"""Playing Cards, by Al Sweigart.

Displays a scrolling stream of randomly selected playing cards. This program
uses the same lane-based approach as Ducklings: each lane can independently
start drawing a new multi-line object.
"""

import random
import shutil
import time

# Pause after each row in seconds.
DELAY = 0.15
# Chance from 0 to 1 that an empty lane receives a card on each row.
DENSITY = 0.10
# Five characters for the card plus one separating space.
CARD_WIDTH = 6
RANKS = ("A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K")
SUITS = ("♠", "♥", "♦", "♣")
# Chance from 0 to 1 that a new card is shown face down.
BACKSIDE_PROBABILITY = 0.15


class Card:
    """A randomly selected playing card drawn one row at a time."""

    def __init__(self):
        self.rank = random.choice(RANKS)
        self.suit = random.choice(SUITS)
        self.is_backside = random.random() < BACKSIDE_PROBABILITY
        self.next_row = 0

    def get_next_row(self):
        if self.is_backside:
            rows = (" ___ ", "|###|", "|###|", "|###|")
        else:
            rows = (
                " ___ ",
                f"|{self.rank:<3}|",
                f"| {self.suit} |",
                f"|_{self.rank:_>2}|",
            )
        row = rows[self.next_row]
        self.next_row += 1
        return row

    @property
    def finished(self):
        return self.next_row == 4


def main():
    width = shutil.get_terminal_size()[0] - 1
    lanes = [None] * (width // CARD_WIDTH)

    while True:
        line = []
        for lane_number, card in enumerate(lanes):
            if card is None and random.random() < DENSITY:
                card = Card()
                lanes[lane_number] = card

            if card is None:
                line.append(" " * CARD_WIDTH)
                continue

            line.append(card.get_next_row() + " ")
            if card.finished:
                lanes[lane_number] = None

        print("".join(line))
        time.sleep(DELAY)


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass