new mention behavior, new filter behavior (#3553)

* new mention behavior, new filter behavior

* and here too, ffs

* docs and reformat

* review handling

redbot/core/bot.py

@@ -943,6 +943,7 @@ class RedBase(
     async def send_filtered(
         destination: discord.abc.Messageable,
         filter_mass_mentions=True,
+        filter_roles=True,
         filter_invite_links=True,
         filter_all_links=False,
         **kwargs,
@@ -969,6 +970,8 @@ class RedBase(
         content = kwargs.pop("content", None)
 
         if content:
+            if filter_roles and isinstance(destination, discord.TextChannel):
+                content = common_filters.sanitize_role_mentions(content, destination.guild.roles)
             if filter_mass_mentions:
                 content = common_filters.filter_mass_mentions(content)
             if filter_invite_links:

redbot/core/commands/context.py

@@ -75,7 +75,10 @@ class Context(DPYContext):
             :func:`~redbot.core.utils.common_filters.filter_mass_mentions`.
             This must take a single `str` as an argument, and return
             the sanitized `str`.
-        \*\*kwargs
+        sanitize_roles : bool
+            Whether or not role mentions should be sanitized for you.
+            Defaults to ``True``
+        **kwargs
             See `discord.ext.commands.Context.send`.
 
         Returns
@@ -86,6 +89,10 @@ class Context(DPYContext):
         """
 
         _filter = kwargs.pop("filter", common_filters.filter_mass_mentions)
+        sanitize_roles = kwargs.pop("sanitize_roles", True)
+
+        if sanitize_roles and content and self.guild:
+            content = common_filters.sanitize_role_mentions(str(content), self.guild.roles)
 
         if _filter and content:
             content = _filter(str(content))

redbot/core/utils/common_filters.py

@@ -1,4 +1,7 @@
 import re
+from typing import Iterable
+
+import discord
 
 __all__ = [
     "URL_RE",
@@ -11,6 +14,7 @@ __all__ = [
     "normalize_smartquotes",
     "escape_spoilers",
     "escape_spoilers_and_mass_mentions",
+    "sanitize_role_mentions",
 ]
 
 # regexes
@@ -173,3 +177,32 @@ def escape_spoilers_and_mass_mentions(content: str) -> str:
         The escaped string.
     """
     return escape_spoilers(filter_mass_mentions(content))
+
+
+def sanitize_role_mentions(content: str, roles: Iterable[discord.Role]) -> str:
+    """
+    Swaps out role mentions for @RoleName
+
+    This should always be used prior to filtering everyone mentions
+
+    Parameters
+    ----------
+    content: str
+        The string to make substitutions to
+    roles: Iterable[discord.Role]
+        The roles to make substitutions for
+
+    Returns
+    -------
+    str
+        The resulting string
+    """
+    transformations = {re.escape(fr"<@&{role.id}>"): f"@{role.name}" for role in roles}
+
+    def repl(obj):
+        return transformations.get(re.escape(obj.group(0)), "")
+
+    pattern = re.compile("|".join(transformations.keys()))
+    result = pattern.sub(repl, content)
+
+    return result