#!/usr/bin/env python3

# https://adventofcode.com/2024/day/6

def get_lines(filename: str) -> list:
    with open(filename, "r") as file:
        return [line.strip() for line in file.readlines()]


def get_lab(lines: list) -> tuple:
    lab = []
    g_row = 0
    g_col = 0
    for row_num, row_content in enumerate(lines):
        row = []
        for col_num, cell_content in enumerate(row_content):
            if cell_content == "^":
                g_row, g_col = row_num, col_num
                row.append('.')
            else:
                row.append(cell_content)
        lab.append(row)
    return lab, g_row, g_col


def next_position(row: int, col: int, direction: int) -> tuple:
    deltas = [(-1, 0), (0, 1), (1, 0), (0, -1)]
    delta_row, delta_col = deltas[direction]
    new_row = row + delta_row
    new_col = col + delta_col
    return new_row, new_col


def pos_invalid(row, col, max_row, max_col) -> bool:
    if 0 <= row <= max_row and 0 <= col <= max_col:
        return False
    return True


def get_visits(lab: list, g_row: int, g_col: int) -> int:
    visits = {}
    g_dir = 0
    max_row = len(lab) - 1
    max_col = len(lab[0]) - 1
    while True:
        new_row, new_col = next_position(g_row, g_col, g_dir)
        visits[g_row, g_col] = True
        if pos_invalid(new_row, new_col, max_row, max_col):
            return len(visits)
        elif lab[new_row][new_col] == "#":
            g_dir = (g_dir + 1) % 4
        else:
            g_row = new_row
            g_col = new_col


def main():
    # lines = get_lines("sample-input.txt")
    lines = get_lines("input.txt")
    lab, g_row, g_col = get_lab(lines)
    visits = get_visits(lab, g_row, g_col)
    print("Part 1: Visited positions:", visits)


if __name__ == '__main__':
    main()