import discord

import config


def istrue(value, key):
    return hasattr(value, key) and getattr(value, key)


class Context:
    def __init__(self, msg, args):
        self.msg = msg
        self.args = args
        self.guild = msg.guild

    async def answer(self, value):
        await self.msg.channel.send(f'{self.msg.author.mention} {value}')


class CommandClientMeta(type):
    def __new__(cls, name, bases, dct):
        commands = []
        for item in dct.copy().values():
            if callable(item) and istrue(item, 'command'):
                if istrue(item, 'help_command'):
                    dct['help_command'] = item
                commands.append(item)
        dct['commands'] = commands
        return super().__new__(cls, name, bases, dct)


class CommandClient(discord.Client, metaclass=CommandClientMeta):
    def get_commands(self):
        return type(self).commands.copy()

    async def run_help(self, ctx):
        return await type(self).help_command(self, ctx)

    async def on_message(self, msg):
        text = msg.content.strip()
        if not text.startswith(config.COMMAND_PREFIX):
            return
        try:
            cmd, *args = [v for v in text[len(config.COMMAND_PREFIX):].split(' ') if v]
        except ValueError:
            return await self.run_help(Context(msg, []))
        ctx = Context(msg, args)
        for command in self.get_commands():
            if cmd in command.names:
                return await command(self, ctx)
        return await self.run_help(ctx)


def command(names=[], description='', is_help=False):
    def meta(f):
        f.command = True
        f.names = names
        f.description = description
        if is_help:
            f.help_command = is_help
        return f
    return meta