import { readFileSync } from 'node:fs';

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

const cycles = input
  .split('\n')
  .filter(line => line)
  .flatMap((() => {
    let x = 1;
    return (line) => {
      if (line.startsWith('noop')) {
        return [x];
      }
      if (line.startsWith('addx')) {
        const add = parseInt(line.substring(5));
        if (isNaN(add)) {
          throw new Error('Invalid value for addx');
        }
        const result = [x, x];
        x += add;
        return result;
      }
    };
  })());

const sumOfSignalStrengths = [20, 60, 100, 140, 180, 220]
  .map(c => {
    const x = cycles[c - 1];
    const strength = c * x;
    return strength;
  })
  .reduce((total, strength) => total + strength);

console.log(
  `The sum of observed signal strengths is: ${sumOfSignalStrengths}`
);

const render = cycles
  .map((x, c) => {
    const scanPos = c % 40;
    return [x - 1, x, x + 1].some(pixelPos => pixelPos === scanPos);
  })
  .reduce((display, pixelVisible, c) => {
    const scanLine = Math.floor(c / 40);
    if (!display[scanLine]) {
      display.push([]);
    }
    display[scanLine].push(pixelVisible ? '#' : ' ');
    return display;
  }, [])
  .map(scanLine => scanLine.join(''))
  .join('\n');

console.log('Display output:');
console.log(render);