Add initial support for buttons and components

1 files changed, 140 insertions, 0 deletions

diff --git a/discord/ui/item.py b/discord/ui/item.py
new file mode 100644
index 00000000..7726407e
--- /dev/null
+++ b/discord/ui/item.py
@@ -0,0 +1,140 @@
+"""
+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
+
+from typing import Any, Callable, Coroutine, Dict, Optional, TYPE_CHECKING, Tuple, Type, TypeVar, Union
+import inspect
+
+from ..interactions import Interaction
+
+__all__ = (
+    'Item',
+)
+
+if TYPE_CHECKING:
+    from ..enums import ComponentType
+    from .view import View
+    from ..components import Component
+
+I = TypeVar('I', bound='Item')
+ItemCallbackType = Callable[[Any, I, Interaction], Coroutine[Any, Any, Any]]
+
+
+class Item:
+    """Represents the base UI item that all UI components inherit from.
+
+    The current UI items supported are:
+
+    - :class:`discord.ui.Button`
+    """
+
+    __slots__: Tuple[str, ...] = (
+        '_callback',
+        '_pass_view_arg',
+        'group_id',
+    )
+
+    __item_repr_attributes__: Tuple[str, ...] = ('group_id',)
+
+    def __init__(self):
+        self._callback: Optional[ItemCallbackType] = None
+        self._pass_view_arg = True
+        self.group_id: Optional[int] = None
+
+    def to_component_dict(self) -> Dict[str, Any]:
+        raise NotImplementedError
+
+    def copy(self: I) -> I:
+        raise NotImplementedError
+
+    def refresh_state(self, component: Component) -> None:
+        return None
+
+    @classmethod
+    def from_component(cls: Type[I], component: Component) -> I:
+        return cls()
+
+    @property
+    def type(self) -> ComponentType:
+        raise NotImplementedError
+
+    def is_dispatchable(self) -> bool:
+        return False
+
+    def __repr__(self) -> str:
+        attrs = ' '.join(f'{key}={getattr(self, key)!r}' for key in self.__item_repr_attributes__)
+        return f'<{self.__class__.__name__} {attrs}>'
+
+    @property
+    def callback(self) -> Optional[ItemCallbackType]:
+        """Returns the underlying callback associated with this interaction."""
+        return self._callback
+
+    @callback.setter
+    def callback(self, value: Optional[ItemCallbackType]):
+        if value is None:
+            self._callback = None
+            return
+
+        # Check if it's a partial function
+        try:
+            partial = value.func
+        except AttributeError:
+            pass
+        else:
+            if not inspect.iscoroutinefunction(value.func):
+                raise TypeError(f'inner partial function must be a coroutine')
+
+            # Check if the partial is bound
+            try:
+                bound_partial = partial.__self__
+            except AttributeError:
+                pass
+            else:
+                self._pass_view_arg = not hasattr(bound_partial, '__discord_ui_view__')
+
+            self._callback = value
+            return
+
+        try:
+            func_self = value.__self__
+        except AttributeError:
+            pass
+        else:
+            if not isinstance(func_self, Item):
+                raise TypeError(f'callback bound method must be from Item not {func_self!r}')
+            else:
+                value = value.__func__
+
+        if not inspect.iscoroutinefunction(value):
+            raise TypeError(f'callback must be a coroutine not {value!r}')
+
+        self._callback = value
+
+    async def _do_call(self, view: View, interaction: Interaction):
+        if self._pass_view_arg:
+            await self._callback(view, self, interaction)
+        else:
+            await self._callback(self, interaction)  # type: ignore