[commands] Add initial implementation of hybrid commands

Hybrid commands allow a regular command to also double as a slash
command, assuming it meets the subset required to function.

discord/ext/commands/bot.py

@@ -67,6 +67,7 @@ if TYPE_CHECKING:
     import importlib.machinery
 
     from discord.message import Message
+    from discord.interactions import Interaction
     from discord.abc import User, Snowflake
     from ._types import (
         _Bot,
@@ -76,6 +77,7 @@ if TYPE_CHECKING:
         ContextT,
         MaybeAwaitableFunc,
     )
+    from .core import Command
 
     _Prefix = Union[Iterable[str], str]
     _PrefixCallable = MaybeAwaitableFunc[[BotT, Message], _Prefix]
@@ -215,6 +217,38 @@ class BotBase(GroupMixin[None]):
 
         await super().close()  # type: ignore
 
+    # GroupMixin overrides
+
+    @discord.utils.copy_doc(GroupMixin.add_command)
+    def add_command(self, command: Command[Any, ..., Any], /) -> None:
+        super().add_command(command)
+        if hasattr(command, '__commands_is_hybrid__'):
+            # If a cog is also inheriting from app_commands.Group then it'll also
+            # add the hybrid commands as text commands, which would recursively add the
+            # hybrid commands as slash commands. This check just terminates that recursion
+            # from happening
+            if command.cog is None or not command.cog.__cog_is_app_commands_group__:
+                self.tree.add_command(command.app_command)  # type: ignore
+
+    @discord.utils.copy_doc(GroupMixin.remove_command)
+    def remove_command(self, name: str, /) -> Optional[Command[Any, ..., Any]]:
+        cmd = super().remove_command(name)
+        if cmd is not None and hasattr(cmd, '__commands_is_hybrid__'):
+            # See above
+            if cmd.cog is not None and cmd.cog.__cog_is_app_commands_group__:
+                return cmd
+
+            guild_ids: Optional[List[int]] = cmd.app_command._guild_ids  # type: ignore
+            if guild_ids is None:
+                self.__tree.remove_command(name)
+            else:
+                for guild_id in guild_ids:
+                    self.__tree.remove_command(name, guild=discord.Object(id=guild_id))
+
+        return cmd
+
+    # Error handler
+
     async def on_command_error(self, context: Context[BotT], exception: errors.CommandError, /) -> None:
         """|coro|
 
@@ -1107,7 +1141,7 @@ class BotBase(GroupMixin[None]):
     @overload
     async def get_context(
         self,
-        message: Message,
+        origin: Union[Message, Interaction],
         /,
     ) -> Context[Self]:  # type: ignore
         ...
@@ -1115,23 +1149,23 @@ class BotBase(GroupMixin[None]):
     @overload
     async def get_context(
         self,
-        message: Message,
+        origin: Union[Message, Interaction],
         /,
         *,
-        cls: Type[ContextT] = ...,
+        cls: Type[ContextT],
     ) -> ContextT:
         ...
 
     async def get_context(
         self,
-        message: Message,
+        origin: Union[Message, Interaction],
         /,
         *,
         cls: Type[ContextT] = MISSING,
     ) -> Any:
         r"""|coro|
 
-        Returns the invocation context from the message.
+        Returns the invocation context from the message or interaction.
 
         This is a more low-level counter-part for :meth:`.process_commands`
         to allow users more fine grained control over the processing.
@@ -1141,14 +1175,20 @@ class BotBase(GroupMixin[None]):
         If the context is not valid then it is not a valid candidate to be
         invoked under :meth:`~.Bot.invoke`.
 
+        .. note::
+
+            In order for the custom context to be used inside an interaction-based
+            context (such as :class:`HybridCommand`) then this method must be
+            overridden to return that class.
+
         .. versionchanged:: 2.0
 
-            ``message`` parameter is now positional-only.
+            ``message`` parameter is now positional-only and renamed to ``origin``.
 
         Parameters
         -----------
-        message: :class:`discord.Message`
-            The message to get the invocation context from.
+        origin: Union[:class:`discord.Message`, :class:`discord.Interaction`]
+            The message or interaction to get the invocation context from.
         cls
             The factory class that will be used to create the context.
             By default, this is :class:`.Context`. Should a custom
@@ -1164,13 +1204,16 @@ class BotBase(GroupMixin[None]):
         if cls is MISSING:
             cls = Context  # type: ignore
 
-        view = StringView(message.content)
-        ctx = cls(prefix=None, view=view, bot=self, message=message)
+        if isinstance(origin, discord.Interaction):
+            return await cls.from_interaction(origin)
 
-        if message.author.id == self.user.id:  # type: ignore
+        view = StringView(origin.content)
+        ctx = cls(prefix=None, view=view, bot=self, message=origin)
+
+        if origin.author.id == self.user.id:  # type: ignore
             return ctx
 
-        prefix = await self.get_prefix(message)
+        prefix = await self.get_prefix(origin)
         invoked_prefix = prefix
 
         if isinstance(prefix, str):
@@ -1180,7 +1223,7 @@ class BotBase(GroupMixin[None]):
             try:
                 # if the context class' __init__ consumes something from the view this
                 # will be wrong.  That seems unreasonable though.
-                if message.content.startswith(tuple(prefix)):
+                if origin.content.startswith(tuple(prefix)):
                     invoked_prefix = discord.utils.find(view.skip_string, prefix)
                 else:
                     return ctx