# --- Day 3: Perfectly Spherical Houses in a Vacuum ---

# Santa is delivering presents to an infinite two-dimensional grid of houses.

# He begins by delivering a present to the house at his starting location, and
# then an elf at the North Pole calls him via radio and tells him where to move
# next. Moves are always exactly one house to the north (^), south (v), east
# (>), or west (<). After each move, he delivers another present to the house
# at his new location.

# However, the elf back at the north pole has had a little too much eggnog, and
# so his directions are a little off, and Santa ends up visiting some houses
# more than once. How many houses receive at least one present?

# For example:

#     > delivers presents to 2 houses: one at the starting location, and one to
# the east.
#     ^>v< delivers presents to 4 houses in a square, including twice to the
# house at his starting/ending location.
#     ^v^v^v^v^v delivers a bunch of presents to some very lucky children at
# only 2 houses.

from typing import Tuple

with open("files/P3.txt") as f:
    moves = [line for line in f.read().strip().split()][0]


def move_up(pos: Tuple[int, int]) -> Tuple[int, int]:
    return pos[0], pos[1] + 1


def move_down(pos: Tuple[int, int]) -> Tuple[int, int]:
    return pos[0], pos[1] - 1


def move_left(pos: Tuple[int, int]) -> Tuple[int, int]:
    return pos[0] - 1, pos[1]


def move_right(pos: Tuple[int, int]) -> Tuple[int, int]:
    return pos[0] + 1, pos[1]


def part_1() -> None:
    pos = [(0, 0)]
    for move in moves:
        if move == "^":
            pos.append(move_up(pos[-1]))
        elif move == "v":
            pos.append(move_down(pos[-1]))
        elif move == "<":
            pos.append(move_left(pos[-1]))
        elif move == ">":
            pos.append(move_right(pos[-1]))

    print(f"{len(set(pos))} houses receive at least one present")


# --- Part Two ---

# The next year, to speed up the process, Santa creates a robot version of
# himself, Robo-Santa, to deliver presents with him.

# Santa and Robo-Santa start at the same location (delivering two presents to
# the same starting house), then take turns moving based on instructions from
# the elf, who is eggnoggedly reading from the same script as the previous
# year.

# This year, how many houses receive at least one present?

# For example:

#     ^v delivers presents to 3 houses, because Santa goes north, and then
# Robo-Santa goes south.
#     ^>v< now delivers presents to 3 houses, and Santa and Robo-Santa end up
# back where they started.
#     ^v^v^v^v^v now delivers presents to 11 houses, with Santa going one
# direction and Robo-Santa going the other.


def part_2():
    santa = [(0, 0)]
    robo_santa = [(0, 0)]
    for idx, move in enumerate(moves):
        if move == "^":
            if idx % 2 == 0:
                santa.append(move_up(santa[-1]))
            else:
                robo_santa.append(move_up(robo_santa[-1]))
        elif move == "v":
            if idx % 2 == 0:
                santa.append(move_down(santa[-1]))
            else:
                robo_santa.append(move_down(robo_santa[-1]))
        elif move == "<":
            if idx % 2 == 0:
                santa.append(move_left(santa[-1]))
            else:
                robo_santa.append(move_left(robo_santa[-1]))
        elif move == ">":
            if idx % 2 == 0:
                santa.append(move_right(santa[-1]))
            else:
                robo_santa.append(move_right(robo_santa[-1]))

    print(
        f"{len(set(santa + robo_santa))} houses receive at least one present"
    )


if __name__ == "__main__":
    part_1()
    part_2()