import logging
import uuid
from typing import TYPE_CHECKING

from src import domain, dto

if TYPE_CHECKING:
    from .. import Usecase

log = logging.getLogger(__name__)


async def create_external_channel(
    self: 'Usecase', input: dto.CreateExternalChannelInput, user_id: uuid.UUID, workspace_id: uuid.UUID
) -> dto.ExternalChannelOutput:
    await self.ensure_workspace_access(workspace_id, user_id)

    existing_channel = await self.database.get_external_channel(workspace_id, telegram_id=input.telegram_id)
    if existing_channel:
        raise domain.ExternalChannelAlreadyExists(input.telegram_id)

    for target_id in input.target_channel_ids:
        target_channel = await self.database.get_target_channel(workspace_id, channel_id=target_id)

        if not target_channel:
            raise domain.TargetChannelNotFound(target_id)

    async with self.database.transaction():
        channel = domain.ExternalChannel(
            telegram_id=input.telegram_id,
            title=input.title,
            username=input.username,
            description=input.description,
            subscribers_count=input.subscribers_count,
            workspace_id=workspace_id,
        )
        await self.database.create_external_channel(channel)

        if input.target_channel_ids:
            await self.database.add_external_channel_to_targets(channel, input.target_channel_ids)

    log.info(
        'External channel %s created and linked to %s target channels', input.telegram_id, len(input.target_channel_ids)
    )

    return dto.ExternalChannelOutput(
        id=channel.id,
        telegram_id=channel.telegram_id,
        title=channel.title,
        username=channel.username,
        description=channel.description,
        subscribers_count=channel.subscribers_count,
    )