"""Utility Functions for grats."""
from itertools import groupby

from oto import response

from backend.constants import error
from backend.models import ows_carveouts


def group_grats_by_tuid(grats):
    """Group list of grats by tuid field.

    Args:
        grats (list): List of InstantGrat.to_dict() objects.

    Returns:
        List of dicts in format [{'tuid': tuid, 'grats': [grats]}, ...].
    """
    items = []
    for tuid, group in groupby(grats, lambda grat: grat.get('tuid')):
        item = {'tuid': tuid}
        grats_data = []
        for item_grat in list(group):
            item_grat.pop('tuid')
            grats_data.append(item_grat)
        item['grats'] = grats_data
        items.append(item)
    return items


def validate_provided_instant_grats_stores(store_ids):
    """Compare provided stores to a list of allowed stores from db.

    Args:
        store_ids (list): List of stores ids to validate.

    Returns:
        response.Response
    """
    allowed_stores_res = ows_carveouts.get_stores_allowed_for_instant_grats()
    if not allowed_stores_res:
        return allowed_stores_res
    allowed_stores = allowed_stores_res.message
    allowed_store_ids = {store['id'] for store in allowed_stores}
    disallowed_stores = set(store_ids) - allowed_store_ids
    if disallowed_stores:
        invalid_stores = {str(store_id) for store_id in disallowed_stores}
        return response.create_error_response(
            code=error.VALIDATION_ERROR_CODE,
            message=error.VALIDATION_ERROR_INVALID_STORES_PROVIDED.format(
                ','.join(invalid_stores)))
    return response.Response()