const sample = await Deno.readTextFile("sample.txt");
const input = await Deno.readTextFile("input.txt");

const solvePart1 = (data: string): number =>
  data
    .split("\n")
    .filter(Boolean)
    .map((line) => line.split(" "))
    .map(([action, amount]): [string, number] => [
      action,
      parseInt(amount) || 0,
    ])
    .reduce(
      ([h, d], [action, amount]): [number, number] => {
        if (action === "forward") {
          return [h + amount, d];
        } else if (action === "down") {
          return [h, d + amount];
        } else if (action === "up") {
          return [h, d - amount];
        }
        throw new Error(`Unknown action ${action}`);
      },
      [0, 0] as [number, number]
    )
    .reduce((total, value) => total * value, 1);

console.log("Sample:", solvePart1(sample));
console.log("Input", solvePart1(input));

const solvePart2 = (data: string): number =>
  data
    .split("\n")
    .filter(Boolean)
    .map((line) => line.split(" "))
    .map(([action, amount]): [string, number] => [
      action,
      parseInt(amount) || 0,
    ])
    .reduce(
      ([h, d, a], [action, amount]): [number, number, number] => {
        if (action === "forward") {
          return [h + amount, d + amount * a, a];
        } else if (action === "down") {
          return [h, d, a + amount];
        } else if (action === "up") {
          return [h, d, a - amount];
        }
        throw new Error(`Unknown action ${action}`);
      },
      [0, 0, 0] as [number, number, number]
    )
    .filter((_, index) => index < 2)
    .reduce((total, value) => total * value, 1);

console.log("Sample:", solvePart2(sample));
console.log("Input", solvePart2(input));