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

from config import CONFIG
from rscollections import AgeBoundDict
from storage import ConfigKey, Storage
import json

class BotMessageReaction:
	"""
	A possible reaction to a bot message that will trigger an action. The list
	of available reactions will be listed at the end of a BotMessage. When a
	mod reacts to the message with the emote, something can happen.

	If the reaction is disabled, reactions will not register. The description
	will still show up in the message, but no emoji is shown. This can be used
	to explain why an action is no longer available.
	"""
	def __init__(self, emoji: str, is_enabled: bool, description: str):
		self.emoji = emoji
		self.is_enabled = is_enabled
		self.description = description

	def __eq__(self, other):
		return other is not None and \
			other.emoji == self.emoji and \
			other.is_enabled == self.is_enabled and \
			other.description == self.description

class BotMessage:
	"""
	Holds state for a bot-generated message. A message is composed, sent via
	`BaseCog.post_message()`, and can later be updated.

	A message consists of a type (e.g. info, warning), text, optional quoted
	text (such as the content of a flagged message), and an optional list of
	actions that can be taken via a mod reacting to the message.
	"""

	TYPE_DEFAULT = 0
	TYPE_INFO = 1
	TYPE_MOD_WARNING = 2
	TYPE_SUCCESS = 3
	TYPE_FAILURE = 4

	def __init__(self,
			guild: Guild,
			text: str,
			type: int = 0, # TYPE_DEFAULT
			context = None,
			reply_to: Message = None):
		self.guild = guild
		self.text = text
		self.type = type
		self.context = context
		self.quote = None
		self.__posted_text = None  # last text posted, to test for changes
		self.__posted_emoji = set()
		self.__message = None  # Message
		self.__reply_to = reply_to
		self.__reactions = []  # BotMessageReaction[]

	def is_sent(self) -> bool:
		"""
		Returns whether this message has been sent to the guild. This may
		continue returning False even after calling BaseCog.post_message if
		the guild has no configured warning channel.
		"""
		return self.__message is not None

	def message_id(self):
		return self.__message.id if self.__message else None

	def message_sent_at(self):
		return self.__message.created_at if self.__message else None

	async def set_text(self, new_text: str) -> None:
		"""
		Replaces the text of this message. If the message has been sent, it will
		be updated.
		"""
		self.text = new_text
		await self.__update_if_sent()

	async def set_reactions(self, reactions: list) -> None:
		"""
		Replaces all BotMessageReactions with a new list. If the message has
		been sent, it will be updated.
		"""
		if reactions == self.__reactions:
			# No change
			return
		self.__reactions = reactions.copy() if reactions is not None else []
		await self.__update_if_sent()

	async def add_reaction(self, reaction: BotMessageReaction) -> None:
		"""
		Adds one BotMessageReaction to this message. If a reaction already
		exists for the given emoji it is replaced with the new one. If the
		message has been sent, it will be updated.
		"""
		# Alias for update. Makes for clearer intent.
		await self.update_reaction(reaction)

	async def update_reaction(self, reaction: BotMessageReaction) -> None:
		"""
		Updates or adds a BotMessageReaction. If the message has been sent, it
		will be updated.
		"""
		found = False
		for i in range(len(self.__reactions)):
			existing = self.__reactions[i]
			if existing.emoji == reaction.emoji:
				if reaction == self.__reactions[i]:
					# No change
					return
				self.__reactions[i] = reaction
				found = True
				break
		if not found:
			self.__reactions.append(reaction)
		await self.__update_if_sent()

	async def remove_reaction(self, reaction_or_emoji) -> None:
		"""
		Removes a reaction. Can pass either a BotMessageReaction or just the
		emoji string. If the message has been sent, it will be updated.
		"""
		for i in range(len(self.__reactions)):
			existing = self.__reactions[i]
			if (isinstance(reaction_or_emoji, str) and existing.emoji == reaction_or_emoji) or \
				(isinstance(reaction_or_emoji, BotMessageReaction) and existing.emoji == reaction_or_emoji.emoji):
				self.__reactions.pop(i)
				await self.__update_if_sent()
				return

	def reaction_for_emoji(self, emoji) -> BotMessageReaction:
		for reaction in self.__reactions:
			if isinstance(emoji, PartialEmoji) and reaction.emoji == emoji.name:
				return reaction
			elif isinstance(emoji, str) and reaction.emoji == emoji:
				return reaction
		return None

	async def __update_if_sent(self) -> None:
		if self.__message:
			await self._update()

	async def _update(self) -> None:
		content: str = self.__formatted_message()
		if self.__message:
			if content != self.__posted_text:
				await self.__message.edit(content=content)
				self.__posted_text = content
		else:
			if self.__reply_to:
				self.__message = await self.__reply_to.reply(content=content, mention_author=False)
				self.__posted_text = content
			else:
				channel_id = Storage.get_config_value(self.guild, ConfigKey.WARNING_CHANNEL_ID)
				if channel_id is None:
					BaseCog.guild_trace(self.guild, 'No warning channel set! No warning issued.')
					return
				channel: TextChannel = self.guild.get_channel(channel_id)
				if channel is None:
					BaseCog.guild_trace(self.guild, 'Configured warning channel does not exist!')
					return
				self.__message = await channel.send(content=content)
				self.__posted_text = content
		emoji_to_remove = self.__posted_emoji.copy()
		for reaction in self.__reactions:
			if reaction.is_enabled:
				if reaction.emoji not in self.__posted_emoji:
					await self.__message.add_reaction(reaction.emoji)
					self.__posted_emoji.add(reaction.emoji)
				if reaction.emoji in emoji_to_remove:
					emoji_to_remove.remove(reaction.emoji)
		for emoji in emoji_to_remove:
			await self.__message.clear_reaction(emoji)
			if emoji in self.__posted_emoji:
				self.__posted_emoji.remove(emoji)

	def __formatted_message(self) -> str:
		s: str = ''

		if self.type == self.TYPE_INFO:
			s += CONFIG['info_emoji'] + ' '
		elif self.type == self.TYPE_MOD_WARNING:
			mention: str = Storage.get_config_value(self.guild, ConfigKey.WARNING_MENTION)
			if mention:
				s += mention + ' '
			s += CONFIG['warning_emoji'] + ' '
		elif self.type == self.TYPE_SUCCESS:
			s += CONFIG['success_emoji'] + ' '
		elif self.type == self.TYPE_FAILURE:
			s += CONFIG['failure_emoji'] + ' '

		s += self.text

		if self.quote:
			s += f'\n\n> {self.quote}'

		if len(self.__reactions) > 0:
			s += '\n\nAvailable actions:'
			for reaction in self.__reactions:
				if reaction.is_enabled:
					s += f'\n   {reaction.emoji} {reaction.description}'
				else:
					s += f'\n   {reaction.description}'

		return s

class BaseCog(commands.Cog):
	def __init__(self, bot):
		self.bot = bot

	# Config

	@classmethod
	def get_cog_default(cls, key: str):
		"""
		Convenience method for getting a cog configuration default from
		`CONFIG['cogs'][<cogname>][<key>]`.
		"""
		cogs: dict = CONFIG['cog_defaults']
		cog = cogs.get(cls.__name__)
		if cog is None:
			return None
		return cog.get(key)

	# Bot message handling

	@classmethod
	def __bot_messages(cls, guild: Guild) -> AgeBoundDict:
		bm = Storage.get_state_value(guild, 'bot_messages')
		if bm is None:
			far_future = datetime.utcnow() + timedelta(days=1000)
			bm = AgeBoundDict(timedelta(seconds=600),
				lambda k, v : v.message_sent_at() or far_future)
			Storage.set_state_value(guild, 'bot_messages', bm)
		return bm

	@classmethod
	async def post_message(cls, message: BotMessage) -> bool:
		await message._update()
		guild_messages = cls.__bot_messages(message.guild)
		if message.is_sent():
			guild_messages[message.message_id()] = message
			return True
		return False

	@commands.Cog.listener()
	async def on_raw_reaction_add(self, payload: RawReactionActionEvent):
		'Event handler'
		if payload.user_id == self.bot.user.id:
			# Ignore bot's own reactions
			return
		member: Member = payload.member
		if member is None:
			return
		guild: Guild = self.bot.get_guild(payload.guild_id)
		if guild is None:
			# Possibly a DM
			return
		channel: GuildChannel = guild.get_channel(payload.channel_id)
		if channel is None:
			# Possibly a DM
			return
		message: Message = await channel.fetch_message(payload.message_id)
		if message is None:
			# Message deleted?
			return
		if message.author.id != self.bot.user.id:
			# Bot didn't author this
			return
		guild_messages = self.__bot_messages(guild)
		bot_message = guild_messages.get(message.id)
		if bot_message is None:
			# Unknown message (expired or was never tracked)
			return
		reaction = bot_message.reaction_for_emoji(payload.emoji)
		if reaction is None or not reaction.is_enabled:
			# Can't use this reaction with this message
			return
		if not member.permissions_in(channel).ban_members:
			# Not a mod (could make permissions configurable per BotMessageReaction some day)
			return
		await self.on_mod_react(bot_message, reaction, member)

	async def on_mod_react(self,
			bot_message: BotMessage,
			reaction: BotMessageReaction,
			reacted_by: Member) -> None:
		"""
		Subclass override point for receiving mod reactions to bot messages sent
		via `post_message()`.
		"""
		pass

	@classmethod
	async def validate_param(cls, context: commands.Context, param_name: str, value,
		allowed_types: tuple = None,
		min_value = None,
		max_value = None) -> bool:
		"""
		Convenience method for validating a command parameter is of the expected
		type and in the expected range. Bad values will cause a reply to be sent
		to the original message and a False will be returned. If all checks
		succeed, True will be returned.
		"""
		# TODO: Rework this to use BotMessage
		if allowed_types is not None and not isinstance(value, allowed_types):
			if len(allowed_types) == 1:
				await context.message.reply(f'⚠️ `{param_name}` must be of type ' +
					f'{allowed_types[0]}.', mention_author=False)
			else:
				await context.message.reply(f'⚠️ `{param_name}` must be of types ' +
					f'{allowed_types}.', mention_author=False)
			return False
		if min_value is not None and value < min_value:
			await context.message.reply(f'⚠️ `{param_name}` must be >= {min_value}.',
				mention_author=False)
			return False
		if max_value is not None and value > max_value:
			await context.message.reply(f'⚠️ `{param_name}` must be <= {max_value}.',
				mention_author=False)
		return True

	@classmethod
	async def warn(cls, guild: Guild, message: str) -> Message:
		"""
		Sends a warning message to the configured warning channel for the
		given guild. If no warning channel is configured no action is taken.
		Returns the Message if successful or None if not.
		"""
		channel_id = Storage.get_config_value(guild, ConfigKey.WARNING_CHANNEL_ID)
		if channel_id is None:
			cls.guild_trace(guild, 'No warning channel set! No warning issued.')
			return None
		channel: TextChannel = guild.get_channel(channel_id)
		if channel is None:
			cls.guild_trace(guild, 'Configured warning channel does not exist!')
			return None
		mention: str = Storage.get_config_value(guild, ConfigKey.WARNING_MENTION)
		text: str = message
		if mention is not None:
			text = f'{mention} {text}'
		msg: Message = await channel.send(text)
		return msg

	@classmethod
	async def update_warn(cls, warn_message: Message, new_text: str) -> None:
		"""
		Updates the text of a previously posted `warn`. Includes configured
		mentions if necessary.
		"""
		text: str = new_text
		mention: str = Storage.get_config_value(
			warn_message.guild,
			ConfigKey.WARNING_MENTION)
		if mention is not None:
			text = f'{mention} {text}'
		await warn_message.edit(content=text)

	@classmethod
	def guild_trace(cls, guild: Guild, message: str) -> None:
		print(f'[guild {guild.id}|{guild.name}] {message}')