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

"""
Cog for detecting username patterns.
"""
from typing import Optional

from discord import Guild, Interaction, Member
from discord.app_commands import Group
from discord.ext.commands import Cog

from config import CONFIG
from rocketbot.cogs.basecog import BaseCog, BotMessage, BotMessageReaction, CogSetting
from rocketbot.storage import Storage
from rocketbot.utils import MOD_PERMISSIONS


class UsernamePatternContext:
	"""
	BotMessage context for a flagged username
	"""
	def __init__(self, member: Member) -> None:
		self.member: Member = member
		self.kicked_by: Optional[Member] = None
		self.banned_by: Optional[Member] = None
		self.ignored_by: Optional[Member] = None

	def reactions(self) -> list[BotMessageReaction]:
		"""
		Generates updated BotMessageReactions based on context state.
		"""
		r: list[BotMessageReaction] = []
		if self.ignored_by:
			r.append(BotMessageReaction(CONFIG['ignore_emoji'], False, f'Ignored by {self.ignored_by.name}'))
		elif self.banned_by:
			r.append(BotMessageReaction(CONFIG['ban_emoji'], False, f'Banned by {self.banned_by.name}'))
		elif self.kicked_by:
			r.append(BotMessageReaction(CONFIG['kick_emoji'], False, f'Kicked by {self.kicked_by.name}'))
			r.append(BotMessageReaction(CONFIG['ban_emoji'], True, 'Ban user'))
		else:
			r.append(BotMessageReaction(CONFIG['kick_emoji'], True, 'Kick user'))
			r.append(BotMessageReaction(CONFIG['ban_emoji'], True, 'Ban user'))
			r.append(BotMessageReaction(CONFIG['ignore_emoji'], True, 'Ignore warning'))
		return r

class UsernamePatternCog(BaseCog, name='Username Pattern'):
	"""
	Detects usernames that match certain flagged patterns. Posts a mod warning
	message on a match.
	"""

	SETTING_ENABLED = CogSetting(
		'enabled',
		bool,
		default_value=False,
		brief='username pattern detection',
		description='Whether new users are checked for username patterns.',
	)

	SETTING_PATTERNS = CogSetting('patterns', None, default_value=None)

	def __init__(self, bot):
		super().__init__(
			bot,
			config_prefix='username',
			short_description='Manages username pattern detection.',
			long_description='When new users join, if their username matches '
							 'a configured pattern the mods will be alerted.'
		)
		self.add_setting(UsernamePatternCog.SETTING_ENABLED)

	def __get_patterns(self, guild: Guild) -> list[str]:
		"""
		Returns an array of username patterns.
		"""
		patterns: list[str] = self.get_guild_setting(guild, self.SETTING_PATTERNS)
		if patterns is None:
			patterns = []
			Storage.set_config_value(guild, 'UsernamePatternCog.patterns', patterns)
		return patterns

	@classmethod
	def __save_patterns(cls,
			guild: Guild,
			patterns: list[str]) -> None:
		"""
		Saves username pattern array.
		"""
		cls.set_guild_setting(guild, cls.SETTING_PATTERNS, patterns)

	username = Group(
		name='username',
		description='Manages username pattern detection.',
		guild_only=True,
		default_permissions=MOD_PERMISSIONS,
		extras={
			'long_description': 'When new users join, if their username matches '
								'a configured pattern the mods will be alerted.',
		},
	)

	@username.command(
		description='Adds a username pattern.',
		extras={
			'long_description': 'When a user joins the server, if their username '
								'matches a configured pattern the mods will be alerted. '
								'Matching is currently a simple substring test.',
			'usage': '<pattern>',
		},
	)
	async def add(self, interaction: Interaction, pattern: str) -> None:
		"""
		Adds a username pattern to match against new members.

		Parameters
		----------
		interaction : Interaction
		pattern : str
			a substring to look for in usernames
		"""
		norm_pattern = pattern.lower()
		patterns: list[str] = self.__get_patterns(interaction.guild)
		if norm_pattern in patterns:
			await interaction.response.send_message(
				f'{CONFIG["warning_emoji"]} Pattern `{norm_pattern}` already added.',
				ephemeral=True
			)
			return
		patterns.append(norm_pattern)
		self.__save_patterns(interaction.guild, patterns)
		await interaction.response.send_message(
			f'{CONFIG["success_emoji"]} Pattern `{norm_pattern}` added.',
			ephemeral=True
		)

	@username.command(
		description='Removes a username pattern.',
		extras={
			'usage': '<pattern>',
		},
	)
	async def remove(self, interaction: Interaction, pattern: str) -> None:
		"""
		Removes a username pattern.

		Parameters
		----------
		interaction : Interaction
		pattern : str
		    the existing username pattern to remove
		"""
		norm_pattern = pattern.lower()
		guild: Guild = interaction.guild
		patterns: list[str] = self.__get_patterns(guild)
		len_before = len(patterns)
		patterns = list(filter(lambda p: p != norm_pattern, patterns))
		if len(patterns) == len_before:
			await interaction.response.send_message(
				f'{CONFIG["warning_emoji"]} Pattern `{norm_pattern}` not found.',
				ephemeral=True,
			)
			return
		self.__save_patterns(guild, patterns)
		await interaction.response.send_message(
			f'{CONFIG["success_emoji"]} Pattern `{norm_pattern}` removed.',
			ephemeral=True,
		)

	@username.command(
		description='Lists existing username patterns.'
	)
	async def list(self, interaction: Interaction) -> None:
		"""Command handler"""
		guild: Guild = interaction.guild
		patterns: list[str] = self.__get_patterns(guild)
		if len(patterns) == 0:
			await interaction.response.send_message(
				f'{CONFIG["success_emoji"]} No patterns defined.',
				ephemeral=True,
			)
		else:
			msg = f'{CONFIG["info_emoji"]} Patterns:\n\n> `' + '`\n> `'.join(patterns) + '`'
			await interaction.response.send_message(
				msg,
				ephemeral=True,
			)

	@Cog.listener()
	async def on_member_join(self, member: Member) -> None:
		"""Event handler"""
		for pattern in self.__get_patterns(member.guild):
			if self.matches(pattern, member.name):
				await self.handle_match(member, pattern)
			elif self.matches(pattern, member.display_name):
				await self.handle_match(member, pattern)

	def matches(self, pattern: str, subject: str) -> bool:
		"""Checks if a username matches a given pattern"""
		if pattern is None:
			return False
		if subject is None:
			return False
		return pattern.lower() in subject.lower()

	async def handle_match(self, member: Member, pattern: str) -> None:
		"""
		Handles a username match.
		"""
		# TODO: Prevent double handling?
		self.log(member.guild, f'User {member.id} {member.display_name} matches pattern "{pattern}"')
		context = UsernamePatternContext(member)
		bm = BotMessage(
			member.guild,
			f'User {member.mention} ({str(member.id)}, {member.display_name}) has ' +
			f'username matching pattern `{pattern}`.',
			BotMessage.TYPE_INFO if self.was_warned_recently(member) else BotMessage.TYPE_MOD_WARNING,
			context)
		self.record_warning(member)
		await bm.set_reactions(context.reactions())
		await self.post_message(bm)

	async def on_mod_react(self,
			bot_message: BotMessage,
			reaction: BotMessageReaction,
			reacted_by: Member) -> None:
		context: UsernamePatternContext = bot_message.context
		if reaction.emoji == CONFIG['kick_emoji']:
			await context.member.kick(
				reason=f'Rocketbot: Flagged username pattern. Kicked by {reacted_by.name}.')
			context.kicked_by = reacted_by
			self.log(context.member.guild, f'User {context.member.name} kicked by {reacted_by.name}')
			await bot_message.set_reactions(context.reactions())
		elif reaction.emoji == CONFIG['ban_emoji']:
			await context.member.ban(
				reason=f'Rocketbot: Flagged username pattern. Banned by {reacted_by.name}.',
				delete_message_days=0)
			context.banned_by = reacted_by
			self.log(context.member.guild, f'User {context.member.name} banned by {reacted_by.name}')
			await bot_message.set_reactions(context.reactions())
		elif reaction.emoji == CONFIG['ignore_emoji']:
			context.ignored_by = reacted_by
			self.log(context.member.guild, f'Warning ignored by {reacted_by.name}')
			await bot_message.set_reactions(context.reactions())