(Route('POST', '/channels/{channel_id}/followers', channel_id=channel_id), json=payload)
+
     # Guild management
 
     def get_guilds(self, limit, before=None, after=None):

discord/webhook.py

@@ -499,6 +499,25 @@ class Webhook:
             raise InvalidArgument('Invalid webhook URL given.')
         return cls(m.groupdict(), adapter=adapter)
 
+    @classmethod
+    def _as_follower(cls, data, *, channel, user):
+        name = "{} #{}".format(channel.guild, channel)
+        feed = {
+            'id': data['webhook_id'],
+            'name': name,
+            'channel_id': channel.id,
+            'guild_id': channel.guild.id,
+            'user': {
+                'username': user.name,
+                'discriminator': user.discriminator,
+                'id': user.id,
+                'avatar': user.avatar
+            }
+        }
+
+        session = channel._state.http._HTTPClient__session
+        return cls(feed, adapter=AsyncWebhookAdapter(session=session))
+
     @classmethod
     def from_state(cls, data, state):
         session = state.http._HTTPClient__session