Rewrite webhooks to play better with typings and rate limits

This unfortunately required splitting the types into two. This led to
a lot of unfortunate code duplication that I didn't really enjoy
writing.

The new design allows users to pass an authentication token to make
webhook requests without the webhook token and allows to finally
edit the webhook channel.

The new design also uses a contextvar to store rate limiting
information so multiple instances or recreating instances no longer
clears the ratelimiting state since it's now essentially a "global"
object.

Closes #6525, closes #6662, closes #2509, closes #1761

1 files changed, 1388 insertions, 0 deletions

diff --git a/discord/webhook/async_.py b/discord/webhook/async_.py
new file mode 100644
index 00000000..6a68aede
--- /dev/null
+++ b/discord/webhook/async_.py
@@ -0,0 +1,1388 @@
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-present Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+from __future__ import annotations
+
+import contextvars
+import logging
+import asyncio
+import json
+import time
+import re
+
+from urllib.parse import quote as urlquote
+from typing import Any, Dict, List, Literal, NamedTuple, Optional, TYPE_CHECKING, Tuple, Union, overload
+
+import aiohttp
+
+from .. import utils
+from ..errors import InvalidArgument, HTTPException, Forbidden, NotFound, DiscordServerError
+from ..message import Message
+from ..enums import try_enum, WebhookType
+from ..user import BaseUser, User
+from ..asset import Asset
+from ..http import Route
+from ..mixins import Hashable
+from ..object import Object
+
+__all__ = (
+    'Webhook',
+    'WebhookMessage',
+    'PartialWebhookChannel',
+    'PartialWebhookGuild',
+)
+
+log = logging.getLogger(__name__)
+
+if TYPE_CHECKING:
+    from ..file import File
+    from ..embeds import Embed
+    from ..mentions import AllowedMentions
+    from ..types.webhook import (
+        Webhook as WebhookPayload,
+    )
+    from ..guild import Guild
+    from ..channel import TextChannel
+    from ..abc import Snowflake
+    import datetime
+
+
+class _Missing:
+    def __bool__(self):
+        return False
+
+    def __repr__(self):
+        return '...'
+
+
+MISSING: Any = _Missing()
+
+
+class AsyncDeferredLock:
+    def __init__(self, lock: asyncio.Lock):
+        self.lock = lock
+        self.delta: Optional[float] = None
+
+    async def __aenter__(self):
+        await self.lock.acquire()
+        return self
+
+    def delay_by(self, delta: float) -> None:
+        self.delta = delta
+
+    async def __aexit__(self, type, value, traceback):
+        if self.delta:
+            await asyncio.sleep(self.delta)
+        self.lock.release()
+
+
+class AsyncWebhookAdapter:
+    def __init__(self):
+        self._locks: Dict[Any, asyncio.Lock] = {}
+
+    async def request(
+        self,
+        route: Route,
+        session: aiohttp.ClientSession,
+        *,
+        payload: Optional[Dict[str, Any]] = None,
+        multipart: Optional[List[Dict[str, Any]]] = None,
+        files: Optional[List[File]] = None,
+        reason: Optional[str] = None,
+        auth_token: Optional[str] = None,
+        params: Optional[Dict[str, Any]] = None,
+    ) -> Any:
+        headers: Dict[str, str] = {}
+        files = files or []
+        to_send: Optional[Union[str, aiohttp.FormData]] = None
+        bucket = (route.webhook_id, route.webhook_token)
+
+        try:
+            lock = self._locks[bucket]
+        except KeyError:
+            self._locks[bucket] = lock = asyncio.Lock()
+
+        if payload is not None:
+            headers['Content-Type'] = 'application/json'
+            to_send = utils.to_json(payload)
+
+        if auth_token is not None:
+            headers['Authorization'] = f'Bot {auth_token}'
+
+        if reason is not None:
+            headers['X-Audit-Log-Reason'] = urlquote(reason, safe='/ ')
+
+        response: Optional[aiohttp.ClientResponse] = None
+        data: Optional[Union[Dict[str, Any], str]] = None
+        method = route.method
+        url = route.url
+        webhook_id = route.webhook_id
+
+        async with AsyncDeferredLock(lock) as lock:
+            for attempt in range(5):
+                for file in files:
+                    file.reset(seek=attempt)
+
+                if multipart:
+                    form_data = aiohttp.FormData()
+                    for p in multipart:
+                        form_data.add_field(**p)
+                    to_send = form_data
+
+                try:
+                    async with session.request(method, url, data=to_send, headers=headers, params=params) as response:
+                        log.debug(
+                            'Webhook ID %s with %s %s has returned status code %s',
+                            webhook_id,
+                            method,
+                            url,
+                            response.status,
+                        )
+                        data = (await response.text(encoding='utf-8')) or None
+                        if data and response.headers['Content-Type'] == 'application/json':
+                            data = json.loads(data)
+
+                        remaining = response.headers.get('X-Ratelimit-Remaining')
+                        if remaining == '0' and response.status != 429:
+                            delta = utils._parse_ratelimit_header(response.headers)
+                            log.debug(
+                                'Webhook ID %s has been pre-emptively rate limited, waiting %.2f seconds', webhook_id, delta
+                            )
+                            lock.delay_by(delta)
+
+                        if 300 > response.status >= 200:
+                            return data
+
+                        if response.status == 429:
+                            if not response.headers.get('Via'):
+                                raise HTTPException(response, data)
+
+                            retry_after = data['retry_after'] / 1000.0  # type: ignore
+                            log.warning('Webhook ID %s is rate limited. Retrying in %.2f seconds', webhook_id, retry_after)
+                            await asyncio.sleep(retry_after)
+
+                        if response.status >= 500:
+                            await asyncio.sleep(1 + attempt * 2)
+                            continue
+
+                        if response.status == 403:
+                            raise Forbidden(response, data)
+                        elif response.status == 404:
+                            raise NotFound(response, data)
+                        else:
+                            raise HTTPException(response, data)
+
+                except OSError as e:
+                    if attempt < 4 and e.errno in (54, 10054):
+                        continue
+                    raise
+
+            if response:
+                if response.status >= 500:
+                    raise DiscordServerError(response, data)
+                raise HTTPException(response, data)
+
+            raise RuntimeError('Unreachable code in HTTP handling.')
+
+    def delete_webhook(
+        self,
+        webhook_id: int,
+        *,
+        token: Optional[str] = None,
+        session: aiohttp.ClientSession,
+        reason: Optional[str] = None,
+    ):
+        route = Route('DELETE', '/webhooks/{webhook_id}', webhook_id=webhook_id)
+        return self.request(route, session, reason=reason, auth_token=token)
+
+    def delete_webhook_with_token(
+        self,
+        webhook_id: int,
+        token: str,
+        *,
+        session: aiohttp.ClientSession,
+        reason: Optional[str] = None,
+    ):
+        route = Route('DELETE', '/webhooks/{webhook_id}/{webhook_token}', webhook_id=webhook_id, webhook_token=token)
+        return self.request(route, session, reason=reason)
+
+    def edit_webhook(
+        self,
+        webhook_id: int,
+        token: str,
+        payload: Dict[str, Any],
+        *,
+        session: aiohttp.ClientSession,
+        reason: Optional[str] = None,
+    ):
+        route = Route('PATCH', '/webhooks/{webhook_id}', webhook_id=webhook_id)
+        return self.request(route, session, reason=reason, payload=payload, auth_token=token)
+
+    def edit_webhook_with_token(
+        self,
+        webhook_id: int,
+        token: str,
+        payload: Dict[str, Any],
+        *,
+        session: aiohttp.ClientSession,
+        reason: Optional[str] = None,
+    ):
+        route = Route('PATCH', '/webhooks/{webhook_id}/{webhook_token}', webhook_id=webhook_id, webhook_token=token)
+        return self.request(route, session, reason=reason, payload=payload)
+
+    def execute_webhook(
+        self,
+        webhook_id: int,
+        token: str,
+        *,
+        session: aiohttp.ClientSession,
+        payload: Optional[Dict[str, Any]] = None,
+        multipart: Optional[List[Dict[str, Any]]] = None,
+        files: Optional[List[File]] = None,
+        wait: bool = False,
+    ):
+        params = {'wait': int(wait)}
+        route = Route('POST', '/webhooks/{webhook_id}/{webhook_token}', webhook_id=webhook_id, webhook_token=token)
+        return self.request(route, session, payload=payload, multipart=multipart, files=files, params=params)
+
+    def edit_webhook_message(
+        self,
+        webhook_id: int,
+        token: str,
+        message_id: int,
+        *,
+        session: aiohttp.ClientSession,
+        payload: Optional[Dict[str, Any]] = None,
+        multipart: Optional[List[Dict[str, Any]]] = None,
+        files: Optional[List[File]] = None,
+    ):
+        route = Route(
+            'PATCH',
+            '/webhooks/{webhook_id}/{webhook_token}/messages/{message_id}',
+            webhook_id=webhook_id,
+            webhook_token=token,
+            message_id=message_id,
+        )
+        return self.request(route, session, payload=payload, multipart=multipart, files=files)
+
+    def delete_webhook_message(
+        self,
+        webhook_id: int,
+        token: str,
+        message_id: int,
+        *,
+        session: aiohttp.ClientSession,
+    ):
+        route = Route(
+            'DELETE',
+            '/webhooks/{webhook_id}/{webhook_token}/messages/{message_id}',
+            webhook_id=webhook_id,
+            webhook_token=token,
+            message_id=message_id,
+        )
+        return self.request(route, session)
+
+    def fetch_webhook(
+        self,
+        webhook_id: int,
+        token: str,
+        *,
+        session: aiohttp.ClientSession,
+    ):
+        route = Route('GET', '/webhooks/{webhook_id}', webhook_id=webhook_id)
+        return self.request(route, session=session, auth_token=token)
+
+    def fetch_webhook_with_token(
+        self,
+        webhook_id: int,
+        token: str,
+        *,
+        session: aiohttp.ClientSession,
+    ):
+        route = Route('GET', '/webhooks/{webhook_id}/{webhook_token}', webhook_id=webhook_id, webhook_token=token)
+        return self.request(route, session=session)
+
+
+class ExecuteWebhookParameters(NamedTuple):
+    payload: Optional[Dict[str, Any]]
+    multipart: Optional[List[Dict[str, Any]]]
+    files: Optional[List[File]]
+
+
+def handle_message_parameters(
+    content: Optional[str] = MISSING,
+    *,
+    username: str = MISSING,
+    avatar_url: str = MISSING,
+    tts: bool = False,
+    file: File = MISSING,
+    files: List[File] = MISSING,
+    embed: Optional[Embed] = MISSING,
+    embeds: List[Embed] = MISSING,
+    allowed_mentions: Optional[AllowedMentions] = MISSING,
+    previous_allowed_mentions: Optional[AllowedMentions] = None,
+) -> ExecuteWebhookParameters:
+    if files is not MISSING and file is not MISSING:
+        raise TypeError('Cannot mix file and files keyword arguments.')
+    if embeds is not MISSING and embed is not MISSING:
+        raise TypeError('Cannot mix embed and embeds keyword arguments.')
+
+    payload = {}
+    if embeds is not MISSING:
+        if len(embeds) > 10:
+            raise InvalidArgument('embeds has a maximum of 10 elements.')
+        payload['embeds'] = [e.to_dict() for e in embeds]
+
+    if embed is not MISSING:
+        if embed is None:
+            payload['embeds'] = []
+        else:
+            payload['embeds'] = [embed.to_dict()]
+
+    if content is not MISSING:
+        if content is not None:
+            payload['content'] = str(content)
+        else:
+            payload['content'] = None
+
+    payload['tts'] = tts
+    if avatar_url:
+        payload['avatar_url'] = str(avatar_url)
+    if username:
+        payload['username'] = username
+
+    if allowed_mentions:
+        if previous_allowed_mentions is not None:
+            payload['allowed_mentions'] = previous_allowed_mentions.merge(allowed_mentions).to_dict()
+        else:
+            payload['allowed_mentions'] = allowed_mentions.to_dict()
+    elif previous_allowed_mentions is not None:
+        payload['allowed_mentions'] = previous_allowed_mentions.to_dict()
+
+    multipart = []
+    if file is not MISSING:
+        files = [file]
+
+    if files:
+        multipart.append({'name': 'payload_json', 'value': utils.to_json(payload)})
+        payload = None
+        if len(files) == 1:
+            file = files[0]
+            multipart.append(
+                {
+                    'name': 'file',
+                    'value': file.fp,
+                    'filename': file.filename,
+                    'content_type': 'application/octet-stream',
+                }
+            )
+        else:
+            for index, file in enumerate(files):
+                multipart.append(
+                    {
+                        'name': f'file{index}',
+                        'value': file.fp,
+                        'filename': file.filename,
+                        'content_type': 'application/octet-stream',
+                    }
+                )
+
+    return ExecuteWebhookParameters(payload=payload, multipart=multipart, files=files)
+
+
+async_context = contextvars.ContextVar('async_webhook_context', default=AsyncWebhookAdapter())
+
+
+class PartialWebhookChannel(Hashable):
+    """Represents a partial channel for webhooks.
+
+    These are typically given for channel follower webhooks.
+
+    .. versionadded:: 2.0
+
+    Attributes
+    -----------
+    id: :class:`int`
+        The partial channel's ID.
+    name: :class:`str`
+        The partial channel's name.
+    """
+
+    __slots__ = ('id', 'name')
+
+    def __init__(self, *, data):
+        self.id = int(data['id'])
+        self.name = data['name']
+
+    def __repr__(self):
+        return f'<PartialWebhookChannel name={self.name!r} id={self.id}>'
+
+
+class PartialWebhookGuild(Hashable):
+    """Represents a partial guild for webhooks.
+
+    These are typically given for channel follower webhooks.
+
+    .. versionadded:: 2.0
+
+    Attributes
+    -----------
+    id: :class:`int`
+        The partial guild's ID.
+    name: :class:`str`
+        The partial guild's name.
+    icon: :class:`str`
+        The partial guild's icon
+    """
+
+    __slots__ = ('id', 'name', 'icon', '_state')
+
+    def __init__(self, *, data, state):
+        self._state = state
+        self.id = int(data['id'])
+        self.name = data['name']
+        self.icon = data['icon']
+
+    def __repr__(self):
+        return f'<PartialWebhookGuild name={self.name!r} id={self.id}>'
+
+    @property
+    def icon_url(self) -> Asset:
+        """:class:`Asset`: Returns the guild's icon asset."""
+        return self.icon_url_as()
+
+    def is_icon_animated(self) -> bool:
+        """:class:`bool`: Returns True if the guild has an animated icon."""
+        return bool(self.icon and self.icon.startswith('a_'))
+
+    def icon_url_as(self, *, format=None, static_format='webp', size=1024):
+        """Returns an :class:`Asset` for the guild's icon.
+
+        The format must be one of 'webp', 'jpeg', 'jpg', 'png' or 'gif', and
+        'gif' is only valid for animated avatars. The size must be a power of 2
+        between 16 and 4096.
+
+        Parameters
+        -----------
+        format: Optional[:class:`str`]
+            The format to attempt to convert the icon to.
+            If the format is ``None``, then it is automatically
+            detected into either 'gif' or static_format depending on the
+            icon being animated or not.
+        static_format: Optional[:class:`str`]
+            Format to attempt to convert only non-animated icons to.
+        size: :class:`int`
+            The size of the image to display.
+
+        Raises
+        ------
+        InvalidArgument
+            Bad image format passed to ``format`` or invalid ``size``.
+
+        Returns
+        --------
+        :class:`Asset`
+            The resulting CDN asset.
+        """
+        return Asset._from_guild_icon(self._state, self, format=format, static_format=static_format, size=size)
+
+
+class _FriendlyHttpAttributeErrorHelper:
+    __slots__ = ()
+
+    def __getattr__(self, attr):
+        raise AttributeError('PartialWebhookState does not support http methods.')
+
+
+class _WebhookState:
+    __slots__ = ('_parent', '_webhook')
+
+    def __init__(self, webhook, parent):
+        self._webhook = webhook
+
+        if isinstance(parent, self.__class__):
+            self._parent = None
+        else:
+            self._parent = parent
+
+    def _get_guild(self, guild_id):
+        if self._parent is not None:
+            return self._parent._get_guild(guild_id)
+        return None
+
+    def store_user(self, data):
+        if self._parent is not None:
+            return self._parent.store_user(data)
+        return BaseUser(state=self, data=data)
+
+    @property
+    def http(self):
+        if self._parent is not None:
+            return self._parent.http
+
+        # Some data classes assign state.http and that should be kosher
+        # however, using it should result in a late-binding error.
+        return _FriendlyHttpAttributeErrorHelper()
+
+    def __getattr__(self, attr):
+        if self._parent is not None:
+            return getattr(self._parent, attr)
+
+        raise AttributeError(f'PartialWebhookState does not support {attr!r}.')
+
+
+class WebhookMessage(Message):
+    """Represents a message sent from your webhook.
+
+    This allows you to edit or delete a message sent by your
+    webhook.
+
+    This inherits from :class:`discord.Message` with changes to
+    :meth:`edit` and :meth:`delete` to work.
+
+    .. versionadded:: 1.6
+    """
+
+    async def edit(
+        self,
+        content: Optional[str] = MISSING,
+        embeds: List[Embed] = MISSING,
+        embed: Optional[Embed] = MISSING,
+        file: File = MISSING,
+        files: List[File] = MISSING,
+        allowed_mentions: Optional[AllowedMentions] = None,
+    ):
+        """|coro|
+
+        Edits a message owned by this webhook.
+
+        This is a lower level interface to :meth:`WebhookMessage.edit` in case
+        you only have an ID.
+
+        .. versionadded:: 1.6
+
+        Parameters
+        ------------
+        message_id: :class:`int`
+            The message ID to edit.
+        content: Optional[:class:`str`]
+            The content to edit the message with or ``None`` to clear it.
+        embeds: List[:class:`Embed`]
+            A list of embeds to edit the message with.
+        embed: Optional[:class:`Embed`]
+            The embed to edit the message with. ``None`` suppresses the embeds.
+            This should not be mixed with the ``embeds`` parameter.
+        file: :class:`File`
+            The file to upload. This cannot be mixed with ``files`` parameter.
+        files: List[:class:`File`]
+            A list of files to send with the content. This cannot be mixed with the
+            ``file`` parameter.
+        allowed_mentions: :class:`AllowedMentions`
+            Controls the mentions being processed in this message.
+            See :meth:`.abc.Messageable.send` for more information.
+
+        Raises
+        -------
+        HTTPException
+            Editing the message failed.
+        Forbidden
+            Edited a message that is not yours.
+        TypeError
+            You specified both ``embed`` and ``embeds`` or ``file`` and ``files``
+        ValueError
+            The length of ``embeds`` was invalid
+        InvalidArgument
+            There was no token associated with this webhook.
+        """
+        await self._state._webhook.edit_message(
+            self.id,
+            content=content,
+            embeds=embeds,
+            embed=embed,
+            file=file,
+            files=files,
+            allowed_mentions=allowed_mentions,
+        )
+
+    async def delete(self, *, delay: Optional[float] = None) -> None:
+        """|coro|
+
+        Deletes the message.
+
+        Parameters
+        -----------
+        delay: Optional[:class:`float`]
+            If provided, the number of seconds to wait before deleting the message.
+            The waiting is done in the background and deletion failures are ignored.
+
+        Raises
+        ------
+        Forbidden
+            You do not have proper permissions to delete the message.
+        NotFound
+            The message was deleted already.
+        HTTPException
+            Deleting the message failed.
+        """
+
+        if delay is not None:
+
+            async def inner_call(delay: float = delay):
+                await asyncio.sleep(delay)
+                try:
+                    await self._state._webhook.delete_message(self.id)
+                except HTTPException:
+                    pass
+
+            asyncio.create_task(inner_call())
+        else:
+            await self._state._webhook.delete_message(self.id)
+
+
+class BaseWebhook(Hashable):
+    __slots__: Tuple[str, ...] = (
+        'id',
+        'type',
+        'guild_id',
+        'channel_id',
+        'token',
+        'auth_token',
+        'user',
+        'name',
+        'avatar',
+        'source_channel',
+        'source_guild',
+        '_state',
+    )
+
+    def __init__(self, data: WebhookPayload, token: Optional[str] = None, state=None):
+        self.auth_token: Optional[str] = token
+        self._state = state or _WebhookState(self, parent=state)
+        self._update(data)
+
+    def _update(self, data: WebhookPayload):
+        self.id = int(data['id'])
+        self.type = try_enum(WebhookType, int(data['type']))
+        self.channel_id = utils._get_as_snowflake(data, 'channel_id')
+        self.guild_id = utils._get_as_snowflake(data, 'guild_id')
+        self.name = data.get('name')
+        self.avatar = data.get('avatar')
+        self.token = data.get('token')
+
+        user = data.get('user')
+        self.user: Optional[Union[BaseUser, User]] = None
+        if user is not None:
+            if self._state is None:
+                self.user = BaseUser(state=None, data=user)
+            else:
+                self.user = User(state=self._state, data=user)
+
+        source_channel = data.get('source_channel')
+        if source_channel:
+            source_channel = PartialWebhookChannel(data=source_channel)
+
+        self.source_channel: Optional[PartialWebhookChannel] = source_channel
+
+        source_guild = data.get('source_guild')
+        if source_guild:
+            source_guild = PartialWebhookGuild(data=source_guild, state=self._state)
+
+        self.source_guild: Optional[PartialWebhookGuild] = source_guild
+
+    def is_partial(self) -> bool:
+        """:class:`bool`: Whether the webhook is a "partial" webhook."""
+        return self.channel_id is None
+
+    def is_authenticated(self) -> bool:
+        """:class:`bool`: Whether the webhook is authenticated with a bot token."""
+        return self.auth_token is not None
+
+    @property
+    def guild(self) -> Optional[Guild]:
+        """Optional[:class:`Guild`]: The guild this webhook belongs to.
+
+        If this is a partial webhook, then this will always return ``None``.
+        """
+        return self._state and self._state._get_guild(self.guild_id)
+
+    @property
+    def channel(self) -> Optional[TextChannel]:
+        """Optional[:class:`TextChannel`]: The text channel this webhook belongs to.
+
+        If this is a partial webhook, then this will always return ``None``.
+        """
+        guild = self.guild
+        return guild and guild.get_channel(self.channel_id)
+
+    @property
+    def created_at(self) -> datetime.datetime:
+        """:class:`datetime.datetime`: Returns the webhook's creation time in UTC."""
+        return utils.snowflake_time(self.id)
+
+    @property
+    def avatar_url(self) -> Asset:
+        """:class:`Asset`: Returns an :class:`Asset` for the avatar the webhook has.
+
+        If the webhook does not have a traditional avatar, an asset for
+        the default avatar is returned instead.
+
+        This is equivalent to calling :meth:`avatar_url_as` with the
+        default parameters.
+        """
+        return self.avatar_url_as()
+
+    def avatar_url_as(self, *, format: Optional[Literal['png', 'jpg', 'jpeg']] = None, size: int = 1024) -> Asset:
+        """Returns an :class:`Asset` for the avatar the webhook has.
+
+        If the webhook does not have a traditional avatar, an asset for
+        the default avatar is returned instead.
+
+        The format must be one of 'jpeg', 'jpg', or 'png'.
+        The size must be a power of 2 between 16 and 1024.
+
+        Parameters
+        -----------
+        format: Optional[:class:`str`]
+            The format to attempt to convert the avatar to.
+            If the format is ``None``, then it is equivalent to png.
+        size: :class:`int`
+            The size of the image to display.
+
+        Raises
+        ------
+        InvalidArgument
+            Bad image format passed to ``format`` or invalid ``size``.
+
+        Returns
+        --------
+        :class:`Asset`
+            The resulting CDN asset.
+        """
+        if self.avatar is None:
+            # Default is always blurple apparently
+            return Asset(self._state, '/embed/avatars/0.png')
+
+        if not utils.valid_icon_size(size):
+            raise InvalidArgument("size must be a power of 2 between 16 and 1024")
+
+        format = format or 'png'
+
+        if format not in ('png', 'jpg', 'jpeg'):
+            raise InvalidArgument("format must be one of 'png', 'jpg', or 'jpeg'.")
+
+        url = f'/avatars/{self.id}/{self.avatar}.{format}?size={size}'
+        return Asset(self._state, url)
+
+
+class Webhook(BaseWebhook):
+    """Represents an asynchronous Discord webhook.
+
+    Webhooks are a form to send messages to channels in Discord without a
+    bot user or authentication.
+
+    There are two main ways to use Webhooks. The first is through the ones
+    received by the library such as :meth:`.Guild.webhooks` and
+    :meth:`.TextChannel.webhooks`. The ones received by the library will
+    automatically be bound using the library's internal HTTP session.
+
+    The second form involves creating a webhook object manually using the
+    :meth:`~.Webhook.from_url` or :meth:`~.Webhook.partial` classmethods.
+
+    For example, creating a webhook from a URL and using :doc:`aiohttp <aio:index>`:
+
+    .. code-block:: python3
+
+        from discord import Webhook, AsyncWebhookAdapter
+        import aiohttp
+
+        async def foo():
+            async with aiohttp.ClientSession() as session:
+                webhook = Webhook.from_url('url-here', session=session)
+                await webhook.send('Hello World', username='Foo')
+
+    For a synchronous counterpart, see :class:`SyncWebhook`.
+
+    .. container:: operations
+
+        .. describe:: x == y
+
+            Checks if two webhooks are equal.
+
+        .. describe:: x != y
+
+            Checks if two webhooks are not equal.
+
+        .. describe:: hash(x)
+
+            Returns the webhooks's hash.
+
+    .. versionchanged:: 1.4
+        Webhooks are now comparable and hashable.
+
+    Attributes
+    ------------
+    id: :class:`int`
+        The webhook's ID
+    type: :class:`WebhookType`
+        The type of the webhook.
+
+        .. versionadded:: 1.3
+
+    token: Optional[:class:`str`]
+        The authentication token of the webhook. If this is ``None``
+        then the webhook cannot be used to make requests.
+    guild_id: Optional[:class:`int`]
+        The guild ID this webhook is for.
+    channel_id: Optional[:class:`int`]
+        The channel ID this webhook is for.
+    user: Optional[:class:`abc.User`]
+        The user this webhook was created by. If the webhook was
+        received without authentication then this will be ``None``.
+    name: Optional[:class:`str`]
+        The default name of the webhook.
+    avatar: Optional[:class:`str`]
+        The default avatar of the webhook.
+    source_guild: Optional[:class:`PartialWebhookGuild`]
+        The guild of the channel that this webhook is following.
+        Only given if :attr:`type` is :attr:`WebhookType.channel_follower`.
+
+        .. versionadded:: 2.0
+
+    source_channel: Optional[:class:`PartialWebhookChannel`]
+        The channel that this webhook is following.
+        Only given if :attr:`type` is :attr:`WebhookType.channel_follower`.
+
+        .. versionadded:: 2.0
+    """
+
+    __slots__: Tuple[str, ...] = BaseWebhook.__slots__ + ('session',)
+
+    def __init__(self, data: WebhookPayload, session: aiohttp.ClientSession, token: Optional[str] = None, state=None):
+        super().__init__(data, token, state)
+        self.session = session
+
+    def __repr__(self):
+        return f'<Webhook id={self.id!r}>'
+
+    @property
+    def url(self):
+        """:class:`str` : Returns the webhook's url."""
+        return f'https://discord.com/api/webhooks/{self.id}/{self.token}'
+
+    @classmethod
+    def partial(cls, id: int, token: str, *, session: aiohttp.ClientSession, bot_token: Optional[str] = None):
+        """Creates a partial :class:`Webhook`.
+
+        Parameters
+        -----------
+        id: :class:`int`
+            The ID of the webhook.
+        token: :class:`str`
+            The authentication token of the webhook.
+        session: :class:`aiohttp.ClientSession`
+            The session to use to send requests with. Note
+            that the library does not manage the session and
+            will not close it.
+        bot_token: Optional[:class:`str`]
+            The bot authentication token for authenticated requests
+            involving the webhook.
+
+        Returns
+        --------
+        :class:`Webhook`
+            A partial :class:`Webhook`.
+            A partial webhook is just a webhook object with an ID and a token.
+        """
+        data: WebhookPayload = {
+            'id': id,
+            'type': 1,
+            'token': token,
+        }
+
+        return cls(data, session, token=bot_token)
+
+    @classmethod
+    def from_url(cls, url: str, *, session: aiohttp.ClientSession, bot_token: Optional[str] = None):
+        """Creates a partial :class:`Webhook` from a webhook URL.
+
+        Parameters
+        ------------
+        url: :class:`str`
+            The URL of the webhook.
+        session: :class:`aiohttp.ClientSession`
+            The session to use to send requests with. Note
+            that the library does not manage the session and
+            will not close it.
+        bot_token: Optional[:class:`str`]
+            The bot authentication token for authenticated requests
+            involving the webhook.
+
+        Raises
+        -------
+        InvalidArgument
+            The URL is invalid.
+
+        Returns
+        --------
+        :class:`Webhook`
+            A partial :class:`Webhook`.
+            A partial webhook is just a webhook object with an ID and a token.
+        """
+        m = re.search(r'discord(?:app)?.com/api/webhooks/(?P<id>[0-9]{17,20})/(?P<token>[A-Za-z0-9\.\-\_]{60,68})', url)
+        if m is None:
+            raise InvalidArgument('Invalid webhook URL given.')
+
+        data: Dict[str, Any] = m.groupdict()
+        data['type'] = 1
+        return cls(data, session, token=bot_token)  # type: ignore
+
+    @classmethod
+    def _as_follower(cls, data, *, channel, user):
+        name = f"{channel.guild} #{channel}"
+        feed: WebhookPayload = {
+            'id': data['webhook_id'],
+            'type': 2,
+            'name': name,
+            'channel_id': channel.id,
+            'guild_id': channel.guild.id,
+            'user': {'username': user.name, 'discriminator': user.discriminator, 'id': user.id, 'avatar': user.avatar},
+        }
+
+        state = channel._state
+        session = channel._state.http._HTTPClient__session
+        return cls(feed, session=session, state=state, token=state.http.token)
+
+    @classmethod
+    def from_state(cls, data, state):
+        session = state.http._HTTPClient__session
+        return cls(data, session=session, state=state, token=state.http.token)
+
+    async def fetch(self, *, prefer_auth: bool = True) -> Webhook:
+        """|coro|
+
+        Fetches the current webhook.
+
+        This could be used to get a full webhook from a partial webhook.
+
+        .. note::
+
+            When fetching with an unauthenticated webhook, i.e.
+            :meth:`is_authenticated` returns ``False``, then the
+            returned webhook does not contain any user information.
+
+        Parameters
+        -----------
+        prefer_auth: :class:`bool`
+            Whether to use the bot token over the webhook token
+            if available. Defaults to ``True``.
+
+        Raises
+        -------
+        HTTPException
+            Could not fetch the webhook
+        NotFound
+            Could not find the webhook by this ID
+        InvalidArgument
+            This webhook does not have a token associated with it.
+
+        Returns
+        --------
+        :class:`Webhook`
+            The fetched webhook.
+        """
+        adapter = async_context.get()
+
+        if prefer_auth and self.auth_token:
+            data = await adapter.fetch_webhook(self.id, self.auth_token, session=self.session)
+        elif self.token:
+            data = await adapter.fetch_webhook_with_token(self.id, self.token, session=self.session)
+        else:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        return Webhook(data, self.session, token=self.auth_token, state=self._state)
+
+    async def delete(self, *, reason: Optional[str] = None, prefer_auth: bool = True):
+        """|coro|
+
+        Deletes this Webhook.
+
+        Parameters
+        ------------
+        reason: Optional[:class:`str`]
+            The reason for deleting this webhook. Shows up on the audit log.
+
+            .. versionadded:: 1.4
+        prefer_auth: :class:`bool`
+            Whether to use the bot token over the webhook token
+            if available. Defaults to ``True``.
+
+        Raises
+        -------
+        HTTPException
+            Deleting the webhook failed.
+        NotFound
+            This webhook does not exist.
+        Forbidden
+            You do not have permissions to delete this webhook.
+        InvalidArgument
+            This webhook does not have a token associated with it.
+        """
+        if self.token is None and self.auth_token is None:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        adapter = async_context.get()
+
+        if prefer_auth and self.auth_token:
+            await adapter.delete_webhook(self.id, token=self.auth_token, session=self.session, reason=reason)
+        elif self.token:
+            await adapter.delete_webhook_with_token(self.id, self.token, session=self.session, reason=reason)
+
+    async def edit(
+        self,
+        *,
+        reason: Optional[str] = None,
+        name: Optional[str] = MISSING,
+        avatar: Optional[bytes] = MISSING,
+        channel: Optional[Snowflake] = None,
+        prefer_auth: bool = True,
+    ):
+        """|coro|
+
+        Edits this Webhook.
+
+        Parameters
+        ------------
+        name: Optional[:class:`str`]
+            The webhook's new default name.
+        avatar: Optional[:class:`bytes`]
+            A :term:`py:bytes-like object` representing the webhook's new default avatar.
+        channel: Optional[:class:`abc.Snowflake`]
+            The webhook's new channel. This requires an authenticated webhook.
+        reason: Optional[:class:`str`]
+            The reason for editing this webhook. Shows up on the audit log.
+
+            .. versionadded:: 1.4
+        prefer_auth: :class:`bool`
+            Whether to use the bot token over the webhook token
+            if available. Defaults to ``True``.
+
+        Raises
+        -------
+        HTTPException
+            Editing the webhook failed.
+        NotFound
+            This webhook does not exist.
+        InvalidArgument
+            This webhook does not have a token associated with it
+            or it tried editing a channel without authentication.
+        """
+        if self.token is None and self.auth_token is None:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        payload = {}
+        if name is not MISSING:
+            payload['name'] = str(name) if name is not None else None
+
+        if avatar is not MISSING:
+            payload['avatar'] = utils._bytes_to_base64_data(avatar) if avatar is not None else None
+
+        adapter = async_context.get()
+
+        # If a channel is given, always use the authenticated endpoint
+        if channel is not None:
+            if self.auth_token is None:
+                raise InvalidArgument('Editing channel requires authenticated webhook')
+
+            payload['channel_id'] = channel.id
+            data = await adapter.edit_webhook(self.id, self.auth_token, payload=payload, session=self.session, reason=reason)
+            self._update(data)
+            return
+
+        if prefer_auth and self.auth_token:
+            data = await adapter.edit_webhook(self.id, self.auth_token, payload=payload, session=self.session, reason=reason)
+            self._update(data)
+        elif self.token:
+            data = await adapter.edit_webhook_with_token(
+                self.id, self.token, payload=payload, session=self.session, reason=reason
+            )
+            self._update(data)
+
+    @overload
+    async def send(
+        self,
+        content: str = MISSING,
+        *,
+        username: str = MISSING,
+        avatar_url: str = MISSING,
+        tts: bool = MISSING,
+        file: File = MISSING,
+        files: List[File] = MISSING,
+        embed: Embed = MISSING,
+        embeds: List[Embed] = MISSING,
+        allowed_mentions: AllowedMentions = MISSING,
+        wait: Literal[True],
+    ) -> WebhookMessage:
+        ...
+
+    @overload
+    async def send(
+        self,
+        content: str = MISSING,
+        *,
+        username: str = MISSING,
+        avatar_url: str = MISSING,
+        tts: bool = MISSING,
+        file: File = MISSING,
+        files: List[File] = MISSING,
+        embed: Embed = MISSING,
+        embeds: List[Embed] = MISSING,
+        allowed_mentions: AllowedMentions = MISSING,
+        wait: Literal[False],
+    ) -> None:
+        ...
+
+    async def send(
+        self,
+        content: str = MISSING,
+        *,
+        username: str = MISSING,
+        avatar_url: str = MISSING,
+        tts: bool = False,
+        file: File = MISSING,
+        files: List[File] = MISSING,
+        embed: Embed = MISSING,
+        embeds: List[Embed] = MISSING,
+        allowed_mentions: AllowedMentions = MISSING,
+        wait: bool = False,
+    ) -> Optional[WebhookMessage]:
+        """|coro|
+
+        Sends a message using the webhook.
+
+        The content must be a type that can convert to a string through ``str(content)``.
+
+        To upload a single file, the ``file`` parameter should be used with a
+        single :class:`File` object.
+
+        If the ``embed`` parameter is provided, it must be of type :class:`Embed` and
+        it must be a rich embed type. You cannot mix the ``embed`` parameter with the
+        ``embeds`` parameter, which must be a :class:`list` of :class:`Embed` objects to send.
+
+        Parameters
+        ------------
+        content: :class:`str`
+            The content of the message to send.
+        wait: :class:`bool`
+            Whether the server should wait before sending a response. This essentially
+            means that the return type of this function changes from ``None`` to
+            a :class:`WebhookMessage` if set to ``True``.
+        username: :class:`str`
+            The username to send with this message. If no username is provided
+            then the default username for the webhook is used.
+        avatar_url: Union[:class:`str`, :class:`Asset`]
+            The avatar URL to send with this message. If no avatar URL is provided
+            then the default avatar for the webhook is used.
+        tts: :class:`bool`
+            Indicates if the message should be sent using text-to-speech.
+        file: :class:`File`
+            The file to upload. This cannot be mixed with ``files`` parameter.
+        files: List[:class:`File`]
+            A list of files to send with the content. This cannot be mixed with the
+            ``file`` parameter.
+        embed: :class:`Embed`
+            The rich embed for the content to send. This cannot be mixed with
+            ``embeds`` parameter.
+        embeds: List[:class:`Embed`]
+            A list of embeds to send with the content. Maximum of 10. This cannot
+            be mixed with the ``embed`` parameter.
+        allowed_mentions: :class:`AllowedMentions`
+            Controls the mentions being processed in this message.
+
+            .. versionadded:: 1.4
+
+        Raises
+        --------
+        HTTPException
+            Sending the message failed.
+        NotFound
+            This webhook was not found.
+        Forbidden
+            The authorization token for the webhook is incorrect.
+        TypeError
+            You specified both ``embed`` and ``embeds`` or ``file`` and ``files``
+        ValueError
+            The length of ``embeds`` was invalid
+        InvalidArgument
+            There was no token associated with this webhook.
+
+        Returns
+        ---------
+        Optional[:class:`WebhookMessage`]
+            The message that was sent.
+        """
+
+        if self.token is None:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        previous_mentions: Optional[AllowedMentions] = getattr(self._state, 'allowed_mentions', None)
+        if content is None:
+            content = ...  # type: ignore
+
+        params = handle_message_parameters(
+            content=content,
+            username=username,
+            avatar_url=avatar_url,
+            tts=tts,
+            file=file,
+            files=files,
+            embed=embed,
+            embeds=embeds,
+            allowed_mentions=allowed_mentions,
+            previous_allowed_mentions=previous_mentions,
+        )
+        adapter = async_context.get()
+        data = await adapter.execute_webhook(
+            self.id,
+            self.token,
+            session=self.session,
+            payload=params.payload,
+            multipart=params.multipart,
+            files=params.files,
+            wait=wait,
+        )
+        if wait:
+            state = _WebhookState(self, parent=self._state)
+            channel = self.channel or Object(id=int(data['channel_id']))
+            return WebhookMessage(data=data, state=state, channel=channel)
+
+    async def edit_message(
+        self,
+        message_id: int,
+        *,
+        content: Optional[str] = MISSING,
+        embeds: List[Embed] = MISSING,
+        embed: Optional[Embed] = MISSING,
+        file: File = MISSING,
+        files: List[File] = MISSING,
+        allowed_mentions: Optional[AllowedMentions] = None,
+    ):
+        """|coro|
+
+        Edits a message owned by this webhook.
+
+        This is a lower level interface to :meth:`WebhookMessage.edit` in case
+        you only have an ID.
+
+        .. versionadded:: 1.6
+
+        Parameters
+        ------------
+        message_id: :class:`int`
+            The message ID to edit.
+        content: Optional[:class:`str`]
+            The content to edit the message with or ``None`` to clear it.
+        embeds: List[:class:`Embed`]
+            A list of embeds to edit the message with.
+        embed: Optional[:class:`Embed`]
+            The embed to edit the message with. ``None`` suppresses the embeds.
+            This should not be mixed with the ``embeds`` parameter.
+        file: :class:`File`
+            The file to upload. This cannot be mixed with ``files`` parameter.
+        files: List[:class:`File`]
+            A list of files to send with the content. This cannot be mixed with the
+            ``file`` parameter.
+        allowed_mentions: :class:`AllowedMentions`
+            Controls the mentions being processed in this message.
+            See :meth:`.abc.Messageable.send` for more information.
+
+        Raises
+        -------
+        HTTPException
+            Editing the message failed.
+        Forbidden
+            Edited a message that is not yours.
+        TypeError
+            You specified both ``embed`` and ``embeds`` or ``file`` and ``files``
+        ValueError
+            The length of ``embeds`` was invalid
+        InvalidArgument
+            There was no token associated with this webhook.
+        """
+
+        if self.token is None:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        previous_mentions: Optional[AllowedMentions] = getattr(self._state, 'allowed_mentions', None)
+        params = handle_message_parameters(
+            content=content,
+            file=file,
+            files=files,
+            embed=embed,
+            embeds=embeds,
+            allowed_mentions=allowed_mentions,
+            previous_allowed_mentions=previous_mentions,
+        )
+        adapter = async_context.get()
+        await adapter.edit_webhook_message(
+            self.id,
+            self.token,
+            message_id,
+            session=self.session,
+            payload=params.payload,
+            multipart=params.multipart,
+            files=params.files,
+        )
+
+    async def delete_message(self, message_id: int):
+        """|coro|
+
+        Deletes a message owned by this webhook.
+
+        This is a lower level interface to :meth:`WebhookMessage.delete` in case
+        you only have an ID.
+
+        .. versionadded:: 1.6
+
+        Parameters
+        ------------
+        message_id: :class:`int`
+            The message ID to delete.
+
+        Raises
+        -------
+        HTTPException
+            Deleting the message failed.
+        Forbidden
+            Deleted a message that is not yours.
+        """
+        if self.token is None:
+            raise InvalidArgument('This webhook does not have a token associated with it')
+
+        adapter = async_context.get()
+        await adapter.delete_webhook_message(
+            self.id,
+            self.token,
+            message_id,
+            session=self.session,
+        )