#!/usr/bin/env python3
# -*- coding: utf-8 -*-

part_sum = 0
matrix = []

# read matrix like day 3
input_file = open("input-ex41", "r")
for line in input_file:
    matrix.append(line.strip())
input_file.close()

zeilen = len(matrix)
spalten = len(matrix[0])

# Ausgabe Matrix und Startposition finden
for i in range(len(matrix)):
    if "S" in matrix[i]:
        zs = i
    print(matrix[i])
for j in range(len(matrix[zs])):
    if "S" in matrix[zs][j]:
        ss = j
start = [zs, ss]
print()
print(f"Startposition: {start}")


def come_from(z, s, pre):
    if pre[0]+1 == z:
        return "N"
    elif pre[0]-1 == z:
        return "S"
    elif pre[1]+1 == s:
        return "W"
    elif pre[1]-1 == s:
        return "E"
    else:
        return "A"


def where_to_go(z, s, pre):
    pipe = matrix[z][s]
    come = come_from(z, s, pre)
    if pipe == "S":
        return "Ende"
    if come == "N" and pipe == "|":
        return z+1, s
    elif come == "S" and pipe == "|":
        return z-1, s
    elif come == "E" and pipe == "-":
        return z, s-1
    elif come == "W" and pipe == "-":
        return z, s+1
    elif come == "N" and pipe == "L":
        return z, s+1
    elif come == "E" and pipe == "L":
        return z-1, s
    elif come == "W" and pipe == "7":
        return z+1, s
    elif come == "S" and pipe == "7":
        return z, s-1
    elif come == "N" and pipe == "J":
        return z, s-1
    elif come == "W" and pipe == "J":
        return z-1, s
    elif come == "E" and pipe == "F":
        return z+1, s
    elif come == "S" and pipe == "F":
        return z, s+1


previous = (start[0], start[1])
aktuell = [start[0], start[1]+1]
count = 1

while True:
    new = where_to_go(aktuell[0], aktuell[1], previous)
    print(aktuell, previous, new)
    matrix[aktuell[0]] = matrix[aktuell[0]][:aktuell[1]] + "X" + matrix[aktuell[0]][aktuell[1]+1:]
    if new == "Ende":
        break
    else:
        count += 1
        previous = (aktuell[0], aktuell[1])
        aktuell = [new[0], new[1]]

print("Counter:", count)
print("HalfCounter:", count/2)

for i in matrix:
    print(i)