#!/usr/bin/env python
# 2022 - Advent Of Code 9 part2

import math

# file = 'input_example.txt'
# file = 'input_example2.txt'
file = 'input.txt'


visited_pos = [[0, 0]]


def parse_file(input_file):
    moves = []
    with open(input_file, encoding="utf-8") as f:
        for line in f.readlines():
            d, u = line.strip().split(' ')
            moves.append((d, int(u)))
        return moves


def col_round(x):
    frac = x - int(x)
    if frac < 0.5:
        return math.floor(x)
    return math.ceil(x)


def move_tail(h, t, i):
    vx = h[0] - t[0]
    vy = h[1] - t[1]

    vlen = round(math.sqrt(vx * vx + vy * vy))
    head_tail_dist = vlen

    if head_tail_dist > 1:
        nx = col_round(vx / vlen)
        ny = col_round(vy / vlen)
        t[0] += nx
        t[1] += ny
        if i == 9:
            v_list = [t[0], t[1]]
            if v_list not in visited_pos:
                visited_pos.append(v_list)


def move_rope(r):
    for i in range(1, 10):
        move_tail(r[i-1], r[i], i)


head_moves = parse_file(file)
print(head_moves)
rope = [[0, 0] for _ in range(0, 10)]


for m in head_moves:
    if m[0] == 'R':
        print(f'right: {m[1]}')
        for _ in range(0, m[1]):
            rope[0][0] += 1
            move_rope(rope)
    if m[0] == 'L':
        print(f'left: {m[1]}')
        for _ in range(0, m[1]):
            rope[0][0] -= 1
            move_rope(rope)
    if m[0] == 'U':
        print(f'up: {m[1]}')
        for _ in range(0, m[1]):
            rope[0][1] += 1
            move_rope(rope)
    if m[0] == 'D':
        print(f'down: {m[1]}')
        for _ in range(0, m[1]):
            rope[0][1] -= 1
            move_rope(rope)

print(visited_pos)
print(len(visited_pos))