1 files changed, 71 insertions, 0 deletions
diff --git a/bot/exts/holidays/holidayreact.py b/bot/exts/holidays/holidayreact.py
new file mode 100644
index 00000000..f0905f03
--- /dev/null
+++ b/bot/exts/holidays/holidayreact.py
@@ -0,0 +1,71 @@
+import logging
+import re
+
+import discord
+from discord.ext.commands import Cog
+
+from bot.bot import Bot
+from bot.constants import Month
+from bot.utils.decorators import in_month
+
+log = logging.getLogger(__name__)
+
+SPOOKY_TRIGGERS = {
+    "spooky": (r"\bspo{2,}[k|p][i|y](er|est)?\b", "\U0001F47B"),
+    "skeleton": (r"\bskeleton\b", "\U0001F480"),
+    "doot": (r"\bdo{2,}t\b", "\U0001F480"),
+    "pumpkin": (r"\bpumpkin\b", "\U0001F383"),
+    "halloween": (r"\bhalloween\b", "\U0001F383"),
+    "jack-o-lantern": (r"\bjack-o-lantern\b", "\U0001F383"),
+    "danger": (r"\bdanger\b", "\U00002620"),
+    "bat": (r"\bbat((wo)?m[ae]n|persons?|people|s)?\b", "\U0001F987"),
+}
+
+
+class HolidayReact(Cog):
+    """A cog that makes the bot react to message triggers."""
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+    @in_month(Month.OCTOBER)
+    @Cog.listener()
+    async def on_message(self, message: discord.Message) -> None:
+        """Triggered when the bot sees a message in a holiday month."""
+        for name, trigger in SPOOKY_TRIGGERS.items():
+            trigger_test = re.search(trigger[0], message.content.lower())
+            if trigger_test:
+                # Check message for bot replies and/or command invocations
+                # Short circuit if they're found, logging is handled in _short_circuit_check
+                if await self._short_circuit_check(message):
+                    return
+                else:
+                    await message.add_reaction(trigger[1])
+                    log.info(f"Added {name!r} reaction to message ID: {message.id}")
+
+    async def _short_circuit_check(self, message: discord.Message) -> bool:
+        """
+        Short-circuit helper check.
+
+        Return True if:
+          * author is a bot
+          * prefix is not None
+        """
+        # Check if message author is a bot
+        if message.author.bot:
+            log.debug(f"Ignoring reactions on bot message. Message ID: {message.id}")
+            return True
+
+        # Check for command invocation
+        # Because on_message doesn't give a full Context object, generate one first
+        ctx = await self.bot.get_context(message)
+        if ctx.prefix:
+            log.debug(f"Ignoring reactions on command invocation. Message ID: {message.id}")
+            return True
+
+        return False
+
+
+async def setup(bot: Bot) -> None:
+    """Load the Holiday Reaction Cog."""
+    await bot.add_cog(HolidayReact(bot))