Store last DM user in RedisCache.

Also now catches the exception if a user has disabled DMs, and adds a
red cross reaction.

https://github.com/python-discord/bot/issues/667

1 files changed, 22 insertions, 12 deletions

diff --git a/bot/cogs/dm_relay.py b/bot/cogs/dm_relay.py
index 494c71066..3fce52b93 100644
--- a/bot/cogs/dm_relay.py
+++ b/bot/cogs/dm_relay.py
@@ -9,6 +9,7 @@ from discord.ext.commands import Cog
 from bot import constants
 from bot.bot import Bot
 from bot.constants import MODERATION_ROLES
+from bot.utils import RedisCache
 from bot.utils.checks import with_role_check
 from bot.utils.messages import send_attachments
 from bot.utils.webhooks import send_webhook
@@ -19,12 +20,14 @@ log = logging.getLogger(__name__)
 class DMRelay(Cog):
     """Relay direct messages to and from the bot."""
 
+    # RedisCache[str, t.Union[discord.User.id, discord.Member.id]]
+    dm_cache = RedisCache()
+
     def __init__(self, bot: Bot):
         self.bot = bot
         self.webhook_id = constants.Webhooks.dm_log
         self.webhook = None
         self.bot.loop.create_task(self.fetch_webhook())
-        self.last_dm_user = None
 
     @commands.command(aliases=("reply",))
     async def send_dm(self, ctx: commands.Context, member: Optional[discord.Member], *, message: str) -> None:
@@ -39,16 +42,23 @@ class DMRelay(Cog):
 
         NOTE: This feature will be removed if it is overused.
         """
-        if member:
-            await member.send(message)
-            await ctx.message.add_reaction("✅")
-            return
-        elif self.last_dm_user:
-            await self.last_dm_user.send(message)
-            await ctx.message.add_reaction("✅")
-            return
-        else:
-            log.debug("Unable to send a DM to the user.")
+        user_id = await self.dm_cache.get("last_user")
+        last_dm_user = ctx.guild.get_member(user_id) if user_id else None
+
+        try:
+            if member:
+                await member.send(message)
+                await ctx.message.add_reaction("✅")
+                return
+            elif last_dm_user:
+                await last_dm_user.send(message)
+                await ctx.message.add_reaction("✅")
+                return
+            else:
+                log.debug("This bot has never gotten a DM, or the RedisCache has been cleared.")
+                await ctx.message.add_reaction("❌")
+        except discord.errors.Forbidden:
+            log.debug("User has disabled DMs.")
             await ctx.message.add_reaction("❌")
 
     async def fetch_webhook(self) -> None:
@@ -74,7 +84,7 @@ class DMRelay(Cog):
                 username=message.author.display_name,
                 avatar_url=message.author.avatar_url
             )
-            self.last_dm_user = message.author
+            await self.dm_cache.set("last_user", message.author.id)
 
         # Handle any attachments
         if message.attachments: