#! /usr/bin/env python3
from copy import copy
from enum import Enum
from typing import Set, Tuple, List, Optional


class Player(Enum):
    UNKNOWN = 0
    ONE = 1
    TWO = 2


def read_decks(filename: str):
    deck1, deck2 = None, None
    cur_deck: List[int] = []
    with open(filename) as f:
        for line in f:
            line = line.strip()
            if line.startswith("Player 1"):
                continue
            if line == "":
                continue
            if line.startswith("Player 2"):
                deck1 = cur_deck
                cur_deck = []
                continue
            cur_deck.append(int(line))

    deck2 = cur_deck

    return deck1, deck2


def play_round(deck1, deck2):
    c1 = deck1.pop(0)
    c2 = deck2.pop(0)

    print(f"{c1} vs {c2} ", end="", flush=True)

    if c1 > c2:
        print("Player 1 wins!")
        deck1 += [c1, c2]
    elif c2 > c1:
        print("Player 2 wins!")
        deck2 += [c2, c1]
    else:
        print("Nobody wins?")
        # raise ValueError("Nobody wins")


RoundHistory = Set[Tuple[Tuple[int, ...], Tuple[int, ...]]]


def recursive_combat(
    deck1: List[int],
    deck2: List[int],
    game: int = 1,
    past_games: Optional[RoundHistory] = None
) -> Player:
    if past_games is None:
        past_games = set()

    print(f"{game}: Starting p2 {deck1} p2 {deck2}")

    # Play until there is an empty deck
    game_round = 0
    winner = Player.UNKNOWN
    while deck1 and deck2:
        game_round += 1

        # Check for looping...
        this_round = (tuple(deck1), tuple(deck2))
        if this_round in past_games:
            print(
                f"{game}:{game_round} Loop detected. Player 1 wins the game!",
            )
            return Player.ONE

        past_games.add(this_round)

        print(f"{game}:{game_round} p1 {deck1} p2 {deck2} ")

        # Draw
        c1 = deck1.pop(0)
        c2 = deck2.pop(0)

        print(f"{game}:{game_round} {c1} vs {c2} ", end="", flush=True)

        winner = Player.UNKNOWN
        if c1 <= len(deck1) and c2 <= len(deck2):
            print("RECURSIVE COMBAT!!!!")
            winner = recursive_combat(
                copy(deck1[:c1]),
                copy(deck2[:c2]),
                game=game+1,
                past_games=past_games.copy(),
            )
        else:
            if c1 > c2:
                winner = Player.ONE
            elif c2 > c1:
                winner = Player.TWO
            else:
                raise ValueError("cards are equal? No way!")

        if winner == Player.ONE:
            print("Player 1 wins!")
            deck1 += [c1, c2]
        elif winner == Player.TWO:
            print("Player 2 wins!")
            deck2 += [c2, c1]
        else:
            print("Nobody wins?")
            raise ValueError("Nobody wins")

    print(f"{game}: Game finished p1 {deck1} p2 {deck2}")

    # Deck is empty!
    if deck1:
        winner = Player.ONE
    elif deck2:
        winner = Player.TWO
    else:
        raise ValueError("unknown winner")

    return winner


def part1():
    deck1, deck2 = read_decks("input.txt")

    print("Initial decks")
    print("Player 1", deck1)
    print("Player 2", deck2)

    while deck1 and deck2:
        play_round(deck1, deck2)

    winning_deck: List[int] = None
    if deck1:
        winning_deck = deck1
        print("Winner! Player 1!")
    elif deck2:
        winning_deck = deck2
        print("Winner! Player 2!")

    score = sum((i*v for i, v in enumerate(reversed(winning_deck), 1)))
    print("Score:", score)


def part2():
    deck1, deck2 = read_decks("input.txt")

    print("Initial decks")
    print("Player 1", deck1)
    print("Player 2", deck2)

    _ = recursive_combat(deck1, deck2)

    winning_deck: List[int] = None
    if deck1:
        winning_deck = deck1
        print("Winner! Player 1!")
    elif deck2:
        winning_deck = deck2
        print("Winner! Player 2!")

    score = sum((i*v for i, v in enumerate(reversed(winning_deck), 1)))
    print("Score:", score)


if __name__ == "__main__":
    part1()
    part2()