AoC 2020 D8 s2

import re
import math

class operation():
    def __init__(self, op, val):
        self.op = op
        self.val = val
        self.fixed = False

    def __str__(self):
        return '[{}, {}]'.format(self.op, self.val)

    def fix(self):
        print('fixing {}'.format(self.op))
        if self.op == 'jmp':
            self.op = 'nop'
        else:
            self.op = 'jmp'
        self.fixed = True

    def restore(self):
        print('restoring {}'.format(self.op))
        if self.op == 'jmp':
            self.op = 'nop'
        else:
            self.op = 'jmp'
        self.fixed = False


data = []
with open('input', 'r') as input_file:
    for line in input_file:
        line = line.strip()
        op = line[0:3]
        val = int(line[4:])
        d = operation(op, val)
        print(d)
        data.append(d)

nodes_visited = []
accumulator = 0
next_node = 0

stack = []
fixed = False

while next_node < len(data):
    if next_node in nodes_visited:
        next_node = nodes_visited.pop()
        while data[next_node].op == 'acc' or fixed:
            if data[next_node].fixed:
                data[next_node].restore()
                fixed = False
            next_node = nodes_visited.pop()
        data[next_node].fix()
        fixed = True
    nodes_visited.append(next_node)
    d = data[next_node]
    print(d.fixed)
    print('{}: {} {}'.format(next_node, d.op, d.val))
    if d.op == 'nop':
        next_node += 1
    elif d.op == 'acc':
        next_node += 1
    elif d.op == 'jmp':
        next_node += d.val

for n in nodes_visited:
    d = data[n]
    if d.op == 'acc':
        # print(d.val)
        accumulator += d.val


print('accumulator: {}'.format(accumulator))