1 files changed, 124 insertions, 0 deletions
diff --git a/bot/exts/moderation/dm_relay.py b/bot/exts/moderation/dm_relay.py
new file mode 100644
index 000000000..14263e004
--- /dev/null
+++ b/bot/exts/moderation/dm_relay.py
@@ -0,0 +1,124 @@
+import logging
+from typing import Optional
+
+import discord
+from async_rediscache import RedisCache
+from discord import Color
+from discord.ext import commands
+from discord.ext.commands import Cog
+
+from bot import constants
+from bot.bot import Bot
+from bot.converters import UserMentionOrID
+from bot.utils.checks import in_whitelist_check
+from bot.utils.messages import send_attachments
+from bot.utils.webhooks import send_webhook
+
+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())
+
+    @commands.command(aliases=("reply",))
+    async def send_dm(self, ctx: commands.Context, member: Optional[UserMentionOrID], *, message: str) -> None:
+        """
+        Allows you to send a DM to a user from the bot.
+
+        If `member` is not provided, it will send to the last user who DM'd the bot.
+
+        This feature should be used extremely sparingly. Use ModMail if you need to have a serious
+        conversation with a user. This is just for responding to extraordinary DMs, having a little
+        fun with users, and telling people they are DMing the wrong bot.
+
+        NOTE: This feature will be removed if it is overused.
+        """
+        if not member:
+            user_id = await self.dm_cache.get("last_user")
+            member = ctx.guild.get_member(user_id) if user_id else None
+
+        # If we still don't have a Member at this point, give up
+        if not member:
+            log.debug("This bot has never gotten a DM, or the RedisCache has been cleared.")
+            await ctx.message.add_reaction("❌")
+            return
+
+        try:
+            await member.send(message)
+        except discord.errors.Forbidden:
+            log.debug("User has disabled DMs.")
+            await ctx.message.add_reaction("❌")
+        else:
+            await ctx.message.add_reaction("✅")
+            self.bot.stats.incr("dm_relay.dm_sent")
+
+    async def fetch_webhook(self) -> None:
+        """Fetches the webhook object, so we can post to it."""
+        await self.bot.wait_until_guild_available()
+
+        try:
+            self.webhook = await self.bot.fetch_webhook(self.webhook_id)
+        except discord.HTTPException:
+            log.exception(f"Failed to fetch webhook with id `{self.webhook_id}`")
+
+    @Cog.listener()
+    async def on_message(self, message: discord.Message) -> None:
+        """Relays the message's content and attachments to the dm_log channel."""
+        # Only relay DMs from humans
+        if message.author.bot or message.guild or self.webhook is None:
+            return
+
+        if message.clean_content:
+            await send_webhook(
+                webhook=self.webhook,
+                content=message.clean_content,
+                username=f"{message.author.display_name} ({message.author.id})",
+                avatar_url=message.author.avatar_url
+            )
+            await self.dm_cache.set("last_user", message.author.id)
+            self.bot.stats.incr("dm_relay.dm_received")
+
+        # Handle any attachments
+        if message.attachments:
+            try:
+                await send_attachments(message, self.webhook)
+            except (discord.errors.Forbidden, discord.errors.NotFound):
+                e = discord.Embed(
+                    description=":x: **This message contained an attachment, but it could not be retrieved**",
+                    color=Color.red()
+                )
+                await send_webhook(
+                    webhook=self.webhook,
+                    embed=e,
+                    username=f"{message.author.display_name} ({message.author.id})",
+                    avatar_url=message.author.avatar_url
+                )
+            except discord.HTTPException:
+                log.exception("Failed to send an attachment to the webhook")
+
+    async def cog_check(self, ctx: commands.Context) -> bool:
+        """Only allow moderators to invoke the commands in this cog."""
+        checks = [
+            await commands.has_any_role(*constants.MODERATION_ROLES).predicate(ctx),
+            in_whitelist_check(
+                ctx,
+                channels=[constants.Channels.dm_log],
+                redirect=None,
+                fail_silently=True,
+            )
+        ]
+        return all(checks)
+
+
+def setup(bot: Bot) -> None:
+    """Load the DMRelay  cog."""
+    bot.add_cog(DMRelay(bot))