import fs from "node:fs";

const data = fs.readFileSync("./inputs/input", "utf8");

console.log(
  "part one:",
  data
    .split("\n")
    .slice(0, -1) // remove empty trailing newline
    .map(
      (v) => v.split(" ").filter((c) => c) // abusing js string nullity to remove empty members
    )
    .reduce(
      (result, current) => {
        // build two arrays, one of each column
        result[0].push(parseInt(current[0], 10));
        result[1].push(parseInt(current[1], 10));
        return result;
      },
      [[], []] as Array<Array<number>>
    )
    .map((list) => [...list].sort()) // hacky return-sorted-values step
    .reduce((result, current) => {
      // rotate arrays into pairs
      current.forEach((n, i) => {
        result[i] === undefined ? (result[i] = [n]) : result[i].push(n);
      });
      return result;
    }, [] as Array<Array<number>>)
    .reduce((result, current) => {
      // do the math
      return result + Math.abs(current[0] - current[1]);
    }, 0)
);

console.log(
  "part two:",
  Object.entries(
    data
      .split("\n")
      .slice(0, -1) // remove empty trailing newline
      .map(
        (v) => v.split(" ").filter((c) => c) // abusing js string nullity to remove empty members
      )
      .reduce((result, current) => {
        // build one object that contains the full set of frequencies
        result[current[0]] = !result[current[0]]
          ? [1, 0]
          : [result[current[0]][0] + 1, result[current[0]][1]];
        result[current[1]] = !result[current[1]]
          ? [0, 1]
          : [result[current[1]][0], result[current[1]][1] + 1];
        return result;
      }, [] as Array<Array<number>>)
  ).reduce((result, current) => {
    // and then just reduce down the object.
    return result + parseInt(current[0], 10) * current[1][0] * current[1][1];
  }, 0)
);