1 files changed, 52 insertions, 0 deletions
diff --git a/bot/converters.py b/bot/converters.py
index 8d2ab7eb8..a2e445d74 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -278,3 +278,55 @@ class ISODateTime(Converter):
             dt = dt.replace(tzinfo=None)
 
         return dt
+
+
+def proxy_user(user_id: str) -> discord.Object:
+    """
+    Create a proxy user object from the given id.
+
+    Used when a Member or User object cannot be resolved.
+    """
+    log.trace(f"Attempting to create a proxy user for the user id {user_id}.")
+
+    try:
+        user_id = int(user_id)
+    except ValueError:
+        log.debug(f"Failed to create proxy user {user_id}: could not convert to int.")
+        raise BadArgument(f"User ID `{user_id}` is invalid - could not convert to an integer.")
+
+    user = discord.Object(user_id)
+    user.mention = user.id
+    user.display_name = f"<@{user.id}>"
+    user.avatar_url_as = lambda static_format: None
+    user.bot = False
+
+    return user
+
+
+class FetchedUser(Converter):
+    """
+    Fetches from the Discord API and returns a `discord.User` or `discord.Object` object, given an ID.
+
+    If the fetching is successful, a `discord.User` object is returned. If it fails and
+    the error doesn't imply the user doesn't exist, then a `discord.Object` is returned
+    via the `user_proxy` function.
+    """
+
+    @staticmethod
+    async def convert(ctx: Context, user_id: str) -> t.Union[discord.User, discord.Object]:
+        """Convert `user_id` to a `discord.User` object, after fetching from the Discord API."""
+        try:
+            user_id = int(user_id)
+            log.trace(f"Fetching user {user_id}...")
+            return await ctx.bot.fetch_user(user_id)
+        except ValueError:
+            log.debug(f"Failed to fetch user {user_id}: could not convert to int.")
+            raise BadArgument(f"The provided argument can't be turned into integer: `{user_id}`")
+        except discord.HTTPException as e:
+            # If the Discord error isn't `Unknown user`, save it in the log and return a proxy instead
+            if e.code != 10013:
+                log.warning(f"Failed to fetch user, returning a proxy instead: status {e.status}")
+                return proxy_user(user_id)
+
+            log.debug(f"Failed to fetch user {user_id}: user does not exist.")
+            raise BadArgument(f"User `{user_id}` does not exist")