"""
Classes for crafting messages from the bot. Content can change as information
changes, and mods can perform actions on the message via emoji reactions.
"""
from datetime import datetime
from typing import Any, Optional, Union

from discord import Guild, Message, PartialEmoji, TextChannel

from config import CONFIG
from rocketbot.storage import ConfigKey, Storage
from rocketbot.utils import bot_log


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):
		"""
		Creates a bot message reaction.
		- emoji: The emoji string
		- is_enabled: Whether the emoji can be used
		- description: What reacting with this emoji does (or an explanation of
		  why it's disabled)
		"""
		self.emoji: str = emoji
		self.is_enabled: bool = is_enabled
		self.description: str = 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

	@classmethod
	def standard_set(cls,
			did_delete: bool = None,
			message_count: int = 1,
			did_kick: bool = None,
			did_ban: bool = None,
			user_count: int = 1) -> list: # list[BotMessageReaction]:
		"""
		Convenience factory for generating any of the three most common
		commands: delete message(s), kick user(s), and ban user(s). All
		arguments are optional. Resulting list can be passed directly to
		`BotMessage.set_reactions()`.

		Params
		- did_delete     Whether the message(s) have been deleted. Pass True or
		                 False if this applies, omit to leave out delete action.
		- message_count  How many messages there are. Used for pluralizing
		                 description. Defaults to 1. Omit if n/a.
		- did_kick       Whether the user(s) have been kicked. Pass True or
		                 False if this applies, omit to leave out kick action.
		- did_ban        Whether the user(s) have been banned. Pass True or
		                 False if this applies, omit to leave out ban action.
		- user_count     How many users there are. Used for pluralizing
		                 description. Defaults to 1. Omit if n/a.
		"""
		reactions: list[BotMessageReaction] = []
		if did_delete is not None:
			if did_delete:
				reactions.append(BotMessageReaction(
					CONFIG['trash_emoji'],
					False,
					'Message deleted' if message_count == 1 else 'Messages deleted'))
			else:
				reactions.append(BotMessageReaction(
					CONFIG['trash_emoji'],
					True,
					'Delete message' if message_count == 1 else 'Delete messages'))
		if did_kick is not None:
			if did_ban is not None and did_ban:
				# Don't show kick option at all if we also banned
				pass
			elif did_kick:
				reactions.append(BotMessageReaction(
					CONFIG['kick_emoji'],
					False,
					'User kicked' if user_count == 1 else 'Users kicked'))
			else:
				reactions.append(BotMessageReaction(
					CONFIG['kick_emoji'],
					True,
					'Kick user' if user_count == 1 else 'Kick users'))
		if did_ban is not None:
			if did_ban:
				reactions.append(BotMessageReaction(
					CONFIG['ban_emoji'],
					False,
					'User banned' if user_count == 1 else 'Users banned'))
			else:
				reactions.append(BotMessageReaction(
					CONFIG['ban_emoji'],
					True,
					'Ban user' if user_count == 1 else 'Ban users'))
		return reactions

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: int = 0
	TYPE_INFO: int = 1
	TYPE_MOD_WARNING: int = 2
	TYPE_SUCCESS: int = 3
	TYPE_FAILURE: int = 4
	TYPE_LOG: int = 5

	def __init__(self,
			guild: Guild,
			text: str,
			type: int = TYPE_DEFAULT, # pylint: disable=redefined-builtin
			context: Optional[Any] = None,
			reply_to: Optional[Message] = None,
			suppress_embeds: bool = False):
		"""
		Creates a bot message.
		- guild: The Discord guild to send the message to.
		- text: Main text of the message.
		- type: One of the TYPE_ constants.
		- context: Arbitrary value that will be passed in the callback. Can be
		  associated data for performing some action. (optional)
		- reply_to: Existing message this message is in reply to. (optional)
		"""
		self.guild: Guild = guild
		self.text: str = text
		self.type: int = type
		self.context: Optional[Any] = context
		self.quote: Optional[str] = None
		self.source_cog = None  # Set by `BaseCog.post_message()`
		self.__posted_text: list[str] = []  # last text posted, to test for changes
		self.__posted_emoji: set[str] = set()  # last emoji list posted
		self.__messages: list[Message] = []  # set once the message has been posted
		self.__reply_to: Optional[Message] = reply_to
		self.__suppress_embeds = suppress_embeds
		self.__reactions: list[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 len(self.__messages) > 0

	def message_ids(self) -> list[int]:
		"""Returns the ids of all actual Messages sent. One bot message may be
		broken into multiple Discord messages."""
		return [ m.id for m in self.__messages ]

	def message_sent_at(self) -> Optional[datetime]:
		"""Returns when the message was sent or None if not sent."""
		return self.__messages[0].created_at if len(self.__messages) > 0 else None

	def has_reactions(self) -> bool:
		"""Whether this message has any reactions defined."""
		return len(self.__reactions) > 0

	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[BotMessageReaction]) -> 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, existing in enumerate(self.__reactions):
			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: Union[BotMessageReaction, str]) -> 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, existing in enumerate(self.__reactions):
			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) -> Optional[BotMessageReaction]:
		"""
		Finds the BotMessageReaction for the given emoji or None if not found.
		Accepts either a PartialEmoji or str.
		"""
		for reaction in self.__reactions:
			if isinstance(emoji, PartialEmoji) and reaction.emoji == emoji.name:
				return reaction
			if isinstance(emoji, str) and reaction.emoji == emoji:
				return reaction
		return None

	async def update_if_sent(self) -> None:
		"""
		Updates the text and/or reactions on a message if it was sent to
		the guild, otherwise does nothing. Does not need to be called by
		BaseCog subclasses.
		"""
		if len(self.__messages) > 0:
			await self.update()

	async def update(self) -> None:
		"""
		Sends or updates an already sent message based on BotMessage state.
		Does not need to be called by BaseCog subclasses.
		"""
		message_bodies: list[str] = self.__formatted_message()
		if len(self.__messages) > 0:
			if message_bodies != self.__posted_text:
				while len(self.__messages) > len(message_bodies):
					last_message = self.__messages.pop(-1)
					await last_message.delete()
					del Storage.get_bot_messages(self.guild)[last_message.id]
				for i in range(min(len(message_bodies), len(self.__messages))):
					await self.__messages[i].edit(content=message_bodies[i])
				while len(self.__messages) < len(message_bodies):
					body = message_bodies[len(self.__messages)]
					message = await self.__messages[0].channel.send(content=body, suppress_embeds=self.__suppress_embeds)
					Storage.get_bot_messages(self.guild)[message.id] = self
					self.__messages.append(message)
				self.__posted_text = message_bodies
		else: # No messages posted yet
			channel: Optional[TextChannel] = None
			for index, body in enumerate(message_bodies):
				if index == 0 and self.__reply_to:
					message = await self.__reply_to.reply(content=body, mention_author=False)
					Storage.get_bot_messages(self.guild)[message.id] = self
					self.__messages.append(message)
					channel = self.__reply_to.channel
				else:
					if channel is None:
						channel_id = Storage.get_config_value(self.guild, ConfigKey.WARNING_CHANNEL_ID)
						if channel_id is None:
							bot_log(self.guild,
								type(self.source_cog) if self.source_cog else None,
								'\u0007No warning channel set! No warning issued.')
							return
						channel: TextChannel = self.guild.get_channel(channel_id) or await self.guild.fetch_channel(channel_id)
						if channel is None:
							bot_log(self.guild,
								type(self.source_cog) if self.source_cog else None,
								f'\u0007Configured warning channel does not exist for guild {self.guild.name} ({self.guild.id})!')
							return
					message = await channel.send(content=body, suppress_embeds=self.__suppress_embeds)
					Storage.get_bot_messages(self.guild)[message.id] = self
					self.__messages.append(message)
			self.__posted_text = message_bodies

		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.__messages[-1].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.__messages[-1].clear_reaction(emoji)
			if emoji in self.__posted_emoji:
				self.__posted_emoji.remove(emoji)

	def __formatted_message(self) -> list[str]:
		"""
		Composes the entire message Markdown from components. Includes the main
		message, quoted text, summary of available reactions, etc. Returned as
		array of message bodies small enough to fit in a Discord message.
		"""
		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'] + ' '
		elif self.type == self.TYPE_LOG:
			s += CONFIG['log_emoji'] + ' '

		s += self.text

		if self.quote:
			quoted = '\n> '.join(self.quote.splitlines())
			s += f'\n\n> {quoted}'

		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}'

		# API complains if *request* is >2000. Unsure how much of that payload is overhead, so will define a max length
		# conservatively of 85-90% of that.
		ideal_message_length = 1700
		max_message_length = 1800
		# First time cutting up message
		bodies = [s]
		while len(bodies[-1]) > max_message_length:
			# Try to cut at last newline before length limit, otherwise last space, otherwise hard cut at limit
			last_body = bodies.pop(-1)
			cut_before = ideal_message_length
			cut_after = ideal_message_length
			last_newline_index = last_body.rfind('\n', max_message_length // 2, max_message_length)
			if last_newline_index >= 0:
				cut_before = last_newline_index
				cut_after = last_newline_index + 1
			else:
				last_space_index = last_body.rfind(' ', max_message_length // 2, max_message_length)
				if last_space_index >= 0:
					cut_before = last_space_index
					cut_after = last_space_index + 1
			body = last_body[:cut_before].strip()
			remainder = last_body[cut_after:].strip()
			while body.endswith('\n>'):
				body = body[:-2]
			while remainder.endswith('\n>'):
				remainder = remainder[:-2]
			bodies.append(body)
			bodies.append(remainder)

		return bodies