python-app-rocketbot/rocketbot/cogs/urlspamcog.py

"""
Cog for detecting URLs posted by new users.
"""
import re
from datetime import timedelta
from discord import Member, Message, utils as discordutils
from discord.ext import commands

from config import CONFIG
from rocketbot.cogs.basecog import BaseCog, BotMessage, BotMessageReaction, CogSetting
from rocketbot.utils 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 = not self.was_warned_recently(message.author)
				self.log(message.guild, f'New user {message.author.name} ' + \
					f'({message.author.id}) posted URL {join_age_str} after ' + \
					'joining.' + (' Mods alerted.' if needs_attention else ''))
			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 = discordutils.remove_markdown(message.clean_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)
			if needs_attention:
				self.record_warning(message.author)

	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