from discord import Guild, Member, Message, PartialEmoji
from discord.ext import commands
from datetime import datetime, timedelta
import math

from config import CONFIG
from rscollections import AgeBoundList, SizeBoundDict
from cogs.basecog import BaseCog, BotMessage, BotMessageReaction
from storage import Storage

class SpamContext:
	def __init__(self, member, message_hash):
		self.member = member
		self.message_hash = message_hash
		self.age = datetime.now()
		self.bot_message = None  # BotMessage
		self.is_kicked = False
		self.is_banned = False
		self.is_autobanned = False
		self.spam_messages = set()  # of Message
		self.deleted_messages = set()  # of Message

class CrossPostCog(BaseCog):
	STATE_KEY_RECENT_MESSAGES = "crosspost_recent_messages"
	STATE_KEY_SPAM_CONTEXT = "crosspost_spam_context"

	CONFIG_KEY_WARN_COUNT = "crosspost_warn_count"
	CONFIG_KEY_BAN_COUNT = "crosspost_ban_count"
	CONFIG_KEY_MIN_MESSAGE_LENGTH = "crosspost_min_message_length"
	CONFIG_KEY_MESSAGE_AGE = "crosspost_message_age"

	MIN_WARN_COUNT = 2
	MIN_BAN_COUNT = 2
	MIN_MESSAGE_LENGTH = 0
	MIN_TIME_SPAN = 1

	def __init__(self, bot):
		super().__init__(bot)
		self.max_spam_contexts = 12

	# Config

	def __warn_count(self, guild: Guild) -> int:
		return Storage.get_config_value(guild, self.CONFIG_KEY_WARN_COUNT) or \
			self.get_cog_default('warn_message_count')

	def __ban_count(self, guild: Guild) -> int:
		return Storage.get_config_value(guild, self.CONFIG_KEY_BAN_COUNT) or \
			self.get_cog_default('ban_message_count')

	def __min_message_length(self, guild: Guild) -> int:
		return Storage.get_config_value(guild, self.CONFIG_KEY_MIN_MESSAGE_LENGTH) or \
			self.get_cog_default('min_message_length')

	def __message_age_seconds(self, guild: Guild) -> int:
		return Storage.get_config_value(guild, self.CONFIG_KEY_MESSAGE_AGE) or \
			self.get_cog_default('time_window_seconds')

	async def __record_message(self, message: Message) -> None:
		if message.author.permissions_in(message.channel).ban_members:
			# User exempt from spam detection
			return
		if len(message.content) < self.__min_message_length(message.guild):
			# Message too short to count towards spam total
			return
		max_age = timedelta(seconds=self.__message_age_seconds(message.guild))
		recent_messages = Storage.get_state_value(message.guild, self.STATE_KEY_RECENT_MESSAGES) \
			or AgeBoundList(max_age, lambda index, message : message.created_at)
		recent_messages.max_age = max_age
		recent_messages.append(message)
		Storage.set_state_value(message.guild, self.STATE_KEY_RECENT_MESSAGES, recent_messages)

		# Get all recent messages by user
		member_messages = [m for m in recent_messages if m.author.id == message.author.id]
		if len(member_messages) < self.__warn_count(message.guild):
			return

		# Look for repeats
		hash_to_count = {}
		max_count = 0
		for m in member_messages:
			key = hash(m.content)
			count = (hash_to_count.get(key) or 0) + 1
			hash_to_count[key] = count
			max_count = max(max_count, count)
		if max_count < self.__warn_count(message.guild):
			return

		# Handle the spam
		spam_lookup = Storage.get_state_value(message.guild, self.STATE_KEY_SPAM_CONTEXT) \
			or SizeBoundDict(self.max_spam_contexts, lambda key, context : context.age)
		Storage.set_state_value(message.guild, self.STATE_KEY_SPAM_CONTEXT, spam_lookup)
		for message_hash, count in hash_to_count.items():
			if count < self.__warn_count(message.guild):
				continue
			key = f'{message.author.id}|{message_hash}'
			context = spam_lookup.get(key)
			is_new = context is None
			if context is None:
				context = SpamContext(message.author, message_hash)
				spam_lookup[key] = context
				context.age = message.created_at
			for m in member_messages:
				if hash(m.content) == message_hash:
					context.spam_messages.add(m)
			await self.__update_from_context(context)

	async def __update_from_context(self, context: SpamContext):
		if len(context.spam_messages) >= self.__ban_count(context.member.guild):
			if not context.is_banned:
				count = len(context.spam_messages)
				await context.member.ban(reason=f'Autobanned by Rocketbot for posting same message {count} times', delete_message_days=1)
				context.is_kicked = True
				context.is_banned = True
				context.is_autobanned = True
				context.deleted_messages |= context.spam_messages
			else:
				# Already banned. Nothing to update in the message.
				return
		await self.__update_message_from_context(context)

	async def __update_message_from_context(self, context: SpamContext) -> None:
		first_spam_message = next(iter(context.spam_messages))
		spam_count = len(context.spam_messages)
		deleted_count = len(context.deleted_messages)
		message = context.bot_message
		if message is None:
			message = BotMessage(context.member.guild, '',
				BotMessage.TYPE_MOD_WARNING, context)
			message.quote = first_spam_message.content
		if context.is_autobanned:
			text = f'User {context.member.mention} auto banned for ' + \
				f'posting the same message {deleted_count} ' + \
				'times. Messages from past 24 hours deleted.'
			await message.set_reactions([])
			await message.set_text(text)
		else:
			await message.set_text(f'User {context.member.mention} posted ' +
				f'the same message {spam_count} times.')
			can_delete = spam_count > deleted_count
			can_kick = not context.is_kicked
			can_ban = not context.is_banned
			await message.add_reaction(
				BotMessageReaction(
					CONFIG['trash_emoji'],
					can_delete,
					'Delete messages' if can_delete else f'Deleted {deleted_count} messages'))
			if can_ban:
				# Only show kick info if they can also be banned. Otherwise we say
				# dumb stuff like "user was kicked, user was banned".
				await message.add_reaction(
					BotMessageReaction(
						CONFIG['kick_emoji'],
						can_kick,
						'Kick user' if can_kick else 'User kicked'))
			else:
				await message.remove_reaction(CONFIG['kick_emoji'])
			await message.add_reaction(
				BotMessageReaction(
					CONFIG['ban_emoji'], 
					can_ban,
					'Ban user' if can_ban else 'User banned'))
		if context.bot_message is None:
			await self.post_message(message)
			context.bot_message = message

	async def __delete_messages(self, context: SpamContext) -> None:
		for message in context.spam_messages - context.deleted_messages:
			await message.delete()
			context.deleted_messages.add(message)
		await self.__update_from_context(context)

	async def __kick(self, context: SpamContext) -> None:
		await context.member.kick(reason='Posting same message repeatedly')
		context.is_kicked = True
		await self.__update_from_context(context)

	async def __ban(self, context: SpamContext) -> None:
		await context.member.ban(reason='Posting same message repeatedly', delete_message_days=1)
		context.deleted_messages |= context.spam_messages
		context.is_kicked = True
		context.is_banned = True
		await self.__update_from_context(context)

	async def on_mod_react(self,
			bot_message: BotMessage,
			reaction: BotMessageReaction,
			reacted_by: Member) -> None:
		context: SpamContext = bot_message.context
		if context is None:
			return

		if reaction.emoji == CONFIG['trash_emoji']:
			await self.__delete_messages(context)
		elif reaction.emoji == CONFIG['kick_emoji']:
			await self.__kick(context)
		elif reaction.emoji == CONFIG['ban_emoji']:
			await self.__ban(context)

	@commands.Cog.listener()
	async def on_message(self, message: Message):
		if message.author is None or message.channel is None or message.guild is None:
			return
		await self.__record_message(message)

	# -- Commands -----------------------------------------------------------

	@commands.group(
		brief='Manages crosspost/repeated post detection and handling',
	)
	@commands.has_permissions(ban_members=True)
	@commands.guild_only()
	async def crosspost(self, context: commands.Context):
		'Command group'
		if context.invoked_subcommand is None:
			await context.send_help()

	@crosspost.command(
		name='setwarncount',
		brief='Sets the number of duplicate messages to trigger a mod warning',
		description='If the same user posts the exact same message ' +
			'content this many times a warning will be posted to the mods,' +
			'even if the messages are posted in different channels.',
		usage='<warn_count:int>',
	)
	async def joinraid_setwarncount(self, context: commands.Context,
			warn_count: int):
		if not await self.validate_param(context, 'warn_count', warn_count,
			allowed_types=(int, ), min_value=self.MIN_WARN_COUNT):
			return
		Storage.set_config_value(context.guild, self.CONFIG_KEY_WARN_COUNT, warn_count)
		await context.message.reply(
			CONFIG['success_emoji'] + ' ' +
			'Mods will be warned if a user posts the exact same message ' +
			f'{warn_count} or more times within ' +
			f'{self.__message_age_seconds(context.guild)} seconds.',
			mention_author=False)

	@crosspost.command(
		name='getwarncount',
		brief='Returns the number of duplicate messages to trigger a mod warning',
	)
	async def joinraid_getwarncount(self, context: commands.Context):
		await context.message.reply(f'ℹ️ Mods will be warned if a user posts ' +
			f'the exact same message {self.__warn_count(context.guild)} or more ' +
			f'times within {self.__message_age_seconds(context.guild)} seconds.',
			mention_author=False)

	@crosspost.command(
		name='setbancount',
		brief='Sets the number of duplicate messages to trigger an automatic ban',
		description='If the same user posts the exact same message ' +
			'content this many times they will be automatically banned and the ' +
			'mods will be alerted.',
		usage='<ban_count:int>',
	)
	async def joinraid_setbancount(self, context: commands.Context,
			ban_count: int):
		if not await self.validate_param(context, 'ban_count', ban_count,
			allowed_types=(int, ), min_value=self.MIN_BAN_COUNT):
			return
		Storage.set_config_value(context.guild, self.CONFIG_KEY_BAN_COUNT, ban_count)
		await context.message.reply(
			CONFIG['success_emoji'] + ' ' +
			'Users will be banned if they post the exact same message ' +
			f'{ban_count} or more times within ' +
			f'{self.__message_age_seconds(context.guild)} seconds.',
			mention_author=False)

	@crosspost.command(
		name='getbancount',
		brief='Returns the number of duplicate messages to trigger an automatic ban',
	)
	async def joinraid_getbancount(self, context: commands.Context):
		await context.message.reply(
			CONFIG['info_emoji'] + ' ' +
			'Users will be banned if they post the exact same message ' +
			f'{self.__ban_count(context.guild)} or more times within ' +
			f'{self.__message_age_seconds(context.guild)} seconds.',
			mention_author=False)

	@crosspost.command(
		name='setminlength',
		brief='Sets the minimum number of characters for a message to count toward spamming',
		description='Messages shorter than this number of characters will not ' +
			'count toward spam counts. This helps prevent flagging common, ' +
			'frequent, short responses like "lol". A value of 0 counts all messages.',
		usage='<min_length:int>',
	)
	async def joinraid_setminlength(self, context: commands.Context,
			min_length: int):
		if not await self.validate_param(context, 'min_length', min_length,
			allowed_types=(int, ), min_value=self.MIN_MESSAGE_LENGTH):
			return
		Storage.set_config_value(context.guild, self.CONFIG_KEY_MIN_MESSAGE_LENGTH, min_length)
		if min_length == 0:
			await context.message.reply(
				CONFIG['success_emoji'] + ' ' +
				f'All messages will count against spam counts, regardless ' +
				'of length.', mention_author=False)
		else:
			await context.message.reply(
				CONFIG['success_emoji'] + ' ' +
				f'Only messages {min_length} characters or longer will ' +
				'count against spam counts.',
				mention_author=False)

	@crosspost.command(
		name='getminlength',
		brief='Returns the number of duplicate messages to trigger an automatic ban',
	)
	async def joinraid_getminlength(self, context: commands.Context):
		min_length = self.__min_message_length(context.guild)
		if min_length == 0:
			await context.message.reply(
				CONFIG['info_emoji'] + ' ' +
				f'All messages will count against spam counts, regardless ' +
				'of length.', mention_author=False)
		else:
			await context.message.reply(
				CONFIG['info_emoji'] + ' ' +
				f'Only messages {min_length} characters or longer will ' +
				'count against spam counts.',
				mention_author=False)

	@crosspost.command(
		name='settimewindow',
		brief='Sets the length of time recent messages are checked for duplicates',
		description='Repeated messages are only checked against recent ' +
			'messages. This sets the length of that window, in seconds. Lower ' +
			'values save memory and prevent false positives.',
		usage='<seconds:int>',
	)
	async def joinraid_settimewindow(self, context: commands.Context,
			seconds: int):
		if not await self.validate_param(context, 'seconds', seconds,
			allowed_types=(int, ), min_value=self.MIN_TIME_SPAN):
			return
		Storage.set_config_value(context.guild, self.CONFIG_KEY_MESSAGE_AGE, seconds)
		await context.message.reply(
			CONFIG['success_emoji'] + ' ' +
			f'Only messages in the past {seconds} seconds will be checked ' +
			'for duplicates.',
			mention_author=False)

	@crosspost.command(
		name='gettimewindow',
		brief='Returns the length of time recent messages are checked for duplicates',
	)
	async def joinraid_gettimewindow(self, context: commands.Context):
		seconds = self.__message_age_seconds(context.guild)
		await context.message.reply(
			CONFIG['info_emoji'] + ' ' +
			f'Only messages in the past {seconds} seconds will be checked ' +
			'for duplicates.',
			mention_author=False)