import math
from operator import itemgetter


def shared_values(set_list):
    '''
    Arguments:
        set_list: a list of sets

    Returns:
        A set of the items that exist in all of the given sets
    '''
    if len(set_list) == 0:
        return set()

    output_set = set_list[0]  # guaranteed to be at least one set in list
    for input_set in set_list[1:]:
        output_set = output_set & input_set
    return (output_set)


def strongest_pokemon(pokemon_list):
    strongest = {"strength": (None, float("-inf")),
                 "speed": (None, float("-inf")),
                 "defense": (None, float("-inf"))}

    for pokemon in pokemon_list:
        for attr in strongest.keys():
            name = pokemon["name"]
            value = pokemon[attr]
            if value > strongest[attr][1]:
                strongest[attr] = (name, value)

    return strongest


def best_veggie_value(market, quantities):
    '''
    Arguments:
        market: a dictionary of dictionaries. Keys are stand names. Values
        (inner dictionaries) are the items this stand sells, as well as the
        stand's discount thresholds.

        quantities: a dictionary of item names as keys with the desired
        quantities as values.

    Returns:
        A new dictionary, keys are stand names and values are a list of items.
    '''
    ret = {}

    for item, count in quantities.items():
        lowest_store_name = ""
        lowest_store_price = math.inf
        for store, menu in market.items():
            store_price = menu.get(item, math.inf)
            total = store_price * count

            if count >= menu['bulk_discount_quantity']:
                total = total * (1 - menu['bulk_discount_percent'])

            if total < lowest_store_price:
                lowest_store_price = total
                lowest_store_name = store

        if lowest_store_name != "":
            ret.setdefault(lowest_store_name, [])
            ret[lowest_store_name].append(item)

    return ret


def best_veggie_value_alt(market, quantities):
    ret = {}

    # intended to be a map, item: (store, price)
    item_prices = {}

    for store, menu in market.items():
        ret.setdefault(store, [])
        for item, count in quantities.items():
            store_price = menu.get(item, math.inf)
            total = store_price * count

            if count >= menu['bulk_discount_quantity']:
                total = total * (1 - menu['bulk_discount_percent'])

            item_prices.setdefault(item, [])
            item_prices[item].append((store, total))

    for item, store_prices in item_prices.items():
        sorted_prices = sorted(store_prices, key=itemgetter(1))
        cheapest_store = sorted_prices[0][0]
        ret[cheapest_store].append(item)

    return ret


if __name__ == '__main__':
    print("Nothing to do here. Did you mean to run final_22wi_tests.py?")