# -*- coding: utf-8 -*-

"""
The MIT License (MIT)

Copyright (c) 2015-2017 Rapptz

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
"""

import discord
import asyncio
import re
import inspect

from .errors import BadArgument, NoPrivateMessage
from .view import StringView

__all__ = [ 'Converter', 'MemberConverter', 'UserConverter',
            'TextChannelConverter', 'InviteConverter', 'RoleConverter',
            'GameConverter', 'ColourConverter', 'VoiceChannelConverter',
            'EmojiConverter', 'IDConverter', 'clean_content' ]

def _get_from_guilds(bot, getter, argument):
    result = None
    for guild in bot.guilds:
        result = getattr(guild, getter)(argument)
        if result:
            return result
    return result

class Converter:
    """The base class of custom converters that require the :class:`.Context`
    to be passed to be useful.

    This allows you to implement converters that function similar to the
    special cased ``discord`` classes.

    Classes that derive from this should override the :meth:`~.Converter.convert`
    method to do its conversion logic. This method must be a coroutine.
    """

    @asyncio.coroutine
    def convert(self, ctx, argument):
        """|coro|

        The method to override to do conversion logic.

        If an error is found while converting, it is recommended to
        raise a :exc:`.CommandError` derived exception as it will
        properly propagate to the error handlers.

        Parameters
        -----------
        ctx: :class:`.Context`
            The invocation context that the argument is being used in.
        argument: str
            The argument that is being converted.
        """
        raise NotImplementedError('Derived classes need to implement this.')

class IDConverter(Converter):
    def __init__(self):
        self._id_regex = re.compile(r'([0-9]{15,21})$')
        super().__init__()

    def _get_id_match(self, argument):
        return self._id_regex.match(argument)

class MemberConverter(IDConverter):
    """Converts to a :class:`Member`.

    All lookups are via the local guild. If in a DM context, then the lookup
    is done by the global cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by mention.
    3. Lookup by name#discrim
    4. Lookup by name
    5. Lookup by nickname
    """

    @asyncio.coroutine
    def convert(self, ctx, argument):
        message = ctx.message
        bot = ctx.bot
        match = self._get_id_match(argument) or re.match(r'<@!?([0-9]+)>$', argument)
        guild = message.guild
        result = None
        if match is None:
            # not a mention...
            if guild:
                result = guild.get_member_named(argument)
            else:
                result = _get_from_guilds(bot, 'get_member_named', argument)
        else:
            user_id = int(match.group(1))
            if guild:
                result = guild.get_member(user_id)
            else:
                result = _get_from_guilds(bot, 'get_member', user_id)

        if result is None:
            raise BadArgument('Member "{}" not found'.format(argument))

        return result

class UserConverter(IDConverter):
    """Converts to a :class:`User`.

    All lookups are via the global user cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by mention.
    3. Lookup by name#discrim
    4. Lookup by name
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        match = self._get_id_match(argument) or re.match(r'<@!?([0-9]+)>$', argument)
        result = None
        state = ctx._state

        if match is not None:
            user_id = int(match.group(1))
            result = ctx.bot.get_user(user_id)
        else:
            arg = argument
            # check for discriminator if it exists
            if len(arg) > 5 and arg[-5] == '#':
                discrim = arg[-4:]
                name = arg[:-5]
                predicate = lambda u: u.name == name and u.discriminator == discrim
                result = discord.utils.find(predicate, state._users.values())
                if result is not None:
                    return result

            predicate = lambda u: u.name == arg
            result = discord.utils.find(predicate, state._users.values())

        if result is None:
            raise BadArgument('User "{}" not found'.format(argument))

        return result

class TextChannelConverter(IDConverter):
    """Converts to a :class:`TextChannel`.

    All lookups are via the local guild. If in a DM context, then the lookup
    is done by the global cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by mention.
    3. Lookup by name
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        bot = ctx.bot

        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
        result = None
        guild = ctx.guild

        if match is None:
            # not a mention
            if guild:
                result = discord.utils.get(guild.text_channels, name=argument)
            else:
                def check(c):
                    return isinstance(c, discord.TextChannel) and c.name == argument
                result = discord.utils.find(check, bot.get_all_channels())
        else:
            channel_id = int(match.group(1))
            if guild:
                result = guild.get_channel(channel_id)
            else:
                result = _get_from_guilds(bot, 'get_channel', channel_id)

        if not isinstance(result, discord.TextChannel):
            raise BadArgument('Channel "{}" not found.'.format(argument))

        return result

class VoiceChannelConverter(IDConverter):
    """Converts to a :class:`VoiceChannel`.

    All lookups are via the local guild. If in a DM context, then the lookup
    is done by the global cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by mention.
    3. Lookup by name
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        bot = ctx.bot
        match = self._get_id_match(argument) or re.match(r'<#([0-9]+)>$', argument)
        result = None
        guild = ctx.guild

        if match is None:
            # not a mention
            if guild:
                result = discord.utils.get(guild.voice_channels, name=argument)
            else:
                def check(c):
                    return isinstance(c, discord.VoiceChannel) and c.name == argument
                result = discord.utils.find(check, bot.get_all_channels())
        else:
            channel_id = int(match.group(1))
            if guild:
                result = guild.get_channel(channel_id)
            else:
                result = _get_from_guilds(bot, 'get_channel', channel_id)

        if not isinstance(result, discord.VoiceChannel):
            raise BadArgument('Channel "{}" not found.'.format(argument))

        return result

class ColourConverter(Converter):
    """Converts to a :class:`Colour`.

    The following formats are accepted:

    - ``0x<hex>``
    - ``#<hex>``
    - ``0x#<hex>``
    - Any of the ``classmethod`` in :class:`Colour`

        - The ``_`` in the name can be optionally replaced with spaces.
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        arg = argument.replace('0x', '').lower()

        if arg[0] == '#':
            arg = arg[1:]
        try:
            value = int(arg, base=16)
            return discord.Colour(value=value)
        except ValueError:
            method = getattr(discord.Colour, arg.replace(' ', '_'), None)
            if method is None or not inspect.ismethod(method):
                raise BadArgument('Colour "{}" is invalid.'.format(arg))
            return method()

class RoleConverter(IDConverter):
    """Converts to a :class:`Role`.


    All lookups are via the local guild. If in a DM context, then the lookup
    is done by the global cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by mention.
    3. Lookup by name
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        guild = ctx.message.guild
        if not guild:
            raise NoPrivateMessage()

        match = self._get_id_match(argument) or re.match(r'<@&([0-9]+)>$', argument)
        params = dict(id=int(match.group(1))) if match else dict(name=argument)
        result = discord.utils.get(guild.roles, **params)
        if result is None:
            raise BadArgument('Role "{}" not found.'.format(argument))
        return result

class GameConverter(Converter):
    """Converts to :class:`Game`."""
    @asyncio.coroutine
    def convert(self, ctx, argument):
        return discord.Game(name=argument)

class InviteConverter(Converter):
    """Converts to a :class:`Invite`.

    This is done via an HTTP request using :meth:`.Bot.get_invite`.
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        try:
            invite = yield from ctx.bot.get_invite(argument)
            return invite
        except Exception as e:
            raise BadArgument('Invite is invalid or expired') from e

class EmojiConverter(IDConverter):
    """Converts to a :class:`Emoji`.


    All lookups are via the local guild. If in a DM context, then the lookup
    is done by the global cache.

    The lookup strategy is as follows (in order):

    1. Lookup by ID.
    2. Lookup by extracting ID from the emoji.
    3. Lookup by name
    """
    @asyncio.coroutine
    def convert(self, ctx, argument):
        match = self._get_id_match(argument) or re.match(r'<:[a-zA-Z0-9]+:([0-9]+)>$', argument)
        result = None
        bot = ctx.bot
        guild = ctx.guild

        if match is None:
            # Try to get the emoji by name. Try local guild first.
            if guild:
                result = discord.utils.get(guild.emojis, name=argument)

            if result is None:
                result = discord.utils.get(bot.emojis, name=argument)
        else:
            emoji_id = int(match.group(1))

            # Try to look up emoji by id.
            if guild:
                result = discord.utils.get(guild.emojis, id=emoji_id)

            if result is None:
                result = discord.utils.get(bot.emojis, id=emoji_id)

        if result is None:
            raise BadArgument('Emoji "{}" not found.'.format(argument))

        return result

class clean_content(Converter):
    """Converts the argument to mention scrubbed version of
    said content.

    This behaves similarly to :attr:`.Message.clean_content`.

    Attributes
    ------------
    fix_channel_mentions: bool
        Whether to clean channel mentions.
    use_nicknames: bool
        Whether to use nicknames when transforming mentions.
    """
    def __init__(self, *, fix_channel_mentions=False, use_nicknames=True):
        self.fix_channel_mentions = fix_channel_mentions
        self.use_nicknames = use_nicknames

    @asyncio.coroutine
    def convert(self, ctx, argument):
        message = ctx.message
        transformations = {}

        if self.fix_channel_mentions:
            transformations.update(
                ('<#%s>' % channel.id, '#' + channel.name)
                for channel in message.channel_mentions
            )

        if self.use_nicknames:
            transformations.update(
                ('<@%s>' % member.id, '@' + member.display_name)
                for member in message.mentions
            )

            transformations.update(
                ('<@!%s>' % member.id, '@' + member.display_name)
                for member in message.mentions
            )
        else:
            transformations.update(
                ('<@%s>' % member.id, '@' + member.name)
                for member in message.mentions
            )

            transformations.update(
                ('<@!%s>' % member.id, '@' + member.name)
                for member in message.mentions
            )

        transformations.update(
            ('<@&%s>' % role.id, '@' + role.name)
            for role in message.role_mentions
        )

        def repl(obj):
            return transformations.get(obj.group(0), '')

        pattern = re.compile('|'.join(transformations.keys()))
        result = pattern.sub(repl, argument)

        transformations = {
            '@everyone': '@\u200beveryone',
            '@here': '@\u200bhere'
        }

        def repl2(obj):
            return transformations.get(obj.group(0), '')

        pattern = re.compile('|'.join(transformations.keys()))
        return pattern.sub(repl2, result)