import logging

from discord.ext.commands import Cog

from bot import constants
from bot.bot import Bot


log = logging.getLogger(__name__)


class ConfigVerifier(Cog):
    """Verify config on startup."""

    def __init__(self, bot: Bot):
        self.bot = bot
        self.channel_verify_task = self.bot.loop.create_task(self.verify_channels())

    async def verify_channels(self) -> None:
        """
        Verify channels.

        If any channels in config aren't present in server, log them in a warning.
        """
        await self.bot.wait_until_guild_available()
        server = self.bot.get_guild(constants.Guild.id)

        server_channel_ids = {channel.id for channel in server.channels}
        invalid_channels = [
            channel_name for channel_name, channel_id in constants.Channels
            if channel_id not in server_channel_ids
        ]

        if invalid_channels:
            log.warning(f"Configured channels do not exist in server: {', '.join(invalid_channels)}.")


def setup(bot: Bot) -> None:
    """Load the ConfigVerifier cog."""
    bot.add_cog(ConfigVerifier(bot))