"""Module that provides generation of upload data."""

import uuid

from oto import response

from assets import config
from assets.models import asset_upload as asset_upload_model
from assets.models import token


def _generate_filename():
    unique_name = uuid.uuid4()
    underscored_name = str(unique_name).replace('-', '_')
    return underscored_name


def get_upload_permission(user_id):
    """Function that generates data required for asset upload.

    Args:
        user_id (string): User id
    Returns:
        response.Response: Contains information for uploading or
            error.
    """
    if not user_id:
        return response.create_error_response(
            'user_required', 'User is required')

    filename = _generate_filename()
    credentials = token.get_s3_token(filename)
    if not credentials:
        return credentials

    asset_upload = asset_upload_model.create_asset_upload(
        user_id, filename, credentials.message.get('token'))
    if not asset_upload:
        return asset_upload

    permission = {
        'bucket': config.RAW_ASSETS_BUCKET_NAME,
        'filename': filename,
        'credentials': credentials.message
    }
    return response.Response(permission)