#!/usr/bin/env python3

import sys
from copy import deepcopy
from termcolor import colored


def show(pipes, marked):
    for y in range(len(pipes)):
        for x in range(len(pipes[y])):
            if marked[y][x] == 'x': print(colored(pipes[y][x], 'blue'), end = '')
            elif marked[y][x] == 'I': print(colored(pipes[y][x], 'green'), end = '')
            else: print(colored(pipes[y][x], 'grey'), end = '')
        print('\n', end = '')


def count_vert(pipe, marked, x):
    p = ''
    t = 0
    for i in range(x):
        if marked[i] == 'x': p += pipe[i]
    p = p.replace('-', '')
    t += p.count('L7')
    p = p.replace('L7', '')
    t += p.count('FJ')
    p = p.replace('FJ', '')
    t += len(p)
    return t


def next_step(pos, pipes):
    y, x = pos
    tile = pipes[y][x]
    east = pipes[y][x+1] if x != len(pipes[y]) - 1 else 'x'
    west = pipes[y][x-1] if x != 0 else 'x'
    north = pipes[y-1][x] if y != 0 else 'x'
    south = pipes[y+1][x] if y != len(pipes) - 1 else 'x'
    if tile in ['-', 'L', 'F'] and east in ['-', '7', 'J']: return (y, x+1)
    elif tile in ['|', '7', 'F'] and south in ['|', 'J', 'L']: return (y+1, x)
    elif tile in ['|', 'J', 'L'] and north in ['|', '7', 'F']: return (y-1, x)
    elif tile in ['-', '7', 'J'] and west in ['-', 'L', 'F']: return (y, x-1)


def measure_loop(start, p):
    pipes = deepcopy(p)
    position = next_step(start,pipes)
    prev_position = position
    position = next_step(position,pipes)
    loop = 2
    while position != start:
        pipes[prev_position[0]][prev_position[1]] = 'x'
        prev_position = position
        position = next_step(position, pipes)
        loop += 1
    pipes[start[0]][start[1]] = 'x'
    return loop, pipes


if __name__ == '__main__':
    pipes = [list(line.strip('\n')) for line in open(sys.argv[1])]
    start = (0,0)
    for i,p in enumerate(pipes):
        if 'S' in p:
            start = (i, p.index('S'))
            pipes[i][p.index('S')] = '-'
            break
    length, marked_loop = measure_loop(start, pipes)

    # challenge 2
    res2 = 0
    for y in range(len(pipes)):
        for x in range(len(pipes[y])):
            if not marked_loop[y][x] == 'x':
                c = count_vert(pipes[y], marked_loop[y], x)
                if (c%2) == 1: 
                    res2 += 1
                    marked_loop[y][x] = 'I'

    show(pipes, marked_loop)

    # challenge 1
    res1 = str(int(length/2))
    print(f"challenge 1:\n{res1}\n")

    res2 = str(res2)
    print(f"challenge 2:\n{res2}\n")