from abc import ABC, abstractmethod
from discord import Guild, Member, Message
from discord.ext import commands
from datetime import timedelta
import re

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

class PatternAction:
	def __init__(self, type: str, args: list):
		self.type = type
		self.arguments = list(args)

	def __str__(self) -> str:
		arg_str = ', '.join(self.arguments)
		return f'{self.type}({arg_str})'

class PatternExpression(ABC):
	def __init__(self):
		pass

	@abstractmethod
	def matches(self, message: Message) -> bool:
		return False

class PatternSimpleExpression(PatternExpression):
	def __init__(self, field: str, operator: str, value):
		self.field = field
		self.operator = operator
		self.value = value

	def matches(self, message: Message) -> bool:
		field_value = None
		if self.field == 'content':
			field_value = message.content
		elif self.field == 'author':
			field_value = str(message.author.id)
		elif self.field == 'author.id':
			field_value = str(message.author.id)
		elif self.field == 'author.joinage':
			field_value = message.created_at - message.author.joined_at
		elif self.field == 'author.name':
			field_value = message.author.name
		else:
			raise ValueError(f'Bad field name {self.field}')
		if self.operator == '==':
			if isinstance(field_value, str) and isinstance(self.value, str):
				return field_value.lower() == self.value.lower()
			return field_value == self.value
		if self.operator == '!=':
			if isinstance(field_value, str) and isinstance(self.value, str):
				return field_value.lower() != self.value.lower()
			return field_value != self.value
		if self.operator == '<':
			return field_value < self.value
		if self.operator == '>':
			return field_value > self.value
		if self.operator == '<=':
			return field_value <= self.value
		if self.operator == '>=':
			return field_value >= self.value
		if self.operator == 'contains':
			return self.value.lower() in field_value.lower()
		if self.operator == '!contains':
			return self.value.lower() not in field_value.lower()
		if self.operator == 'matches':
			p = re.compile(self.value.lower())
			return p.match(field_value.lower()) is not None
		if self.operator == '!matches':
			p = re.compile(self.value.lower())
			return p.match(field_value.lower()) is None
		raise ValueError(f'Bad operator {self.operator}')

	def __str__(self) -> str:
		return f'({self.field} {self.operator} {self.value})'

class PatternCompoundExpression(PatternExpression):
	def __init__(self, operator: str, operands: list):
		self.operator = operator
		self.operands = list(operands)

	def matches(self, message: Message) -> bool:
		if self.operator == '!':
			return not self.operands[0].matches(message)
		elif self.operator == 'and':
			for op in self.operands:
				if not op.matches(message):
					return False
			return True
		elif self.operator == 'or':
			for op in self.operands:
				if op.matches(message):
					return True
			return False
		else:
			raise RuntimeError(f'Bad operator "{self.operator}"')

	def __str__(self) -> str:
		if self.operator == '!':
			return f'(!( {self.operands[0]} ))'
		else:
			strs = map(str, self.operands)
			joined = f' {self.operator} '.join(strs)
			return f'( {joined} )'

class PatternStatement:
	def __init__(self, name: str, actions: list, expression: PatternExpression, original: str):
		self.name = name
		self.actions = list(actions)  # PatternAction[]
		self.expression = expression
		self.original = original

class PatternContext:
	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):
	def __init__(self, bot):
		super().__init__(bot)

	# def __patterns(self, guild: Guild) -> list:
	# 	patterns = Storage.get_state_value(guild, 'pattern_patterns')
	# 	if patterns is None:
	# 		patterns_encoded = Storage.get_config_value(guild, 'pattern_patterns')
	# 		if patterns_encoded:
	# 			patterns = []
	# 			for pe in patterns_encoded:
	# 				patterns.append(Pattern.decode(pe))
	# 			Storage.set_state_value(guild, 'pattern_patterns', patterns)
	# 	return patterns

	def __get_patterns(self, guild: Guild) -> dict:
		patterns = Storage.get_state_value(guild, 'PatternCog.patterns')
		if patterns is None:
			patterns = {}
			patterns_encoded = Storage.get_config_value(guild, 'PatternCog.patterns')
			if patterns_encoded:
				for pe in patterns_encoded:
					name = pe.get('name')
					statement = pe.get('statement')
					try:
						ps = PatternCompiler.parse_statement(name, statement)
						patterns[name] = ps
					except RuntimeError as e:
						self.log(guild, f'Error parsing saved statement "{name}". Skipping: {statement}')
			Storage.set_state_value(guild, 'PatternCog.patterns', patterns)
		return patterns

	def __save_patterns(self, guild: Guild, patterns: dict) -> None:
		to_save = []
		for name, statement in patterns.items():
			to_save.append({
				'name': name,
				'statement': statement.original,
			})
		Storage.set_config_value(guild, 'PatternCog.patterns', to_save)

	@commands.Cog.listener()
	async def on_message(self, message: Message) -> None:
		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.author.permissions_in(message.channel).ban_members:
			# Ignore mods
			return

		patterns = self.__get_patterns(message.guild)
		for name, statement in patterns.items():
			if statement.expression.matches(message):
				await self.__trigger_actions(message, statement)
				break


	async def __trigger_actions(self, message: Message, statement: PatternStatement) -> None:
		context = PatternContext(message, statement)
		should_alert_mods = False
		action_descriptions = []
		self.log(message.guild, f'Message from {message.author.name} matched pattern "{statement.name}"')
		for action in statement.actions:
			if action.type == 'ban':
				await message.author.ban(
					reason=f'Rocketbot: Message matched custom pattern named "{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.type == '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.type == 'kick':
				await message.author.kick(
					reason=f'Rocketbot: Message matched custom pattern named "{statement.name}"')
				context.is_kicked = True
				action_descriptions.append('Author kicked')
				self.log(message.guild, f'{message.author.name} kicked')
			elif action.type == 'modwarn':
				should_alert_mods = True
				action_descriptions.append('Mods alerted')
			elif action.type == 'reply':
				await message.reply(
					f'{action.arguments[0]}',
					mention_author=False)
				action_descriptions.append('Autoreplied')
				self.log(message.guild, f'{message.author.name} autoreplied to')
		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=BotMessage.TYPE_MOD_WARNING if should_alert_mods else BotMessage.TYPE_INFO,
			context=context)
		bm.quote = message.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=f'Rocketbot: Message matched custom pattern named ' + \
					'"{statement.name}". Kicked by {reacted_by.name}.')
			context.is_kicked = True
		elif reaction.emoji == CONFIG['ban_emoji']:
			await context.message.author.ban(
				reason=f'Rocketbot: Message matched custom pattern named ' + \
					'"{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'
		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):
		pattern_str = PatternCompiler.expression_str_from_context(context, name)
		try:
			statement = PatternCompiler.parse_statement(name, pattern_str)
			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 Exception 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):
		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:
		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}`:\n```\n{statement.original}\n```\n'
		await context.message.reply(msg, mention_author=False)

class PatternCompiler:
	TYPE_ID = 'id'
	TYPE_MEMBER = 'Member'
	TYPE_TEXT = 'text'
	TYPE_INT = 'int'
	TYPE_FLOAT = 'float'
	TYPE_TIMESPAN = 'timespan'

	FIELD_TO_TYPE = {
		'content': TYPE_TEXT,
		'author': TYPE_MEMBER,
		'author.id': TYPE_ID,
		'author.name': TYPE_TEXT,
		'author.joinage': TYPE_TIMESPAN,
	}

	ACTION_TO_ARGS = {
		'ban': [],
		'delete': [],
		'kick': [],
		'modwarn': [],
		'reply': [ TYPE_TEXT ],
	}

	OPERATORS_IDENTITY = set([ '==', '!=' ])
	OPERATORS_COMPARISON = set([ '<', '>', '<=', '>=' ])
	OPERATORS_NUMERIC = OPERATORS_IDENTITY | OPERATORS_COMPARISON
	OPERATORS_TEXT = OPERATORS_IDENTITY | set([ 'contains', '!contains', 'matches', '!matches' ])
	OPERATORS_ALL = OPERATORS_IDENTITY | OPERATORS_COMPARISON | OPERATORS_TEXT

	TYPE_TO_OPERATORS = {
		TYPE_ID: OPERATORS_IDENTITY,
		TYPE_MEMBER: OPERATORS_IDENTITY,
		TYPE_TEXT: OPERATORS_TEXT,
		TYPE_INT: OPERATORS_NUMERIC,
		TYPE_FLOAT: OPERATORS_NUMERIC,
		TYPE_TIMESPAN: OPERATORS_NUMERIC,
	}

	WHITESPACE_CHARS = ' \t\n\r'
	STRING_QUOTE_CHARS = '\'"'
	SYMBOL_CHARS = 'abcdefghijklmnopqrstuvwxyz.'
	VALUE_CHARS = '0123456789dhms<@!>'
	OP_CHARS = '<=>!(),'

	@classmethod
	def expression_str_from_context(cls, context: commands.Context, name: str) -> str:
		pattern_str = context.message.content
		command_chain = [ name ]
		cmd = context.command
		while cmd:
			command_chain.insert(0, cmd.name)
			cmd = cmd.parent
		command_chain[0] = f'{context.prefix}{command_chain[0]}'
		for cmd in command_chain:
			if pattern_str.startswith(cmd):
				pattern_str = pattern_str[len(cmd):].lstrip()
		return pattern_str

	@classmethod
	def parse_statement(cls, name: str, statement: str) -> PatternStatement:
		tokens = cls.tokenize(statement)
		token_index = 0
		actions, token_index = cls.read_actions(tokens, token_index)
		expression, token_index = cls.read_expression(tokens, token_index)
		return PatternStatement(name, actions, expression, statement)

	@classmethod
	def tokenize(cls, statement: str) -> list:
		tokens = []
		in_quote = False
		in_escape = False
		all_token_types = set([ 'sym', 'op', 'val' ])
		possible_token_types = set(all_token_types)
		current_token = ''
		for ch in statement:
			if in_quote:
				if in_escape:
					if ch == 'n':
						current_token += '\n'
					elif ch == 't':
						current_token += '\t'
					else:
						current_token += ch
					in_escape = False
				elif ch == '\\':
					in_escape = True
				elif ch == in_quote:
					current_token += ch
					tokens.append(current_token)
					current_token = ''
					possible_token_types |= all_token_types
					in_quote = False
				else:
					current_token += ch
			else:
				if ch in cls.STRING_QUOTE_CHARS:
					if len(current_token) > 0:
						tokens.append(current_token)
						current_token = ''
						possible_token_types |= all_token_types
					in_quote = ch
					current_token = ch
				elif ch == '\\':
					raise RuntimeError("Unexpected \\")
				elif ch in cls.WHITESPACE_CHARS:
					if len(current_token) > 0:
						tokens.append(current_token)
					current_token = ''
					possible_token_types |= all_token_types
				else:
					possible_ch_types = set()
					if ch in cls.SYMBOL_CHARS:
						possible_ch_types.add('sym')
					if ch in cls.VALUE_CHARS:
						possible_ch_types.add('val')
					if ch in cls.OP_CHARS:
						possible_ch_types.add('op')
					if len(current_token) > 0 and possible_ch_types.isdisjoint(possible_token_types):
						if len(current_token) > 0:
							tokens.append(current_token)
							current_token = ''
							possible_token_types |= all_token_types
					possible_token_types &= possible_ch_types
					current_token += ch
		if len(current_token) > 0:
			tokens.append(current_token)

		# Some symbols might be glommed onto other tokens. Split 'em up.
		prefixes_to_split = [ '!', '(', ',' ]
		suffixes_to_split = [ ')', ',' ]
		i = 0
		while i < len(tokens):
			token = tokens[i]
			mutated = False
			for prefix in prefixes_to_split:
				if token.startswith(prefix) and len(token) > len(prefix):
					tokens.insert(i, prefix)
					tokens[i + 1] = token[len(prefix):]
					i += 1
					mutated = True
					break
			if mutated:
				continue
			for suffix in suffixes_to_split:
				if token.endswith(suffix) and len(token) > len(suffix):
					tokens[i] = token[0:-len(suffix)]
					tokens.insert(i + 1, suffix)
					mutated = True
					break
			if mutated:
				continue
			i += 1
		return tokens

	@classmethod
	def read_actions(cls, tokens: list, token_index: int) -> tuple:
		actions = []
		current_action_tokens = []
		while token_index < len(tokens):
			token = tokens[token_index]
			if token == 'if':
				if len(current_action_tokens) > 0:
					a = PatternAction(current_action_tokens[0], current_action_tokens[1:])
					cls.__validate_action(a)
					actions.append(a)
				token_index += 1
				return (actions, token_index)
			elif token == ',':
				if len(current_action_tokens) < 1:
					raise RuntimeError('Unexpected ,')
				a = PatternAction(current_action_tokens[0], current_action_tokens[1:])
				cls.__validate_action(a)
				actions.append(a)
				current_action_tokens = []
			else:
				current_action_tokens.append(token)
			token_index += 1
		raise RuntimeError('Unexpected end of line')

	@classmethod
	def __validate_action(cls, action: PatternAction) -> None:
		args = cls.ACTION_TO_ARGS.get(action.type)
		if args is None:
			raise RuntimeError(f'Unknown action "{action.type}"')
		if len(action.arguments) != len(args):
			arg_list = ', '.join(args)
			if len(args) == 0:
				raise RuntimeError(f'Action "{action.type}" expects no arguments, got {len(action.arguments)}.')
			else:
				raise RuntimeError(f'Action "{action.type}" expects {len(args)} arguments, got {len(action.arguments)}.')
		for i in range(len(args)):
			datatype = args[i]
			action.arguments[i] = cls.parse_value(action.arguments[i], datatype)

	@classmethod
	def read_expression(cls, tokens: list, token_index: int, depth: int = 0, one_subexpression: bool = False) -> tuple:
		# field op value
		# (field op value)
		# !(field op value)
		# field op value and field op value
		# (field op value and field op value) or field op value
		indent = '\t' * depth
		subexpressions = []
		last_compound_operator = None
		while token_index < len(tokens):
			if one_subexpression:
				if len(subexpressions) == 1:
					return (subexpressions[0], token_index)
				elif len(subexpressions) > 1:
					raise RuntimeError('Too many subexpressions')
			compound_operator = None
			if tokens[token_index] == ')':
				if len(subexpressions) == 0:
					raise RuntimeError('No subexpressions')
				elif len(subexpressions) == 1:
					return (subexpressions[0], token_index)
				else:
					return (PatternCompoundExpression(last_compound_operator, subexpressions), token_index)
			if tokens[token_index] in set(["and", "or"]):
				compound_operator = tokens[token_index]
				if last_compound_operator and compound_operator != last_compound_operator:
					subexpressions = [ PatternCompoundExpression(last_compound_operator, subexpressions) ]
					last_compound_operator = compound_operator
				else:
					last_compound_operator = compound_operator
				token_index += 1
			if tokens[token_index] == '!':
				(exp, next_index) = cls.read_expression(tokens, token_index + 1, depth + 1, one_subexpression=True)
				subexpressions.append(PatternCompoundExpression('!', [exp]))
				token_index = next_index
			elif tokens[token_index] == '(':
				(exp, next_index) = cls.read_expression(tokens, token_index + 1, depth + 1)
				if tokens[next_index] != ')':
					raise RuntimeError('Expected )')
				subexpressions.append(exp)
				token_index = next_index + 1
			else:
				(simple, next_index) = cls.read_simple_expression(tokens, token_index, depth)
				subexpressions.append(simple)
				token_index = next_index
		if len(subexpressions) == 0:
			raise RuntimeError('No subexpressions')
		elif len(subexpressions) == 1:
			return (subexpressions[0], token_index)
		else:
			return (PatternCompoundExpression(last_compound_operator, subexpressions), token_index)

	@classmethod
	def read_simple_expression(cls, tokens: list, token_index: int, depth: int = 0) -> tuple:
		indent = '\t' * depth

		if token_index >= len(tokens):
			raise RuntimeError('Expected field name, found EOL')
		field = tokens[token_index]
		token_index += 1

		datatype = cls.FIELD_TO_TYPE.get(field)
		if datatype is None:
			raise RuntimeError(f'No such field "{field}"')

		if token_index >= len(tokens):
			raise RuntimeError('Expected operator, found EOL')
		op = tokens[token_index]
		token_index += 1

		if op == '!':
			if token_index >= len(tokens):
				raise RuntimeError('Expected operator, found EOL')
			op = '!' + tokens[token_index]
			token_index += 1

		allowed_ops = cls.TYPE_TO_OPERATORS[datatype]
		if op not in allowed_ops:
			if op in cls.OPERATORS_ALL:
				raise RuntimeError(f'Operator {op} cannot be used with field "{field}"')
			else:
				raise RuntimeError(f'Unrecognized operator "{op}" - allowed: {list(allowed_ops)}')

		if token_index >= len(tokens):
			raise RuntimeError('Expected value, found EOL')
		value = tokens[token_index]

		value = cls.parse_value(value, datatype)

		token_index += 1
		exp = PatternSimpleExpression(field, op, value)
		return (exp, token_index)

	@classmethod
	def parse_value(cls, value: str, type: str):
		if type == cls.TYPE_ID:
			p = re.compile('^[0-9]+$')
			if p.match(value) is None:
				raise ValueError(f'Illegal id value "{value}"')
			# Store it as a str so it can be larger than an int
			return value
		if type == cls.TYPE_MEMBER:
			p = re.compile('^<@!?([0-9]+)>$')
			m = p.match(value)
			if m is None:
				raise ValueError(f'Illegal member value. Must be an @ mention.')
			return m.group(1)
		if type == cls.TYPE_TEXT:
			# Must be quoted.
			if len(value) < 2 or \
					value[0:1] not in cls.STRING_QUOTE_CHARS or \
					value[-1:] not in cls.STRING_QUOTE_CHARS or \
					value[0:1] != value[-1:]:
				raise ValueError(f'Not a quoted string value: {value}')
			return value[1:-1]
		if type == cls.TYPE_INT:
			return int(value)
		if type == cls.TYPE_FLOAT:
			return float(value)
		if type == cls.TYPE_TIMESPAN:
			p = re.compile('^(?:[0-9]+[dhms])+$')
			if p.match(value) is None:
				raise RuntimeError("Illegal timespan value \"{value}\". Must be like \"100d\", \"5m30s\", etc.")
			p = re.compile('([0-9]+)([dhms])')
			days = 0
			hours = 0
			minutes = 0
			seconds = 0
			for m in p.finditer(value):
				scalar = int(m.group(1))
				unit = m.group(2)
				if unit == 'd':
					days = scalar
				elif unit == 'h':
					hours = scalar
				elif unit == 'm':
					minutes = scalar
				elif unit == 's':
					seconds = scalar
			return timedelta(days=days, hours=hours, minutes=minutes, seconds=seconds)
		raise ValueError(f'Unhandled datatype {datatype}')