"""Functions to help play and score a game of blackjack.

How to play blackjack:    https://bicyclecards.com/how-to-play/blackjack/
"Standard" playing cards: https://en.wikipedia.org/wiki/Standard_52-card_deck
"""

CARD_VALUES = {
    "1": 1,
    "2": 2,
    "3": 3,
    "4": 4,
    "5": 5,
    "6": 6,
    "7": 7,
    "8": 8,
    "9": 9,
    "10": 10,
    "J": 10,
    "Q": 10,
    "K": 10,
    "A": 1
}


def value_of_card(card):
    """Determine the scoring value of a card.

    :param card: str - given card.
    :return: int - value of a given card (J, Q, K = 10, 'A' = 1) numerical value otherwise.
    """
    return CARD_VALUES[card]


def higher_card(card_one, card_two):
    """Determine which card has a higher value in the hand.

    :param card_one, card_two: str - cards dealt.  J, Q, K = 10, 'A' = 1, all others are numerical value.
    :return: higher value card - str. Tuple of both cards if they are of equal value.
    """
    value_one = value_of_card(card_one)
    value_two = value_of_card(card_two)

    return (card_one, card_two) if value_one == value_two else card_one if value_one > value_two else card_two

def value_of_ace(card_one, card_two):
    """Calculate the most advantageous value for the ace card.

    :param card_one, card_two: str - card (J, Q, K == 10, numerical value otherwise)
    :return: int - value of the upcoming ace card (either 1 or 11).
    """

    return 11 if value_of_card(card_one) + value_of_card(card_two) < 11 else 1

def is_blackjack(card_one, card_two):
    """Determine if the hand is a 'natural' or 'blackjack'.

    :param card_one, card_two: str - cards dealt.  J, Q, K = 10, 'A' = 11, all others are numerical value.
    :return: bool - if the hand is a blackjack (two cards worth 21).
    """
    value_one = value_of_card(card_one)
    value_two = value_of_card(card_two)

    return value_one + value_two == 11 and (card_one == 'A' or card_two == 'A')

def can_split_pairs(card_one, card_two):
    """Determine if a player can split their hand into two hands.

    :param card_one, card_two: str - cards in hand.
    :return: bool - if the hand can be split into two pairs (i.e. cards are of the same value).
    """
    return value_of_card(card_one) == value_of_card(card_two)

def can_double_down(card_one, card_two):
    """Determine if a blackjack player can place a double down bet.

    :param card_one, card_two: str - first and second cards in hand.
    :return: bool - if the hand can be doubled down (i.e. totals 9, 10 or 11 points).
    """

    return 8 < value_of_card(card_one) + value_of_card(card_two) < 12
