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

"""
Cog for matching messages against guild-configurable criteria and taking
automated actions on them.
"""
from datetime import datetime
from typing import Optional

from discord import Guild, Member, Message, utils as discordutils
from discord.ext import commands

from config import CONFIG
from rocketbot.cogs.basecog import BaseCog, BotMessage, BotMessageReaction
from rocketbot.cogsetting import CogSetting
from rocketbot.pattern import PatternCompiler, PatternDeprecationError, \
	PatternError, PatternStatement
from rocketbot.storage import Storage

class PatternContext:
	"""
	Data about a message that has matched a configured statement and what
	actions have been carried out.
	"""
	def __init__(self, message: Message, statement: PatternStatement):
		self.message = message
		self.statement = statement
		self.is_deleted = False
		self.is_kicked = False
		self.is_banned = False

class PatternCog(BaseCog, name='Pattern Matching'):
	"""
	Highly flexible cog for performing various actions on messages that match
	various criteria. Patterns can be defined by mods for each guild.
	"""

	SETTING_PATTERNS = CogSetting('patterns', None)

	def __get_patterns(self, guild: Guild) -> dict[str, PatternStatement]:
		"""
		Returns a name -> PatternStatement lookup for the guild.
		"""
		patterns: dict[str, PatternStatement] = Storage.get_state_value(guild,
			'PatternCog.patterns')
		if patterns is None:
			jsons: list[dict] = self.get_guild_setting(guild, self.SETTING_PATTERNS) or []
			pattern_list: list[PatternStatement] = []
			for json in jsons:
				try:
					ps = PatternStatement.from_json(json)
					pattern_list.append(ps)
					try:
						ps.check_deprecations()
					except PatternDeprecationError as e:
						self.log(guild, f'Pattern {ps.name}: {e}')
				except PatternError as e:
					self.log(guild, f'Error decoding pattern "{json["name"]}": {e}')
			patterns = { p.name:p for p in pattern_list}
			Storage.set_state_value(guild, 'PatternCog.patterns', patterns)
		return patterns

	@classmethod
	def __save_patterns(cls,
			guild: Guild,
			patterns: dict[str, PatternStatement]) -> None:
		to_save: list[dict] = list(map(lambda ps: ps.to_json(), patterns.values()))
		cls.set_guild_setting(guild, cls.SETTING_PATTERNS, to_save)

	@classmethod
	def __get_last_matched(cls, guild: Guild, name: str) -> Optional[datetime]:
		last_matched: dict[str, datetime] = Storage.get_state_value(guild, 'PatternCog.last_matched')
		if last_matched:
			return last_matched.get(name)
		return None

	@classmethod
	def __set_last_matched(cls, guild: Guild, name: str, time: datetime) -> None:
		last_matched: dict[str, datetime] = Storage.get_state_value(guild, 'PatternCog.last_matched')
		if last_matched is None:
			last_matched = {}
			Storage.set_state_value(guild, 'PatternCog.last_matched', last_matched)
		last_matched[name] = time

	@commands.Cog.listener()
	async def on_message(self, message: Message) -> None:
		"""Event listener"""
		if message.author is None or \
				message.author.bot or \
				message.channel is None or \
				message.guild is None or \
				message.content is None or \
				message.content == '':
			return
		if message.channel.permissions_for(message.author).ban_members:
			# Ignore mods
			return

		patterns = self.__get_patterns(message.guild)
		for statement in sorted(patterns.values(), key=lambda s : s.priority, reverse=True):
			other_fields = {
				'last_matched': self.__get_last_matched(message.guild, statement.name),
			}
			if statement.expression.matches(message, other_fields):
				self.__set_last_matched(message.guild, statement.name, message.created_at)
				await self.__trigger_actions(message, statement)
				break

	async def __trigger_actions(self,
			message: Message,
			statement: PatternStatement) -> None:
		context = PatternContext(message, statement)
		should_post_message = False
		message_type: int = BotMessage.TYPE_DEFAULT
		action_descriptions = []
		self.log(message.guild, f'Message from {message.author.name} matched ' + \
			f'pattern "{statement.name}"')
		for action in statement.actions:
			if action.action == 'ban':
				await message.author.ban(
					reason='Rocketbot: Message matched custom pattern named ' + \
						f'"{statement.name}"',
					delete_message_days=0)
				context.is_banned = True
				context.is_kicked = True
				action_descriptions.append('Author banned')
				self.log(message.guild, f'{message.author.name} banned')
			elif action.action == 'delete':
				await message.delete()
				context.is_deleted = True
				action_descriptions.append('Message deleted')
				self.log(message.guild, f'{message.author.name}\'s message deleted')
			elif action.action == 'kick':
				await message.author.kick(
					reason='Rocketbot: Message matched custom pattern named ' + \
						f'"{statement.name}"')
				context.is_kicked = True
				action_descriptions.append('Author kicked')
				self.log(message.guild, f'{message.author.name} kicked')
			elif action.action == 'modinfo':
				should_post_message = True
				message_type = BotMessage.TYPE_INFO
				action_descriptions.append('Message logged')
			elif action.action == 'modwarn':
				should_post_message = not self.was_warned_recently(message.author)
				message_type = BotMessage.TYPE_MOD_WARNING
				action_descriptions.append('Mods alerted')
			elif action.action == 'reply':
				await message.reply(
					f'{action.arguments[0]}',
					mention_author=False)
				action_descriptions.append('Autoreplied')
				self.log(message.guild, f'autoreplied to {message.author.name}')
		if should_post_message:
			bm = BotMessage(
				message.guild,
				f'User {message.author.name} tripped custom pattern ' + \
					f'`{statement.name}`.\n\nAutomatic actions taken:\n• ' + \
					('\n• '.join(action_descriptions)),
				type=message_type,
				context=context)
			self.record_warning(message.author)
			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)

	async def on_mod_react(self,
			bot_message: BotMessage,
			reaction: BotMessageReaction,
			reacted_by: Member) -> None:
		context: PatternContext = bot_message.context
		if reaction.emoji == CONFIG['trash_emoji']:
			await context.message.delete()
			context.is_deleted = True
		elif reaction.emoji == CONFIG['kick_emoji']:
			await context.message.author.kick(
				reason='Rocketbot: Message matched custom pattern named ' + \
					f'"{context.statement.name}". Kicked by {reacted_by.name}.')
			context.is_kicked = True
		elif reaction.emoji == CONFIG['ban_emoji']:
			await context.message.author.ban(
				reason='Rocketbot: Message matched custom pattern named ' + \
					f'"{context.statement.name}". Banned by {reacted_by.name}.',
					delete_message_days=1)
			context.is_banned = True
		await bot_message.set_reactions(BotMessageReaction.standard_set(
			did_delete=context.is_deleted,
			did_kick=context.is_kicked,
			did_ban=context.is_banned))

	@commands.group(
		brief='Manages message pattern matching',
	)
	@commands.has_permissions(ban_members=True)
	@commands.guild_only()
	async def pattern(self, context: commands.Context):
		"""Message pattern matching command group"""
		if context.invoked_subcommand is None:
			await context.send_help()

	@pattern.command(
		brief='Adds a custom pattern',
		description='Adds a custom pattern. Patterns use a simplified ' + \
			'expression language. Full documentation found here: ' + \
			'https://git.rixafrix.com/ialbert/python-app-rocketbot/src/' + \
			'branch/master/patterns.md',
		usage='<pattern_name> <expression...>',
		ignore_extra=True
	)
	async def add(self, context: commands.Context, name: str):
		"""Command handler"""
		pattern_str = PatternCompiler.expression_str_from_context(context, name)
		try:
			statement = PatternCompiler.parse_statement(name, pattern_str)
			statement.check_deprecations()
			patterns = self.__get_patterns(context.guild)
			patterns[name] = statement
			self.__save_patterns(context.guild, patterns)
			await context.message.reply(
				f'{CONFIG["success_emoji"]} Pattern `{name}` added.',
				mention_author=False)
		except PatternError as e:
			await context.message.reply(
				f'{CONFIG["failure_emoji"]} Error parsing statement. {e}',
				mention_author=False)

	@pattern.command(
		brief='Removes a custom pattern',
		usage='<pattern_name>'
	)
	async def remove(self, context: commands.Context, name: str):
		"""Command handler"""
		patterns = self.__get_patterns(context.guild)
		if patterns.get(name) is not None:
			del patterns[name]
			self.__save_patterns(context.guild, patterns)
			await context.message.reply(
				f'{CONFIG["success_emoji"]} Pattern `{name}` deleted.',
				mention_author=False)
		else:
			await context.message.reply(
				f'{CONFIG["failure_emoji"]} No pattern named `{name}`.',
				mention_author=False)

	@pattern.command(
		brief='Lists all patterns'
	)
	async def list(self, context: commands.Context) -> None:
		"""Command handler"""
		patterns = self.__get_patterns(context.guild)
		if len(patterns) == 0:
			await context.message.reply('No patterns defined.', mention_author=False)
			return
		msg = ''
		for name, statement in sorted(patterns.items()):
			msg += f'Pattern `{name}` (priority={statement.priority}):\n```\n{statement.original}\n```\n'
		await context.message.reply(msg, mention_author=False)

	@pattern.command(
		brief='Sets a pattern\'s priority level',
		description='Sets the priority for a pattern. Messages are checked ' +
			'against patterns with the highest priority first. Patterns with ' +
			'the same priority may be checked in arbitrary order. Default ' +
			'priority is 100.',
	)
	async def setpriority(self, context: commands.Context, name: str, priority: int) -> None:
		"""Command handler"""
		patterns = self.__get_patterns(context.guild)
		statement = patterns.get(name)
		if statement is None:
			await context.message.reply(
				f'{CONFIG["failure_emoji"]} No such pattern `{name}`',
				mention_author=False)
			return
		statement.priority = priority
		self.__save_patterns(context.guild, patterns)
		await context.message.reply(
			f'{CONFIG["success_emoji"]} Priority for pattern `{name}` ' + \
			f'updated to `{priority}`.',
			mention_author=False)