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

import math

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


visited_pos = [[0, 0]]
head_pos = [0, 0]
tail_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):
    vx = h[0] - t[0]
    vy = h[1] - t[1]

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

    # print(f'head_tail_dist: {head_tail_dist}')
    if head_tail_dist > 1:
        # print('move tail!')

        nx = col_round(vx / vlen)
        ny = col_round(vy / vlen)
        print(f'x:{vx}/{nx} y: {vy}/{ny} len: {vlen}')

        t[0] += nx
        t[1] += ny
        print(f'head_pos: {h}')
        print(f'new tail_pos: {t}')
        v_list = [t[0], t[1]]
        if v_list not in visited_pos:
            visited_pos.append(v_list)
        # visited_pos.append(v_list)


head_moves = parse_file(file)
print(head_moves)

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

print(visited_pos)
print(len(visited_pos))