feat(message): add the new ex query param to Attachment with some util property

changelog/1118.feature.rst

@@ -0,0 +1 @@
+Add :attr:`.Attachment.expires_at` and :attr:`.Attachment.is_expired` properties to :class:`.Attachment`.

disnake/message.py

@@ -21,6 +21,7 @@
     cast,
     overload,
 )
+from urllib.parse import parse_qs, urlparse
 
 from . import utils
 from .components import ActionRow, MessageComponent, _component_factory
@@ -302,6 +303,7 @@ class Attachment(Hashable):
         "description",
         "duration",
         "waveform",
+        "_ex",
         "_flags",
     )
 
@@ -321,8 +323,33 @@ def __init__(self, *, data: AttachmentPayload, state: ConnectionState) -> None:
         self.waveform: Optional[bytes] = (
             b64decode(waveform_data) if (waveform_data := data.get("waveform")) else None
         )
+        _params = urlparse(self.url)
+        self._ex = parse_qs(_params.query).get("ex")
         self._flags: int = data.get("flags", 0)
 
+    def expires_at(self) -> Optional[datetime.datetime]:
+        """The date when this attachment will expire.
+        ``None`` if the ``ex`` param is not present in :attr:`.Attachment.url`.
+
+        :return type: Optional[:class:`datetime.datetime`]
+        """
+        if not self._ex:
+            return
+
+        timestamp = int(self._ex[0], 16)
+        return datetime.datetime.fromtimestamp(timestamp, tz=datetime.timezone.utc)
+
+    def is_expired(self) -> bool:
+        """Whether this attachment expired or not.
+
+        :return type: :class:`bool`
+        """
+        ex = self.expires_at()
+        if not ex:
+            return False
+
+        return utils.utcnow() >= ex
+
     def is_spoiler(self) -> bool:
         """Whether this attachment contains a spoiler.