import { readFileSync } from 'node:fs';

let sampleMode = true;

const sampleArray1 = readFileSync('sample.txt').toString().split("\n");
const sampleArray2 = readFileSync('sample2.txt').toString().split("\n");
const inputArray = readFileSync('input.txt').toString().split("\n");

const usedArray1 = sampleMode ? sampleArray1 : inputArray;
const usedArray2 = sampleMode ? sampleArray2 : inputArray;

// Part One

console.time("part1");

// Parse the graph
const graph = new Map();

for (const element of usedArray1) {
  const [node, targets] = element.split(': ');
  graph.set(node, targets.split(' '));
}

// Count paths from 'you' to 'out' using memoization
const memo = new Map();

function countPaths(node) {
  if (node === 'out') return 1n;
  if (memo.has(node)) return memo.get(node);
  if (!graph.has(node)) return 0n;

  let total = 0n;
  for (const next of graph.get(node)) {
    total += countPaths(next);
  }

  memo.set(node, total);
  return total;
}

const part1 = countPaths('you');

console.timeEnd("part1");
console.log(part1.toString());


// Part Two

console.time("part2");

// Re-parse graph for part 2 (may use different sample file)
const graph2 = new Map();
for (const element of usedArray2) {
  const [node, targets] = element.split(': ');
  graph2.set(node, targets.split(' '));
}

// Count paths between any two nodes using memoization
const memo2 = new Map();

function countPathsBetween(from, to) {
  const key = `${from}->${to}`;
  if (memo2.has(key)) return memo2.get(key);

  if (from === to) return 1n;
  if (!graph2.has(from)) return 0n;

  let total = 0n;
  for (const next of graph2.get(from)) {
    total += countPathsBetween(next, to);
  }

  memo2.set(key, total);
  return total;
}

// Paths from svr to out visiting both dac and fft:
// Either: svr -> dac -> fft -> out
// Or:     svr -> fft -> dac -> out

const path1 = countPathsBetween('svr', 'dac') * countPathsBetween('dac', 'fft') * countPathsBetween('fft', 'out');
const path2 = countPathsBetween('svr', 'fft') * countPathsBetween('fft', 'dac') * countPathsBetween('dac', 'out');

const part2 = path1 + path2;

console.timeEnd("part2");
console.log(part2.toString());

// functions