Silence: use aware datetimes

`datetime.timestamp()` assumes naïve `datetime`s are in local time, so
getting POSIX timestamps in UTC isn't easy for naïve ones. Technically,
the timestamp's timezone doesn't matter if all code is on the same page
and parsing it with the same timezone. Keeping it in the local timezone
would be okay then, but I feel safer locking it to UTC explicitly.

1 files changed, 6 insertions, 5 deletions

diff --git a/bot/cogs/moderation/silence.py b/bot/cogs/moderation/silence.py
index 02d8de29e..adf469661 100644
--- a/bot/cogs/moderation/silence.py
+++ b/bot/cogs/moderation/silence.py
@@ -2,7 +2,7 @@ import asyncio
 import json
 import logging
 from contextlib import suppress
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from typing import Optional
 
 from discord import TextChannel
@@ -111,7 +111,7 @@ class Silence(commands.Cog):
         await ctx.send(f"{Emojis.check_mark} silenced current channel for {duration} minute(s).")
 
         self.scheduler.schedule_later(duration * 60, ctx.channel.id, ctx.invoke(self.unsilence))
-        unsilence_time = (datetime.utcnow() + timedelta(minutes=duration))
+        unsilence_time = (datetime.now(tz=timezone.utc) + timedelta(minutes=duration))
         await self.muted_channel_times.set(ctx.channel.id, unsilence_time.timestamp())
 
     @commands.command(aliases=("unhush",))
@@ -218,12 +218,13 @@ class Silence(commands.Cog):
                 self.notifier.add_channel(channel)
                 continue
 
-            dt = datetime.utcfromtimestamp(timestamp)
-            if dt <= datetime.utcnow():
+            dt = datetime.fromtimestamp(timestamp, tz=timezone.utc)
+            delta = (dt - datetime.now(tz=timezone.utc)).total_seconds()
+            if delta <= 0:
                 await self._unsilence_wrapper(channel)
             else:
                 log.info(f"Rescheduling silence for #{channel} ({channel.id}).")
-                self.scheduler.schedule_at(dt, channel_id, self._unsilence_wrapper(channel))
+                self.scheduler.schedule_later(delta, channel_id, self._unsilence_wrapper(channel))
 
     def cog_unload(self) -> None:
         """Cancel scheduled tasks."""