const fs = require('fs/promises');

const createNode = (parent) => {
  return {
    parent,
    children: {},
    localSize: 0
  };
};

let answer = 0;

(async () => {
  const input = await fs.readFile("./input.txt", 'utf8');

  const lines = input.split("\n");

  const files = createNode();

  lines.reduce((node, line) => {
    const cd = line.match(/^\$ cd (.*)$/);
    if(cd) {
      if(cd[1] == "..") {
        return node.parent;
      }
      return node.children[cd[1]];
    }
    const dir = line.match(/^dir (.*)$/);
    if(dir) {
      node.children[dir[1]] = createNode(node);
    }
    const file = line.match(/^(\d+) .*$/);
    if(file) {
      node.localSize += parseFloat(file[1]);
    }

    return node;

  }, files);


  const fullSize = totalSmallerDirs(files);

  console.log("FULL SIZE: ", fullSize);

  console.log("SPACE NEEDED: ",  fullSize - 40000000);

  const [_, bestDeletionCandidate] = findBestDeletionCandidate(files, fullSize - 40000000);
  console.log("Best candidate for deletion is of size: ", bestDeletionCandidate);
})();

const totalSmallerDirs = (node) => {
  let totalSize =  node.localSize;

  totalSize += sum(Object.values(node.children).map(totalSmallerDirs));

  if(totalSize <= 100000) {
    answer += totalSize;
  }
  return totalSize;
}

const findBestDeletionCandidate = (node, spaceNeeded) => {
  let totalSize =  node.localSize;

  const childrenResults = Object.values(node.children).map(child => findBestDeletionCandidate(child, spaceNeeded));
  totalSize += sum(childrenResults.map(([x]) => x));
  const deletionCandidates = childrenResults.map(([_, y]) => y);
  deletionCandidates.push(totalSize);
  console.log("Deletion Candidates: ", deletionCandidates);

  return [totalSize, deletionCandidates.reduce((best, current) => current < best && current >= spaceNeeded ? current : best, Infinity)];
}
const sum = (arr) => arr.reduce((total, num) => total+num, 0);