python-app-rocketbot/cogs/urlspamcog.py

import re
from datetime import timedelta
from discord import Member, Message
from discord.ext import commands

from cogs.basecog import BaseCog, BotMessage, BotMessageReaction, CogSetting
from config import CONFIG
from rbutils import describe_timedelta

class URLSpamContext:
	"""
	Data about a suspected spam message containing a URL.
	"""
	def __init__(self, spam_message: Message):
		self.spam_message = spam_message
		self.is_deleted = False
		self.is_kicked = False
		self.is_banned = False

class URLSpamCog(BaseCog, name='URL Spam'):
	"""
	Detects users posting URLs who just joined recently: a common spam pattern.
	Can be configured to take immediate action or just warn the mods.
	"""

	SETTING_ENABLED = CogSetting('enabled', bool,
			brief='URL spam detection',
			description='Whether URLs posted soon after joining are flagged.')
	SETTING_ACTION = CogSetting('action', str,
			brief='action to take on spam',
			description='The action to take on detected URL spam.',
			enum_values=set(['nothing', 'modwarn', 'delete', 'kick', 'ban']))
	SETTING_JOIN_AGE = CogSetting('joinage', float,
			brief='seconds since member joined',
			description='The minimum seconds since the user joined the ' + \
				'server before they can post URLs. URLs posted by users ' + \
				'who joined too recently will be flagged. Keep in mind ' + \
				'many servers have a minimum 10 minute cooldown before ' + \
				'new members can say anything. Setting to 0 effectively ' + \
				'disables URL spam detection.',
			usage='<seconds:int>',
			min_value=0)

	def __init__(self, bot):
		super().__init__(bot)
		self.add_setting(URLSpamCog.SETTING_ENABLED)
		self.add_setting(URLSpamCog.SETTING_ACTION)
		self.add_setting(URLSpamCog.SETTING_JOIN_AGE)

	@commands.group(
		brief='Manages URL spam detection',
	)
	@commands.has_permissions(ban_members=True)
	@commands.guild_only()
	async def urlspam(self, context: commands.Context):
		'URL spam command group'
		if context.invoked_subcommand is None:
			await context.send_help()

	@commands.Cog.listener()
	async def on_message(self, message: Message):
		'Event listener'
		if message.author is None or \
				message.author.bot or \
				message.guild is None or \
				message.channel is None or \
				message.content is None:
			return
		if not self.get_guild_setting(message.guild, self.SETTING_ENABLED):
			return

		action = self.get_guild_setting(message.guild, self.SETTING_ACTION)
		join_seconds = self.get_guild_setting(message.guild, self.SETTING_JOIN_AGE)
		min_join_age = timedelta(seconds=join_seconds)
		if action == 'nothing':
			return
		if not self.__contains_url(message.content):
			return
		join_age = message.created_at - message.author.joined_at
		join_age_str = describe_timedelta(join_age)
		if join_age < min_join_age:
			context = URLSpamContext(message)
			needs_attention = False
			if action == 'modwarn':
				needs_attention = True
				self.log(message.guild, f'New user {message.author.name} ' + \
					f'({message.author.id}) posted URL {join_age_str} after ' + \
					'joining. Mods alerted.')
			elif action == 'delete':
				await message.delete()
				context.is_deleted = True
				self.log(message.guild, f'New user {message.author.name} ' + \
					f'({message.author.id}) posted URL {join_age_str} after ' + \
					'joining. Message deleted.')
			elif action == 'kick':
				await message.delete()
				context.is_deleted = True
				await message.author.kick(
					reason=f'Rocketbot: Posted a link {join_age_str} after joining')
				context.is_kicked = True
				self.log(message.guild, f'New user {message.author.name} ' + \
					f'({message.author.id}) posted URL {join_age_str} after ' + \
					'joining. User kicked.')
			elif action == 'ban':
				await message.author.ban(
					reason=f'Rocketbot: User posted a link {join_age_str} after joining',
					delete_message_days=1)
				context.is_deleted = True
				context.is_kicked = True
				context.is_banned = True
				self.log(message.guild, f'New user {message.author.name} ' + \
					f'({message.author.id}) posted URL {join_age_str} after ' + \
					'joining. User banned.')
			bm = BotMessage(
					message.guild,
					f'User {message.author.mention} posted a URL ' + \
					f'{join_age_str} after joining.',
					type = BotMessage.TYPE_MOD_WARNING if needs_attention else BotMessage.TYPE_INFO,
					context = context)
			bm.quote = message.content
			await bm.set_reactions(BotMessageReaction.standard_set(
				did_delete=context.is_deleted,
				did_kick=context.is_kicked,
				did_ban=context.is_banned))
			await self.post_message(bm)

	async def on_mod_react(self,
			bot_message: BotMessage,
			reaction: BotMessageReaction,
			reacted_by: Member) -> None:
		context: URLSpamContext = bot_message.context
		if context is None:
			return
		sm: Message = context.spam_message
		if reaction.emoji == CONFIG['trash_emoji']:
			if not context.is_deleted:
				await sm.delete()
				context.is_deleted = True
				self.log(sm.guild, f'URL spam by {sm.author.name} deleted ' + \
					f'by {reacted_by.name}')
		elif reaction.emoji == CONFIG['kick_emoji']:
			if not context.is_deleted:
				await sm.delete()
				context.is_deleted = True
			if not context.is_kicked:
				await sm.author.kick(
					reason=f'Rocketbot: Kicked for URL spam by {reacted_by.name}')
				context.is_kicked = True
				self.log(sm.guild, f'URL spammer {sm.author.name} kicked ' + \
					f'by {reacted_by.name}')
		elif reaction.emoji == CONFIG['ban_emoji']:
			if not context.is_banned:
				await sm.author.ban(
					reason=f'Rocketbot: Banned for URL spam by {reacted_by.name}',
					delete_message_days=1)
				context.is_deleted = True
				context.is_kicked = True
				context.is_banned = True
				self.log(sm.guild, f'URL spammer {sm.author.name} banned ' + \
					f'by {reacted_by.name}')
		else:
			return
		await bot_message.set_reactions(BotMessageReaction.standard_set(
			did_delete=context.is_deleted,
			did_kick=context.is_kicked,
			did_ban=context.is_banned))

	@classmethod
	def __contains_url(cls, text: str) -> bool:
		p = re.compile(r'http(?:s)?://[^\s]+')
		return p.search(text) is not None