import os
import sys

inputfile = os.path.join(os.path.dirname(__file__), "input/day03_input")


def draw_path(inst):
    path = set()
    dists = {}
    cnt = 0
    ptr = (0, 0)
    for d, l in ((x[0], x[1:]) for x in inst.split(',')):
        for _ in range(int(l)):
            if d == 'D':
                ptr = (ptr[0], ptr[1] - 1)
            elif d == 'R':
                ptr = (ptr[0] + 1, ptr[1])
            elif d == 'U':
                ptr = (ptr[0], ptr[1] + 1)
            else:
                ptr = (ptr[0] - 1, ptr[1])
            cnt += 1
            if ptr not in dists or dists[ptr] > cnt:
                dists[ptr] = cnt
            path.add(ptr)
    return (path, dists)


def test_day3a():
    paths = []
    result = sys.maxsize

    with open(inputfile) as fp:
        for line in fp.readlines():
            paths.append(draw_path(line)[0])
    for x, y in paths[0].intersection(paths[1]):
        dist = abs(x) + abs(y)
        result = dist if dist < result else result
    assert result == 399


def test_day3b():
    paths = []
    distances = []
    result = sys.maxsize

    with open(inputfile) as fp:
        for line in fp.readlines():
            computed = draw_path(line)
            paths.append(computed[0])
            distances.append(computed[1])
    for point in paths[0].intersection(paths[1]):
        dist = distances[0][point] + distances[1][point]
        result = dist if dist < result else result
    assert result == 15678