Pre-check site before applying a ban action from filters

Author: jb3

bot/exts/filtering/_settings_types/actions/infraction_and_notification.py

@@ -15,6 +15,7 @@
 from bot.exts.filtering._filter_context import FilterContext
 from bot.exts.filtering._settings_types.settings_entry import ActionEntry
 from bot.exts.filtering._utils import CustomIOField, FakeContext
+from bot.exts.moderation.infraction import _utils as infraction_utils
 from bot.utils.time import humanize_delta, parse_duration_string, relativedelta_to_timedelta
 
 log = get_logger(__name__)
@@ -87,14 +88,14 @@ async def invoke(
         alerts_channel: discord.TextChannel,
         duration: InfractionDuration,
         reason: str
-    ) -> None:
+    ) -> str | None:
         """Invokes the command matching the infraction name."""
         command_name = self.name.lower()
         command = bot_module.instance.get_command(command_name)
         if not command:
             await alerts_channel.send(f":warning: Could not apply {command_name} to {user.mention}: command not found.")
             log.warning(f":warning: Could not apply {command_name} to {user.mention}: command not found.")
-            return
+            return None
 
         if isinstance(user, discord.User):  # For example because a message was sent in a DM.
             member = await get_or_fetch_member(channel.guild, user.id)
@@ -105,14 +106,20 @@ async def invoke(
                     f"The user {user} were set to receive an automatic {command_name}, "
                     "but they were not found in the guild."
                 )
-                return
+                return None
 
         ctx = FakeContext(message, channel, command)
+        if self is Infraction.BAN:
+            active_infraction = await infraction_utils.get_active_infraction(ctx, user, "ban", send_msg=False)
+            if active_infraction:
+                return "already banned"
+
         if self.name in ("KICK", "WARNING", "WATCH", "NOTE"):
             await command(ctx, user, reason=reason or None)
         else:
             duration = arrow.utcnow().datetime + duration.value if duration.value else None
             await command(ctx, user, duration, reason=reason or None)
+        return passive_form[self.name]
 
 
 class InfractionAndNotification(ActionEntry):
@@ -203,10 +210,11 @@ async def action(self, ctx: FilterContext) -> None:
                 log.error(f"Unable to apply infraction as the context channel {channel} can't be found.")
                 return
 
-            await self.infraction_type.invoke(
+            infraction_action = await self.infraction_type.invoke(
                 ctx.author, ctx.message, channel, alerts_channel, self.infraction_duration, self.infraction_reason
             )
-            ctx.action_descriptions.append(passive_form[self.infraction_type.name])
+            if infraction_action:
+                ctx.action_descriptions.append(infraction_action)
 
     def union(self, other: Self) -> Self:
         """