rewrite: Refactor ui utils, add pagers.

bot/utils/ui/transformed.py

@@ -0,0 +1,91 @@
+from typing import Any, Type, TYPE_CHECKING
+from enum import Enum
+
+import discord
+import discord.app_commands as appcmd
+from discord.app_commands.transformers import AppCommandOptionType
+
+
+__all__ = (
+    'ChoicedEnum',
+    'ChoicedEnumTransformer',
+    'Transformed',
+)
+
+
+class ChoicedEnum(Enum):
+    @property
+    def choice_name(self):
+        return self.name
+
+    @property
+    def choice_value(self):
+        return self.value
+
+    @property
+    def choice(self):
+        return appcmd.Choice(
+            name=self.choice_name, value=self.choice_value
+        )
+
+    @classmethod
+    def choices(self):
+        return [item.choice for item in self]
+
+    @classmethod
+    def make_choice_map(cls):
+        return {item.choice_value: item for item in cls}
+
+    @classmethod
+    async def transform(cls, transformer: 'ChoicedEnumTransformer', interaction: discord.Interaction, value: Any):
+        return transformer._choice_map[value]
+
+    @classmethod
+    def option_type(cls) -> AppCommandOptionType:
+        return AppCommandOptionType.string
+
+    @classmethod
+    def transformer(cls, *args) -> appcmd.Transformer:
+        return ChoicedEnumTransformer(cls, *args)
+
+
+class ChoicedEnumTransformer(appcmd.Transformer):
+    # __discord_app_commands_is_choice__ = True
+
+    def __init__(self, enum: Type[ChoicedEnum], opt_type) -> None:
+        super().__init__()
+
+        self._type = opt_type
+        self._enum = enum
+        self._choices = enum.choices()
+        self._choice_map = enum.make_choice_map()
+
+    @property
+    def _error_display_name(self) -> str:
+        return self._enum.__name__
+
+    @property
+    def type(self) -> AppCommandOptionType:
+        return self._type
+
+    @property
+    def choices(self):
+        return self._choices
+
+    async def transform(self, interaction: discord.Interaction, value: Any, /) -> Any:
+        return await self._enum.transform(self, interaction, value)
+
+
+if TYPE_CHECKING:
+    from typing_extensions import Annotated as Transformed
+else:
+
+    class Transformed:
+        def __class_getitem__(self, items):
+            cls = items[0]
+            options = items[1:]
+
+            if not hasattr(cls, 'transformer'):
+                raise ValueError("Tranformed class must have a transformer classmethod.")
+            transformer = cls.transformer(*options)
+            return appcmd.Transform[cls, transformer]