import { readFileSync } from 'node:fs';

const input = readFileSync('input', 'utf-8');

function decToSnafu(num) {
  const maxP = Math.floor(Math.log(num * 2) / Math.log(5));

  return new Array(maxP + 1)
    .fill()
    .map((_, i) => i)
    .reverse()
    .reduce(([snafu, remainder], p) => {
      const sign = remainder < 0 ? -1 : 1;
      const mult = Math.floor(Math.abs(remainder) / Math.pow(5, p) + 0.5);

      const val = sign * Math.pow(5, p) * mult;
      const char = ['=', '-', '0', '1', '2'][sign * mult + 2];
      
      return [snafu + char, remainder - val];
    }, ['', num])[0];
}

function snafuToDec(snafu) {
  return snafu
    .split('')
    .reverse()
    .map((d, p) =>
      Math.pow(5, p) *
      (['=', '-', '0', '1', '2'].indexOf(d) - 2)
    )
    .reduce((total, num) => total + num);
}

const total = input
  .split('\n')
  .filter(line => !!line.trim())
  .map(line => snafuToDec(line))
  .reduce((total, value) => total + value);

const totalSnafu = decToSnafu(total);

console.log('The sum of all fuel requirements in SNAFU is:', totalSnafu);